Lecture Exam #3 - Central Nervous System

What are the functions of the meninges?

***Meninges are three CT membranes that lie just external to the CNS organs*** Functions: - cover and protect the CNS - protect blood vessels and enclose venous sinuses - contain cerebrospinal fluid - form partitions in the skull

One part of the reticular formation is called the reticular activating system (RAS). What is the function of RAS?

- the neurons in the Reticular Activating System (RAS) receive send a continuous stream of impulses to cerebral cortex, keeping the cortex alert and conscious and enhancing its excitability - filters the flood of sensory inputs (habituation) => repetitive, familiar, or weak signals are filtered out, but unusual, significant, or strong impulses do reach consciousness => the ability to filter out known background stimuli so they do not keep you awake

With what other structures (or regions) of the brain is the reticular formation connected?

- the neurons of the reticular formation form three broad columns along the length of the brain stem: 1) the midline raphe nuclei neurons, which are flanked laterally by (2) the medial (large cell) group of nuclei and (3) the lateral (small cell) group of nuclei - the reticular neurons is their farflung axonal connections - individual reticular neurons project to the hypothalamus, thalamus, cerebral cortex, cerebellum, and spinal cord (making the reticular neurons ideal for governing the arousal of the brain as a whole)

What is memory?

- the storage and retrieval of information - essential for learning and incorporating our experiences into behavior and are part and parcel of our consciousness - different kinds of memory: declarative (fact) memory (names, faces, words, and dates), procedural (skills) memory (piano playing), motor memory (riding a bike), and emotional memory (your pounding heart when you hear a rattlesnake nearby)

In what segmental levels of the cord are the lateral horns located?

- the thoracic and superior lumbar segments

What is the septum pellucidum?

- thin median membrane that separates the lateral ventricles

Where are the cell bodies of motor neurons located?

- ventral (anterior) horns

What are the major functions of the hypothalamus?

- vital to overall homeostasis (main visceral control center of body) - controls the autonomic nervous system (ANS) - initiates physical responses to emotions => perceives pleasure, fear, rage, sex drives - regulates body temperature - regulates food intake - regulates water balance and thirst - regulates sleep-wake cycles - controls endocrine system function (releasing and inhibiting hormones)

What causes the cervical and lumbar enlargements?

- where the nerves serving the upper and lower limbs arise

Identify and contrast the four frequency classes of brain wave seen in an EEG

1) Alpha waves (8-13 Hz) - awake but relaxed (calm, relaxed state of wakefulness) - relatively regular and rhythmic - low amplitude - synchronous waves - brain = "idling" 2) Beta waves (14-30 Hz) - awake, alert (mentally alert, as when concentrating on some problem or visual stimulus) - rhythmic - less regular than alpha - higher frequency 3) Theta waves (4-7 Hz) - common in children - uncommon in awake adults but may appear when concentrating - more irregular 4) Delta waves (4 Hz or less) - deep sleep and when reticular activating system is suppressed (i.e., during anesthesia) - high amplitude waves - indicate brain damage in awake adults

Identify and describe the two most common types of neural tube defects.

1) Anencephaly - results from the failure to close of the anterior neural tube (always fatal) 2) Spina bifida - results from the failure to close of the posterior neural tube (cleft spine)

Name and describe the function of the three different types of fiber tracts in the brain.

1) Association: - connect different parts of the same hemisphere - Short: connect adjacent gyri - Long: bundled into tracts and connect different cortical lobes - run horizontally 2) Commissural: - connect corresponding gray areas of the two hemispheres - allow the 2 hemispheres to function as a whole - largest = corpus callosum - less prominent = anterior and posterior commissures - run horizontally 3) Projection: - either enter the cerebral cortex from lower brain or cord centers or descend from the cortex to lower areas (connect higher brain to lower brain) - sensory information reaches the cerebral cortex and motor output leaves through these projection fibers - tie the cortex to the rest of the nervous system and to the body's receptors and effectors - run vertically

Identify and describe the function of the main visceral motor nuclei of the medulla.

1) Cardiovascular center - includes the cardiac center, which adjusts the force and rate of heart contraction to meet the body's needs, and the vasomotor center, which changes blood vessel diameter to regulate blood pressure 2) Respiratory center - generate the respiratory rhythm and (in concert with pontine centers) control the rate and depth of breathing 3) Various other centers - additional centers regulate activities like vomiting, hiccuping, swallowing, sneezing, and coughing

Determine the appropriate techniques to assess cerebral functional sensory areas, specifically the visual, auditory, olfactory and vestibular cortices.

