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292 Cards in this Set
- Front
- Back
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Diencephalon
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-btw cerebral cortex and brainstem
-medial to internal capsule -divided in the midline by the 3rd ventricle |
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dienchephalon subdivisions
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-epithalamus
-dorsal thalamus (aka thalamus) -ventral thalamus -subthalamus -hypothalamus |
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Epithalamus parts
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-habenuclear complex (limbic)
-pineal gland (serotonin) -posterior commissure (links nuclei) |
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Habenuclear complex
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-part of epithalamus
-involved in limbic pathway |
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pineal gland
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-part of epithalamus
-synthesizes seratonin and converts it to melatonin |
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posterior commissure
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-part of epithalamus
-links pretectal and other nuclei of the two sides -just below pineal gland |
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Dorsal thalamus (thalamus) parts
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-thalamic nuclei provides a strong link to the cerebral cortex
-external medullary lamina -internal medullary lamina |
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Ventral thalamus
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-reticular nucleus of thalamus
-ventral geniculate nucleus (LGNv) |
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Subthalamus
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-subthalamic n. (Luys) and zona incerta
-located btw the hypothalamus and the dorsal thalamus -involved with basal ganglia and extrapyramidal activity |
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Hypothalamus function
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-controlling center of ANS
-neurobehavioral functions and regulation of hormones released by the hypophysis |
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parts of the hypothalamus
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-hypothalamic nuclei
-infundibulum -hypophysis (pituitary gland) -hypohyseal portal system |
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thalamus blood supply
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-branches of PCA
-branches of ACA -branches of internal cartoid, ant communicating, and post comm |
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function of dorsal thalamus
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-relay of all sensory info to cortex (except smell)
-info about motor activities to cortex -integrates sensory info and projects to assoc cortex -relays emotional and affective info -part of "Papez circuit" --> limbic -alertness, arousal, sleep |
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Anterior nuclear group of thalamus
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-afferent input: mamillary body
-projects to: cingulate gyrus -limbic functions |
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Lateral-ventral tier of thalamus
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-VA, VL, VPL, VPM, LGN, MGN
-motor, somatic sensation, vision, audition |
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ventral anterior thalamus
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-afferent: globus pallidus
-projects to: premotor cortex (area 6) -motor functions |
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ventral lateral thalamus
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-afferent: dentate nucleus of cerebellum
-projects to: motor and premotor cortex (areas 4 and 6) -motor functions |
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VPL of thalamus
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-afferent: dorsal column- med lemniscus and spinothalamic
-projects to: somatosensory cortex (areas 3, 1, 2) -somatic sensation of contralat body |
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VPM of thalamus
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-afferent: sensory nuclei of trigeminal nerve
-projects to: somatosensory cortex (areas 3, 1, 2) -somatic sensation of contralat face |
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LGN of thalamus
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-afferent: retinal ganglion cells
-projects to: primary visual cortex (area 17) -vision |
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MGN of thalamus
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-afferent: inferior colliculus
-projects to: primary auditory complex (areas 41, 42) -audition |
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Lateral-dorsal tier of thalamus
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-lateral dorsal, lateral posterior, pulvinar
-emotional expression and sensory integration |
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lateral dorsal nucleus of thalamus
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-afferent: cingulate gyrus
-projects to: cingulate gyrus -emotional expression |
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lateral posterior nucleus of thalamus
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-afferent: parietal cortex
-projects to: parietal cortex -sensory integration |
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pulvinar nucleus of thalamus
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-afferent: superior colliculus, POT lobes
-projects to: POT lobes -sensory info integration |
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medial dorsal nucleus of thalamus
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-afferent: amygdaloid nuclear coplex, olfactory, hypothalamus
-projects to: prefrontal cortex -limbic functions |
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diffuse-projection nuclei of thalamus
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-midline nuclei
-intralaminar nuclei (CM, CL, PF) -reticular nucleus |
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Midline nuclei of thalamus
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-afferent: reticular formation and hypothalamus
-projects to: basal forebrain -limbic functions |
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Intralaminar nuclei of thalamus
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-CM, CL, PF (surrounded by internal medullary lamina)
-afferent: reticular formation, spinothalamic tract, globus pallidus, cortical areas -projects to: basal ganglia and cortex -role in pain, sleep, wakefulness |
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reticular nucleus of thalamus
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-afferent: cortex, thalamus, brainstem RF
-projects to: thalamic nuclei -modulates thalamic activity |
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thalamic syndrome
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-usually damage to VPL
-initially, transitory contralat hemianalgesia -then painful sensations with noxious stimuli -later, pain from pressure, touch, vibration -later, dysesthesia -threshold for pain, temp, tactile is raised on ipsilat side (once threshold is reached, pain has strong emotional overtone) |
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functional characteristics of non-specific syndrome
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-activated by repepitive, low-freq stimulation
-cortical recruitment response that waxes and wanes -control the level of excitability of neurons over wide areas of cortex |
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anatomical organization of cortex
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-derived from telencephalon
-subdivided into archicortex (hippocampus/dentate gyrus), paleocortex (olfactory), neocortex (large) |
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Frontal lobe
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-precentral gyrus
-superior and middle frontal gyri -inferior frontal gyrus (orbital, triangular, opercular) -prefrontal cortex -orbital gyri -gyrus rectus |
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Parietal lobe
