Brainstem II

Question 1

Describe Gray matter of brainstem

Answer 1

central Core gray matter= reticular formation =
Complex network cell bodies, dendrites and synapses involved in some very complex functions carried out by brainstem

Question 2

describe caudal medulla—> rostral medulla brainstem

Answer 2

As move up = brainstem changes shape

Question 3

Describe generally what reticular formation involved in

Answer 3

Numerous integrative functions of brainstem (same as spinal cord circuits)

Question 4

name the 3 things reticular formation involved in

Answer 4

Stereotyped motor responses
Autonomic functions
Ascending arousal (reticular activating system)

Question 5

describe stereotyped motor responses of brainstem

Answer 5

Facial expressions - programmed like smile, chewing
Output through facial nerve

Question 6

describe autonomic functions of brainstem

Answer 6

Sensory input from visceral organs terminating in brainstem (nuclei of solitary tract)
C fibers in brain go into spinal cord —> brainstem
Sensory input converges onto brainstem and becomes organized outputs
Hypothalamus controls brainstem = controls autonomic output

Question 7

describe ascending arousal (reticualr activating system) of brainstem

Answer 7

Attention, sleep wake cycles…

Question 8

what is brainstem

Answer 8

Organizing centre for a variety fo stereotyped motor programs like facial expressions, chewing and swallowing

Question 9

what is periaqueductal gray = specifically

Answer 9

exemplifies integrative functions of reticualr formation
Coordinates behaviours, ex of control of stereotyped behaviours

Question 10

periaqueductal gray is connected to = specifically

Answer 10

Connected to regions of brainstem involved in autonomic, somatic and behavioural responses to higher brain regions involved in fear

Question 11

describe when stimulate pag in cats

Answer 11

Increased respiration and cardiac function, piloerection (hair stands up/goosebumps), hissing and arching of back

Question 12

describe when stimulate pag in mice

Answer 12

Results in freezing or escape responses

Question 13

describe when stimulate pag in humans

Answer 13

Causes stereotyped defencsive behaviours and feelings of anxiety

Question 14

what is periaqueductal gray = physically

Answer 14

Gray matter around aqueduct (cerebral aqueduct)

Question 15

what is periaqueductal gray = does What

Answer 15

Involved in responses to threats = like when cat meets another cat = causes complex behavioural response
Some response = autonomic like increase hr, dilate pupils
Some responses = behavioural like arching back and hissing
= functions = automatic
If stimulate = elicit behaviour
If stimulate region of hypothalamus = get same response

Question 16

descrie when stimulate pag or use opioids

Answer 16

Suppresses pain = strong analgesia, bc they feel threatened so suppress pain
In Hamsun = feel dread/anxiety (not a good therapeutic avenue)

Question 17

What Does pag do

Answer 17

Organizes these responses - autonomic behaviour
Organizes other outputs found in other parts of brainstem that controls behaviour/responses = complex set behavioural responses

Question 18

describe cat brain awake vs a sleep

Answer 18

Awake = low amp random noise
Alegre number of neurons doing many things
Over large patch in brain so electrical activity averages out

Asleep = Initial stage slow wave sleep = bursts of firing, neurons in cerebral cortex firing synchronously, rhythmically, oscillations on eeg

Question 19

desvribe rem sleep eeg

Answer 19

eeg looks same as awake

Question 20

in cat = lesion at level of caudal medulla

Answer 20

Did not affect arousal
Cats had awake eeg

Question 21

in cat = lesion at level of rostral pons/caudal midbrain

Answer 21

persistent sleep like sate
So = something in brainstem in this region is responsible for keeping animal awake
Ascending arousal system = brainstem —> rest fo rbain

Question 22

what are results of cat lesions = the ascending arousal system

Answer 22

Ascending arousal system that started in brainstem and activated cerebral cortex

Question 23

describe ascending projections from brainstem Arousal system

Answer 23

comprise a dorsal pathway that goes through thalamus
And a ventral pathway that projects directly to cortex
Long axons extend into thalamus and cerebral cortex, small number of neurons found in clusters in brainstem = innervate rest of neurons in brain bc branching

Question 24

describe ventral pathway

Answer 24

Cell bodies in brainstem —> cortex

Question 25

describe dorsal patwhay

Answer 25

cell bodies in brainstem project to thalamus then neurons in thalamus project to cortex

Question 26

what do the acendings projections do generally

Answer 26

Set overall tone of brain = if alert, asleep, mood Broad global effects No precise 1:1 connections but affect large regions of brain

Question 27

define neuro modulators

Answer 27

Norepi, histamine, dopamine, serotonin Not involved in fast transmission, changes biochemical/phsyiologucla properties = changes protein synthesis or gene expression, opens a G protein coupled receptor - found in little clusters

Question 28

norepi = neurons originate where And project to

Answer 28

Locus coeruleus (clusters, 10s of thousands of neurons) Project to entire brain and spinal cord

Question 29

norepi = ascending projections involved in..