Primary Visual Cortex - Snellen chart (read smallest line, if more than half of line is correct, patient passes the test) - Use red and green lines to test for color blindness Primary Auditory Cortex - Rinne and Weber test (tuning fork- test if patient can hear vibrations bilaterally) Primary Olfactory Cortex - Sniff test (put different scents under nose with nostrils occluded) => cinnamon, pepper, alcohol swabs, coffee beans Vestibular (balance) - heel to toe test (close eyes and put arms out to test if straight/wobbly)

What structures make up the limbic system?

a) Cingulate gyrus, parahippocampal gyrus, dentate gyrus b) Hippocampus and amygdala (amygdaloid body) c) parts of several nuclei of the thalamus and hypothalamus *Limbic system structures communicate via the fornix and other tracts (i.e., fiber tracts)*

What type of sensory information is carried by the anterior spinothalamic tract? by the lateral spinothalamic tract?

Anterior spinothalamic tract: - relays crude touch, pressure, tickle, itch, and pain sensations to the thalamus - transmits impulses to opposite side of brain for interpretation by somatosensory cortex Lateral spinothalamic tract: - relays pain and temperature sensations to the thalamus - transmits impulses to opposite side of brain for interpretation by somatosensory cortex

What type of efferent information is carried by the lateral corticospinal tracts? by the anterior corticospinal tracts? by the corticobulbar tracts?

Lateral - control muscles of the extremities Anterior - control muscles of the neck and part of the trunk Corticobulbar - LMNs control precise, voluntary movements of muscles in face and neck

Identify and describe the direct (pyramidal) tracts, including location of upper and lower motor neurons of the tract and level at which decussation occurs.

Lateral corticospinal (=> anterior horns of the spinal cord): fibers decussate in medullary pyramids - UMNs: gray matter of cerebrum - LMNs: anterior horn of lumbar spinal cord Anterior corticospinal (=> anterior horns of the spinal cord): fibers descussate at level of exit from the cord - UMNs: gray matter of cerebrum - LMNs: anterior horn of lumbar spinal cord Corticobulbar (=> nuclei of cranial nerves in brain stem): - UMNs: axons terminate in motor nuclei 9 pairs of cranial nerve (III-VII) and (IX-XII) - LMNs: fibers carried in cranial nerves

What is meant by the term hemispheric (or cerebral) lateralization? by the term cerebral dominance?

Lateralization: division of labor between the hemispheres; each hemisphere has abilities not completely shared by its partner Dominance: indicates the hemisphere that is dominant for or controls language

What is the main function of the thalamus? other functions?

Main function: - relays sensory information (THE relay station for information coming into the cerebral cortex) - information is sorted out and "edited" Other functions: - plays a key role in mediating sensation, motor activities, cortical arousal, learning, and memory (receives inputs that help regulate emotion and visceral function, instructions that help direct the activity of the motor cortices from the cerebellum and basal nuclei, and inputs for memory or sensory integration)

What is located in the lateral horns?

- cell bodies of autonomic (sympathetic division) motor neurons that serve visceral organs

Describe the organization of the white matter of the cord.

- composed of myelinated and nonmyelinated nerve fibers that allow communication between different parts of the spinal cord and between the cord and brain - fibers run in three directions: 1) ascending - up to higher centers (sensory inputs) 2) descending - down the cord from the brain or within the cord to lower levels (motor outputs) 3) transverse - across from one side of the cord to the other (commissural fibers) - ascending and descending tracts make up most of the white matter - white matter on each side of the cord is divided into three white columns or funiculi (dorsal, lateral, and ventral funiculus) - each funiculus contains several tracts, and each tract is made up of axons with similar destinations and functions

Function: Primary motor cortex

- controls *voluntary contractions* of specific muscles or groups of muscles on the *opposite side* of the body

What are the major functions of the dominant hemisphere?

- controls language abilities, math, and logic - works when we compose a sentence, add numbers, memorize a list - most people with left cerebral dominance are right-handed (left-handed people are more likely to have co-dominance b/w the hemispheres)

Function: Frontal eye field

- controls voluntary scanning movements of the eye

What type of sensory information is carried by the spinocerebellar tracts?

- convey information about muscle/tendon stretch to the cerebellum to coordinate skeletal muscle activity

What are the functions of the cerebellum?