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-postcentral gyrus
-sup parietal lobule -inf parietal lobule (supramarginal and angular gyri) -precuneus -paracentral lobule |
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Temporal lobe
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-sup, middle, inf temporal gyri
-fusiform (occitotemporal) gyrus -parahippocampal gyrus -hippocampus |
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occipital lobe
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-lateral occipital gyri
-cuneus and lingual gyri |
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cortex blood supply
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-ACA, MCA, PCA
-ant and post comm -all from circle of Willis |
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major venous drainage of cortex
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-superior sagittal sinus, inf sagittal, striaght sinus, transverse sinus, sigmoid sinus
-drain into internal jugular |
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Archicortex structure
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-hippocampus and dentate gyrus
-3 layers |
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Neocortex structure
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-6 layers
-I: molecular layer (cells sparse) -II: ext granular layer -III: ext pyramidal layer -IV: int granular layer -V: int pyramidal (large cells) -VI: multiform layer (mix of cell types) |
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axons in cerebral cortex
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myelinated axons run in horizontal bands and vertical bundles
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functional units of cortex: columns and modules
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-each column extends through the 6 layers
-columns of cortical neurons are interconnected within the same hemisphere and btw the two hemispheres -functional columns form modules in various cortical areas (ie visual) |
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Brodmann's 3, 1, 2
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-postcentral gyrus
-primary somatosensory |
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Brodmann's 4
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-precentral gyrus
-primary motor |
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Brodmann's 17
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-cuneus and lingual gyrus
-primary visual |
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Brodmann's 41, 42
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-transverse gyri of Heschl
-primary auditory |
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Brodmann's 44, 45
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-Broca's area of speech
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general function of cortex
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-perception of somatic, visual, auditory, olfactory sensation
-planning and executing voluntary movements -emotions and behavior -mental functioning -memory |
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lesion of primary motor cortex
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contralateral paralysis
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lesion of primary sensory cortex
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contralat loss of somatic sensation
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lesion of primary visual cortex
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contralat hemianopia
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lesion of supramarginal gyrus (area 40)
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astereognosis (can see and feel object but can't recognize meaning)
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lesion of angular gyrus (area 39)
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-dominant side alexia and agraphia
-nondominant: spatial distorion and contralat neglect (only draw one side of clock) |
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lesion of Broca's (area 44, 45)
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-dom: motor aphasia
-nondom: difficulty expressing emotional aspect of language |
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Auditory loss
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-need BI-lateral loss of areas 41 and 42 for complete hearing loss
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dominant side Wernicke's
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sensory aphasia or receptive aphasia
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non-dominant side Wernicke's
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difficulty understanding emotional language
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hypothalamus is functionally related to which systems:
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-ANS
-endocrine -limbic |
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hypothalamus location
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-makes up walls and floor of third ventricle
-separate from thalamus by hypothalamic sulcus -optic chiasm and lamina terminalis anteriorly -mammillary bodies posteriorly |
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median eminence
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-ant part of infundibulum
-where hypothalamic neurons release factors carried by the portal vessels to the anterior pituitary |
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tuber cinereum (gray protberance)
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-bulge located btw the optic chiasm and mammillary bodies
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hypothal zones
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-lateral, medial, periventricular
-medial and lateral zones separated by the fornix and mammilothalamic tract |
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lateral zone of the hypothal
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-loose neuronal cell groups
-transversed by the fibers of the medial forebrain bundle -lateral preoptic nucleus, lateral hypothalamic area, lateral tuberal nucleus (tuberomammillary) |
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lateral preoptic nucleus
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-part of lateral zone of hypothal
-anterior portion -telecephalic developmentally -role in nonREM sleep |
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lateral hypothalamic area
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-part of lateral zone of hypothal
-induces eating when stimulated (ablation causes anorexia and starvation) -median forebrain bundle runs through it (lots of functions) |
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lateral tuberal (tuberomammillary) nucleus
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-ventrolateral surface of lateral zone of hypothalamus
-large neurons that release histamine as a NT to forebrain -globally projecting -attention and arousal -inhibited during sleep |
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medial zone of hypothalamus
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-lots of cells- compact
-preoptic, supraoptic (anterior), tuberal (middle), and mammillary (posterior) regions PSTM |
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preoptic area
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-part of medial zone of hypothal
-telencephalic origin -contains medial preoptic nucleus (regulates gonadotropin secretion from adenohypophysis) -INAH1-4 including sexually dimorphic INAH3 reg by testosterone |
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supraoptic area
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-medial zone of hypothalamus
-contains suprachiasmatic, anterior hypothalamic, paraventricular and supraoptic nuclei |
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suprachiasmatic nucleus
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-immediately dorsal to optic chiasm
-receives direct input from retina -role in circadian rhythms |
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anterior hypothalamic nucleus
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-btw suprachiasmatic and paraventricular nuclei
-WARM sensing -stimulatory drive of PNS |
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bilateral lesion of anterior hypothalamic area results in...
