Marieb Anatomy + Physiology Chapter 12: The Central Nervous System

Brain Structure Involved in Memory

- Specific pieces of each memory are thought to be stored in nearby regions of the brain that need them so new inputs can be quickly associated with the old. - Different types of memory are created in different parts of the brain

Gyri

Elevated ridges of tissue in the cerebral cortex. Seperated by shallow grooves called SULCI

Cervical + Lumbar Enlargements

Enlargements of the spinal cord in the lumbar + cervical regions

Osmoreceptors

- Neurons located in the hypothalamus that regulate thirst. - When thirsty, osmoreceptors excite hypothalamic nuculi, antidiuretic hormone (ADH) is released from the kidneys from the posterior pituitary causing the kidneys to retain water.

Paraplegia

- Occurs as a result of damage to the transection (cross section) of the spinal cord between T1 + L1 - Both lower limbs are paralyzed

Biological clock

Suprachiasmatic Nucleus (contains the preoptic nucleus)

Filum Terminale

A fibrous extension of the conus covered by pia mater, extending inferiorly from the conus medullaris to the coccyx where it ANCHORS the spinal cord so it is not jostled by body movements

PARESTHESIAS

Abnormal sensations that occur as a result of damage to the spinal cord

Contralateral

Opposite

Cephalization

An elaboration of the ROSTRAL (anterior) portion of CNS along with an increase in the numer of neurons in the head.

Rostral

Anterior

Epithalamus

- One of three parts of the DIENCEPHALON - At the most DORAL part of the diencephalon - Contains the PINEAL GLAND which secretes MELATONIN (sleep inducing signal) - Along with the hypothalamic nuclei, helps regulate sleep wake cycle

Circadian Rhythmm

- 24 hour rhythm - Controlled by the HYPOTHALAMUS: its SUPRACHIASMATIC NUCLEUS ( a biological clock) regulates its PREOPTIC NUCLEUS (sleep inducing center). - The preoptic nucleus puts the cerebral cortex to sleep by INHIBITING the brain stem's reticular activating system (RAS) - RAS centers help maintain the awake state + also mediate some sleep stages especially dreaming sleep

TONIC-CLONIC SEIZURES

(grand mal) Most severe + convulsive. May cause broken bones, loss of bowls + bladder control. Lasts for a few minutes.

ABSENCE SEIZURES

(petit mal) Mild forms in which expression goes blank for a few seconds + consciousness disappears. Usually happen in young children, ending before age 10.

Pia Mater

- "Gentle Mother" - Composed of delicate connective tissue + richly invested with tiny blood vessels - CLINGS tightly to the brain like cellophane wrap. - Small arteries entering the brain carry ragged sheaths of pia matter with them for short distances

Amytotrophic Lateral Sclerosis (ALS)

- "Lou Gehrig's Disease" - Neuromuscular condition that progressively destroys ventral horn motor neurons + fibers of the pyramidal tracts. - As the disease progresses, the sufferer loses the ability to speak, swallow, and breathe. - Death typically occurs within 5 years - Environmental + genetic factors interact to cause ALH. 10% of cases mutations are inherited. Spontaneous mutations are probably involved in the rest.

Dura Mater + its 2 layers

- "Tough Mother" - Strongest meninge - Two layered sheet of fibrous connective tissue - The two layers are FUSED together except in certain areas where tehy separate to enclose DURAL VENOUS SINUSES that collect venous blood from the brain + directs it into the internal jugular veins of the neck - In some areas the meningeal dura mater extend inward to form DURAL SEPTA which form flat partitions which subdivide the cranial cavity to limit excessive movement of the brain. Two Layers: 1.) PERIOSTEAL LAYER- Superficial. Attaches to the inner surface of the skull (its periosteum). NO dural periosteal layer in the spinal cord. 2.) MENGEAL LAYER- Forms the true external covering of the brain + continues caudally in the vetebral canal as the spinal dura mater -

Short-Term Memory

- "Working memory" - Limited to SEVEN or EIGHT chunks of information, such as the digits of a telephone number or sequence of words in an elaborate sentence - 5% of the information taken in my our sensory imputs are commited to STM

Orexins

- "wake up" chemicals released just before we awaken - Peptides released by hypothalamic neurons

Cerebellum: Anatomy

- 11% total brain mass - Protrudes under the occipital lobes of the cerebral hemispheres where it is separated by the transverse cerebral fissure - Bilaterally symmetrical - NO direct connections to the cerebral cortex - The VERMIS connects its 2 apple sized CEREBELLAR HEMISPHERES medially. - The surface is heavily convoluted with transversely oriented pleatlike gyri called FOLIA ("leaves"). - Deep fissures subdivide each hemisphere in to ANTERIOR, POSTERIOR + FLOCCULONODULAR LOBES - Has a thin outer cortex of GREY MATTER - PURKINJE CELLS are large cells with extinsively branched dendrites are the ONLY cortical neurons that send axons through the white matter to synapse with the central nuclei of the cerebellum - ARBOR VITAE ("tree of life") is the pattern of WHITE MATTER that resembles a branching tree - Anterior + posterior lobes have 3 sensory maps of the ENTIRE body + COORDINATE BODY MOVEMENTS - The lateral parts of each hemisphere INTEGRATE information from the association areas of the cerebral cortex + appear to play a role in PLANNING movements rather than EXECUTING them. - The flocculonodular lobes RECEIVE inputs from the equilibrium apparatus of the inner ears + adjust posture to maintain balance

Brain Stem + its 3 Parts

- 2.5% of brain mass - Deep gray matters SURROUNDED by white matter fiber tracts - Also has grey matter embedded in the white matter - Produce the rigidly programmed, automatic behaviors NECESSARY FOR SURVIVAL. - Provides a pathway for fiber tracts running between higher + lower neural centers. - Associated with 10 of the 12 pairs of cranial nerves, so it is heavily involved with innervating the head. 3 Parts: 1.) Midbrain 2.) Pons 3.) Medulla Oblongada

Coma

- Significant UNRESPONSIVENESS to sensory stimuli for an extended period - NOT deep sleep - Brain remains active + oxygen consumption resembles that of the waking state

Spinal Cord

- 42cm (17 inches) long + 1.8cm (3/4 inch) wide - Two way conduction pathway to and from the brain - Protected by bone, meninges + cerebrospinal fluid - SPINAL DURA MATER is NOT attached to the bones fo the vertebral column - EPIDURAL SPACE is between the bony vertebrae + the dura mater. It is a soft padding of fat + a network of veins. - Cerebospinal fluid fills the subarachnoid space between the ARACHNOID + PIA MATER - Spinal cord ENDS between L1 + L2

Cerebral Hemispheres + 3 Basic Regions

- 83% Brain Mass - Superior part of brain - Each cerebral hemisphere has 3 basic regions: 1.) A superficial CEREBRAL CORTEX of GRAY MATTER 2.) Internal WHITE MATTER 3.) BASAL NUCLEI, which are ISLANDS of grey matter situated deep within the white matter

Cerebral Palsy

- A neuromuscular disability in which the voluntary muscles are poorly controlled or paralyzed as a result of brain damage - May be a result of a temporary lack of oxygen during a difficult delivery - May cause spasticity, speech difficulties + other motor impairments + half of victims have seizures, half are mentally retarded and a third have some degree of deafness. - LARGEST single cause of physical disability in children - Affects 3 out of 1000 births

Sleep

- A state of partial unconsciousness from which a person can be aroused by stimulation. - Cortical activity is depressed but BRAIN STEM continues to function. - Environmental monitoring continues to some extent as we can be aroused from sleep (alarm in morning + people who sleepwalk can avoid objects + navigate stairs while truly asleep)

Spinal Shock

- A transient period of functional loss that follows the injury. - It immediately depresses ALL reflex activity CAUDAL to the lesion site - Bowel + bladder reflexes stop, blood pressure falls + all muscles (somatic + visceral) below the injury are paralyzed + insensitive.. - Neural function usually returns within a few hours. - If function does not return in 48 hours, paralysis is permanent in most cases - Anyone with a spinal cord transection (damage to the cross sectioning of the spinal cord) must be watched for symptoms.

