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100 Cards in this Set
- Front
- Back
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Brain Functions and Principal Parts of the Brain
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* Functions in memory, sensations, emotions, decision making, behavior (all based on A/P)
* Parts of the Brain: -- Cerebrum -- Diencephalon >>thalamus & hypothalamus -- Cerebellum -- Brainstem >>medulla, pons & midbrain |
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Meninges
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1. Dura mater
-- outermost, tough membrane -- outer periosteal layer against bone -- where separated from inner meningeal layer forms dural venous sinuses draining blood from brain -- supportive structures formed by dura mater (falx cerebri, falx cerebelli and tentorium cerebelli) -- epidural space filled with fat in lower back region (epidural anaesthesia during childbirth) 2. Arachnoid mater -- the spider web filamentous layer 3. Pia mater (delicate) -- a thin vascular layer adherent to contours of brain |
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Meningitis
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* Inflammation of the meninges
* Serious disease of infancy and childhood --between 3 months and 2 years of age * Bacterial and virus invasion of the CNS by way of the nose and throat -- pia mater and arachnoid are most likely to be affected * Signs include high fever, stiff neck, drowsiness and intense headache and may progress to coma * Diagnose by examining the CSF |
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Blood Supply to the Brain
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* Arterial blood supply is branches from circle of Willis on base of brain (page 699)
* Vessels on surface of brain----penetrate tissue * Brain uses 20% of our bodies oxygen & glucose needs (brain main source of energy is glucose, can use ketone, under emergency, but will kill neurons quickly) -- blood flow to an area increases with activity in that area -- deprivation of O2 for 4 min does permanent injury (at that time, lysosome release enzymes) |
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Blood-Brain-Barrier (BBB) and Blood-CSF Barrier
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* Blood-brain barrier
-- protects cells from some toxins and pathogens (proteins & antibiotics can not pass) -- tight junctions seal together epithelial cells, continuous basement membrane, astrocyte processes covering capillaries -- permeable to lipid-soluble materials (alcohol, O2, CO2, nicotine and anesthetics) -- circumventricular organs (CVO is a weak spot in hypothalamus) in 3rd & 4th ventricles at breaks in the barrier where blood has direct access >>monitoring of glucose, pH, osmolarity & other variations >>allows route for HIV virus to invade the brain * Blood-CSF barrier at choroid plexus is ependymal cells joined by tight junctions |
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CerebroSpinal Fluid
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* 80-150 ml of Clear liquid fills ventricles and canals & bathes its external surface (in subarachnoid space)
* Brain produces & absorbs about 500 ml/day --filtration of blood through choroid plexus(maker of CSF) --has more Na+ & Cl- but less K+ & Ca+2 than plasma (ependymal cells modify CSF content) * Functions --buoyancy (floats brain so it neutrally buoyant) --protection (cushions from hitting inside of skull) --chemical stability (rinses away wastes and optimal ionic concentrations for A/P) * Escapes from 4th ventricle to surround the brain * Absorbed by arachnoid villi into venous sinus * CSF is not used as nutrition source |
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Ventricles and CerebroSpinal Fluid (CSF)
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* Internal chambers within the CNS
--lateral ventricles found inside cerebral hemispheres --third ventricle is single vertical space under corpus callosum --cerebral aqueduct runs through midbrain --fourth ventricle is small chamber between pons & cerebellum --central canal runs down through spinal cord * Lined with ependymal cells and containing choroid plexus of capillaries that produce CSF |
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Drainage of CSF from Ventricles
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--One median aperture & two lateral apertures allow CSF to exit from the interior of the brain
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Reabsorption of CSF
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* Reabsorbed through arachnoid villi
--grape-like clusters of arachnoid penetrate dural venous sinus --20 ml/hour reabsorption rate (same as production rate) |
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Hydrocephalus