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-hyperthermia
(loss of warm-sensing neurons) |
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paraventricular nucleus
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-heterogeneous with difference output signals
-neurons that release AVP- water conservation -oxytocin- milk let down and release -CRH- stress responsive -other neurons project to interomediolateral cell column to excite symp pregang neurons |
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supraoptic nucleus
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-contains neurons that synthesize AVP and oxytocin
-project to neurohypophysis via supraopticohypophyseal tract) where they release into general circulation |
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tuberal area
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-part of medial zone of hypothalamus
-contains dorsomedial, ventromedial, and arcuate nuclei |
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dorsomedial hypothalamic nucleus functions
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-stim= aggression and savage behavior
-also functions in bp regulation |
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ventromedial nucleus
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-stim= urge to eat
-satiety center |
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bilateral lesion of ventromedial nucleus
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-hyperphagia
-savage behavior |
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arcuate nucleus
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-in tuber cinereum
-controls release of ant pituitary hormones via projections to median eminence and portal vasculature -prominent role in feeding behavior |
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mammillary area of hypothalamus
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-consists of posterior nucleus and mammillary nucleus
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posterior hypothalamic nucleus
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-part of mammillary area of hypothalamus
-COLD sensing neurons |
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bilateral lesion of posterior nucleus of hypothalamus
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-complete inability to thermoregulate = poikilothermia
-axons from anterior part (warm sensing) pass through here and are also destoyed |
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mammillary nucleus
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-learning and memory, part of limbic system
-input from hippocampus via fornix -project to ant nucleus of thalamus via mammillothalamic tract -damage=memory disturbance |
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periventricular zone of hypothalamus
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-contains paraventricular nucleus
-layer of cells lining the wall of the third ventricle at supraoptic and tuberal levels |
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hypothalamus connections with what portions of the neuraxis?
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-basal forebrain regions (limbic)
-brainstem regions (ANS) |
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fornix
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-tract to deliver axonal projections from hippocampus to mammillary bodies
-divides lateral and medial hypothalamus |
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mammilothalamic tract
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-from mammillary bodies to ant nucleus of the thalamus
-key part of Papez circuit |
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stria terminalis
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-amygdaloid complex to medial zones of hypothalamus
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medial forebrain bundle
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-most complex fiber pathway in CNS
-at least 50 distinct parts -extends through entire lateral hypothalamic zone -interconnects reiongs from septal nuclei to brainstem |
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supraopticohypophyseal tract
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-from supraoptic and PVN to neurohypophysis
-oxytocin or AVP to post pituitary |
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tuberoinfundibular tract
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-arcuate nucleus to hypophyseal portal system at the median eminence of the infundibulum
-release into portal vasculature |
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hypothalamospinal tract
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-descending axons that drive spinal cord pregang neurons of SNS and PNS
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hypothalamospinal tract pathway
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stress-related input (amygdala, prefrontal cortex) --> PVN --> brainstem --> spinal cord --> pregang symp neurons
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3 fundamental capacities of the hypothalamus
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-access sensory info from entire body
-establishes a biological set point for temp, blood osmolarity, glucose, Na, hormone levels -when a deviation from set point is detected, it responds by adjusting the autonomic, endocrine, and behavioral responses to restore homeostasis |
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major regulatory functions of the hypothalamus
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-body temp
-feeding and energy metabolism -emergency response to stress -bp and electrolyte composition -reproduction functions |
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heat dissipation
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-anterior hypothal nucleus senses heat
-trigger dissipation via sweating, cutaneous vascular dilation, accel respiration by activation of PNS |
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disease-associated fever
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-inflammatory cytokines and pyrogens act on anterior hypothal
-alter set points |
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cold sensitivity
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-neurons in posterior hypothalamus
-trigger heat conservation via sympathetic outflow and activation of appropriate endocrine responses to alter metabolic rate |
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stress responsiveness in the hypothalamus
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-afferent regulatory control by prefrontal cortex, limbic forebrain, brainstem
-CRH synthesized and released -ant pituitary sim adrenal to release cortisol --> liberates energy sources |
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arcuate nucleus and feeding
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-set 1 of neurons: AgRP and NPY --> signal increased feeding and decrease in metabolism
-set 2 of neurons: POMC and CART --> signal decreased feeding and increased metabolism |
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brainstem satiety center
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-nucleus solitary tract
-integrates signals from arcuate nucleus about feeding |
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gherlin
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-released from stomach just prior to a meal
-acts on AgRP/NPY -increase food intake |
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PPY
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-released from GI tract immediately following a meal
-acts on POMC/CART -decreases food intake |
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leptin
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-released from fat cells
-decreases food intake |
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craniopharyngioma
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-tumor from Rathke's pouch
-pressure on optic chiasm --> bitemporal hemianopsia (tunnel vision) -pressure on hypothal: adiposity, diabetes insipidus, temp reg disturbances, somnolence |
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hypothal disturbances of memory
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-posterior hypothal lesions involving mammillary complex
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Klein-Levin syndrome
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-hypothal lesion in adolescent males
-bulemia, hypersomnolence, hypersexuality -may result in decreased dopaminergic tone |
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41 yo man with MS. Acute onset of hypothermia; dies of sudden cardiac arrest. Where's the lesion?
