wvu psio 743 exam 2

memory trace

- (Engram) the neural change leading to retention - Short term memory: seconds to hours, rapid turnover, occurs in hippocampus (small capacity) - Long term memory: Days to years, transfer to long term begins at hippocampus; if not consolidated, data will be lost

Experience / instruction leads to:

- Acquisition of knowledge / skill - Reward and punishment plays a role

default mode network

- Brain system devoted to resting state processes (not externally cued tasks - Focuses on internal signals (daydreaming/mind wandering) - may be important for preparing brain to focus on conscious activities, or retrieving/manipulating memories - Uses about 60-80% of brain's energy

Areas associated with language

- Broca's and Wernicke's areas, integrates expression and comprehension - Prefrontal association cortex, planning, problem solving, consequences. The site of working memory! - Parietal temporal occipital association cortex, integrates somatic, auditory, and visual sensations (picture relationship of the body to external environment) - Limbic association cortex, motivation, emotion, memory

4 ways brain is protected

- CNS is in skull and spinal column - Brain floats in cerebrospinal fluid - meninges separate brain from bone - blood brain barrier limits contact with blood

electroencephalogram

- Collective postsynaptic potential activity of cortical neurons (EPSPs and IPSPs) - Distinct patterns (or the absence of patterns) of wave amplitude and frequency are diagnostic of: cerebral dysfunction (epilepsy), brain death, stages of sleep

Working memory (part of memory trace)

- Data coupled to previously stored data for interpretation and immediate use for task-at-hand - Important for comprehension, reasoning, planning

recording from single neurons

- Demonstrates how information is encoded in the frequency of action potentials - Greater stimulus = higher frequency - Not reflective of population of neurons

Molecular mechanisms of memory

- Different for short v long term - Memories stored in neuronal networks, encoded in patterns of synaptic transmission

Limbic system

- Formed from: cerebral cortex, basal nuclei, thalamus, hypothalamus - Associated with: emotion, basic survival, socio-sexual behavior patterns, motivation, learning and memory

Wernicke's area

- Governs comprehension, receives input from visual and auditory cortex - Important for both speaking and written language - Formulates coherent patterns of speech and sends commands to Broca's area

Addiction

- Ingestion of a substance/engagement in an activity that stimulates reward - Behavior = habitual at expense of social or psychological needs

Neurotransmitters implicated in addiction

- Norepinephrine, dopamine, serotonin - Elicit high rates of self - stimulation in lab animals - Psychoactive drugs alter mood via affecting neurotransmitter levels or actions ex: amphetamine = stimulation of dopamine release, Prozac = blocks serotonin reuptake

Mechanisms of long term memory

- Permanent functional or structural changes, like the addition of new synaptic connections, increased numbers of dendrites or terminals

Limbic linkage to higher cortical areas

- Required to develop proper behaviors in relationship to the external environment (the implementation of motor responses) - Reinforce/modify/suppress behavior responses based on understanding of the situation - Parallel tracts likely to play roles (fear): Fast response (gut reaction) - mediated via amygdala) Slow response (rational analysis giving rise to appropriate reaction given situational awareness)

recording from multiple neurons

- Shows that neurons within a neural network may fire together for a short period of time - Information is further encoded through changes in the pattern of firing within a network (synchronicity)

Memory

- The storage of acquired knowledge - Retrieval of desired info from long-term may take time

Consolidation

- The transfer of short term traces to long term storage Requires ACTIVE PRACTICE / REHERSAL - Recalled memory must also be reconsolidated - Involves long term potentiation

Mechanisms of long term potentiation

- Transfer of memory to long term. lasts for days to weeks - Occurs in hippocampus, increased usage of pre-existing synaptic connection to excite postsynaptic neuron - Increased use = stronger connection (opposite is true = long term depression) - Specific to the activated pathway, it doesn't affect other presynaptic inputs