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* Blockage of drainage of CSF (due to tumor/ inflammation, developmental malformation/ meningitis/ hemorrhage/injury)
* Continued production cause an increase in pressure (aka: hydrocephalus/ water in brain) * In newborn or fetus, the fontanels allow this internal pressure to cause expansion of the skull and damage to the brain tissue * Neurosurgeon implants a drain shunting the CSF to the veins of the neck or the abdomen |
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Hindbrain--Medulla Oblongata
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* 3 cm extension of spinal cord
* Ascending & descending nerve tracts * Nuclei of sensory & motor cranial nerves (IX, X, XI, and XII) * Cardiac center adjusts rate & force of heart beat *Vasomotor center adjusts BV's diameter * Respiratory centers control rate & depth of breathing * Reflex centers for coughing, sneezing, gagging, swallowing, vomiting, salivation, sweating, movements of tongue & head |
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Ventral Surface of Medulla Oblongata
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1. Ventral surface bulge
--pyramids --large motor tract --decussation of most fibers (left cortex controls right muscles) 2. Olive = olivary nucleus --neurons send input to cerebellum --proprioceptive signals (maintain balance) --gives precision to movements |
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Dorsal Surface of Medulla Oblongata
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* Nucleus gracilis & nucleus cuneatus = sensory neurons
--relay information to thalamus on opposite side of brain * 5 cranial nerves arise from medulla (cranial nerve VIII to XII) |
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Cranial Nerve XII (Hypoglossal Nerve)
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* mainly motor nerve
* Provides tongue movements of speech, food manipulation & swallowing * Damage results in inability to protrude tongue if both are damaged or deviation towards injured side & ipsilateral atrophy if one side is damaged * Mixed, primarily motor |
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Cranial nerve XI (Accessory Nerve)
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* Cranial portion
--arises medulla --skeletal muscles of throat & soft palate * Spinal portion --arises cervical spinal cord --sternocleidomastoid and trapezius muscles * mainly motor nerve * Damage causes impaired head, neck & shoulder movement, head turns towards injured side |
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Cranial Nerve X (Vagus Nerve)
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* sensory and motor nerve
* Receives sensations from viscera * Controls cardiac muscle and smooth muscle of the viscera, * Controls secretion of digestive fluids * Damage causes hoarseness/ loss of voice, impaired swallowing & fatal if both are cut * Deals with 95% of parasympathetic functions * Almost all motor (from ANS) |
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Cranial Nerve IX (Glossopharyngeal Nerve)
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* sensory and motor nerve
* Provides control over swallowing, salivation, gagging, sensations from posterior 1/3 of tongue, control of Blood Pressure and respiration * Damage results in loss of bitter & sour taste & impaired swallowing |
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Cranial Nerve VIII (Vestibulo-cochlear nerve)
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* sensory nerve
* Cochlear branch begins in medulla --receptors in cochlea --for hearing --if damaged deafness/ tinnitus (ringing) is produced * Vestibular branch begins in pons --receptors in vestibular apparatus --for sense of balance * Damage produces deafness, vertigo, nausea, loss of balance & nystagmus |
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Cranial Nerve VII (Facial nerve)
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* sensory and motor nerve
* Provides facial expressions, sense of taste on anterior 2/3’s of tongue, salivary glands and tear, nasal & palatine glands * Damage produces sagging facial muscles (ie: Bell's Palsy) & disturbed sense of taste (missing sweet & salty) * Clinical test: --Test anterior 2/3’s of tongue with substances such as sugar, salt, vinegar, and quinine --test response of tear glands to ammonia fumes --test motor functions by asking subject to close eyes, smile, whistle, frown, raise eyebrows, etc. |
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Intelligence (Crystallized/Fluid/IQ Fluctuations)
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Despite widespread use of intelligence tests, no widely-accepted definition of "intelligence" exists. Psychologists tend to view intelligence as either a global mental capacity (e.g., Wechsler, Spearman) or as independent factors (e.g., Gardner). Operationally, intelligence is what intelligence tests measure.