- coordinates skeletal muscular activity - helps to smooth skilled movements - regulates posture and balance - integrates sensory input by comparing intended movement with actual movement - functions at an unconscious level and does not directly stimulate skeletal muscles - injury results in ataxia, a condition marked by loss of muscle tone and muscle coordination - plays a role in thinking, language, and emotion

What are the functions of the limbic system?

- emotional, or affective (feelings), brain - establish emotional state (ex. happy, sad, grief-stricken, angry) - hippocampus/amygdaloid body: plays a role in memory (storage and retrieval)

What cells produce CSF?

- ependymal cells of the choroid plexus (within each ventricle produces CSF)

What structural features create the blood-brain barrier?

- exceptionally impermeable tight junctions between capillary endothelial cells 1) endothelium of capillary wall 2) a relatively thick basal lamina surrounding the external face of each capillary 3) the bulbous "feet" of astrocytes clinging the the capillaries

Describe the general structure of the spinal cord, with reference to size, the gray matter, white matter, meninges and spaces

- extends from the foramen magnum of the skull to the first or second lumbar vertebra, just inferior to the ribs - two-way conduction pathway to and from the brain - major reflex center - protected by bone, meninges, and cerbrospinal fluid - the single-layered spinal dura mater is not attached to the bony walls of the vertebral column - between the bony vertebrae and the spinal dura mater is an epidural space filled with soft padding of fat and a network of veins - cerebrospinal fluid fills the subarachnoid space between the arachnoid and pia mater meninges - gray matter located inside, white matter outside

What is the reticular formation? Where is it located?

- extends through the central core of the medulla oblongata, pons, and midbrain - it is composed of loosely clustered neurons in what is otherwise white matter - collection of 100+ nuclei and other connections in the dorsal part of the brain stem

What are the structural outcomes of the fact that the brain develops within a restricted space?

- folds up to occupy the available space 1) the midbrain and cervical flexures => move the forebrain toward the brainstem 2) posterior and lateral growth of cerebral hemispheres => take a horseshoe-shaped course and grow posteriorly and laterally => almost completely envelop the diencephalon and the midbrain 3) Surface convolutions (sulci and gyri) => the cerebral hemispheres crease and fold into convolutions => dramatically increase surface area to pack in more neurons

What is the function of CSF?

- found in and around the brain and spinal cord - forms a liquid cushion that gives buoyancy to CNS structures - effectively reduces brain weight by 97% and prevents the delicate brain from crushing under its own weight

What separates the pons from the cerebellum?

- fourth ventricle - Aqueduct of Sylvius

What are the general functions of the basal nuclei?

- functionally associated with the subthalamic nuclei (located in the lateral "floor" of the diencephalon) and the substancia nigra of the midbrain - receive input from the entire cerebral cortex, subcortical nuclei, and each other - influence muscle movements directed by the primary motor cortex - have no direct access to motor pathways - participate in emotion and cognition, learning and behavior, and "activity selection" for motor function - filter out incorrect/inappropriate responses and pass only the best responses to the cortex - disorders: Parkinson's and Huntington's

What are the basal ganglia (aka basal nuclei)?

- group of subcortical nuclei - third basic region of each hemisphere - collection of nuclei found on both sides of the thalamus

Describe the structure & function of a choroid plexus. Where are the choroid plexuses located?

- hang from the roof of each ventricle and form the CSF - frond-shaped clusters of broad, thin-walled capillaries enclosed first by mater and then by a layer of ependymal cells lining the ventricles - choroid plexus ependymal cells are joined by tight junctions and have ion pumps that allow them to filter and actively transport only certain ions across their membranes into the CSF pool - help cleanse the CSF by removing waste products and unnecessary solutes

What region of the diencephalon serves as a link between the nervous and endocrine systems?

- hypothalamus

What structures are included in the diencephalon?

- hypothalamus - thalamus (80%) - epithalimus

Which is the dominant hemisphere for most people?

- in about 90% of people, the left hemisphere is dominant

What structures comprise the basal nuclei?