Short term memory molecular mechanisms

- Transient modifications of pre-existing synaptic connections, like increases in neurotransmitter release or increases in neurotransmitter receptors Habituation: lowers responsiveness to repetitive indifferent stimulus. - Depression of synaptic activity via reduction in calcium influx leading to reduced downstream neurotransmitter release Sensitization: increases responsiveness to mild stimuli following a strong stimulus - Enhancement of synaptic activity via presynaptic facilitation via increase in calcium influx, leading to increased downstream neurotransmitter release

Reward/Punishment centers

- preference (desirable) vs aversion (undesirable) - Motivation: the concept that a preferred outcome drives behavior, thus directing towards achieving a goal - thirst - seeking water (homeostatic drive) - Painful trailing - attempt to win a race

2 tells for how strong a stimulus is?

1. what is the rate of action potentials? 2. how many receptors are fired?

dura mater

2 layers, dural or venous sinuses, filled by blood thick, outermost layer

receptor mechanics

2 types: if receptor is a specialized cell, it will synapse on an afferent when it releases graded potentials. receptor cell's job is to generate enough membrane potential change to activate exocytosis through calcium entry if it is a specialized afferent ending, the distal region of afferent has the stimulus sensitive channel. the graded potential occurs there and the action potential occurs where there are more voltage gated Na+ channels

decoded stimulus intensity

2 ways! larger receptor potentials = faster frequency of action potentials in afferent neurons larger stimulus = more receptors responding

Astrocytes and BBB

Astrocytes project to capillaries They don't form the BBB, but they help: - Signal endothelial cells to form tight junctions - Promote production of carrier proteins and ion channels - Participate in transportation of some substances - Pericytes give functional support

Supporting cells (neuroglia)

Astrocytes, oligodendrocytes, microglia

Brain metabolic protection

Brain gets 15% of all cardiac output, using 20% of the O2 and 50% of the glucose No methods of nutrient storing, neuroglobin is similar to hemoglobin (an O2 binding protein) Constant delivery of blood, and if glucose is too low then the brain can use ketones

nervous system organization

CNS = brain and spinal chord --------------------------------- PNS = afferent vs efferent Afferent = takes from sensory and visceral stimuli, sends input to CNS from periphery --------------- Efferent = somatic vs autonomic, takes output from CNS to periphery Somatic = motor neurons = skeletal muscles Autonomic = sympathetic, parasympathetic, enteric --------------- Stimuli from digestive tract isn't under ONS, but sends info to enteric system

How are aspects of memory stored?

Different parts of memory are stored separately, visual - occipital lobe, tactile to parietal, etc.)

sympathetic vs parasympathetic

Efferent, Autonomic, work to innervate most organs, works with the enteric system

specialized ascending pathway for sensory modalities

First-order neuron - Neuron that first detects stimulus, terminal in spinal cord Second-order neuron - In spinal cord or medulla, terminal at thalamus Third-order neuron - In thalamus, terminal in cerebrum or cerebellum

Where is BBB not present?

Hypothalamus - water soluble hormones released into blood Choroid plexus - blood-cerebrospinal fluid barrier Retina - blood-retinal barrier if protection

can amplitude be an indicator of how strong a stimulus is?

No, every action potential from an afferent, it will have the same amplitude every time it fires. We measure frequency to determine strength

What passes through BBB?

O2, CO2, alcohol, and steroid hormones pass through easily H2O diffuses easily through aquaporins Everything else is exchanged by highly selective membrane bound carriers and transcytotic mechanisms

Diencephalon:

Part of forebrain, includes hypothalamus and thalamus Thalamus: - Sensory relay station (except for olfaction), ascending sensory information is directed to correct areas - Sleep/waking control - part of the reticular activating system (damage can lead to a coma) - Episodic memory and feelings of like it or hate it Hypothalamus: - Links autonomic nervous system and endocrine system - Homeostatic regulator (body temp, urine output/thirst, food intake, anterior pituitary hormone secretion, produces posterior pituitary hormones, uterine contraction/milk secretion, ANS coordination, emotional/behavioral patterns, sleep/wake cycle