1. CRYSTALLIZED INTELLIGENCE: Abilities that are primarily a function of learning and experience. Crystallized intelligence is less affected by physiological condition and, therefore, less negatively affected by aging. 2. FLUID INTELLIGENCE: Abilities, such as memory span and mental speech, that are affected by physiological condition and maturation. 3. IQ FLUCTUATIONS: Although cross-sectional studies demonstrate a gradual decline in IQ starting in late adolescence, longitudinal studies show that IQ scores are relatively stable throughout the lifespan. At least during the school years, however, IQ fluctuations as high as 15 points are not uncommon. |
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Injury to the medula
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* Hard blow to the back of the head may be fatal
* Cranial nerve malfunctions on same side as injury --loss of sensation or paralysis of throat/tongue --irregularities in breathing and heart rhythm |
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Pons
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* Bulge in the brainstem (1" long) rostral to the medulla
* Ascending sensory tracts and Descending motor tracts (white fiber tract--myelinated) * Pathways in & out of cerebellum * Pneumotaxic & apneustic areas help control breathing * Mid-cerebellar peduncles carry sensory into to cerebellum (nerves V-VII) * Nuclei concerned with sleep, hearing, balance, taste, eye movements, facial expression, facial sensation, swallowing, bladder control & posture (cranial nerves V to VIII) |
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Cranial Nerve V (Trigeminal nerve)
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* the largest nerve (motor and sensory nerve)
* Mainly sensory nerve to face (touch, pain and temperature) and muscles of mastication * Damage produces loss of sensation & impaired chewing |
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Midbrain
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* One inch in length
* Extends from pons to diencephalon * Cerebral aqueduct connects 3rd ventricle above to 4th ventricle below |
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Midbrain: Cross-Section
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* Mesencephalon
* Central aqueduct * CN III and IV (for eye movement) * Cerebral peduncles --hold corticospinal tract * Tegmentum connects to cerebellum & helps control fine movements through red nucleus * Substantia nigra sends inhibitory signals to basal ganglia & thalamus (degeneration leads to tremors and Parkinson disease) |
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Superior & Inferior Colliculus (aka: Corpora Quadrigemini)
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* Tectum (4 nuclei)
--superior colliculus (tracking moving objects ) --inferior colliculus (reflex turning of head to sound) |
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Reticular Formation (part I)
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* Clusters of gray matter
scattered throughout pons, midbrain & medulla * Motor Arm --regulate balance & posture --relaying information from eyes & ears to cerebellum --gaze centers allow you to track moving object --includes cardiac & vasomotor centers --origin of descending pain relieve (analgesic) pathways |
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Reticular Formation (part II)
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* Reticular Activating System
--alerts cerebral cortex to sensory signals (sound of alarm, flash light, smoke or intruder) to awaken from sleep --maintains consciousness & helps keep you awake with stimuli from ears, eyes, skin and muscles --regulates sleep --injury leads to irreversible coma |
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Diencephalon: Thalamus
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* Oval mass of gray matter protruding into lateral ventricle (part of diencephalon)
* Receives nearly all sensory information on its way to cerebral cortex --integrate & directs info to appropriate area * Interconnected to limbic system >> involved in emotional & memory functions |
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Cerebellum
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* 2 cerebellar hemispheres and vermis (central area)
* Function: --correct voluntary muscle --contraction and posture based on sensory data from body about actual movements --sense of equilibrium * Transverse fissure between cerebellum & cerebrum * Cerebellar cortex (folia) & central nuclei are grey matter * Arbor vitae (tree of life) = white matter |
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Cerebellar Peduncles
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* Superior, middle & inferior peduncles attach to brainstem
-- inferior carries sensory -- information from spinal cord middle carries sensory fibers from cerebral cortex & basal ganglia -- superior carries motor fibers that extend to motor control areas |
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Diencephalon Surrounding 3rd Ventricle
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* Surrounds 3rd ventricle
* Superior part of walls is thalamus * Inferior part of walls & floor is hypothalamus |
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Thalamus
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* 1 inch long mass of gray mater in each half of brain (connected across the 3rd ventricle by intermediate mass)
* Relay station for sensory information on way to cortex * Crude perception of some sensations |
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Thalamic Nuclei
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* Nuclei have different roles
-- relays auditory and visual impulses, taste and somatic sensations -- receives impulses from cerebellum/basal ganglia -- anterior nucleus concerned with emotions, memory and acquisition of knowledge (cognition) |
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Hypothalamus