- includes the caudate nucleus, putamen (lateral lentiform nucleus), and globus pallidus (medial lentiform nucleus, closer to the thalamus)

Function: Somatosensory association area

- integrates sensory inputs (temperature, pressure) relayed to it via the primary somatosensory cortex to produce of an object being *felt: its size, texture, and relationship to its parts* - functions in integrating and interpreting sensory inputs, especially touch sensations

Function: Vestibular cortex

- involved in conscious awareness of balance (position of head in space)

Function: Visceral sensory area

- involved in conscious perception of the visceral sensations, upset stomach, full bladder

Function: Auditory association area

- involved in perception/interprets characteristic of sound (pitch, rhythm, loudness, location)

Function: Gustatory cortex

- involved in pereceiving taste stimuli (from throat or tongue)

What happens in the decussation of the pyramids?

- just above the medulla-spinal cord junction, most of these fibers cross over to the opposite side before continuing into the spinal cord (called decussation) - as a result of this crossover, each cerebral hemisphere chiefly controls the voluntary movements of muscles on the opposite side of the body

What is the function of the arachnoid granulations?

- knoblike projections of the arachnoid mater that protrude superiorly through the dura mater and into the superior sagittal sinus - the granulations absorb CSF into the venous blood of the sinus

What are the pyramids? Where are they located?

- large bulges on the anterior surface of the medulla, containing descending motor tracts - longitudinal ridges formed by the corticospinal and corticobulbar tracts

Describe the general structure of the cerebellum.

- large mass of tissue located on the dorsal surface below the occipital lobes and posterior to the pons and medulla - separated from the cerebrum by the transverse fissure and tentorium cerebelli (extension of the dura matter) - cortex of the cerebellum - thin superficial layer of gray matter and deep arbor vitae (pattern of white matter) - bilaterally symmetrical, connected by vermis - surface is heavily convoluted with fine, transversely oriented gyri known as folia - deep fissures subdivide each hemisphere into anterior, posterior, and flocculondular lobes - connected to the brain stem by 3 cerebellar peduncles

Identify the specific ascending pathways.

- lemniscal, or dorsal column, medial pathways (formed by tracts in the dorsal white column called fasciculus cuneatus and fasciculus gracilis)

What are the major functions of the non-dominant hemisphere?

- more free-spirited - involved in visual-spatial skills, intuition, artistic and musical skills, creativity

Describe the characteristics of rapid eye movement sleep, including mention of typical EEG pattern and general physiological characteristics in your description.

- most of the skeletal muscles are actively inhibited (except ocular muscles and diaphragm) and go limp - most dreaming occurs - the flitting eye movements are following the visual imagery of our dreams - temporary paralysis prevents us from acting out our dreams

Which of the meninges adheres to the external surface of the brain & spinal cord?

- pia mater

What gland produces & secretes melatonin? What is the function of this hormone?

- pineal gland - melatonin is a sleep-inducing signal and antioxidant

Function: Posterior association area

- plays a role in *recognizing patterns and faces,* localizing us and out surroundings in space, and binding different sensory inputs into a coherent whole

Function: Affective language area

- present in the opposite area of Broca's and Wernicke's - nonverbal components of language

What is the function of the blood-brain barrier?

- protective mechanism that helps maintain the brain's stable environment

Function: Primary somatosensory cortex

- receives information from the general (somatic) *sensory* receptors in the skin and from the proprioceptors (position sense receptors) in *skeletal muscles, joints, and tendons*

Function: Primary auditory cortex

- receives input for the cochlea (hearing apparatus) of inner ear regarding *pitch, loudness, location*

Function: Visual association area

- receives input from the primary visual cortex and the thalamus - interprets visual stimuli (color, form, movement) and compares it to past experiences

Function: Olfactory cortex

- receives input related to smell and functions in conscious awareness of odors - not relayed by the thalamus

Function: Primary visual cortex

- receives sensory input regarding shape, color, and movement

Function: Premotor cortex

- seems to be involved in *planning movements* and in *controlling learned, skilled movements* (playing a musical instrument) - selects and sequences basic motor movements into more complex tasks

In what meningeal space does CSF circulate?

- subarachnoid space of the arachnoid mater

What are the dural venous sinuses? How are they formed? In what part of the CNS are they located? What is their function?