Medulla Oblongada: Function + 3 functional groups

- AN autonomic reflex center involved in maintaining body homeostasis - Contains 3 important functional groups: 1.) CARDIOVASCULAR CENTER: Includes the CARDIAC CENTER )adjusts the force + rate of heart contraction to meet the body's needs) + the VASOMOTOR CENTER (changes blood vessel diameter to regulate blood pressure). 2.) RESPIRATORY CENTERS: Generate the respiratory rhythm + control the rate + depth of breathing (with help from the PONS) 3.) VARIOUS OTHER CENTERS: Vomiting hiccuping, swallowing, coughing + sneezing

Dorsal Roots

- Afferent fibers carring impulses from peripheral sensory receptors that fan out as the DORSAL ROOTLETS before they enter the spinal cord. - DORSAL ROOT GANGLION (spinal ganglion) contain the cell bodies of the associated sensory neurons in this enlarged region of the dorsal root

Primary Brain Vesicles

- After the neural tube forms, its anterior (rostral) end begins to expand + constrictions appear that mark off the 3 primary brain vesicles. 1.) PROSENCEPHALON (forebrain) 2.) MESENCEPHALON (midbrain) 3.) RHOMBENCEPHALON (hindbrain)

Fainting

- Also called Syncope - A brief loss in consciousness - Often indicates inadequate cerebral blood flow due to low blood pressure - May follow hemorrhage or sudden emotional stress

Concussion

- Alteration in brain function - Usually temporary following a blow to the head

5 Secondary Brain Vesicles

- Arise from the Primary Brain Vesicles Arising from Prosencephalon (forebrain): 1.) Telencephalon (develops into the CEREBRUM) 2.) Diencephalon (develops into the DIENCEPHALON + the RETINA) Airsing from Mesencephalon (midbrain): 3.) Mesencephalon (develops into the MIDBRAIN in the brain stem) Arising from the Rhombencephan (hindbrain): 4.) Metencephalon (develops into the PONS in the brain stem + the CEREBELLUM) 5.) Myelencephalon (develops into the MEDULLA OBLONGATA in the brain stem)

4 Brain Regions

- Based off the medical scheme 1.) Cerebral hemispheres 2.) Diencephalon (Thalamus, Hypothalamus + Epithalamus) 3.) Brain Stem ( Midbrain, Pons + Medulla Oblongada) 4.) Cerebellum

How Space Constraints Affect Brain Development

- Because the brain grows MORE rapidly than the membranous skull that contains it, it FOLDS UP to occupy the available space. - The MIDBRAIN + CERVICAL FLEXURES move the forebrain toward the brain stem. - The cerebral hemispheres are forced to take a horsehoe-shaped course + grow posteriorly + laterally. As a result, they grow BACK OVER + almost completely envelop the diencephalon + midbrain - By week 26 the growth of the cerebral hemispheres causes their surfaces to crease + fold into convolutions which increases their surface area + allows more neurons to occupy the limited space

Subdural / Subarachnoid hemorrhage

- Bleeding in the subdural / subarachnoid space - Death may result - Individuals are initially lucid and then begin to deteriorate neurologically are probably hemorrhaging intracranially - Blood accumulating in the skull increases intracranial pressure + compresses brain tissue. If the pressure forces the brain stem inferiorly through the foramen magnum, control of blood pressure, heart rate and respiration is lost.

CHOROID PLEXUSES

- Capillaries that hang from the roof of each ventrical + form the CSF. They are enclosed first by the pia mater + then by a layer of ependymal cells lining the ventricles. -- The ependymal cells are joined by tight junctions + have ion pumps that modify the filtrate by actively transporting certain ions across their membranes into the CSF pool. They also help cleanse the CSF. - The long cilia of the ependymal cells help kepp the CSF in constant motion.

Insomnia

- Chronic inability to obtain the QUALITY or AMOUNT of sleep needed to function adequately - Sleep requirements vary from 4 - 9hrs

Cauda Equina

- Collection of nerve roots at the inferior end of the vertebral canal - The shape reflects the fact that during fetal development the vertebral column grows faster than the spinal cord, forcing the lower spinal nerve roots to chase their exit points inferiorly through the vertebral canal.

Vestibular (equilibrium) Cortex

- One of Eight Sensory Areas of the Cerebral Cortex - Part of the cortex responsible for conscious awarenss of balance + the position of the head in space - Located in the posterior part of the insula + adjacent parietal cortex

White Matter in Spinal Cord + Its 3 Directions

- Composed of myelinated + nonmyelinated nerve fibers that allow communication between different parts of the spinal cord + between the cord + brain. Fibers run in 3 Directions: 1.) Ascending: UP to higher centers (SENSORY imputs) 2.) Descending: DOWN to 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 + 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) that are named according to their position (DORSAL, LATERAL< AND VENTRAL FUNICULI)

Meminges + 3 Types

- Connective tissue membranes that lie just extrenal to the CNS - Cover + protect CNS - Protect blood vessels + enclose venous sinuses - Contain cerebrospinal fluid - Form partitions in the skull - Meninx is singular 1.) DURA MATER 2.) ARACHNOID MATER 3.) PIA MATER

Ventricles

- Continuous with one another + with the central canal of the spinal cord - Filled with cerebospinal fluid + lined by EPENDYMAL CELLS - Includes: LATERAL VENTRICLES, SEPTUM PELLUCIDUM, THIRD VENTRICLE, FORTH VENTRICLE - Three openings mark the forth ventricle: the two LATERAL APERTURES + the MEDIAN APERTURE. These apertures connect the ventricles to the subarachnoid space, a fluid filled space surrounding the brain

Amnesia + Two Types

- Damage to the hippocampus + surrounding medial temporal lobe structures on either side results in only slight memory loss - Bilateral destruction causes WIDESPREAD amnesia 1.) ANTEROGRADE Amnesia: Consolidated memories are NOT lost but NEW sensory imputs cannot be associated with old + the person lives in the here + now from that point on 2.) RETROGRADE Amnesia: Loss of memories formed in the DISTANT PAST.

Cerebral White Matter + 3 Fiber Classifications

- Deep matter to the cortical grey area - Responsible for COMMUNICATION between the crebral areas + between the cerebral cortex + lower CNS centers - Largely consist of MYLINATED fibers bundled into large tracts. - Classified according to the direction they run. 3 Classifications: 1.) ASSOCIATION FIBERS: Connect different parts of the SAME hemisphere. Horizontal running fibers. 2.) COMMISSURAL FIBERS: Connect CORRESPONDING gray areas of the two hemispheres. These COMMISSURES allow the two hemispheres to function as a COORDINATED WHOLE. The largest is the CORPUS CALLOSUM. Less prominent are the ANTERIOR + POSTERIOR COMMISSURES. Horizontal running fibers. 3.) PROJECTION FIBERS: Enter the cerebral cortex from lower brain or cord centers or descend from the cortex to lower areas. Sensory information reaches the cerebral cortex + motor output leaves it THROUGH these fibers. The TIE the CORTEX to the REST of the NERVOUS SYSTEM + to the body's receptors + effectors. At the top of the brain stem, the fibers form a band called the INTERNAL CAPSULE that passes between the thalamus + some basal nuclui. Beyon dthat point, the fibers radiate though the white matter to the cortex called the CORONA RADIATA. Cross in the brain stem at the DESSUSSATION OF PYRAMIDS, which creates CONTRA LATERAL CONTROL. Vertically running fibers.