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* About a dozen nuclei in 4 major regions
-- mammillary bodies are relay station for olfactory reflexes -- infundibulum suspends the pituitary gland * Major regulator of homeostasis -- receives somatic and visceral input, taste, smell & hearing information -- monitors osmotic pressure and temperature of blood |
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Functions of Hypothalamus
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* Controls and integrates activities of the ANS which regulates smooth, cardiac muscle and glands
* Synthesizes regulatory hormones that control the anterior pituitary * Contains cell bodies of axons that end in posterior pituitary (where they secrete hormones) * Regulates rage, aggression, pain, pleasure & arousal * Feeding, thirst & satiety centers * Controls body temperature * Regulates daily patterns of sleep |
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Epithalamus
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* Pineal gland
-- endocrine gland the size of small pea -- secretes melatonin during darkness -- promotes sleepiness & sets biological clock * Habenular nuclei -- emotional responses to odors |
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Subthalamus and CVO (Circum Ventricular Organ)
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* Subthalamus
-- small area just inferior to thalamus -- work with basal ganglia, cerebrum & cerebellum to control body movements * Circumventricular (CVO) organs: -- in walls of 3rd & 4th ventricles -- monitor changes in blood chemistry because lack BBB (parts of hypothalamus, pineal & pituitary gland) -- sites of entry of HIV virus into brain (causing dementia) |
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Cranial Nerve IV (Trochlear Nerve)
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* motor nerve
* Superior oblique eye muscle * Damage causes double vision & inability to rotate eye infero-laterally |
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Cranial Nerve III (Oculomotor Nerve)
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* motor nerve
* Levator palpebrae raises eyelid (ptosis) * 4 extrinsic eye muscles (inferior oblique, superior, inferior, and medial rectus) * 2 intrinsic eye muscles --accomodation for near vision (changing shape of lens during reading) --constriction of pupil * Damage causes drooping eyelid, dilated pupil, double vision, difficulty focusing & inability to move eye in certain directions |
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Cerebellar Peduncles
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* Superior, middle & inferior peduncles attach to brainstem
-- inferior carries sensory -- information from spinal cord middle carries sensory fibers from cerebral cortex & basal ganglia -- superior carries motor fibers that extend to motor control areas |
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Diencephalon Surrounding 3rd Ventricle
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* Surrounds 3rd ventricle
* Superior part of walls is thalamus * Inferior part of walls & floor is hypothalamus |
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Thalamus
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* 1 inch long mass of gray mater in each half of brain (connected across the 3rd ventricle by intermediate mass)
* Relay station for sensory information on way to cortex * Crude perception of some sensations |
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Thalamic Nuclei
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* Nuclei have different roles
-- relays auditory and visual impulses, taste and somatic sensations -- receives impulses from cerebellum/basal ganglia -- anterior nucleus concerned with emotions, memory and acquisition of knowledge (cognition) |
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Hypothalamus
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* About a dozen nuclei in 4 major regions
-- mammillary bodies are relay station for olfactory reflexes -- infundibulum suspends the pituitary gland * Major regulator of homeostasis -- receives somatic and visceral input, taste, smell & hearing information -- monitors osmotic pressure and temperature of blood |
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Functions of Hypothalamus
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* Controls and integrates activities of the ANS which regulates smooth, cardiac muscle and glands
* Synthesizes regulatory hormones that control the anterior pituitary * Contains cell bodies of axons that end in posterior pituitary (where they secrete hormones) * Regulates rage, aggression, pain, pleasure & arousal * Feeding, thirst & satiety centers * Controls body temperature * Regulates daily patterns of sleep |
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Epithalamus
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* Pineal gland
-- endocrine gland the size of small pea -- secretes melatonin during darkness -- promotes sleepiness & sets biological clock * Habenular nuclei -- emotional responses to odors |
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Subthalamus and CVO (Circum Ventricular Organ)
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* Subthalamus
-- small area just inferior to thalamus -- work with basal ganglia, cerebrum & cerebellum to control body movements * Circumventricular (CVO) organs: -- in walls of 3rd & 4th ventricles -- monitor changes in blood chemistry because lack BBB (parts of hypothalamus, pineal & pituitary gland) -- sites of entry of HIV virus into brain (causing dementia) |
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Cranial Nerve IV (Trochlear Nerve)
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* motor nerve
* Superior oblique eye muscle * Damage causes double vision & inability to rotate eye infero-laterally |
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Cranial Nerve III (Oculomotor Nerve)
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* motor nerve