- the brain's two dural layers (periosteal and meningeal) fuse together exept in certain areas, where they separate to enclose dural venous sinuses - part of the dura mater - collect venous blood from the brain and direct it into the internal jugular veins of the neck

What is the general function of each of the following structures located in the midbrain? - Cerebral peduncles - Substantia nigra - Red nucleus - Cerebral aqueduct - Corpora quadrigemina: superior colliculus (pl. colliculi) and inferior colliculus (pl. colliculi)

*Cerebral peduncles ("little feet of the cerebrum"):* - form vertical pillars that hold up the cerebrum - contain large pyramidal (corticospinal) motor tracts, which are descending to the cord *Substantia nigra (R. & L.):* - dark color reflects a high content of melanin pigment (precursor for NT dopamine) - regulate activity in basal nuclei - play a role in Parkinson's disease progression (degeneration of the dopamine-releasing neurons of the substantia nigra) *Red nucleus (R. & L.):* - reddish hue due to its rich blood supply and the presence of iron pigment in its neurons -some cause limb flexion - embedded in the reticular formation (a system of small nuclei scattered through the core of the brain stem) - allows for coordinated movement - nerve fibers extend from the cerebrum to cerebellum *Cerebral aqueduct:* - hollow passageway that connects the third and fourth ventricles *Superior cerebellar peduncles:* - connect midbrain with cerebellum *Corpora quadrigemina:* - largest midbrain nuclei - four domelike protrusions of the dorsal midbrain surface - Superior colliculi: visual reflex centers that coordinate head, eye, and neck movement - Inferior colliculi: auditory reflex centers that coordinate movements of the head and trunk

Name the neurons which comprise the ascending (i.e., sensory) pathways. Where are the cell bodies of each type of neuron located?

*Consist of 2 or 3 successive neurons* - First order: => cell bodies located in ganglia (dorsal root or cranial) -- starting outside CNS in PNS (sensory comes from outside) - Second order: => cell bodies lie in the dorsal horn of the spinal cord or in medullary nuclei - Third order: => located in the thalamus (except for spinocerebellar)

Locate the first-, second-, and third-order neurons of the spinothalamic tracts. Where do these tracts decussate?

*both tracts decussate at/near their level of cord entry* - first-order neurons: conduct impulses from the cutaneous receptors of the skin and from proprioceptors to the spinal cord or brain stem, where they synapse with second-order neurons - second-order neurons: reside in the dorsal horn of the spinal cord or in medullary nuclei; transmit impulses to the thalamus or to the cerebellum where they synapse - third-order neurons: relay impulses to the somatosensory cortex of the cerebrum (none in the cerebellum)

How many periods of REM sleep (on average) does an adult experience per night?

- 4 or 5 periods of REM sleep

Function: Prefrontal cortex

- AKA anterior association area - very complicated processing - involved with *intellect, complex learning abilities (cognition), recall, personality* - receives input from many regions

Function: Broca's area

- AKA motor speech area - functions in translating thoughts to speech *(producing speech)* - preparing to speak and thinking about (planning) many voluntary movements other than speech

What is the primary EEG wave form during periods when an adult is alert and concentrating and problem-solving? when one is alert and relaxed?

- Beta waves - Alpha waves

What important structures are located in the pons?

- Deeper longitudinal tracts that connect higher brain centers and the spinal cord - Middle cerebellar peduncles (connect the pons with the corresponding side of the cerebellum) - CNs V-VII (nuclei of 3 pairs) - Pneumotaxic centers - Apneustic centers *D*on't *M*ake *C*onnie *P*issed, *A*lright?

Describe the pattern of NREM and REM sleep over one sleep period (i.e., during one night).

- During the first 30-45 minutes of the sleep cycle, we pass through the first two stages of NREM sleep and into NREM stages 3 and 4 (slow-wave sleep) - As we pass through these stages and slip into deeper sleep, the frequency of the EEG waves declines, but their amplitude increases; blood pressure and heart rate also progressibly decrease - About 90 minutes after sleep begins, after reaching NREM stage 4, the EEG pattern changes abruptly, becomes very irregular and appears to backtrack quickly through the stages until alpha waves (more typical of awake state) reappear, indicating the onset of REM sleep - Oxygen use by the brain is tremendous during REM --greater than during the awake state

Generally speaking, where is the limbic system located?

- a group of structures located on the medial aspect of each cerebral hemisphere and diencephalon - its cerebral structures encircle the upper part of the brain stem

What is sleep?

- a state of partial unconsciousness from which a person can be aroused by stimulation - for the most part, cortical activity is depressed during sleep, but brain stem functions continue (i.e., control of respiration, heart rate, and blood pressure) - the brain remains active and oxygen consumption resembles that of the waking state

Identify the nonspecific ascending pathways.

- anterior and lateral spinthalamic tracts *These tracts carry inputs from many different types of sensory receptors*

What type of sensory information is carried by the fasciculi cuneatus? by the fasciculi gracilis?