Alar Plate

- Dorsal clusters of neuroblasts that become interneurons during fetal development - Form the white matter of spinal cord

Basal Plate

- Dorsal clusters of neuroblasts that develop into MOTOR NEURONS + sprout axons that grow out to the effector organs during fetal development

Limbic System

- EMOTIONAL, or affective (feelings) brain - A group of structures located on the medial aspect of each cerebral hemisphere + diencephalon. It encircles the upper part of the brain stem - The AMYGDALOID BODY is critical for responding to perceived threats iwth fear or aggression - The CINGULATE GYRUS pay a role in EXPRESSING our emotions through gestures + resolving mental conflicts when we are frusterated - The FORNIX + other fiber tracts LINK limbic structures together - Odors triggering emotional memories originate in the limbic system in the primitive rhinencephalon - Most limbic system output is relayed through the hypothalamus. Because the hypothalamus is the neural clearinghouse for both autonomic (visceral) function + emotional response, it is not surprising that some people under STRESS fall prey to visceral illnesses, such as high blood pressure + heartburn + PSYCHOSOMATIC ILLNESSES. - Communication between the cerebral cortex + limbic system explains why emotions sometimes OVERRIDE logic + conversely why reason can stop us from expressing our emotions in inappropriate situations. - The HIPPOCAMPUS + amygdaloid body also PLAY A ROLE IN MEMORY

Declarative Memory

- Factual Memory - Learns explicit information such as names, faces, words + dates - Related to our CONSCIOUS thoughts + our ability to manipulate symbols + language - When FACT memories are committed to LTM, they are usually filed with the CONTEXT in which they are learned

Huntington's Disease

- Fatal hereditary disorder, strikes during middle age - Mutant huntingtin protein accumulates in brain cells + the tissue dies leading to massive degeneration of the basal nuclei + later the cerebral cortex - Initial symptoms are wild, jerky, almost continuous "flapping" movements called CHOREA. Involuntary movement. - Usually fatal within 15 years of onset of symptoms - The opposite of Parkinson's disease - Treated with drugs that BLOCK dopamine's effects

Lumbar Tap (puncture)

- Getting a sample of cerebrospinal fluid for testing - Enters from the subarachnoid space

Diencephalon + its 3 Parts

- Grey matter areas 1.) Thalamus 2.) Hypothalamus 3.) Epithalamus

Brain Waves + its 4 Frequencies

- How EEGs are recorded - Generated by the synaptic activity at the surface of the CORTEX rather than by action potentials of white matter. - The amplitude reflects the synchronous activity of MANY neurons + NOT the degree of electrical activity of INDIVIDUAL neurons. - Usually they are complex + low amplitude - During sleep, neurons tend to fire SYNCRONOUSLY producing similar high amplitude brain waves. Four Frequencies: 1.) ALPHA WAVES: Regular + rhythmic, low amplitude, synchronous waves. Indicate that the brain is "idling". A calm, relaxed state of wakefulness. 2.) BETA WAVES: Rhythmic, but LESS REGULAR than alpha waves + with a higher frequency. Occur when we are MENTALLY ALERT, as when concentrating on some problem or visual stimulus. 3.) THETA WAVES: Irregular. Common in children. Uncommon in awake adults but may appear when concentrating. 4.) DELTA WAVES: High-amplitude waves see during deep sleep + when the reticular activating system is damped, such as during anesthesia. In awake adults, they indicate brain damage.

Brain Injuries

Brain damage is caused NOT ONLY by localized injury at the site of the blow (COUP injury) but also has a RICOCHETING effect as the brain hits the opposite end of the skull (CONTRECOUP injury).

RINENCEPHALON

- Includes all parts of the cerebrum that receive olfactory signals though mostly devoted to the olfacotry cortex. - During evolution, most of the "old" rhinencephalon has taken on anew functions concerned with EMOTIONS + MEMORY. - It has become part of the "newer" emotional brain called the LIMBIC SYSTEM. - The only portions still devoted to smell are the OLFACTORY BULBS + TRACTS

Brain Death

- Irreversible coma - A dead brain in an otherwise living body

Reticular Formation

- Keeps the brain CONSCIOUS! - Extends though the central core of the medually oblongata, pons + midbrains - Composed of loosely clustered neurons in what is otherwise white matter. - The neurons form THREE borad columns along the length of the brain stem 1.) RAPHE NUCLEI 2.) MEDIAL (large cell) GROUP OF NUCLEI 3.) LATERAL (small cell) GROUP OF NUCLEI - Have far reaching axonal connections which project ot eh hypothalamus, thalamus, cerebral cortex, cerebellum + spinal cord, making reticular neurons ideal for governing the AROUSAL of the brain as a whole - Unless INHIBITED by other brain areas, the RETICULAR ACTIVATING SYSTEM (RAS) send a CONTINUOUS stream of impulses to the cerebral cortex, keeping the cortex alert + CONSCIOUS! + enhancing its excitability - FILTERS out repetitive, familiar or weak signals but UNUSUAL significant or strong impulses do reach consciousness - Between the RAS + crebral cortex disregard perhaps 99% of all sensory stimuli as unimportant. If not the sensory overload would drive us crazy - It is inhibited by SLEEP CENTERS in the hypothalamus + is depressed by alcohol, sleeping pills +tranqilizers - Injury to this part of the brain results in permanent unconsciousness - Helps regulate skeletal + visceral muscle activity

Narcolepsy

- Lapse ABRUPTLY into REM sleep from the awake state - Episodes last about 15 minutes - Can occur without warning + are often triggered by a pleasurable event (good joke, game of poker) - In most patients an emotionally intense experience can trigger CATAPLEXY (a suddenloss of voluntary muscle control similar to that seen during REM sleep). Cataplexy can last seconds to minutes in which the mind is fully conscious but unable to move. - Orexins are selectively destroyed by the patients immune system

Nondeclarative Memory + its 3 Categories

- Less conscious or unconscious memory - Acquired through experience + usually repetition - Do NOT preserve the CIRCUMSTANCES of learning + they are best remembered in DOING 3 Categories: 1.) PROCEDURAL (skills) MEMORY: Piano playing 2.) MOTOR MEMORY: Riding a bike 3.) EMOTIONAL MEMORY: Pounding heart when you hear a rattlesnake nearby

Basal Nuclei

- Located deep WITHIN white matter - INclede: CAUDATE NUCLEUS, PUTAMEN + GLOUS PALLIDUS. - STRIATUM (caudate nucleus + putamen) - Functionally associated with the SUBTHALAMIC NUCLEI + the SUBSTANTIA NIGRA of the midbrain - Reciee input from the entire cerebral cortex + from other subcortical nuclei + each other. - Influence muscle movmentes directed by the primary motor cortex although they have NO DIRECT ACCESS to motor pathways - Play a role in cognition + emotion - Seem to filter out incorrect or inappropriate responses, passing only the best responses to the cortex - Precise role is elusive - NO direct connections to the cerebral cortex

Arachnoid Mater

- Middle menix - Separated from the dura mater by a narrow serous cavity called the SUBDURAL space which contains a film of fluid. Beneath the arachnoid membrane is the wide SUBARACHNOID SPACE which has web like extensions that secure the arachnoid mater to the underlying pia mater. It also contains the cerebrospinal fluid + the largest blood vessels serving the brain. ARACHNOID VILLI protrude superiorly through the dura mater and into the superior saggittal sinus. They absorb cerebrospinal fluid into the venous blood of the sinus.