* Levator palpebrae raises eyelid (ptosis) * 4 extrinsic eye muscles (inferior oblique, superior, inferior, and medial rectus) * 2 intrinsic eye muscles --accomodation for near vision (changing shape of lens during reading) --constriction of pupil * Damage causes drooping eyelid, dilated pupil, double vision, difficulty focusing & inability to move eye in certain directions |
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Cerebrum (Cerebral Hemispheres)
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* Cerebral cortex= gray matter
overlying white matter * 3 mm thick containing billions of cells * grew so quickly formed folds (gyri) and grooves (sulci or fissures) * Longitudinal fissure separates LandR cerebral hemispheres * Corpus callosum is band of white matter connecting L&R cerebral hemispheres * Each hemisphere is subdivided into 4 lobes |
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Cerebral Cortex
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* Surface layer of gray matter (3 mm thick)
* Neocortex (six-layered tissue) --newest part of the cortex (paleocortex & archicortex) --layers vary in thickness in different regions of brain * 2 types of cells --stellate cells (have dendrites projecting in all directions) --pyramidal cells (have an axon that passes out of the area) |
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Cerebral White Matter
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* Association fibers between gyri in same hemisphere
* Commissural fibers from one hemisphere to other * Projection fibers form descending & ascending tracts |
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Tracts of Cerebral White Matter
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* Most of volume of cerebrum is white matter
* Types of tracts: 1. projection tracts = extend vertically from brain to spinal cord forming internal capsule 2. commissural tracts= cross from one hemisphere to the other --corpus callosum is wide band of white fiber tracts --anterior & posterior commissures are pencil-lead sized 3. association tracts= connect lobes & gyri of each hemisphere to each other |
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Somesthetic Sensation
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* Somesthetic signals travel up gracile and cuneate fascicui and spino-thalamic tracts of spinal cord
* Somatosensory area is postcentral gyrus |
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Sensory Homonculus
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* Demonstrates that the area of the cortex dedicated to the sensations of various body parts is proportional to how sensitive that part of the body is.
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Special Senses
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* Organs of smell, vision, hearing & equilibrium project to specialized regions of the brain
* Locations --taste is lower end of postcentral gyrus --smell is medial temporal lobe & inferior frontal lobe --vision is occipital lobe --hearing is superior temporal lobe --equilibrium is mainly the cerebellum, but to unknown areas of cerebral cortex via the thalamus |
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Sensory Area of Cerebral Cortex
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* Receive sensory information from the thalamus
*Primary somatosensory area = postcentral gyrus = 1,2,3 (in the central sulcus) * Primary visual area = 17 (anterior portion of occipital lobe) * Primary auditory area = 41 & 42 (temporal side of central sulcus) * Primary gustatory area = 43 (between primary auditory area and somatosensory area) |
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Association Area of Cerebral Cortex
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* Somatosensory area = 5 & 7 (integrate & interpret)
* Visual association area = 18 & 19 (recognize & evaluate) * Auditory association area(Wernicke’s) = 22(words become speech) * Gnostic area = 5,7,39 & 40 (integrate all senses & respond) * Premotor area = 6 (learned skilled movements such as typing) * Frontal eye field =8 (scanning eye movements such as phone book) |
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Sensory Association Areas
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* Association areas interpret sensory information
* Somesthetic association area (parietal lobe) --position of limbs, location of touch or pain, and shape, weight & texture of an object * Visual association area (occipital lobe) --identify the things we see --faces are recognized in temporal lobe * Auditory association area (temporal lobe) --remember the name of a piece of music or identify a person by his voice |
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Motor Areas of Cerebral Cortex
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* Voluntary motor initiation
* Primary motor area = 4 = precentral gyrus -- controls voluntary contractions of skeletal muscles on other side * Motor speech area = 44 = Broca’s area -- production of speech= control of tongue & airway |
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Motor Control
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* Intention to contract a muscle begins in motor association (premotor) area of frontal lobes
* Precentral gyrus (primary motor area) processes that order by sending signals to the spinal cord --pyramidal cells called upper motor neurons --supply muscles of contralateral side due to decussation * Motor homunculus is proportional to number of muscle motor units in a region (fine control) |
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Cerebral Palsy
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* Loss of motor control and coordination
* Damage to motor areas of the brain --infection of pregnant woman with rubella virus --radiation during fetal life --temporary lack of O2 during birth * Not a progressive disease, but irreversible |
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Functions of Cerebrum Lobes
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* Frontal contains voluntary