- associated with receptors for conscious proprioception, fine, and discriminative touch, pressure, and vibration 1) Fasciculi cuneatus - carries impulses to upper body 2) Fasciculi gracilis - carries impulses to lower body

Identify and describe the structures and/or materials which protect the brain & spinal cord.

- bone (the skull) - membranes (the meninges) - watery cushion (cerebrospinal fluid) - blood brain barrier protects the brain from harmful substances in the blood

On assessment of the newborn with spina bifida, what are possible findings?

- bowel incontinence - bladder muscle paralysis (which promotes UTIs and kidney failure) - lower limb paralysis

What is located in the dorsal root ganglia?

- cell bodies of associated sensory neurons

Locate the first-, second-, and third-order neurons of the fasciculus cuneatus and fasciculus gracilis. Where do these tracts decussate?

1) Dorsal root ganglia - carry impulses to medulla and synapse with second order neurons 2) Nucleus cuneatus/gracillis - decussate in medulla and enter medial lemniscus on contralateral side of the cord and extend to thalamus 3) Thalamus - carries signal to specific region of the somatosensory cortex of the brain

Locate the first- and second-order neurons of the anterior and posterior spinocerebellar tracts. Explain why these tracts carry sensory information from one side of the body to the ipsilateral side of the cerebellum.

1) Dorsal root ganglia - synapse at level of entry to the cord 2) Dorsal horn - carry signal to thalamus *Carry input to ipsilateral cerebellum* - either NO decussation (posterior spinocerebellar) or TWO decussations (anterior spinocerebellar) in the pathway to end up on the same side of the cerebellum

List the meninges and spaces in order (from superficial to deep, or vice versa).

1) Dura mater (falx cerebri, falx cerebelli, tentorium cerebelli) => periosteal layer => meningeal layer 2) Arachnoid mater => arachnoid granulations => subdural space => subarachnoid space 3) Pia mater

Describe the embryologic origins of the brain, beginning with formation of the neural plate.

1) Embryo begins as a flat disk with 3 distinct tissue layers: endoderm, mesoderm, ectoderm 2) Neurulation: formation of the neural tube (all of the CNS derives from the neural tube) --- Formation of the neural plate --- Neural plate develops into neural tube ***Brain formation begin as an embryonic structure called the neural tube*** 3) Ectoderm begins to thicken, forming the neural plate 4) Neural plate rapidly begins to invaginate - forms a groove which is surrounded on both sides by raised edges called neural folds 5) Neural folds fuse, forming the neural tube 6) Central cavity of the neural tube is called the neurocoel (will ultimately become the central canal, ventral body cavity, cerebral aqueduct) 7) As the neural folds come together, some neural ectoderm is pinched off and moves to a position just lateral to the neural tube --forming the neural crest (all PNS derives from neural crest)

Identify the factors that can influence memory consolidation (i.e., transfer from STM => LTM) and describe their effect.

1) Emotional state - learn best when we are alert, motivated, surprised, aroused - norepinephrine, a NT involved in memory processing of emotionally charged events, is released when we are excited or "stressed out" 2) Rehearsal - repetition 3) Association - tying "new" information to "old" information already stored in our LTM 4) Automatic memory - not all impressions that become part of LTM are consciously formed

Name the five lobes of the cerebrum and identify the sulci or fissures that separate one lobe from another.

1) Frontal lobe 2) Parietal lobe 3) Occipital lobe 4) Temporal lobes 5) Insula - Central Sulcus: separates the frontal and parietal lobe - Parieto-Occipital Sulcus: separates the parietal and occipital lobe - Lateral Sulcus: outlines the temporal lobe and separates it from the parietal and frontal lobe

Name and identify the location of the four functional zones of gray matter (present on each side of the cord).

1) Gray commissure: lateral gray masses connected by a crossbar of gray matter; encloses the central canal 2) Dorsal (posterior) horns: two dorsal projections of the gray matter; form columns of gray matter that run the entire length of the spinal cord 3) Ventral (anterior) horns: two ventral projections of the gray matter; form columns of gray matter that run the entire length of the spinal cord 4) The thoracic and superior lumbar segments of the spinal cord: have an additional pair of gray matter columns called the small lateral horns

Name the ventricles of the brain. Describe the location of each ventricle and identify the structures that connect the ventricles.