Slow Wave Sleep

- NREM stages 3 + 4 - FREQUENCY of EEG waves DECLINES, but their AMPLITUDE increases - Blood pressure + heart rate DECREASE - Most nightmares occur during NREM stages 3 + 4

Quadriplegia

- Occurs as a result of damage to the transection (cross section) of the spinal cord in the CERVICAL region - All four limbs are paralyzed

2 Auditory Areas

- One of Eight Sensory Areas of the Cerebral Cortex 1.) PRIMARY AUDITORY CORTEX: - Located in the superior margin of the temporal lobe abuttin gthe lateral sulcus - Sound energy exciting the hearing receptors of the inner ear causes impulses to be transmitted to the primary audiotry cortex where they are INTERPRETED as PITCH, LOUDNESS + LOCATION 2.) AUDITORY ASSOCIATION AREA: - Permits the perception of the sound stimulus, which we "hear" as speech, a scream, music, thunder, noise, etc - Memories of sounds heard in the past appear to be sored here for reference - Wernicke's area includes parts of the auditory cortex

2 Visual Areas

- One of Eight Sensory Areas of the Cerebral Cortex 1.) PRIMARY VISUAL CORTEX: - Located on the extreme posterior tip of the occipital lobe but most of it is buried deep int he CALCARINE SULCUS in the occipital lobe - LARGEST cortical sensory area - Receives visual information that originates on the retina of the eye - Contralateral map of visual space, analoguous to the body on the somatosensory cortex - Damage causes functional blindness 2.) VISUAL ASSOCIATION AREA: - SURROUNDS the primary visual cortex + covers much of the occipital lobe - Communicating with the primary visual cortex, it uses PAST visual experiences to interpret visual stimuli (color, form + movement) enabling us to recognize a flower or a person's face + to appreciate what we are seeing - Damage causes incomprehension of what is visible

Visceral Sensory Area

- One of Eight Sensory Areas of the Cerebral Cortex - Involved in conscious perception of VISCERAL sensations, such as: upset stomach, full bladder + the feeling that your lungs will burst if you hold your breath too long - Located in the cortex of the insula just posterior to the gustatory contrtex

Olfactory Cortex

- One of Eight Sensory Areas of the Cerebral Cortex - Located on the medial aspect of the temporal lobe in the PIRIFORM LOBE which is dominated by the hooklike UNCUS - Afferent fibers from smell receptors in the superior nasal cavities send impulses along the olfactory tracts that are ultimately relayed to the olfactory cortex - Allows us to have conscious awareness of different odors - Part of the primitive RINENCEPHALON which includes all parts of the cerebrum that receive olfactory signals. During evolution, most of the "old" rhinencephalon has taken on anew functions concerned with EMOTIONS + MEMORY. It has become part of the "newer" emotional brain called the LIMBIC SYSTEM. The only portions still devoted to smell are the OLFACTORY BULBS + TRACTS

Encephalitis

Brain inflammation

Somatosensory Association Cortex

- One of Eight Sensory Areas of the Cerebral Cortex - Posterior to the primary somatosensory cortex + has many connections with it - The major function of this area is to integrate sensory inputs (TEMPERATURE, PRESSURE, etc) relayed to it via the primary somatosensory cortex to produce and UNDERSTANDING OF AN OBJECT BEING FELT: its size, texture + the relationship to its parts

Gustatory Cortex

- One of Eight Sensory Areas of the Cerebral Cortex - Region involved in perceiving taste stimuli - Precieves: Sweet, sower, bitter + salty - Located in insula just deep to the temporal lobe

Primary Somatosensory Cortex

- One of Eight Sensory Areas of the Cerebral Cortex - Resides in the postcentral gyrus of the parietal lobe - Neurons receive information from the general (somatic) sensory receptors in the skin + from proprioceptors (position sense receptors) in skeletal muscles, joints + tendons. The neurons then identify the body region being stimulated (using SPACIAL DISCRIMINATION) - Body is represented spatially + upside down according to the site of stimulus imput + the irght hemisphere receives input from the left side of the body - The amount of sensory cortex devoted to a particular body region is related to that region's sensitivity (how many receptors it has) NOT its size - The FACE + FINGERTIPS are the most sensitive body areas, so these regions are the LARGEST parts of the SOMATOSENSORY HOMUNCULUS

Broca's Area

- One of four motor areas of the cerebral cortex - Anterior to the inferior region of the premotor area - Present in ONE hemisphere only (usually the left) - Its a special MOTOR SPEECH AREA that DIRECTS the MUSCLES involved in speech production. - Also becomes active as we PREPARE to speak + even when we think about many voluntary motor activities other than speech

Frontal Eye Field

- One of four motor areas of the cerebral cortex - Anterior to the premotor cortex + superior to Broca's area - Controls VOLUNTARY MOVEMENTS of the EYES

Premotor Cortex

- One of four motor areas of the cerebral cortex - Helps PLAN movements - Selects + sequences basic motor movements into more complex tasks, such as playing a musical instrument or typing - Coordinates movement of several muscle groups either simultaneously or sequentially, mainly by sending activating impulses to the primary motor cortex. - ALSO influences motor activity by supplying about 15% of pyramidal tract fibers

Primary Motor Cortex

- One of four motor areas of the cerebral cortex - Located in the PRECENTRAL GYRUS of the frontal lobe - Large neurons called PYRAMIDAL CELLS allow us to CONSCIOUSLY CONTROL the precise or skilled voluntary movements of our skeletal muscles. Their long axons form MASSIVE voluntary motor tracts called PYRIMIDAL TRACTS or CORTICOSPINAL TRACTS. - Mapped using SOMATOTOPY, in which the body is mapped UPSIDE DOWN with the head at the inferior and lateral part + the toes at the superior and medial part - Most of the neurons control muscles in body areas having the most precise motor control face, tongue + hands. Consequently these regions are disproportionately large in the MOTOR HOMUNCULUS (diagram of somatotopy)

DELTA WAVES

- One of the four brain frequencies of brain waves - High-amplitude waves see during deep sleep + when the reticular activating system is damped, such as during anesthesia. In awake adults, they indicate brain damage.

THETA WAVES

- One of the four brain frequencies of brain waves - Irregular. Common in children. Uncommon in awake adults but may appear when concentrating.

ALPHA WAVES

- One of the four brain frequencies of brain waves - Regular + rhythmic, low amplitude, synchronous waves. Indicate that the brain is "idling". A calm, relaxed state of wakefulness.

BETA WAVES

- One of the four brain frequencies of brain waves - Rhythmic, but LESS REGULAR than alpha waves + with a higher frequency. Occur when we are MENTALLY ALERT, as when concentrating on some problem or visual stimulus.

Prosencephalon

- One of the three primary brain vesicles. - Forebrain - Divides into the following SECONDARY BRAIN VESICLES: TELENCEPHALON (endbrain) + DIENCEPHALON (interbrain) + the METENCEPHALON (afterbrain) + MYELENCEPHALON (spinal brain)

Rhombencephalon

- One of the three primary brain vesicles. - Hindbrain

Mesencephalon

- One of the three primary brain vesicles. - Midbrain

COMMISSURAL FIBERS

- One of three fibers of cerebral white matter - Connect CORRESPONDING gray areas of the two hemispheres. These COMMISSURES allow the two hemispheres to function as a COORDINATED WHOLE. The largest is the CORPUS CALLOSUM. Less prominent are the ANTERIOR + POSTERIOR COMMISSURES. Horizontal running fibers.

ASSOCIATION FIBERS

- One of three fibers of cerebral white matter - Connect different parts of the SAME hemisphere. Horizontal running fibers.

PROJECTION FIBERS

- One of three fibers of cerebral white matter - Enter the cerebral cortex from lower brain or cord centers or descend from the cortex to lower areas. Sensory information reaches the cerebral cortex + motor output leaves it THROUGH these fibers. The TIE the CORTEX to the REST of the NERVOUS SYSTEM + to the body's receptors + effectors. At the top of the brain stem, the fibers form a band called the INTERNAL CAPSULE that passes between the thalamus + some basal nuclui. Beyon dthat point, the fibers radiate though the white matter to the cortex called the CORONA RADIATA. - Cross in the brain stem at the DESSUSSATION OF PYRAMIDS, which creates CONTRA LATERAL CONTROL. - Vertically running fibers.