motor functions and areas for planning, mood, smell and social judgement * Parietal contains areas for sensory reception & integration of sensory information * Occipital is visual center of brain * Temporal contains areas for hearing, smell, learning, memory, emotional behavior * Insula is still little known |
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Cognition
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* Cognition is mental processes such as awareness, perception, thinking, knowledge & memory
-- 75% of brain is association areas where integration of sensory & motor information occurs * Examples of effects of brain lesions --parietal lobe= contralateral neglect syndrome --temporal lobe= agnosia (inability to recognize objects) or prosopagnosia (inability to recognize faces) --frontal lobe= problems with personality (inability to plan & execute appropriate behavior) |
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Accidental Lobotomy of Phineas Gage
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* Accidental destruction of ventromedial region of both frontal lobes
* Personality change to an irreverent, profane and fitful person * Neuroscientists believe planning, moral judgement, and emotional control are functions of the prefrontal cortex |
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Emotion
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* Prefrontal cortex controls how emotions are expressed (seat of judgement)
* Emotions form in hypo-thalamus & amygdala --artificial stimulation produces fear, anger, pleasure, love, parental affection, etc. --electrode in median forebrain bundle in rat or human and a foot pedal (press all day to the exclusion of food--report a quiet, relaxed feeling) * Much of our behavior is learned by rewards and punishments or responses of others to them |
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Basal Nuclei
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* Masses of gray matter deep to cerebral cortex
* Receive input from substantia nigra & motor cortex & send signals back to these regions * Involved in motor control & inhibition of tremors |
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Parkinson's Disease
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* Progressive disorder striking victims at age 60
* Environmental toxins may be the cause * Neurons from the substantia nigra do not release enough dopamine onto basal ganglia --tremor, rigidity, bradykinesia (slow movement) or hypo-kinesia (decreasing range of movement) --may affect walking, speech, even facial expression * Treatments --drugs to increase dopamine levels, or to prevent its breakdown --surgery to transplant fetal tissue or removal of part of globus pallidus to slow tremors |
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Limbic System
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* Loop of cortical structures surrounding deep brain
--amygdala, hippocampus, fornix & cingulate gyrus * Amydala important in emotions and hippocampus in memory -- rest are not sure * Emotional brain--intense pleasure & intense pain * Strong emotions increase efficiency of memory |
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Reticular Activating System
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* RAS has connections to
cortex & spinal cord. * Many types of inputs activate the RAS---pain, light, noise, muscle activity, touch * Produces state of wakefulness called consciousness * Coma is sleep-like state deep coma has no reflexes death if cardiovascular reflexes are lost |
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Sleep
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* State of altered or partial consciousness from which a person can be aroused
* Triggers for sleep are unclear --adenosine levels increase with brain activity --adenosine levels inhibit activity in RAS --caffeine prevents adenosine from inhibiting RAS * Two types of normal sleep 1. NREM = non-rapid eye movement sleep 2. REM = rapid eye movement sleep |
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Non-Rapid Eye Movement Sleep
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* Stage 1
--person is drifting off with eyes closed (first few minutes) * Stage 2 --fragments of dreams --eyes may roll from side to side * Stage 3 --very relaxed, moderately deep --20 minutes, body temp & BP have dropped * Stage 4 = deep sleep --bed-wetting & sleep walking occur in this phase |
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REM Sleep
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* Most dreams occur during REM sleep
* In first 90 minutes of sleep: --go from stage 1 to 4 of NREM, --go up to stage 2 of NREM to REM sleep * Cycles repeat until total REM sleep totals 90 to 120 minutes * Neuronal activity & oxygen use highest in REM sleep * Total sleeping & dreaming time decreases with age |
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EEG and Brain Waves
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* Electroencephalogram records voltage changes from postsynaptic potentials in cerebral cortex
* Differences in amplitude & frequency distinguish 4 types of brain waves |
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Brain Waves and Sleep
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* States of consciousness can be correlated with EEG
* 4 types of brain waves --alpha occur when awake & resting with eyes closed --beta occur with eyes open performing mental tasks --theta occur during sleep or emotional stress --delta occur during deep sleep * Sleep is temporary state of unconsciousness --coma is state of unconsciousness with no possible arousal --reticular formation seems to regulate state of alertness --suprachiasmatic nucleus acts as biological clock to set our circadian rhythm of sleep and waking |
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Stages of Sleep
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1.Non-REM sleep occurs in stages (4 stages occurring in first 30 to 45 minutes of sleep)