1) Lateral Ventricles - pair => one deep within each cerebral hemisphere - large C-shaped chambers that reflect pattern of cerebral growth - lie close together anteriorly - separated by only a thin median membrane called septum pellucidum 2) Third Ventricle - narrow - each lateral ventricle communicates with the narrow third ventricle in the diencephalon via a channel called the interventricular foramen 3) Fourth Ventricle - continuous with the third ventricle via the canal-like cerebral aqueduct that runs through the midbrain - lies in the hindbrain dorsal to the pons and superior medulla - continuous with the central canal of the spinal cord inferiorly

Identify the three major regions (levels) of the brain stem.

1) Midbrain 2) Pons 3) Medullary Oblongata

What are the two main types of sleep?

1) Non-rapid eye movement (NREM) sleep 2) Rapid eye movement (REM)

Within what lobe or region of the cerebrum are each of the above areas (#13) located?

1) Primary motor cortex - frontal lobe in the precentral gyrus 2) Premotor cortex - frontal lobe, just anterior to precentral gyrus 3) Broca's area - frontal lobe, just above the lateral sulcus and anterior to the inferior portion of the premotor cortex 4) Frontal eye field - frontal lobe 5) Primary auditory cortex - superior part of temporal lobe, near lateral cerebral sulcus 6) Auditory association area - inferior and posterior to the primary auditory cortex 7) Prefrontal cortex - anterior portions of the frontal lobe 8) Posterior association area - parts of temporal, parietal, and occipital lobes 9) Primary somatosensory cortex - postcentral gyrus of each parietal lobe 10) Somatosensory association area - just posterior to the primary somatosensory cortex 11) Primary visual cortex - extreme posterior tip and medial surface of the occipital lobe at the calcarine sulcus (note: medial surface of the occipital lobe is in the logitudinal fissure) 12) Visual association area - surrounds the primary visual cortex in the occipital lobe 13) Olfactory cortex - primarily in the medial aspect of the tempral lobe 14) Gustatory cortex - mainly in the insula, just above the lateral cerebral sulcus and deep to the temporal lobe 15) Vestibular cortex - posterior insula 16) Visceral sensory area - surrounds primary visual cortex in the occipital lobe 17) Affective language area - opposite side of Broca's and Wernicke's area - Frontal: primary motor cortex, premotor cortex, Broca's area, frontal eye field, prefrontal cortex - Parietal: primary somatosensory cortex, somatosensory association cortex - Occipital: primary visual cortex, visual association area - Temporal: primary auditory cortex, auditory association area, olfactory cortex - Insula: gustatory cortex, visceral sensory area, vestibular/equilibrium cortex

Identify and describe the main categories of long-term memory.

1) Procedural memory - responsible for knowing how to do things (i.e., memory of motor skills) - does not involve conscious thought - ex. knowledge of how to ride a bicycle, walk, talk 2) Semantic memory - storing information about the world - involves conscious thought - knowledge about the meaning of words and general/common knowledge - ex. colors, capitals of countries 3) Episodic memory - storing information about events that we have experienced in our lives - involves conscious thought - ex. memory of the 1st day of school

Identify the adult brain structures associated with each of the three primary brain vesicles.

1) Prosencephalon (forebrain) - divides into: (a) Telencephalon => Adult brain structures: cerebrum (cerebral hemispheres, cortex, white matter, basal nuclei) (b) Diencephalon => Adult brain structures: thamalus, hypothalamus, epithalamus, retina 2) Mesencephalon (midbrain) - does not divide => Adult brain structures: brain stem: midbrain 3) Rhombencephalon (hindbrain) - divides into: (a) metencephalon => Adult brain structures: brain stem: pons; cerebellum (b) myelencephalon => Adult brain structures: brain stem: medulla oblongata

Identify and tell the difference between the three types of spina bifida

1) Spina bifida occulta - closed neural tube - least serious - dimple or path of hair over nonfusion - no external manifestations 2) Meningocele - open spinal defect - filled with cerebrospinal fluid and meninges 3) Myelomeningocele - most severe - open spinal defect - cyst that may contain portions of the spinal cord and spinal nerve roots (protrude through the opening) *larger cyst = contains more neural structures*

Describe the path of CSF circulation, beginning at the lateral ventricles.