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-bilateral anterior and posterior nuclei of hypothal
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21 yo man with MS. Begins drinking and peeing lots. No hx of diabetes insipidus. Where is the lesion?
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-over supraoptic nucleus
-can't produce AVP --> can't absorb water |
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lesion of lateral hypothalamus
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-causes weight loss
(normall, lateral hypothal makes you grow laterally bc it stimluates appetite) |
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lesion of medial hypothalamus
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-causes weight gain
(normally inhibits appetite) |
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Prader-Willi syndrome
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-deletion of chrom 15q
-chronic feeling of hunger/ insatiable appetite |
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ANS controls...
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-pupillary control
-cardiovascular -GI -genitourinary -point and shoot |
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ANS spinal cord lesions...
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-weakness
-sensory loss -GI: constipation, retention -GU: urgency, incontinence -sex: vaginal dryness, pain, ED, anorgasmia |
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autonomic bowel dysfunction
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-constipation and retention
-can cause disrupted breathing -impaction |
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autonomic urinary control
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-PNS: constricts bladder wall
-SNS: constricts urinary sphincter |
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normal urinary continence
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-inhibit parasymp (relax bladder wall)
-stimulate symps (constrict sphincter) |
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normal urination
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-stim parasymps (constrict bladder wall)
-inhibit symps (relax sphincter) |
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Incontinence may arise from...
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-hyperactive bladder or underactive sphincter
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how do you treat a hyperactive bladder
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anti-cholinergics to relax bladder wall
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how do you treat an overactive sphincter
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anti-adrenerics to relax sphincter or intermittent self-catheterization
(if you give anti-cholinergics, worse) |
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ANS and pupillary control
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-symp: dilate pupil
-parasymp: constrict pupil |
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Aniscoria (R eye dilated, L constricted) where could lesion be
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-R parasymp
or -L symp use ambient light-darkness to differentiate |
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how do you differentiate btw opp eye symp vs parasymp lesions?
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-take pt from light to darkness, see if one eye dilates more than the other
-if one fails to dilate properly, lesion is symp ipsilateral |
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clinical triad of Horner's
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-small pupil
-ptosis -decreased sweating (sympathetic chain injury) |
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where could a lesion causing Horner's be?
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-hypothalamus
-brainstem -thoracic spinal cord -superior cerv gang -carotid plexus |
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How many neurons are involved in the symp pathway to the eye?
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-tectospinal spinal tract
-pregang fibers (sup cerv gang) -postgang fibers |
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internal carotid artery dissection
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-causes partial Horner's
-blood clot in wall of ICA -arterial wall expands, compressing carotid plexus -small pupil and ptosis, but normal sweating because external carotid plexus is unaffected |
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why is forehead sweating still intact after an internal carotid artery dissection?
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the sympathetics to the sweat glands run along the EXTERNAL carotid artery
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what is the main feature of Kluver Bucy syndrome?
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-increased oral activities
-placidity -hypersexuality |
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limbic system
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-site where cortical info and hypothalamic impulses are integrated
-homeostasis (autonomic reg), olfaction, memory, emotion (HOME) |
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Papez's circuit
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cingulate --> hippocampus --> fornix --> mammillary bodies --> ant thalamus --> cingulate
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McLean expansion of Papez's circuit
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-includes association cortex, amygdala, hypothalamus, prefrontal cortex
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what justifies the concept of the limbic system?