Thalamus

- One of three parts of the DIENCEPHALON - 80% Diencehalon - Egg shaped nuclei - An INTERTHALAMIC ADHESION connects the nuclei - Greek for "inner room" - RELAY information ENTERING cerebral cortex - Afferent impulses from ALL parts of the body converge on the thalamus + synapse with at least one of its nuclei - Information is sorted out and "edited" - Impulses having to do with simlar functions are relayed as a GROUP via the internal capsule to the appropriate area in the rest of the brain - As AFFERENT impulses reach the thalamus, we have a crude recognition of the sensation as plesant or unpleasant. However, specific stimulus localization + discrimination occur in the crebral cortex. - Plays a ey role in mediating sensation, motor activites, cortical arousal, learning + memory. - Gateway to the cerebral cortex

Hypothalamus + its 7 Chief Roles

- One of three parts of the DIENCEPHALON - Named for its position BELOW the thalamus - Caps the brain stem -MAMMILLARY BODIES paired pealike in the nucli are relay stations in the OLFACTORY pathways. - Between the optic chiasma + mamillary bodies is the INFUNDIBULUM that connects the PITUITARY GLAND to the base of the hypothalamus. - MAIN VISCERAL CONTROL CENTER of the body. - Important to overall body homeostasis 1.) CONTROL THE AUTONOMIC NERVOUS SYSTEM 2.) INITIATE PHYSICAL RESPONSES TO EMOTIONS (rapid heart beat, perceiving pleasure, fear, rage, sweating, etc) 3.) REGULATE BODY TEMPERATURE 4.) REGULATE FOOD INTAKE 5.) REGULATE WATER BALANCE + THIRST 6.) REGULATE SLEEP-WAKE CYCLES 7.) CONTROL ENDOCRINE SYSTEM FUNCTION

Midbrain

- One of three parts of the brain stem - Located between the diencephalon + pons - Contains TWO CEREBRAL PEDUNCLES that contain LARGE pyramidal motor tracts descending toward the spinal cord - Pain supression, visual reflex centers - The CREBRAL AQUEDUCT runs through the midbrain which connects the third + forth ventricles - TECTUM (midbrain's roof) - PERIAQUEDUCTAL GRAY MATTER is involved in PAIN SUPRESSION + links the fear-perceiving amygdaloid body + ANS pathways that control the "fight-or-flight" response. - CORPA QUADRIGEMINA (largest midbrain nuclei) - SUPERIOR COLLICULI is a visual reflec center that COORDINATS head + eye movements when we visually forllow a moving object - INFERIOR COLLICULI are part of the auditory relay from the hearing receptors of the ear to the sensory cortex. Also act in REFLEXIVE RESPONSES to SOUND, such as the STARTLE REFLEX which causes you to move your head to an unexpected sound - SUBSTANTIA NIGRA's dark color reflects a high content of MELANIN pigment, a precursor of dopamine. Functionally linked to the basal nucli. - RED NUCLEUS is deep to the substantia nigra. Red due to the rich BLOOD SUPPLY + presence of iron pigments. RELAY nuclei in some descending motor pathways that effect limb flexion + are embeded in the reticular formation

Pons

- One of three parts of the brain stem - Middle of brain stem - Helps medulla oblongada with breathing - Some pontine nuclei are part of the reticular formation. - Cheifly composed of CONDUCTION TRACTS oriented in 2 directions: 1.) Deep projection fibers run LONGITUDINALLY as part of the pathway between higher brain centers + the spinal cord 2.) Superficial ventral fibers are oriented TRANSVERSELY + DORSALLY forming the MIDDLE CEREBELLAR PEDUNCLES + connect the pons biaterally with the two sides of the cerebellum dorsally. These fibers issue from several PONTINE NUCLEI which relay "conversations" between the motor cortex + cerebellum

Medulla Oblongada: Structure

- One of three parts of the brain stem - Most inferior part of the brain stem, at the level of the foraman magnum of the skull - The central canal of the spinal cord continues upward into the medulla - In the ventral midline are two longitudinal ridges called PYRAMIDS formed by the large pyramidal tracts descending from the motor cortex - Above the medulla-spinal cord junction is a crossover part called the DECUSSATION OF THE PYRAMIDS. Because of this crossover each cerebral hemisphere cheifly controls the voluntary movements of muscles on the opposite side of the body - INFERIOR CEREBELLAR PEDUNCLES are fiber tracts that connect the medulla to the cerebellum - OLIVES are lateral to the pyramids + are caused by the wavy gray matter underlying them called INFERIOR OLIVARY NUCLEI + they relay sensory information on the degree of stretch in muscles + joints to the cerebellum - HYPOGLOSSAL NERVES emerge from the groove between the pyramids + olives on each side - Cranial nerves glosopharyngeal nerves + vagus nerves - VESTIBULOCOCHLEAR NERVES synapse with the COCHLEAR NUCLEI + with the VESTIBULAR NUCLEI in both the pons + medulla that help mediate responses that maintain equilibrium

ANTERIOR ASSOCIATION AREA

- Part of the MULTIMODAL ASSOCIATION AREAS of the cerebral cortex. - In the frontal lobe (PREFRONTAL CORTEX). The most complicated region of all. Involved in INTELLECT, complex LEARNING ABILITIES (cognition), RECALL + PERSONALITY. Contains working memory which is necessary for abstract ideas, judgment, reasoning, persistence + planning. Develop slowly in children, which implies that the prefrontal cortex matures lowly + depends heavily on positive + negative feedback from our social environment. - Tumors or lesions in this area may cause mental + personality disorders including loss of judgement, attentiveness + inhibitions. The affected individual may be oblivious to social restraints.

LIMBIC ASSOCIATION AREA

- Part of the MULTIMODAL ASSOCIATION AREAS of the cerebral cortex. - Includes the cingulate gyrus, parahippocampal gyrus + hoppocampus. Part of the limbic system, the limbic association area provides the EMOTIONAL impact that makes a scene important to us.

POSTERIOR ASSOCIATION AREA

- Part of the MULTIMODAL ASSOCIATION AREAS of the cerebral cortex. - Parts of the temporal, parietal + occipital lobes. Plays role in recognizing patterns + faces + localizing us in our surroundings in space + binding different sensory inputs into a coherent whole. - Tumors or lesions in this area may cause loss of awareness of self in space. They may refuse to wash or dress the side of their body opposite the lesion as "that dosen't belong to me".

Wernicke's Area

- Patients with lesions in this area are able to speak in a nonsensical "word salad" and have difficulty learning language

Broca's Area

- Patients with lesions in this area cause difficulty speaking (+ sometimes cannot write or use sign language)

Long-Term Potentiation (LTP)

- Persistent increase in synaptic strength that has been shown to be cricial for memory information - First identified in hippocampal neurons that uses the amino acid glutamate as a neurotransmitter - NMDA receptor (type of glutamate receptor) acts as a calcium channel + initiate the cellular changes that bring about LTP.