--stage 1 is drifting sensation (would claim was not sleeping) --stage 2 still easily aroused --stage 3 vital signs change= BP, pulse & breathing rates drop (reached in 20 minutes) --stage 4 is deep sleep= difficult to arouse >>seems to have a restorative effect 2. REM sleep occurs about 5 times a night --rapid eye movements under the eyelids, vital signs increase, EEG resembles awake person, dreams and penile erections occur --may help sort & strengthen information from memory |
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Sleep Stages and Brain Waves
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* Brain waves change as we pass through 4 stages of sleep
--alpha waves: stage 1 (drowsy) --sleep spindles: stage 2 (light sleep) --theta and delta waves: stages 3-4(deep sleep) --beta waves: fully awake, eyes open Notice how REM sleep periods become longer and more frequent in the second half of the night |
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Learning and Memory
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* Learning is acquiring new knowledge
* Memory is retaining that knowledge 1. short-term memory --recall phone number while dialing --depends upon electrical events (reverberating circuits) 2. long-term memory --frequent retrieval of specific information helps with memory consolidation (learning) --structural or biochemical changes occurs (increase in dendrites, enlarge endbulbs, increase in presynaptic terminals or formation of additional membrane receptors) 3. Automatic Memory * Recently acquired memory lost first with coma or shock treatments |
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Memory and Synaptic Plasticity
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* Memories are not stored in individual cells
* Physical basis of memory is a pathway of cells --called a memory trace or engram --new synapses or existing synapses have been modified to make transmission easier (synaptic plasticity) * Synaptic potentiation --process of making transmission easier --correlates with different forms of memory >>immediate memory >>short-term memory >>long-term memory |
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Immediate Memory
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* Ability to hold something in your thoughts for just a few seconds
* Feel for the flow of events (sense of the present) * Our memory of what just happened “echoes” in our minds for a few seconds --reverberating circuits |
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Short Term Memory
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* Lasts from a few seconds to several hours
--quickly forgotten if distracted with something new * Working memory allows us to keep something in mind long enough search for keys, dial the phone --reverberating circuits * Facilitation causes memory to longer lasting --tetanic stimulation (rapid, repetitive signals) causes Ca+2 accumulates & cell becomes more likely to fire * Posttetanic potentiation (to jog a memory) --Ca+2 level in synaptic knob has stayed elevated long after tetanic stimulation, so little stimulation will be needed to recover that memory |
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Long Term Memory
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* May last up to a lifetime
* Types of long-term memory --declarative is retention of facts as text or words --procedural is retention of motor skills (keyboard) * Physical remodeling of synapses with new branching of axons or dendrites * Molecular changes called long-term potentiation --tetanic stimulation causes ionic changes (Ca+2 entry) >>neuron produces more neurotransmitter receptors >>synthesizes more protein used for synapse remodeling >>releases nitric oxide signals presynaptic neuron to release more neurotransmitter |
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Potentiation
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* N-Methyl D-Aspartate receptors
* Co-activation by glutamate and glycine * Voltage and ligand regulated * Mg++ blocks channel, but depolarization pushes Mg out of channel and allows Ca++ to enter cell * The movement of Ca++ begins 2nd mess system making neurotransmitter release easier presynaptically and leads to the release of increased receptors postsynaptically |
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Memory
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* Information management requires learning, memory & forgetting (eliminating the trivia)
--pathological inability to forget have trouble with reading comprehension --anterograde amnesia= can not store new data --retrograde amnesia= can not remember old data * Hippocampus is important in organizing sensory & cognitive information into a memory --lesion to it causes inability to form new memories * Cerebellum helps learn motor skills * Amygdala important in emotional memory * Memories can haunt you |
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Language
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* Includes reading, writing, speaking & understanding words
* Wernicke’s area permits recognition of spoken & written language & creates plan of speech --angular gyrus processes text into a form we can speak * Broca’s area generates motor program for larynx, tongue, cheeks & lips --transmits that to primary motor cortex for action * Affective language area lesions produce aprosodia --area area as Broca’s on opposite hemisphere |
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Aphasia (part I)
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* Language areas are located in the left cerebral hemisphere of most people
* Inability to use or comprehend words = aphasia * Any language deficit resulting from lesions in same hemisphere as Wernicke’s & Broca’s areas * Lesion to Broca’s = nonfluent aphasia --slow speech, difficulty in choosing words --know what want to say but can not speak --entire vocabulary may be 2 to 3 words |
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Aphasia (part II)
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* Lesion to Wernicke’s = fluent aphasia