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-common physiologic and neurochemical properties
-intricate anatomic connections -common behavioral associations |
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common physiologica/neurochemical properties in limbic system
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-herpes virus has special affinity for these regions
-susceptible to kindling and develop of seizure foci -high density cholinergic innervation and opiate receptors |
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fornix tract cx
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hippocampus to mammillary and septal nuclei
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stria terminalis tract cx
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amygdala to septum and hypothalamus
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ventral amygdalofugal pathway cx
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amygdala to hypothalamus and brainstem nuclei
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mammillothalamic tract cx
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mammillary bodies to ant thalamus
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medial forebrain bundle cx
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hypothalamic nuclei to amygdala and brainstem nuclei
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perforant path cx
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entorhinal cortex to dentate (hippocampus)
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cingulum tract cx
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cingulate gyrus to parahippocampal gyrus; hippocampus with midbrain
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outer cortical structures
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-orbital frontal lobe
-cingulate -entorhinal cortex |
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cingulate cortex
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-rostral: emotions and memory
-caudal: visual spatial and memory |
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orbital frontal lobe
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-personality
-behavioral control -self awareness |
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temporal lobe
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-includes hippocampus, parahippocampus, entorhinal cortex
-memory |
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inner cortical structures
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-anterior thalamic nucleus
-mammillary bodies -hypothalamus -septal nucleus |
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hypothalamus
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-pleasure center, autonomic, endocrine integration
-neurons project to pituitary, reg ACTH and TSH secretion -maternal behavior, bp, feeding, temp regulation, immune response |
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amygdala
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-preservation of SELF behavior
-emotion, social behavior, aggression and defense, sexual behavior, affect regulation |
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septum function
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-preservation of SPECIES
-sexual behavior -emotionality |
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Kluver-Bucy syndrome cause
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-bilateral large temporal lobe lesions
-include amygdala, hippocampus, uncus -from trauma, herpes, Pick's, Alz's, infarction, focal status epilepticus -increased oral activity, bulemia, hypermetamorphosis, placidity, visual agnosia, hypersexual |
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Kluver-Bucy syndrome signs
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-psychic blindness (can't detect meaning of objects based on visual criteria)
-oral -hypermetamorphosis (notice and react to every stimulus) -placidity/ tameness (no rxn to fear or anger) -hypersexual |
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Geschwind syndrome anatomy
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-sensory limbic hyperconnection
-strengthening synpatic cx -develops in pts with hx of epilepsy |
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Geschwind syndrome symptoms
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-increased philosophic concern
-usually hyposexual -hypergraphia -viscosity (hard to break off conversations) -overly emotionalized world |
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most pleasurable regions in brain
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-lateral hypothalamus
-medial forebrain bundle |
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addictive drugs
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-mesolimbic dopamine system
-heroin increases neuronal firing rate of dopamine cells -cocaine inhibits reuptake of dopamine |
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brain pleasure regions
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-lateral septal region
-portions of amygdala -parts of hippocampus (laterla, medial forebrain bundle, nuc accumbens) -ant cingulate cortex |
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lesions to ventromedial nuc of hypothalamus
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-produce pain, rage, or strong aversive rxns and long lasting hyperremotionality
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amygdala lesions
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-modulation and experience of emotional rxns
-lesions: tameness or reduced emotionability |
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amygdala in humans
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-thought to play a major role in the integration of emotions and memory
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septal lesions
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-changes in sexual behavior
-rage-like attacks and increased irritability |
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hippocampus lesions
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-amnestic states
-declarative memory problems |
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amnestic states can result form lesions in the?
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hippocampus, dorsal medial nuc of thalamus, mammillary nuclei
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declarative memory
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-episodic= personal events
-semantic= facts known, not actively remembered |
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hippocampal formation
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-hippocampus, dentate gyrus, subiculum
-neocortex has extensive cx with hippocampus and amygdala -efferent=fornix -afferent=perforant path |
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hippocampus function
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-formation of episodic memories in humans
-dedicated to spatial mapping in animals |
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Wernicke Karsakof's syndrome
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-thiamine deficiency in alcoholics
-confusion, disorientation, oculomotor dysfunction, ataxia -chronic anterorgrade and temporally-graded retrograde amnesia |
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lesions in Wernicke Karsakoff's
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mammillary bodies and thalamus
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lesions of cingulate gyrus
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-emotional blunting
-dec motivation -lowered threshold for fear or startle -decreased pain -OCD |
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akinetic mutism
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-associated with bilateral ant cingulate cortex lesion
-can do anything, but absolutely no motivation to do so |
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Gilles de Tourette syndrome
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-abnormal ant cingulate
-complex coordinated movement patterns are evoked by electrical stim of AC |
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bilateral cingulate and orbitofrontal lesions
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reduced judgement and inability to interpret social cues
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intentional lesions of AC
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-can relieve obsessive compulsive behaviors
-helpful for some chronic pain patients -associated with sociopathy-- blunted autonomic repsonse to emotional stimuli |
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disconnecting AC from thalamus
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-reduced GTS syndromes
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anterior cingulate function
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-integration of thought, motivation, and emotion with movement
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lesions in AC can cause...