Caudal

- Posterior - Towards the tail

REM Sleep

- Skeletal muscles (except ocular muscles + diaphragm) are actively INHIBITED - Skeletal muscle paralysis prevents us from acting out our dreams - Most dreaming occurs - Oxygen use by the brain is GREATER than in the awake state - Occurs about every 90 minutes - 1st REM lasts about 5-10 minutes - Final REM lasts about 20-50 minutes - Occupies HALF sleeping time in infants to 10 year olds, then stabilizes at about 25%

Preoptic Nucleus

- Sleep inducing center located in the SUPRACHIASMATIC NUCLEUS in the HYPOTHALAMUS - Puts the cerebral cortex to sleep by INHIBITING the brain stem's reticular activating system (RAS) - RAS centers help maintain the awake state + also mediate some sleep stages especially dreaming sleep

Cerebellar Processing

- Predicts body movement - Fine tunes motor activity, using the following process: 1.) Motor areas of the cerebral cortex, via the relay nuclei in the brain stem, notify the cerebellum of their intent to INITIATE voluntary muscle contractions. 2.) At the same time, the cerebellum RECEIVES info from proprioceptors thoughout the body + from visual + equilibrium pathways. This info. enables the cerebellum to evaluate BODY POSITION + MOMENTUM 3.) The cerebellar cortex CALCULATES the best way to COORDINATE the force, direction + extend of muscle contraction to prevent overshoot, maintain posture + ensure smooth, coordinated movements. 4.) Then, via the superior peduncles, the cerebellum dispatches to the cerebral motor cortex is "blueprint" for COORDINATING movement. Cerebellar fibers also sent information to brain stem nuclei, which in turn influence motor neurons of the spinal cord. - Continually compares the body's performance with the higher brain's intention + sends out messages to initiate appropriate CORRECTIVE measures. - Cerebellar injury results in loss of muscle stone + clumsy unsure movements

Alzheimer's Disease (AD)

- Progressive degernative disease of the brain that ultimately results in dementia - Nearly half of people in nursing homes - Between 5 - 15% of people over 65 develop it - Causes memory loss, shortened attention span disorientation + eventual language loss as well as moodiness, irritability + confusion - May be caused by aggregations of beta-amyloid peptide exerted threw PRIONS which are toxic - Presence of NEUROFIBRILLARY TANGLES inside neurons are common.

Blood Brain Barrier

- Protective mechanism that helps maintain a stable environment for the brain - Bloodborne substances in the brain's capillaries must pass through three layers before they reach the neurons: 1.) The endothelium of the capillary wall 2.) A thick basal lamina surrounding the external face of each capillary 3.) The bulbous "feet" of the astrocytes clinging to the capillaries - The astrocyte "feet" supply the required signals for endothelial cells to form TIGHT JUNCTIONS. These tight junctions join seamelssly together to form the blood brain barrier - Least permeable capillaries in the body - Some areas are open: hypotalamus (to regulate water balence, body temp) + the vomiting center of the brain ALLOWS: Glucose, essential amino acids + some electrolytes to move passively by facilitated diffusion through the endothelial cell membranes PREVENTS: Metabolic wastes, proteins, toxins and most drugs PUMPS OUT: Nonessential amino acids + potassium ions INEFFECTIVE AGAINST: Fats, fatty acids, oxygen, carbon dioxide, fat soluble molecules, alcohol, nicotine + anesthetics

Electroencephalogram (EEG)

- Records aspects of normal brain function - Works by placing electrodes on the scalp + connecting the electrodes to an apparatus that measures voltage differences between various cortical areas - The patterns are called BRAIN WAVES, generated by the synaptic activity at the surface of the CORTEX rather than by action potentials of white matter. - Brain waves can be classified into 4 frequency classes

Cerebrospinal Fluid (CSF)

- Reduces brain weight by 97% - Prevents the delicate brain from crushing under its own weight - Protects the brain + spinal cord from blows and other trauma - Helps nourish the brain - Similar in composition to blood plasma, though it contains less protein - CHOROID PLEXUSES are capillaries that hang from the roof of each ventrical + form the CSF. They are enclosed first by the pia mater + then by a layer of ependymal cells lining the ventricles. The ependymal cells are joined by tight junctions + have ion pumps that modify the filtrate by actively transporting certain ions across their membranes into the CSF pool. They also help cleanse the CSF. The long cilia of the ependymal cells help kepp the CSF in constant motion. - 150 ml (1/2 cup) in adults - Replaced every 8 hours or so - 500 ml of CSF is formed daily - Moves freely through the ventricles - Enters the subarachnoid space via the LATERAL + median apertures in the walls of the fourth ventricle

Epileptic Seizures

- Reflects a torrent of electrical discharges by GROUPS of brain neurons + during their uncontrolled activity no other messages can get through. - Happens in 1 in 100 people - Not associated with, nor does it cause, intellectual impairment - Sometimes genetic but can also e caused by blows to head, stroke, infections or tumors. - Causes uncontrollable jerking + may also cause an AURA before the seizure - ABSENCE SEIZURES: (petit mal) Mild forms in which expression goes blank for a few seconds + consciousness disappears. Usually happen in young children, ending before age 10 - TONIC-CLONIC SEIZURES: (grand mal) Most severe + convulsive. May cause broken bones, loss of bowls + bladder control. Lasts for a few minutes. - Anticonvulsive drugs, VAGUS NERVE STIMULATOR or DEEP BRAIN STIMULATOR can deliver impulses to vagus nerve or brain to stabilize activity.

Parkinson's Disease

- Results form degeneration of the dopamine releasing neurons of the substantia nigra. As those neurons deteriorate, the dopamine deprived basal nuclei they target become overactive - Afflicted individuals have a persistent TREMOR, a forward bent walking posture + a shuffling gait, stiff facial expression + slow at executing + initiating movement. - Drug L-dopa can help alleviate symptoms - Treated with drugs that enhance dopamine's effects

Spina Bifida

- Results from incomplete formation of the VETEBRAL ARCHES + typically involves the lumbosacral region - The laminae + spinous processes are missing on at least one vertebra - Neural defects occur - In the past, 70% of cases were caused by inadequate amounts of B vitamin folic acid in the maternal diet. This as dropped significantly in countries that have introduced mandatory supplementation of folic acid in bread, flour + pasta products - SPINA BIFIDA OCCULTA: least serious type, involves one or only a few vertebrae + causes NO neural problems - SPINA BIFIDA CYSTICA: More common + more severe form. Produces a saclike cyst that protrudes dorsally from the child's spine. The cyst may contain meninges + cerebrospinal fluid or even portions of the spinal cord + spinal roots. The infant experiences bowel incontinence, bladder muscle paralysis + lower limb paralysis.

Denticulate Ligaments

- Secure the spinal cord ot he tough dura mater menix - Formed from the saw toothed shelves of the pia mater

Long-Term Memory

- Seemingly limitless capacity - Memories may be forgotten eventually - Our ability to store + retrieve information declines with aging - Memories transferred to LTM take time to become permanent - MEMORY CONSOLIDATION aids in the categorization of LTM

Contusion

- Serious concussions that bruise the brain and cause permanent neurological damage

Sulci

- Shallow grooves in the cerebral cortex - Divide each hemisphere into FIVE lobes: frontal, parietal, temporal, occipital + insula

3 Stages of Development of the Neural Tube From the Embryonic Ectoderm

- Starts in a 3 week old embryo 1.) The ectoderm thickens along the dorsal midline axis of the embryo to form the NEURAL PLATE. The neural plate invaginates, forming a NEURAL GROOVE flanked by NEURAL FOLDS 2.) Small groups of neural fold cells migrate LATERALLY from between the surface ectoderm + the neural groove, forming the NEURAL CREST. The neural crest cells give rise to some neurons destined to reside in ganglia. 3.) As the neural groove deepens, the superior edges of the neural folds fuse, forming the NEURAL TUBE , which soon detaches from the surface ectoderm + sinks to a deeper position. - The neural tube forms by the forth week of pregnancy

Cerebovascular Accidents (CVAs)

- Strokes - "Brain attacks" - Occur when blood circulation to a brain area is blocked and brain tissue dies - A blood clot that blocks a cerebral artery is a common cause - Less frequently, strokes are caused by bleeding - Those that survive a CVA are commonly paralyzed on one side of the body - Glutamate binding to NMDA recepters opens NMDA channels that allow Ca+ to enter the stimulated neuron. After brain injury, "buckets" of glutamate are unleashed, which act as an EXCITOTOXIN, exciting the surrounding cells to death. Ca+ damages mitochondria.