--speech normal & excessive, but makes little sense * Anomic aphasia = speech & understanding are normal but text & pictures make no sense --damage to common integrative area or auditory association area= faulty understanding of spoken or written words >>word deafness = an inability to understand spoken words >>word blindness = an inability to understand written words * Others = understanding only 1st half of words or writing only consonants |
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Cerebral Laterization
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* Left hemisphere is categorical hemisphere
--specialized for spoken & written language, sequential & analytical reasoning (math & science), analyze data in linear way * Right hemisphere is representational hemisphere --perceives information more holistically, perception of spatial relationships, pattern, comparison of special senses, imagination & insight, music and artistic skill * Highly correlated with handedness --91% of people right-handed with left side is categorical * Lateralization develops with age --trauma more problems in males since females have more communication between hemisphere (corpus callosum is thicker posteriorly) |
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Hemespheric Laterization
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* Functional specialization of each hemisphere more pronounced in men
* Females have larger connections between 2 sides * Damage to left side produces aphasia * Damage to same area on right side produces speech with little emotional inflection |
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Optic Nerve
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* Provides vision
* Damage causes blindness in visual field |
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Olfactory Nerve
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* Provides sense of smell
* Damage causes impaired sense of smell * Terminate in olfactory cortex |
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Cranial Nerve Zero
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* First described in Humans in 1913
* Pheromones * Begin in olfactory epithelium, but terminate in lateral and medial septal nuclei and pre-optic areas (hot button sex regions) |
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Development Anatomy of the Nervous System
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* Begins in 3rd week
--ectoderm forms thickening (neural plate) --plate folds inward to form neural groove --edges of folds join to form neural tube * Neural crest tissue forms: --spinal & cranial nerves --dorsal root & cranial nerve ganglia --adrenal gland medulla * Layers of neural tube form: --marginal layer which forms white matter --mantle layer forms gray matter --ependymal layer forms linings of cavities within NS |
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Development of Principal Parts
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* By end of 4th week, 3 anterior enlargements occur:
--prosencephalon --mesencephalon --rhombencephalon * By 5th week, 5 enlarged areas exist: --Prosencephalon --telencephalon --diencephalon --Mesencephalon --Rhombencephalon --metencephalon --myelencephalon * Neural tube defects --associated with low levels of folic acid (B vitamins) --spina bifida is failure to close of vertebrae --anencephaly is absence of skull & cerebral hemispheres |
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Aging and the Nervous System
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* Years 1 to 2
--rapid increase in size due to increase in size of neurons, growth of neuroglia, myelination & development of dendritic branches * Early adulthood until death --brain weight declines until only 93% by age 80 --number of synaptic contacts declines --processing of information diminishes --conduction velocity decreases --voluntary motor movements slow down --reflexes slow down |
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Cerebrovascular Accident (CVA)
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* aka: stroke
* 3rd leading cause of death after heart attacks and cancer * 2 types of strokes: --ischemic due to decreased blood flow --hemorrhagic due to rupture of blood vessel * Risk factors --high blood pressure, high cholesterol, heart disease, diabetes, smoking, obesity, alcohol * Tissue plasminogen activator (t-PA) used within 3 hours of onset will decrease permanent disability |
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Transient Ischemic Attack (TIA)
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* Episode of temporary cerebral dysfunction
* Cause --impaired blood flow to the brain * Symptoms --dizziness, slurred speech, numbness, paralysis on one side, double vision --reach maximum intensity almost immediately --persists for 5-10 minutes & leaves no deficits * Treatment is aspirin or anticoagulants; artery bypass grafting or carotid endarterectomy |
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Alzheimer Disease
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* Dementia = loss of reasoning, ability to read, write, talk, eat & walk
* Afflicts 11% of population over 65 * Causes --Loss of neurons that release acetylcholine (nucleus basalis) --Plaques of abnormal proteins outside neurons --Tangled protein filaments within neurons --other risk factors= head injury, heredity (APO4 chromosome) * Beneficial effects of estrogen, vitamin E, ibuprofen & ginko biloba |
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Brain Injuries
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* Causes of damage
--displacement or distortion of tissue at impact --increased intracranial pressure --infections --free radical damage after ischemia * Concussion= temporary loss of consciousness --headache, drowsiness, confusion, lack of concentration * Contusion= bruising of brain (less than 5 min, unconsciousness but blood in CSF) * Laceration= tearing of brain (fracture or bullet) --increased intracranial pressure from hematoma |