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-excessive amplification of emotional signals
-amplification of motor behavior -excessive filtering of emotions and motor behavior |
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orbital frontal lobe syndrome
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-childlike
-disinhibited, tactless, boastful inattentive, eat gluttonously |
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frontal/convexity or dorsolateral frontal lobe syndrome
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-apathetic
-slow -little initiative or spontaneity -vacancy of expression |
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medial frontal syndrome
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-akinetic mutism
-inert -speechless -intact sleep wake cycle -loss of drive to move/speak |
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laterality
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cerebral hemisphere that is specialized for a group or class of cognitive functions
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dominance
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-cerebral hemisphere that is specialized for language
-typically L |
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crossed dominance
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-condition of R hemisperic dominance for language
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Crowding
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-condition that occurs after early L hemisphere damage where development of language shift to the R hemisphere
-at expense of development of cognitive capacities typically assoc with R hemisphere (ie visual-spatial skills) |
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pathological left-handedness
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-condition of L handedness that has occurred bc of early injury to L hemisphere that causes a shift in natural handedness pattern
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Approx what percent of the entire population is R-handed; and what percent of R handers are L hemisphere dominant for language?
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90%
95% |
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Broca's aphasia is characterized by what?
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-non fluent speech
-poor repetition -relatively spared comprehension |
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measuring handedness
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-inventories (range of activities)
-hand used for writing -90% R dextrals, 10% L sinistrals |
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Intracarotid amobarbital test (IAT) (Wada test)
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-measures dominance
-catheter: ICA --> barbiture is injected into one hemisphere --> anesthetized --> tests of language -used only when you have brain function abnormalities |
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fMRI for measuring dominance
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-based on changes in the ratio of oxyHb to deoxyHb to the brain from moment to moment
-noninvasive -can be performed in healthy individuals |
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Atypical dominance patterns are more common in what handed people?
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-left handers
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early brain damage increases what?
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-incidence of atypical dominance
-particularly in those with left or mixed handedness |
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Significantly more patients with epilepsy show what dominance pattern?
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-symmetric and R hemisphere dominance patterns relative to healthy normals
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left-handedness and cerebral dominance patterns
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-atypical speech representation is more frequent
-negative familial sinistrality have more typical language representation |
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injury to L hemisphere before age 1
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-development of language spared
-often generalized cognitive deficit |
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injury to L hemisphere btw age 1&5
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-language spared (shifts to non-dominant hemisphere)
-possible visual-spatial deficit (crowding) |
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injury to L hemisphere after age 5
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-language no longer spared
-circumscribed language deficits emerge |
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what injury will cause selective shift of language zones?
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-selective injury to anterior or posterior speech zones
-causes a shift of the functions associated with that zone only |
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what injury will cause a complete shift in language function?
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-injury to the core or central speech zones
-known as crossed-dominance |
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what hemisphere is usually dominant for language and how is this changed?
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-left hemisphere dominance for language is the rule
-changed by early brain injury and familial left handedness |
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lateralization of the hemispheres
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-relative and complementary
-probably increases with age before puberty, decreases with age thereafter |
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disorders of speech
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-involve malfunction of the muslces of speech articulation
-include: mutism, aphonia, aphemia, dysarthria |
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mutism
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-absence of speech: organic or elective
-may be psychogenic -extensive bifrontal brain damage of bilateral lesions in supp motor area |
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aphonia
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-loss of capacity to produce vocal sound
-due to injury in PNS that enervates muscles of the vocals cords |
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aphemia
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-loss of capacity to produce words, can produce sounds
-disconnection syndrom due to a whitematter lesion beneath Broca's that serves as final output pathway for speech production |
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disorders of language
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-aphasias
-acquired disturbances of linguistic functions due to injury of the CNS |
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all aphasias be classified by the integrity of what?
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-fluency
-comprehension -repetition |
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how is fluency evaluated
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-phrase length
-degree of apparent effort in speech production -prosody (preservation of melodic elements of speech) |
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nonfluent speech
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-few than 3 words per utterance
-laborious in production -monotonic in delivery |
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core language zones
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-Wernicke's area (sup temporal lobe)
-Broca's area (post and inf frontal lobe) -arcuate fasciculus (whitematter connection) |
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Global aphasias typically occur when?
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-when the functions of both ant and post aspects of the core language zones are impaired
-no fluency, comprehension or repetition |
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Transcortical aphasias
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-repetition of speech is preserved
-loss of fluency (motor) and comprehension (sensory) |
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when do transcortical motor aphasias occur
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-lesions to the premotor region
or -SMA lesions |
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transcortical sensory aphasias occur when?
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-with lesions of the angular gyrus
or -lesions to poster and inferior temporal lobe |
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isolation aphasia
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-lesions of both transcortical motor and sensory aphasias are present
-effectively isolates the core speech zones from the remainder of the hemisphere |
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Broca's aphasia
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-nonfluent
-profound impairment in speech articulation -repetition is impaired bc of articulation impairment |
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Wernicke's aphasia
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-fluent aphasia
-profound impairment in speech sound recognition and language comprehension -repetition is impaired bc of speech comprehension difficulties |
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Conduction aphasia
|
-fluent aphasia
-associated with profound impairment in repetition -relatively preserved comprehension -problem with speech sound storage area or arcuate fasciculus |
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transcortical sensory aphasia
|
-fluent aphasia
-language comprehension deficits at the word level -repetition is preserved |
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4 levels of consciousness
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-awake (arousable and maintained without stim)
-sleepy (arousable but falls back asleep) -stupor (arousable but unable to maintain wakefulness) -coma (unarousable with any stim) |
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diminished level of consciousness indicates what?