Movement in relation to BBB

Passage between wall forming cells is anatomically prevented - tight junctions prevent movement of almost all substances between cells Transport through cells is physiologically restricted

Frontal lobe

Primary role is control of skeletal muscles - Voluntary motor activity, speaking ability - Connected to all other brain parts, puts together knowledge/experiences, very evolved and flexible - Elaboration of thought - Motor control of complex movements

Parietal lobes

Primary role is somatosensory processing - Somesthetic perception = touch, pressure, hot, cold, pain - Proprioception = awareness of body position (sensory homunculus) - Sends sensory input to higher sensory areas or further elaboration, analysis, and integration

4 classes of mod altering drugs

SSRI, SNRI, TCAs, MAOIs

Somatic vs autonomic

Somatic = efferent, motor neurons supplying the skeletal muscles Autonomic = efferent, fibers innervating smooth + cardiac muscle, and glands

dural sinuses

Sublayers of the dura that have divided to form a route for blood. The purpose of this structure is to drain blood away from the brain and scalp.

Cranial nerves come from:

The brain stem, it gives rise to he cranial nerves except for the vagus nerve that innervates thoracic and abdominal cavities (it is a major parasympathetic nerve)

To govern synthesis of proteins, what is required? (LTP)

The mechanisms of long term memory require the activation of specific genes that govern synthesis f proteins for: - Formation of new synaptic connections - Changes in pre/post synaptic membranes (animals reared in a sensory rich environment will have greater branching and elongation of dendritic spines) - cAMP (cAMP responsive element binding protein acts on DNA to influence protein synthesis); and IEGs (immediate early genes govern protein synthesis which is critical for structural change, neurotransmitter synthesis, and receptors) - Changes in myelination (increased myelination = greater speed of transmission

Why can't specialized receptor cells have action potentials?

They don't have the voltage gated sodium potassium channels to have a threshold to reach to trigger one!! you need Na+/K+ for action potentials

arachnoid villi

Where CSF is reabsorbed into blood at dural sinuses

direct neuronal recording provides:

a better understanding of regional differences in function

Readiness potential

a collective potential energy that must be achieved, activates the motor cortex. Areas of the brain that contribute to formation of motor plan: - Supplementary motor area, programs complex movements - Premotor cortex, uses memory to plan complex movement and requires detail of body's position to "target" - Posterior parietal cortex, integrates sensory input related to complex movements - Cerebellum, planning, initiating, timing complex movements more complex movements = more activity in these areas

receptor cells

a separate cell that synapses onto an afferent cell(2 diff cells!!!). The receptor cell is neural tissue, NOT a neuron (no action potential). It is sensitive to a change, and will exhibit changes in its membrane potential to depolarize as a graded potential 1. the cell will have channels sensitive to its specific modality, then Na+ channels will open = depolarization as Na+ goes in it 2. the local depolarization opens voltage gated Ca2+ channels 3. Ca2+ going into cell will trigger exocytosis of neurotransmitter 4. neurotransmitter will activate afferent cell (another graded potential forms in receptive region of afferent cell) 5. Na+ entry via the voltage gated channels initiate the action potential in the afferent fiber which then self propagates to CNS

Use dependent competition

a type of plasticity - the cortex of individuals can vary cortical architexture can change through use, an example from the text: a monkey using a different finger to press a button on a keyboard for a reward

three functional classes of neurons

afferent, efferent, and interneurons

sensation

are sensory processes resulting from an external or internal stimulation of a receptor

Blood brain barrier is formed by?

brain capillary walls

How may stimuli be detected?

by a specialized nerve ending of an afferent or by a separate specialized neuron innervating an afferent

sensory afferents

carry conscious input from: somatic sensation - somesthetic sensation and proprioception Special senses - vision, hearing, equilibrium, etc (labelled lines)