Answer 29

Sleep wake cycles, arousal and attention

Question 30

descrve overall role of norepi neurons during sleep wake cycle

Answer 30

Fire during wakefulness Firing decrease during slow wave sleep Silent during rem sleep

Question 31

norepi neurons = wake

Answer 31

Active

Question 32

norepi neurons = slow wave sleep

Answer 32

Less firing as drift into slow wave sleep

Question 33

norepi neurons = rem

Answer 33

Basically stop firing REM = dreaming, eeg looks like you a wake up

Question 34

norepi neurons =wake after rem

Answer 34

Starts firing again

Question 35

what does firing of norepi neurons correlate with

Answer 35

Levels fo attention

Question 36

describe norepi neurons during inattentive state

Answer 36

Fire at steady rate

Question 37

describe norepi neurons during focused attention

Answer 37

At novel event = fire, burst ap = shift attention

Question 38

describe norepi neurons during scanning

Answer 38

A lot happening, not sure what to pay attention to So fire a lot at a v high frequency Trying to figure our what to pay attention to

Question 39

serotonin neeurons originate where

Answer 39

brainstem Raphe nuclei (cell bodies clusters on midline of brainstem)

Question 40

serotonin neeurons project where

Answer 40

Whole brain and spinal cord

Question 41

dopamine neurons originate where

Answer 41

Small clusters in mid brain = substantia nigra and ventral tegmental area

Question 42

dopamine neurons project to where

Answer 42

From substantia nigra —> basal ganglia From vta —> cerebral cortex

Question 43

what is dopamine signalling involved in

Answer 43

Cognition, movement and learning Addictive drugs increase dopamine release

Question 44

describe substantia nigra

Answer 44

Neurons that degenerate in Parkinson’s =leads to movement abnormalities

Question 45

describe vta

Answer 45

Another set of neurons near midline Projects to regions of brain involved in —> connecting reward to learning System associated with normal learning Also associated with addiction = abnormal learning, pathological learning, like release of da when gamble —> drive by casino = get same release = addiction

Question 46

where Do dopamine neurons project to generally

Answer 46

Basal ganglia Front parts of cortex - involved in decision making, learning, addiction

Question 47

where do ach neurons originate from

Answer 47

Basal forebrain (more anterior cluster)

Question 48

where do ach neurons project t

Answer 48

Cerebral cortex Hippocampus Amygdala

Question 49

how/where/what does ach do in brain

Answer 49

Acts through ionotropic nicotinic receptors (why cigs addictive) and Metabotropic muscarinic receptors (g protein coupled, also involved In sleep/wake, arousal)

Question 50

descrive Alzheimer’s disease

Answer 50

Ach neurons = among first to die

Question 51

describr how sensory info is transformed

Answer 51

Transformed as it moves through ach synaptic level Receptive fields of output neurons are diff and more complex than receptive fields of input neurons In does not equal out What comes out not identical to what does in Primary afferents have rfs, secondary also has rf as patch of skin but different - its transformed

Question 52

describe labelled lines = complicated features

Answer 52

Can be cross talk between labelled lines Labelled lines consistently persevered even as get more complex, and converge/diverge

Question 53

describe higher order neurons in sensory pathway = gen

Answer 53

have more compelx rfs than primary afferents Partly bc of convergence and divergence of lower order inputs At every level have convergence and divergence Sensory system builds up sensory perception

Question 54

describe convergence

Answer 54

Single secondary neuron gets input from multiple sensory neurons = input integrated, combine input to determine output Rf of secondary neuron = larger than one input neurons

Question 55

describe divergence

Answer 55

One neuron synapses with many different secondary neurons

Question 56

what does lateral inhibition allow

Answer 56

Allows a strong central signal to pass through Filters out weak surrounding signals Mechanism = sharpens contrast of sensory signals Divergence transforms message

Question 57

describe whole process of lateral inhibition

Answer 57

Ex = 3 primary afferents sensitive to skin pressure on surface —> secondary neurons all excitatory synapses Above and below = lower freq ap bc less activated Middle aff = high freq ap bc most pressure here = release a bunch of glutamate = ap fires = goes up to thalamus But = branches excite inhibitory neurons = inhibit the other 2 neurons Output diff from input Weaker firing = suppressed = increases contrast/sharpness of signal, only central signal goes through

Question 58

where is lateral inhibition found

Answer 58

Found everywhere in sensory systems

Question 59

What is connected to reticualr formation

Answer 59

cranial nerve nuclei

Question 60

What does cerebral cortex do

Answer 60

modulates lower circuitry

Question 61

Describe eeg

Answer 61

electrode stuck on top of skull Non invasive Attached to amplifier and record electrical activity of neurons in brain

Question 62

Describe serotonin

Answer 62

modulated by ssris Has something to Do with mood