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-a lesion in reticular activating system
-metabolic or structural coma |
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metabolic coma
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-affects bilateral cerebral hemisphere
-problem getting nutrients to brain (low glucose, O2, medication overdose) |
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structural coma
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-lesion in brainstem or bilateral thalami or bilateral hemispheres
-need both sides |
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Where is a lesion producing non-fluent aphasia?
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-inferior frontal lobe in dominant hemisphere (Broca's area)
|
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Where is a lesion producing fluent aphasia?
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-superior temporal lobe in dominant hemisphere (Wernicke's Area)
|
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What is conduction aphasia characterized by?
|
-impaired repetition
-normal fluency and comprehension -lesion in arcuate fasciculus |
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What is global aphasia characterized by?
|
-impaired fluency, comprehension, and repetition
-pt completely mute, doesn't follow commands, looks blank when spoken to ie complete MCA occlusion |
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L hemisphere contributes attention...
|
to the R
|
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R hemisphere contributes attention...
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bilaterally, but L>R
|
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R hemisphere lesion causes neglect on which side?
|
severe neglect of the L
|
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L hemisphere lesion causes attention...
|
-mild neglect of the R
|
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If you want to look to the L, which frontal eye field sends signal
|
R frontal eye field
|
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R hemiparesis and eyes look to the L, where is the lesion?
|
left frontal lobe (L frontal eye field and L motor cortex)
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primary sensation
|
-from postcentral gyrus (primary somatosensory cortex)
-pin prick -hot/cold -vibration |
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cortical sensation
|
-Where or what is it?
-need coordination of senses and multiple brain areas |
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agraphesthesia
|
can't determine numbers written on palm
|
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astereognosis
|
can't determine shape of object placed in hand
|
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Agraphesthesia and astereognosis in an extremity both localize where?
|
to the contralateral parietal lobe
|
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lesions closer to the optic chiasm are what?
|
usually more incongruous
|
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posterior occipital lobe mediates vision where?
|
-in the central aspect of the visual fields
|
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anterior occipital lobe mediates vision where?
|
-in the peripheral aspect of the visual fields
|
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what artery supplies the tip of the occipital lobe?
|
-mainly the PCA
-can receive collateral flow from the MCW |
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localization of cognition and emotion in hypothalamus
|
-primitive emotional responses
-fight, flight, feed, mate |
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localization of cognition and emotion in frontal cortex
|
-highest cognitive function
-control over emotions -judgment, decision making, mortality, compassion, responsibility -reciprocal neg feedback with hypothalamus |
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localization of cognition and emotion in prefrontal cortex
|
-production and appreciation of art
-beauty as an emotion |
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localization of cognition and emotion in amygdala
|
-storage of emotional memories
|
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localization of cognition and emotion in hippocampus
|
-episodic memory
|
|
|
synaptic plasticity
|
-the ability of synpases to change their strengths in response to experience and a cellular model of learning and memory
-Ca2+ has different responses to increase AMPA threshold or decrease AMPA receptors |
|
|
glutamatergic receptors in learning and memory
|
-AMPA: basal synaptic transmission
-NMDA receptors: binds Glu and allows Ca2+ to enter and act on AMPA signalers; blocked by Mg2+ (activated when cells are depolar) |
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studying learning and memory at behavioral level
|
-water maze
-fear conditioning |
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water maze
|
-hippocampal-dependent task
-spatial memory |
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cued fear conditioning
|
-amygdala-dep task
-put in a new environment but same stim--> freeze |
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contextual fear conditioning
|