Visceral afferents

carry subconscious input, although pain may be perceived

graded potentials

changes in membrane potential that propagate away from the locus of stimulation with decrement (the strength of the depolarization/hyperpolarization decreases w/ time/distance) No refractory periods = summation with rapidly successive stimuli normally - influx of sodium ions = depolarizations greater stimulus = larger receptor potential

receptors

detect change, respond to modalities, a stimulus causes graded potentials

embryonic development

from neuroectoderm - neural tube closes, by the end of the 4th week the brain and spinal cord begin developing

cerebral hemispheres

functionally asymmetrical Left: normally dominant, includes language, fine motor control, logical; analytical; sequential; verbal tasks, processes info in fine detail, fragmented Right: excels in non-language skills, spatial perception, artistic and musical talents, processes info holistically

Broca's area

governs expression and controls muscles necessary for speaking

Gray vs White matter

gray matter - mostly neuronal cell bodies and glial cells white matter - mostly bundles of myelinated fibers

smaller receptive field =

greater acuity/discrimination

specialized afferents

have receptive membranes, distal region of afferent has the stimulus sensitive channels that will open and allow Na+ into the cell (depolarization). the current flow between the depolarized receptor ending and the adjacent region will open voltage gated Na+ channels, the graded potentials occur around here once large enough, that Na+ entry will initiate the action potential in the afferent fiber and it will self propagate to the CNS No action potential at membrane because too few sodium channels = high threshold

lateral inhibition

helps us to focus and get discrimination as to where a point of stimulus is

pia mater

highly vascular, vessels of arachnoid mater pass through it from brain, it forms the choroid plexuses

sensory acuity

how accurate is the information coming from receptors reacting to a stimulus

Microglia

immune support Ependymal cells are epithelial cells that line ventricles

Forebrain

includes cerebrum and diencephalon

Cerebrum

includes the cerebral cortex (the outer shell of gray matter) and the white matter structures (axon tracts like corpus callosum and basal nuclei) Cortex divided into: Frontal, Parietal, Occipital, Temporal lobes Gyri = ridges Sulci = valleys Important for higher functioning - memory, decision making, planning, sensation/perception, and motor functions

Perception

is further defined as the conscious awareness of those sensory processes

Effector organs

made up of muscle and gland tissue: skeletal, smooth, and cardiac muscle; exocrine glands and some endocrine glands

Oligodendrocytes

make up myelin sheath in CNS (in the PNS, schwann cells do this)

Pain receptors!

mechanical nociceptors - respond to mechanical damage: cutting, crushing, pinching Thermal nociceptors - respond to temperature extremes polymodal nociceptors - respond to all damaging stimuli and irritating chemicals released from damaged tissues

Afferent neurons

most anatomy is in periphery, sends sensory information to an integrator (which is in CNS) long peripheral axon (afferent fiber) extends from receptor to the cell body, a short central axon passes from body to spinal cord

Cerebellum

motor coordination/balance and equilibrium has 3 parts! Vestibulocerebellum - balance and eye movement Spinocerebellum - voluntary movements, ensures smooth movements and is important for phasic activities Cerebrocerebellum - gives input to cortical motor areas and storage of procedural memories

adequate stimulus

needs this to get a graded potential large enough to excite an action potential the amount of pressure to trigger a pressure receptor/enough chemical/enough light etc.

Enteric system

nerve network in wall of digestive tract. it can act independently, but is also works via autonomic fibers that terminate on the enteric neurons.

