Central Nervous System (CNS)

Central Nervous System (CNS)

brain and spinal cord

Cephalization

evolutionary development of rostral (anterior) portion of CNS

Brain Development

brain and spinal cord start as neural tube

Prosencephalon (forebrain)

telencephalon, diencephalon

Mesencephalon (midbrain)

remains undivided

Rhombencephalon (hindbrain)

mesencephalon, myelencephalon

Gray Matter

short, nonmyelinated neurons and cell bodies

White Matter

myelinated and nonmyelinated axons

Cortex

outer layer of gray matter in the cerebrum and cerebellum

Ventricles

fluid-filled chambers with CSF lined by ependymal chambers

Lateral ventricles

paired large, C-shaped chambers

Cerebral Hemisphere (cerebrum)

forms superior part of brain (83%) mass

Cerebral Cortex

superficial grey matter

Basal Nuclei

island of gray matter deep within white matter

Motor

control voluntary movements

Senory

conscious awareness of sensation

Association

intergrate diverse info

Lateralization

of hemispheres (left and right)

Somatotopy

point for point of the body to a specific point on the CNS

Homunculi

the relative amount and location of cortical tissue devoted to each function is proportional to distorted body diagrams

Pyramidal Cells

large neurons that allow skilled & conscious control of skeletal muscle movements

Premotor Cortex

helps plan skilled motor activities

Broca’s Area

motor speech area

Frontal Eye Field

controls voluntary eye movement

Primary Somatosensory Cortex (awareness)

located in postcentral guys, receives general sensory information from skin and proprioceptors of skeletal muscle, joints and tendons

Somatosensory Association Cortex (sensation)

integrates sensory input from primary somatosensory cortex for understanding the object, determines characteristics of objects being felt (size, texture)

Primary Auditory Cortex

interprets information from inner ear as pitch, loudness, location

Auditory Association Area

stores memories of sounds-permits perception of sound stimulus

Primary Auditory Cortex

conscious awareness of odors

Primary Visual Cortex

receives information from retinas

Visual Association Area

uses past visual experience to interpret stimuli (recognizing faces)

Vestibular Cortex

responsible for conscious awareness of balance

Gustatory Cortex

perception of space

Visceral Sensory Area

conscious preception of visceral sensations

Cerebral Cortex: Multimodal association area

receive inputs and send outputs from/to multiple areas (allow us to give meaning to information received, store in memory, and tie to previous experience, decide on actions)

Anterior Association Area (prefrontal cortex)

most complicated cortical region (intellect, cognition, recall, personality), contains working memory needed for abstract ideas, judgment, reasoning, persistence, planning

Posterior Association Area

large region in temporal, parietal, occipital lobes, (recognizing patterns and faces, localizing us in space, contains Wernicke’s area)

Limbic Association Area

part of limbic system, functions (provides emotional impact that makes a scene more important to us help establish memories

Association Fibers

horizontal → connect different parts of the same hemisphere

Commissural Fibers

horizontal → connect grey matter of two hemispheres

Projection Fibers

vertical → connect hemispheres with lower brain or spinal cord

Basal Nuclei

island of gray matter deep within white matter (primarily involved in control of movement)

Diecephalon

composed of three paired grey-matter structures

Thalamus (inner room)

bilateral egg-shaped nucleus (sorts, edits and transmits incoming information)

Hypothalamus (below thalamus)

composed of mammillary bodies & pituitary gland (homeostatic control and regulatory center of the body

Epithalamus (coming off of thalamus)

contains pineal gland (secretes melatonin)

Cerebral Peduncles

two ventral bulges (pillars golding up cerebrum)

Periaqueductal Gray Matter

nuclei (pain suppression and fight of flight response)

Corpora Quadigemina

paired dorsal protrusions

Superior Collicul

visual reflex centers (coordinate head-eye movements when following objects)

Inferior Colliculi

auditory relay centers (startle reflex)

Substantia Nigra

functional linked to basal nuclei (degeneration of this area →parkinson’s disease)

Red Nucleus

involved in limb flexion

Pons “Bridge”

bulging region wedged between midbrain and medulla, composed of fibers that conduct impulses between different regions of brain

Medulla Oblongata

blends into the spinal cord at foramen magnum, origin of cranial nerve

Pyramids

two ventral longitudinal ridges formed by pyramidal tracts from motor cortex

Decussation of Pyramids

point where pyramidal tracts cross over to opposite sides of body

Olives

nuclei that relay sensory information on degree of stretch in muscles and joints of cerebellum

Cardiac Center

adjusts force and rate of heart condition

Vasomotor Center

adjust blood vessels diameter for blood

Respiratory Center

generate respiratory rhythm, control rate and depth of breathing

Cerebellum

11% of brain mass, posterior to pons and superior to medulla, processes input subconsciously from rest of brain and sensory receptors to provide

Arbor Vitae

thin cortex of gray matter with distinctive tree patterns

Superior Cerebellar Peduncles

cerebellum ← → midbrain

Middle Cerebellar Peduncles

pons → cerebellum

Inferior Cerebellar Peduncles

medulla ← → cerebellum

Functional Brain Systems

span across multiple structures

Limbic system

includes cerebral and diencephalon structures (functions: mediates emotional response, involved in memory processing)

Reticular Formation

located in central core of brainstem (function: maintains cerebral cortical alertness

Fornix

fiber tract linking all limbic system regions (interacts with prefrontal lobes)

Reticular Formation

a network of neurons that regulates arousal and consciousness, influencing attention and sleep-wake cycles.

Broca’s Area

facts (names, words, faces)

Procedural

skills (playing piano)

Motor Memory

motor skills (riding bike)

Emotional Memory

experiences linked to emotion (heart pounding)

Short Term Memory (STM)

temporary holding of information (7-8 pieces)

Long Term Memory (LTM)

limitless capacity (factors affecting transfer of STM → LTM)

Emotional State

best if alert, motivated or suprised

Rehearsal

repetition, practice

Association

typing new information with old memories

Automatic Memory

subconscious information stored in LTM

Memory Consolidation

fitting new facts into categories already stored in cerecral cortex

Slight Memory Loss

damage to hippocampus or temporal lobe on either side (memory regained within short time period)

Amnesia

bilateral destruction

Electroencephalogram (EEG)

records electrical activity accompanying brain function (electrodes placed on the scalp measure electrical potential differences between various cortical areas)

Alpha Waves

(8-13 Hz)-regular and rhythmic “idling” brain

Beta Waves

(14-30 Hz)-rhythmic, but less regular, mentally alert

Theta Waves

(4-7 Hz)-more irregular, common in children

Delta Waves

(4 Hz or less)- high amplitude, deep sleep or anesthesia-brain damage if awake

Epileptic Seizure

torrent of electrical discharges of groups of neurons (prevent any other messages from getting through, lose consciousness)

Aura

(sensory hallucinations) may precede seizure

Absence Seizures

mild seizures of young children: expression goes blank

Tonic-Clonic Seizures

most severe, last several minutes

Consciousness

perception of sensation, voluntary initiation and control of movement, higher mental processing

Dura Mater

strongest meninx, composed of two layers of fribrous CT

Periosteal Layer

attaches to inner surface of skull (only in brain not spinal cord)

Meningeal Layer

true external covering of brain (extends to vertebral canal as spinal dura mater)

Arachnoid Layer

middle layer with spider web-like extensions

Subarachnoid Space

contains CSF and largest blood vessels of brain