-hippocampus AND amygdala-dep
-put in conditioned environment and they automatically freeze even without stim |
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Long-term potentiation (LTP)
|
-enhancing synaptic strength
-induction via learning -maintenance |
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Long-term depression (LTD)
|
-despressing synaptic strength
|
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CaMKII
|
-enzyme that phosphorylates targets
-important for LTP -stim by Ca2+ -causes more AMPA receptors so response comes at a lower stimulus |
|
|
Calcineurin
|
-enzyme that dephosphorylates targets
-important for LTD -stim by Ca2+ -decreases AMPA receptors so more of a stimulus is needed |
|
|
neurogranin
|
-controls synaptic plasticity balance
-regulates CaMKII availability -increased NG means inc CaMKII |
|
|
aging and learning/memory
|
-synaptic plasticity imbalance
-changes in levels of CaMKII, calcineurin, NG -LTD begins to dominate over LTP (inc calcineurin, dec NG, dec CaMKII) |
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TBI
|
external physical force causing impairment
|
|
|
gen categories of brain injury
|
-congenital (pre-birth or during birth process)
-acquired (after birth process) |
|
|
types of TBI
|
-blunt/closed
-penetrating/open (skull is fractured) |
|
|
primary TBIs
|
-skull fx
-contusion -hematoma (subdural or epidural) -intracerebral hemorrhage -diffuse axonal injury -coup-contra-coup |
|
|
coup-contra coup
|
-contusion at site of impact
-brain slide back -contusion at opposite side |
|
|
diffuse axonal injury
|
-rotational forces cause stretching and snapping of axons
-unrepairable -ie shaken baby |
|
|
secondary TBI
|
-evolves over a period of hours/days after inital trauma
-edema -increased intracranial pressure -intracranial infection -epilepsy -hypoxemia |
|
|
mild TBI
|
-13-15 Glasgow coma scale
-20-60min LOC -<24hr post-traumatic amnesia |
|
|
moderate TBI
|
-9-12 Glasgow coma scale
-1-24hrs LOC -1-7 days post-traumatic amnesia |
|
|
severe TBI
|
-3-8 Glasgow coma scale
->24hr LOC ->7 days post-traumatic amnesia |
|
|
Glasgow coma scale
|
-best eye, motor, verbal response that a clinician can elicit
-can't factor in how much stimulus was required -15=best, 3=worst |
|
|
high risk groups for TBI
|
-males 15-24 yo
-substance abusers -infants (64% d/t child abuse) -elderly (fall risk) -those with prior brain injury |
|
|
TBI can result in difficulties with...
|
-executive control functions (memory, money and time management, judgment, concentration, planning, confusion)
-psychosocial and emotional fx -physical abilities |
|
|
treatment of TBI
|
-acute: stabilize pt
-sub-acute: rehab pt and return to community -chronic: rehab and longterm care |
|
|
post-TBI evaluation
|
-physical exam and hx and neurological testing
-neurophyschosocial testing to assess intellectual deficits, emotional, behavioral problems -CT/MRI to look for structure changes -PET, fMRI, SPECT to look for fx changes |
|
|
consequences of CNS injury at cellular injury
|
-neuronal injury
-axonal injury -oligodendrocyte injury/demyelination -astrocyte activation --> scarring -microglia activation |
|
|
injury to cell body
|
no regeneration of neuron
|
|
|
regenerating axons in periphery
|
-possible if severed away from cell body
-severed axon retracts and ends seal -distal segment degen's and is phagocytosed by mac's -chromatolysis of Nissl -axon regen follows route of Schwann cells (so axon must be in PNS) |
|
|
primary mech of SCI
|
-vertebral displacement
-vascular rupture and ischemia (concussive, contusive, shearing, stretching forces) |
|
|
secondary mech of SCI
|
-membrane-assoc events (lipid hydrolysis)
-vascular events (blood is toxic to neurons) -inflamm (immune recruitment) -biochemical events (NT accumulation, excitotoxicity) |
|
|
what is necessary for a neuron to regenerate
|
-axon must be in periphery
-cell body can be in PNS or CNS as long as it is intact |
|
|
clinical definition of SCI
|
-a lesion of the SC that results in paralysis and/or a corresponding loss of sensation
|
|
|
paraplegia
|
-injury in thoracic/lumbar/sacral regions
-paralysis from waist down |
|
|
quadriplegia
|
-lesion in cervical region
-paralysis from shoulders down |
|
|
complete SCI
|
-no motor or sensory in lower sacral or anal area
(ASIA A) |
|
|
incomplete SCI
|
-some level of motor or sensory below level of injury
(ASIA B-E) |
|
|
intervention strategies for SCI
|
-limit inital degen/ limit inflamm
-stim axonal growth and regen (best if before scar forms) -block exogenous inhib of regen (myelin, NOGO) |
|
|
timeline of events in SCI
|
-1st 30 min: vascular compromise, axonal changes
-2hrs: hypoperfusion of cord, microglia and PMNs infiltrate -6hrs: edema, inflamm cells, axolemma rupture -1wk: injury is infiltrated by mac's, Wallerian degen of axons and secondary demyel. occurs |
|
|
autonomic dysreflexia
|
-post SCI
-abnormal CV episodes -triggered by noxious and non-noxious stimuli |
|
|
pain syndromes
|
-post SCI
-allodynia -hyperalgesia |
|
|
Brown-sequard
|
-cord hemisection
-ipsilateral paralysis -contralateral loss of pain/temp |
|
|
syringomyelia
|
-pain/temp and motor loss increase over time
-occurs as syrinx in middle of cord gets progressively larger |
|
|
suprapubic catheter
|
-SCI treatment
-improves QOL -limits infections, can limit autonomic dysreflexia episodes |