Analgesic system

pain suppression Periaqueductal gray mater, medulla, and reticular formation - Release enkephalin, (which Binds u-opioid receptors, Morphine is agonist. Also, endorphins and dynorphin) - Suppresses release of Substance P

Basal Nuclei

part of cerebrum Essential in controlling movement: - inhibit muscle tone through body - Maintains purposeful activity and suppresses useless patterns (damage = resting tremors like in Parkinson's) - Helps monitor and coordinate slow, purposeful movements (postural/supportive muscular activity) Part of a complex feedback pathway with thalamus and cerebral cortex: - Thalamus positively reinforces motor activity initiated by cortex - Basal nuclei is inhibitory on Thalamus to stop unnecessary movements leading to smooth controlled movement

Astrocytes

physical support, formation of blood brain barrier, helping to move nutrients and wastes between the blood and nervous tissues, repair, play role in synaptic transmission (limit neurotransmitter actions, mediate synaptic functions and formation) K+ uptake

efferent neurons

primarily in PNS, cell bodies originate in the CNA where the centrally located presynaptic inputs converge on them to (in uence) their outputs to effector organs efferent axons (efferent fibers) leave the CNS to go to muscles/glands they innervate, where they'll send their message for the organs to act on/from.

Adaptation

receptors can adapt to a stimulus, 2 types! tonic receptors adapt slowly - good for maintaining information about a stimulus - muscle stretch, pain, or proprioceptors phasic receptors adapt quickly - the changes in intensity of a stimulus is monitored - touch receptors

Glutamate

released by afferents that influence second order neurons Activates two different receptors: AMPA and NMDA AMPA activation works similar to Sub. P NMDA activation makes 2nd order neurons hyperexcitable, and Increased sensitivity of injured area to further stimulation

Substance P

released by afferents that influence second order neurons Sub P pathway: Cortex - Localizes pain Thalamus - Initial perception Reticular formation - Increases alertness, Hypothalamic and limbic connection (also from thalamus elicit behavioral and emotional responses)

arachnoid mater

richly vascularized, subarachnoid space filled with CSF,

cerebrospinal fluid

same density as brain, so brain floats, and CSF absorbs shock produced by choroid plexus, circulates and is reabsorbed by arachnoid villi Lower K+ conc. and greater Na+ conc. free exchange between CSF and interstitial fluid, NOT between blood and interstitial fluid

SAD DAVE

sensory = afferent = dorsal Dorsal = afferent Ventral = efferent

A -delta fibers

small (1-6 um), myelinated fibers, fast pain pathway with info like mechanical or temperature damage

C fibers

smaller (<1 um) slow pain pathway from polymodal nociceptors

sensory transduction

stimulus energy converted to receptor potentials (usually graded potentials).

Plasticity

structural changes associated with nervous functions: growth of new dendrites, increases in synaptic connections existing neurons can form new synaptic connections based on an individuals experiences only true for certain areas of the brain, and sometimes only for a certain time like during development

receptive field

the region of the sensory surface that, when stimulated, causes a change in the firing rate of that neuron

modalities

the type of stimulus a receptor responds to (heat, light, sound, etc.

each receptive field covers a smaller area of skin when...

there is a higher density of receptors

Na+ and Ca2+

these receptors tend to be stretch sensitive in mechanosensitive cells. you don't HAVE to have the Na+ channel opening, the Ca2+ channel will open alone due to stretch. either way depolarization will occur because positive ions are going into the cell

Cerebral cortex

thin, outer layer of cerebrum, gray matter Functions in: sensory perception, voluntary movement, language, personality, thinking, memory, decision making Organized: by six layers of vertical columns with a varied distribution of cell types (stellate, pyramidal, etc.)

Brain stem

vegetative functions, 3 parts! Midbrain: cerebral peduncles and corpora quadrigemina Pons: Cerebellar peduncles, respiratory control centers Medulla oblongata: cardiac and respiratory centers

venous sinuses

venous blood draining from the brain empties into these sinuses to be returned to the heart

Reticular Activating System (RAS)

wakefulness, alertness, visceral control - bodies main circuit breaker - Receives and integrates all sensory input, sends up to cerebral cortex via ascending fibers - Controls overall degree of cortical awareness - Cortex will also send signals down to activate the RAS DAMAGE = circuit breaker trips and shuts the body down