1) The choroid plexus of each ventricle produces CSF 2) CSF flows through the ventricles and into the subarachnoid space via the median and lateral apertures of the fourth ventricle 3) As CSF flows through the subarachnoid space, the long cilia of the ependymal cells help keep the CSF in constant motion 4) In the subarachnoid space, CSF bathes the outer surfaces of the brain and spinal cord. 5) CSF reurns to the blood (absorbed) in the dural venous sinuses via the arachnoid granulations

Distinguish between CVAs (cerebrovascular accidents or strokes) and TIAs (transientischemic attacks). What is the effect of each on brain function?

CVAs: - single most common nervous system disorder and the third leading cause of death in North America - AKA stroke - occurs when blood circulation to a brain area is blocked and brain tissue dies of ischemia, a reduction of blood supply that impairs the delivery of oxygen and nutrients - most common cause = blood clot that blocks a cerebral artery - many who survive are paralyzed on one side of the body (hemiplegia) - others commonly exhibit sensory deficits or have difficult understanding or vocalizing speech TIAs: - temporary episodes of reversible cerebral ischemia ("incomplete" stroke) - last from 5-50 minutes - characterized by temporary numbness, paralysis, or impaired speech - "red flags" = warning of impending, more serious CVAs

What is a concussion? Distinguish between concussion and contusion.

Concussion: - an alteration in brain function, usually temporary, following a blow to the head - victim may be dizzy or lose consciousness Contusion: - more serious concussion in which the brain is bruised and permanent neurological damage occurs - in cortical contusions, the individual may remain conscious

From what primary germ layer does all nervous tissue originate?

Ectoderm

What single factor can prevent most cases of neural tube defects?

Folic acid in maternal diet

What does gray matter comprise? white matter?

Gray matter: - neuronal cell bodies and their dendrites White matter: - myelinated nerve fibers

What is the role of the hypothalamus and the RAS relative to sleep and sleep-wake cycles?

Hypothalamus: - responsible for the timing of the sleep cycle - suprachiasmatic nucleus (a biological clock) regulates its preoptic nucleus (a sleep-inducing center) - Hypothalamic neurons: just before we wake, these neurons release peptides called orexins, which act as "wake-up" chemicals RAS centers: - help maintain the awake state but also mediate some sleep stages, especially dreaming sleep - by inhibiting the brain stem's reticular activating system, the preoptic nucleus puts the cerebral cortex to sleep

Identify the stages of memory and describe the characteristics of each.

Short-term Memory (STM): - working memory - preliminary step - the power that lets you look up a telephone number, dial it, and then never think of it again - limited to 7 or 8 chunks of information (such as digits of a telephone number or the sequence of words in an elaborate sentence) - STM serves as a temporary holding bin for data that we may or may not want to retain Long-term Memory (LTM): - seems to have a limitless capacity - although STM cannot recall numbers much longer than a telephone number, we can remember scores of telephone numbers by committing them to LTM - however, LTMs can be forgotten, and so our memory bank continually changes with time - out ability to store and retrieve memory declines with aging

Identify and describe the characteristics of each of the stages of non-rapid eye movement (NREM) sleep. Be sure to include mention of typical EEG patterns and general physiological characteristics in your descriptions.

Stage 1: Relaxation begins; EEG shows alpha waves; arousal is easy Stage 2: Irregular EEG with sleep spindles (short high-amplitude bursts); arousal is more difficult Stage 3: Sleep deepens; theta and delta waves appear; vital signs decline Stage 4: EEG is dominated by delta waves; arousal is difficult; bed-wetting, night terrors, and sleepwalking may occur

Name the two neurons that comprise the somatic motor pathways. Where are the cell bodies of each type of neuron located?

Upper Motor Neurons (UMNs) - pyramidal cells of motor cortex and other neurons in the subcortical nuclei - regulate muscle tone, posture, and balance - synapse w/ lower motor neuron Lower Motor Neurons (LMNs) - motor/alpha-motor; anterior horn of the cord or in cranial nerve or nuclei of the brain stem - axons extend through peripheral nerves to skeletal muscles

In parts of the brain surrounding the third & fourth ventricles, the blood-brain barrier breaks down (i.e., there are relatively loose tight junctions between ependymal cells and between endothelial cells in capillary walls). We say that these regions are not "under the blood-brain barrier" and call the affected areas circumventricular organs (CVOs). What is the functional significance of the CVOs? Identify the main CVOs.

Vomiting center: - monitors the blood for poisonous substances Hypothalamus: - able to sample the chemical composition of blood - needs to be exposed to osmolarity imbalances and increased temperature