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89 Cards in this Set
- Front
- Back
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how is the cortex divided into types? |
number of cell layers |
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neocortex |
95% of the cerebral hemisphere, 6 layers of cells |
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paleocortex |
-found at the base of the telencephalon- infereior frontal lobe, olfactory area and limbic system - 3 layers of cells |
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archicirtex |
-found at the inferior temporal lobe, hippocampus - limbic area -3 layers |
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pyramidal cells |
-must numerous in the cerebral cortex -have a long apical (top) dendrite that extends toward the surface -several basl dendrites, which spread horizontally -use glutamate -most have long axons which reach out of their cortex -major contributer to agranular cortex |
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stellate cells |
-small with radiate shape -multipolar --principle interneuron of cortex -receive input from other cortical areas, within each area and from association areas -use GABA -major contributer to granular cortex |
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Glia (of cortex) |
-astrocytes, oligodendrocytes & microglia -particular to the cortex: bipolar, chandelier, horizontal and basket cells (were not sure what these do, and there is not too many of them) |
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Agranular cortex |
-pyramidal cells |
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Primary sensory areas project mainly to _______ cortical areas |
adjacent |
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granular cortex |
-have few large pyramidal cells -are dominated by small cells
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columnar organization |
-each layer communicates with other layers superficail and deep to it -vertical bundles of afferents and efferents -one parameter (orientation) is consistent within a group of columns which make up larger fx modules -neocortex has minicolumns of 100 neurons
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in the neorcortex axons spread thru______ |
horizontal bands |
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in which layers are these horizontal bands? |
IV- inner layer of baillarger V- inner layer of Baillarger |
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where do afferents in the neocortex come from? |
-other cortical areas via association or comissural fibers -subcortical sites |
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association fibers |
arise in the same hemisphere |
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comissural fibers |
arise in the C/L hemisphere |
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what is the major input source for the cortex? |
thalamus- projections via internal capsule |
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6 layers of the internal cortex |
1. molecular layer 2. external granular layer 3.external pyramidal layer 4.internal granular layer 5.internal pyramidal layer 6. Multiform (polymorphic) layer |
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molecular layer |
-1st layer, closest to pia matter -mostly axons and dendrites few cell bodies |
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external granular layer |
-2nd layer -input from assocaition and transcallosal fibers |
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external pyramid layer |
-3rd layer -input transcallosal comissural fibers --output association fibers |
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internal granular layer |
-4th layer -highest cell density -input is from the thalmus-thalamocortical fibers |
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internal pyramidal layer |
-5th layer -output brainstem, spinal cord and straitum |
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multiform layer |
-6th layer, deepes layer, closest to white matter -populated by large, modified pyramidal cells with multipolar characteristics -output to thalamus (regulatory projections) |
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describe the formation of the cortex |
-from telencephalon (rostral end of the neural tube, -2 layers: ventricular zone & marginal zone
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ventricular zone |
-in the neural tube close to the central space -an area of cell proliferation & division |
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marginal zone |
-in development, close to the pia matter -area where cells mature and begin to function |
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radial glial fibers |
fibers which cells use to migrate from ventricular zone to marginal zone. |
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___1___ are closes to the ventricular zone ___2________ are closest to the pia matter |
1. oldest 2. youngest |
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what occurs after clls migrate and take up their final positions |
axons extends with growth cones, path of travel is determined by trophic factors, cell-to-cell contact, extra cellular matrix, and regular neural communication. When a growth cone comes in contact with a target a synapse is formed. excess neurons are produced --> widespread connections. Connections not used will be destroyed. |
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trophic factor |
diffusable chemicals that guide cells to a particular target |
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neurons that are wired together___________ |
fire togeteher |
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what determines the number of neurons that survive in a particular area? |
the amount of target tissue the neurons interact with during development. neurotrophic factors are limited and only cells that are successful in competeing for them have them travel retrogradely to the neurons cell body |
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neurotrophic factors |
-maintain the metabolism of a cell and/or its -switch off apoptosis programprocesses |
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what takes over for neurotrophic factors after the pathway is formed? |
synaptic activity |
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critical period of development |
-periord when expereince leads to maintenance or creation of neural connections and hence the continued logevity of the cell - wiring acheived during a critical period is mostly permanent -couple of weeks/ months around time of birth |
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The visual cortex will form the basic properties of circuity ___________________ experience |
even without visual |
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What happens to visual circuitry in cases of a modified visual expereince? |
-it will be detrimentally affected, for example if one eye is covered the ocular dominance columns will shift and the cortex will rewire to only receive info from the uncovered eye (critical time period) -will not develop later in life |
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fasiculi |
efferent projections in the I/L hemisphere which travel in bundles |
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what areas do efferent fibers connect with in the cortex? |
-most go to subcortical structures via the internal capsule, but can also travel to other cortical areas I/L or C/L |
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superior longitudinal fasiculus |
-aka arcuate -superior to insula -connects frontal lobe to occipital, parietal, and temporal lobes |
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superior occipitofrontal fasiculus |
-parallels corpus callosum -connects frontal and superior parts of occipital and parietal lobes |
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inferior occipitofrontal fasiculus |
-inferior to insula -connects frontal and temporal lobes to occitpital lobe |
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unicate fasiculus |
hooks around lateral sulcus to connect frontal and temporal lobes |
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comissures |
-where efferents project to C/L hemispheres -end in areas related to those from which they arise -connect mirror image sites on right and left brian |
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corpus callosum |
-largest commissure -superior to diencephalon -transfer of info from side to side |