Cerebral Edema

- Swelling of the brain - Can aggravate the injury or cause death

Reflex Tests

- Tap knee with reflex hammer to produce the "knee-jerk" response which shows that your spinal cord + upper brain centers are functioning normally - Abnormal responses may indicate an intracranial hemorrhage, multiple sclerosis or hydrocephalus

Sleep Apnea

- Temporary cessation of breathing during sleep - Victim awakes abruptly due to APOXIA (lack of oxygen), a condition that may occur HUNDREDS of times a night. - OBSTRUCTIVE sleep apnea (most common type) occurs when loss of MUSCLE TONE during sleep allows excess fatty tissue or other structural abnormalities to block the upper airways - Associated with obesity + made worse by alcohol + other depressents

Transient Ischemic Attacks (TIAs)

- Temporary episodes of reversible cerral ischemia - Last from 5-50 minutes - Cause temporary numbness, paralysis or impaired speech - They are "red flags" for impending serious CVAs.

Cerebral Cortex

- The "executive suite" of the nervous system where our CONSCIOUS MIND is found - Composed of GRAY MATTER - Billions of neurons arranged in SIX layers - 40% of brain mass - 1/8 inch thick - Its many convolutions effectively TRIPLE its surface area - Specific motor + sensory functions are localized in discrete cortical areas called DOMAINS - Higher mental functions such as memory + language are spread over LARGE AREAS of the cortex in overlaping domains Four Generalizations: 1.) Contains 3 kinds of functional areas: MOTOR areas, SENSORY areas + ASSOCIATION areas 2.) Each hemisisphere is chiefly concerned with the sensory + motor functions of the CONTRALATERAL side of the body 3.) The two hemisphere are NOT entirely equal in function. There is lateralization ( specialization) of cortical functions 4.) NO functional area of the cortex acts alone + conscious behavior involves the entire cortex in one way or another

Anencephaly

- The cerebrum + part of the brain stem never develop because the NEURAL FOLDS fail to fuse rosterally - The child is totally vegetative, unable to see, hear, or process sensory inputs. Muscles are flaccid + no voluntary movement is possible. - Death occurs soon after birth

Lateralization of Cortical Functioning

- There is a division of labor between the two cerebral hemispheres - LATERALIZATION: each hemisphere has abilities NOT completely shared by its partner - CEREBRAL DOMINANCE: Designates the hemisphere that is DOMINANT FOR LANGUAGE - In 90% of people the LEFT hemisphere has greater control over language abilities, math + logic - The other hemisphere (usually the right) is more free-spirited, involved in visual-spatial skills, intuition, emotion + artistic + musical skills. - Most individuals with left cerebral dominance are RIGHT HANDED - The remaining 10% of people, the roles of the hemispheres are reversed or the hemispheres share their functions - Typically, right-cerebral-dominant people are left handed + male

3 Cerebellar Peduncles (in cerebellum)

- Three paired fiber tracts connect the CEREBELLUM to the BRAIN STEM - All fibers entering + leaving the cerebellum are IPSILATERAL (from and to the same side of the body) 1.) SUPERIOR CEREBELLAR PEDUNCLES: Connecting the cerebellum + midbrain carry instructions from neurons in the deep cerebellar neclei to the cerebral motor cortex via thalamic relays. NO direct connections to the cerebral cortex 2.) MIDDLE CEREBELLAR PEDUNCLES: Carry one way communications from the pons to the cerebellum, advising the cerebellum of VOLUNTARY MOTOR ACTIVITIES initiated by the motor cortex (via relays in the pontine nuclei) 3.) INFERIOR CEREBELLAR PEDUNCLES: Connect medulla + cerebellum. CONVEY SENSORY INFORMATION to the cerebellum from (1) muscle proprioceptors throughout the body, and (2) the vestibular nuclei of the brain stem, which are concerned with EQUILIBRIUM + BALANCE

IPSILATERAL

- To and from the same side of the body - All fiber entering + leaving the cerebellum are ipsilateral

Procedural Memory

- Type of nondeclarative memory - DOPAMINE released by SUBSTANTIA NIGRA is necessary for this circuit to function - Skills memory - Piano playing

Emotional Memory

- Type of nondeclarative memory - Pounding heart when you hear a rattlesnake nearby

Motor Memory

- Type of nondeclarative memory - Riding a bike

Cerebral Angiography

- Used to visualize the location of a blood clot + the catheter. - Dye is injected to make arteries to stand out in an X ray

4 Generalizations About Neuronal Pathways

1.) DECUSSATION: Most pathways cross fromone side of the CNS to the other at some point 2.) RELAY: Most pathways consist of a chain of two or three neurons that contribute to successive tracts of the pathway 3.) SOMATOTOPY: A precise spatial relationship among the tract fibers that reflects the orderly mapping of the body. 4.) SYMMETRY: All pathways + tracts are paired symmetrically with a member of the pair present on each side of the spinal cord or brain

Multimodal Association Areas + its 3 Parts

- Where personality comes from - Receives inputs from MULTIPLE senses + sends outputs to MULTIPLE areas - Allows us to give meaning to the information that we receive, store it in memory, tie it to previous experience + knowledge + decide which action to take. Those decisions are relayed to the premotor cortex which in turn communicates with the motor cortex. - Where sensations thoughts + emotions become conscious 1.) ANTERIOR ASSOCIATION AREA: In the frontal lobe (PREFRONTAL CORTEX). The most complicated region of all. Involved in INTELLECT, complex LEARNING ABILITIES (cognition), RECALL + PERSONALITY. Contains working memory which is necessary for abstract ideas, judgment, reasoning, persistence + planning. Develop slowly in children, which implies that the prefrontal cortex matures lowly + depends heavily on positive + negative feedback from our social environment. 2.) POSTERIOR ASSOCIATION AREA: Parts of the temporal, parietal + occipital lobes. Plays role in recognizing patterns + faces + localizing us in our surroundings in space + binding different sensory inputs into a coherent whole. 3.) LIMBIC ASSOCIATION AREA: Includes the cingulate gyrus, parahippocampal gyrus + hoppocampus. Part of the limbic system, the limbic association area provides the EMOTIONAL impact that makes a scene important to us.

3 Suppositions about Consciousness

1.) Consciousness involves SIMULTANEOUS activity of LARGE areas of the cerebral cortex. 2.) It is SUPERIMPOSED on other types of neural activity (Neurons + neuronal pools are involved BOTH in localized activities + in cognition) 3.) It is HOLISTIC + totally INTERCONNECTED.

4 Factors Influencing Memory Transfer from STM to LTM

1.) EMOTIONAL STATE: We learn best when we are alert, motivated, suprised + aroused. NOREPINEPHRINE is involved in memory processing of emotionally charged events, is released when we are excited or "stressed out" 2.) REHEARSAL: Rehearsing or repeating the material enhances memory 3.) ASSOCIATION: Tying "new" information to "old" information already stored in LTM appears to be important in remembering facts 4.) AUTOMATIC MEMORY: NOT all impressions of LTM are CONSCIOUSLY formed. A student concentrating on a lecturer's speech may record an automatic memory of the pattern of the lecturer's tie.