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anterior comissure |
-located anterior to interthalamic adhesion -connect inferior parts of temporal lobes
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posterior comissure |
-located rostral to superior colliculus (inferior to pineal gland -crossing fibers from superior colliculus to cortex |
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Primary cortical areas |
-areas driven by a single modality -where the majority of thalamic fibers terminate or cortical output originates |
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Unimodal association areas |
-areas adjacent to primary cortical areas -inputs mainly from 1* cortical neurons (little thalamic on the side wink wink) -elaborates on work of 1* |
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multimodal association areas |
-found in the inferior parietal lobe, large part of prefrontal and temporal lobes -neurons respond to multisensory modalities -input by cortical neurons -change response do to different circumstances -higher level intellectual function |
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Primary Visual Cortex |
-located around the calcerine sulcus -input fron LGN -central C/L field represented posteriorly (mostly at the occipital pole) -peripheral C/L field represented anteriorly -area where initial processing occurs |
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visual association cortex |
-remainder of the occipital lobe -input from 1* visual cortex and superior collic -motion, color, etc analyzed to a greater extent here |
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Primary auditory cortex |
-posterosuperior temporal lobe -input from MGN via sublenticular limb of IC
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auditory association cortex |
-input from 1* auditory cortex and MGN |
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Somatosensory cortex |
-post central gyrus -input from VPM/VPL -body area mapped out seperately in each area - contains cutaneous, deep/joints and muscle receptors |
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primary motor cortex |
-precentral gyrus -input from cortex -output to cerebellum, BG and spinal cord |
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olfactory cortex |
-paleocortex -orbital surface of frontal lobe -input from olfactory tracts -projects both directly and via dorsal medial nucleus to olfactory association cortex on orbital surface of frontal lobe |
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Gustatory cortex (insula) |
-deep to frontal and temporal lobes -input from solitary tract (CN VII, IX, X) -near somatosensory for tongue and olfactory area |
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vetibular cortex |
-input from vestibular neuclei and VPM -largely inknown fx -associated with somatosensory cortex -near auditory cortex |
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Association cortex |
-for higher mental fx (language, music, visual arts)
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fMRI |
sensitive to blood flow changes |
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PET |
-positron emission tomography -able to label molecules to study where they go -monitor isotope release of gamma rays within the body where changes are occuring |
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dominant hemisphere |
-side involved w/ language -left is dominant for most, although some left handed people are right dominent |
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non-dominent hemisphere |
-has qualities such a spatial orientation associated with it |
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left hemisphere - does what? |
language, math and logic |
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right hemisphere- does what? |
insight, visual spatial skills, intuition and artsy skills |
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aphasia |
impairment or loss of the faculty to understand or use spoken or written language. usually linked to lesions in brocas or weirnikes |
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Broca's Area local |
-opercular and triangle parts of the prefrontal gyrus
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lesion to Broca's |
-damage causes nonfluent motor/expressive aphasia -able to understand others -leaves out words, relies on stock phrases |
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Wernicke's area local |
-posterior superior temporal gyrus and inferior parietal lobule -contains mechanism for formulation of language |
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damage to Wernicke's |
-fleunt/sensory or receptive aphasia -speaks lots of words, but makes no sense (word salad) -difficulty comprehending language |
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Global aphasia |
-damage to both areas -pt have severe communication difficulties & will be limited in speaking and comprehension |
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conductive aphasia |
-lesion at 2 areas connected by the superior longitudinal fasiculus -typically have intact auditory comprehension, fluent speah production, but poor speach repetition |
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dsyslexia |
-subtle form of fluent aphasia -located in dominant hemispher -trouble with spelling/reading; reads mirror image of words or words backwards -due to anatomical changes in cortex, malformed layers or misplaced cell |
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agnosia |
inability to recognize objects. -may be visual, sensory/tactile or auditory |
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poserior somatosensory area |
-filled with assocaition areas, -uni related to vision,auditory or somatosensory -damage here causes specific agnosias |
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posterior parietal cortex |
-multimodal association area -mostly in the right lobe -keeps track of body parts and things in the outside world-spatial orientation |
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lesions in the posterior parietal cortex |
-causes neglect of the C/L visual space and somatosensory info, e.g. ignoring 1/2s of objects or even own body - generally deficits in spatial orietation; may have trouble finding maps. joey in friends episode -usually accompanied by partial paralysis or somatosensory loss |
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Apraxia |
inability to preform certain actions, everything works, but specific actions cannot be preformed |
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what artery causes lesions in posterior pareital cortex? |
stroke of MCA |
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anterior motor areas of the cerebral cortex |
-motor -controls activities of other cortical areas -exectutive fx (personality) -input from dorsal medial nuclues |
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Dorsolateral prefrontal cortex |
-plays a role in working memory -eg remembering a phone number until finished dialing -damage causes trouble with problem solving, short-term memory, planning and maintaining attention |
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ventromedial prefrontal cortex |
-interconnected with limbic structures -damage causes impulsiveness, trouble surpressing innapropriate responses and emotional reactions. -makes agressive people more sedate -changes perception of pain |
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Schizophrenia |
-characterized by delusions and hallucinations -frontal lobe disorder -genetic and environmental link |
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4 areas fof anatomical change with Schizophrenia |
-reduced blood to left globus pallidus -altered blood flow to frontal lobes -hippocampus smaller, temporal lobe thinner -enlarged ventricles |
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Alzheimer's |
-progressive degenerative disease involving synapses within the cortex, hippocampus amygdala -death/dysfx of pyramidal cells -no effect on sensory or motor -memory disorder -tangle of dendrites in cortex -genetic link |
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disconnect syndrome |
-lesions involve fasiculli and/or comissures -pure word blindness
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pure word blindness |
-able to write, but not to read -able to speak and comprehend -can be due to stroke of posterior cerebral, which destroys left visual cortex and splenium of corpus callosum, language still connected to motor, but cut off from visual |