5 Things that Happen on the Molecular Level when Learning

1.) Neuronal RNA content is altered + newly synthesized mRNAs are delivered to axons + dendrites 2.) Dendraic spines change shape 3.) Unique extracellular proteins are deposited at synapses involved in long-term memory 4.) Number + size of presynaptic terminals may increase 5.) Presynaptic neurons release more neurotransmitter

2 Major types of Sleep

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

3 Ways Sound is Interpreted in the Primary Auditory Cortex

1.) Pitch 2.) Loudness 3.) Location

4 Zones of Spinal Grey Matter

1.) Somatic Sensory (SS) 2.) Visceral Sensory (VS) 3.) Visceral (autonomic) Motor (VM) 4.) Somatic Motor (SM)

Mass of adult brain

1500g (3.3lb)

8 Sensory Areas of Cerebral Cortex

Areas concerned with conscious awareness of sensation. Occur in the parietal, insular, temporal + occipital lobes 1.) Primary Somatosensory Cortex 2.) Somatosensory Association Cortex 3.) Visual Areas (2) 4.) Auditory Areas (2) 5.) Vestibular (equilibrium) Cortex 6.) Olfactory Cortex 7.) Gustatory Cortex 8.) Visceral Sensory Area

Infarcts

Areas of dead brain tissue

DURAL SEPTA

Areas of the meningeal dura mater that extend inward to form flat partitions which subdivide the cranial cavity in order to limit excessive movement of brain. FALX CEREBRI- Dips into the longitudinal fissure between the cerebral hemispheres. Attaches to the crista galli of the ethmoid bone FALX CEREBELLI- Runs along the vermis of the cerebellum TENTORIUM CEREBELLI- Horizontal dural fold that extends into the transverse fissure between the cerebral hemispheres + the cerebellum

Medial Geniculate Bodies

Auditory relay center in thalamus

Cognitive Functions of the Cerebellum

Based on observations of patients with cerebellar injuries, the cerebellum also pays a role in thinking, language + emotion. The cerebellum may COMPARE the ACTUAL output of these systems with the EXPECTED output + adjust accordingly.

Encephalo

Brain

Central Nervous System (CNS)

Brain + Spinal Cord

Conus Medullaris

Cone shaped structure where the spinal cord terminates

Consciousness + 4 grades

Conscious perception of sensations, voluntary initation + control of movement, and capabilities associated with higher mental processing (memory, logic, judgement, perseverance and so on). - Defined on a CONTINUUM that GRADES behavior in response to stimuli as: 1.) Alertness ( Highest state + cortical activity) 2.) Drowsiness / Lethargy (which proceeds sleep) 3.) Stupor 4.) Coma (most depressed)

Non-Rapid Eye Movement (NREM) Sleep + its 4 stages

Consists of 4 Stages: 1.) Relaxation begins; EEG shows ALPHA waves; arousal is easy 2.) Irregular EEG with sleep SPINDLES (short high-amplitude bursts); arousal is more difficult. 3.) Sleep deepens; theta + delta waves appear; vital signs decline. 4.) Dominated by delta waves; arousal is difficult; bed-wetting, night terrors, and sleepwalking may occur.

4 Motor Areas of the Cerebral Cortex

Controls voluntary movement 1.) Primary Motor Cortex: CONSCIOUSLY CONTROL voluntary movements of our skeletal muscles 2.) Premotor Cortex: Helps PLAN movements 3.) Broca's Area: MOTOR SPEECH AREA that DIRECTS the MUSCLES involved in speech production 4.) Frontal Eye Field: Controls VOLUNTARY MOVEMENTS of the EYES

Fissures

Deeper grooves in cerebral cortex

2 Functional Brain Systems

Functional brain systems are networks of neurons that work together but span relatively large distances in the brain, so they cannot be localized to specific regions. 1.) The Limbic System 2.) The Reticular Formation

Grey Matter + Spinal Roots

GRAY COMISSURE: Grey matter that encloses the central canal in the spinal cord DORSAL HORNS + VENTRAL HORNS: Projections of gry matter form colums of grey matter that run the ENTIRE length of the spinal cord. LATERAL HORNS: Additional pair of gray matter columns in the thoracic + superior lumbar segments of the spinal cord - All neurons whose cell bodies are in the spinal cord grey matter are MULTIPOLAR - The dorsal horns consist entirely of INTERNEURONS - Ventral neurons house somatic motor neurons

SPACIAL DISCRIMINATION

How neurons identify the body region being stimulated in the primary somatosensory cortex

Last of the CNS area to mature

Hypothalamus

Ventral Roots

IN spinal cord. Its ventral rootlets send motor neuron axons out to the skeletal muscles (effector organs)

Meningitis

Inflammation of the meninges

Memory Consolidation

Involves fitting new facts into the categories of knowledge already stored in the cerebran cortex

Pyramidal Cells

Large neurons in the primary motor cortex of the cerebral cortex that allow us to CONSCIOUSLY control our skeletal muscles.

PARALYSIS

Loss of motor function as a result of damage to the spinal cord

Somatotopy

Mapping of the body in CNS structures

Spastic Paralysis

Occurs when only the upper motor neurons of the primary motor cortex are damaged. This results in the spinal motor neurons remain intact + spinal reflex activity continues to stimulate the muscles IRREGULARLY. As a result, the muscles remain healthy longer but their movements are no longer subject to voluntary control. In many cases, the muscles SHORTEN permanently.

Hemiplegia

Paralysis on ONE side of the body

FLACCID PARALYSIS

Results form severe damage to the VENTRAL root or horn cells + causes the nerve impulses to not be able to reach the skeletal muscles + they will therefore deteriorate

Longitudinal Fissure

Separates the cerebral hemispheres

Transverse Cerebral Fissure

Separates the cerebral hemispheres from the cerebelum below

Central Sulcus

Seperates the primary motor cortex from the somatosensory cortex

Ascending Pathways to the Brain + its 3 Successive Neurons

The ascending pathways conduct sensory impulses upward, typically through chains of three successive neurons. 1.) FIRST-ORDER NEURONS: Cell bodies arise in GANGLION + conduct impulses from the cutaneous receptors of the skin + from proprioceptors to the spinal cord or brain stem where they synapse with SECOND-ORDER NEURONS. Impulses from facial area are transmitted by cranial nerves + spinal nerves conduct somatic sensory impulses FROM the rest of the body TO the CNS. 2.) SECOND-ORDER NEURONS: Cell bodies reside in the DORSAL HORN of spinal cord OR in the MEDULLARY NUCLEI. They transmit impulses TO the THALAMUS or to the CEREBELLUM where they synapse. 3.) THIRD-ORDER NEURONS: Have cell bodies in the THALAMUS. They relay impulses to the SOMATOSENSORY CORTEX of the CEREBRUM. (no third order neurons in the cerebellum). Three pathways: ---1.) Dorsal Column-medial lemniscal pathways: Formed by the paired tracts of the DORSAL WHITE COLUMN of hte spinal cord and the FASCICULUS GRACILIS + the the MEDIAL LEMNISCUS ---2.) SPINOTHALAMIC PATHWAYS: Consist of the LATERAL + VENTRAL SPINOTHALAMIC TRACTS. Their fibers cross over in the spinal cord. Transmit information about pain + temperature + coarse touch + pressure. ---3.) Spinocerebellar Pathways: Consists of the VENTRAL + DORSAL SPINOCEREBELLAR TRACTS. Convey information about muscle or tendon stretch to the cerebellum, which uses this information to coordinate skeletal muscle activity.

2 Types of Memory

The brain distinguishes between factual knowledge + skills 1.) DECLARATIVE (facts) MEMORY 2.) NONDECLARATIVE MEMORY

Neural Tube

The embryonic strucure that the brain + spinal originated as

Postpolio Syndrome

The progressive muscle weakness + atrophy that occurs in the survivors of polio.

Spinal Cord Trauma

The spinal cord is elastic, stretching with every turn of the head or bend of the trunk but it is exquiseitely sensitive to direct pressure. Any localized damage to the spinal cord or its roots leads to some functional loss, either PARALYSIS (loss of motor function) or PARESTHESIAS (abnormal sensations).

Lateral Geniculate Bodies

Visual relay center in thalamus