NEUR200-UNIT3 UMD

what three categories are biological rhythms categorized into

circadian, ultradian, infradian

how long do circadian cycles last

1 day

how long do ultradian cycles last

< 1 day

how long do infradian cycles last

>1 day

what signals guide rhythms

light, exercise, meals, temperature

suprachiasmatic nucleus

maintains biorhythms, melatonin releases by pineal gland

what cells project to the SCN

ganglion cells

what do ganglion cells have

photosensitive pigments

what are photosensitive pigments sensitive to

blue light

how does light go from the eye to the SCN in mammals

retinohypothalamic pathway

where is the biological clock in the SCN

above optic chiasm

what can SCN lesions disrupt

circadian rhythms

what is a phase shift

activity shift in response to stimuli

what are phase shifts entrained to

stimuli

zeitgeber

cues an animal uses for environments

light

controls human behavior

sleep

changes over lifespan

sleep stages

waking, stage 1, stage 2, stage 3, REM

waking stage

EEG shows desynced behavior, beta wave activity, small voltage changes, fourier transform can graph this

Stage 1

alpha waves during relaxation at 8-12 hZ, vertex spikes, muscle distension, slow heart rate

Stage 2

sleep spindles, start falling asleep, K-complexes, slow cortical firing rates, slow heart and respiration rates, decreased muscle tension

sleep spindles,

12-16 hZ, 0.5-2 seconds

what are sleep spindles important for

learning and memory consolidation

What are k-complexes important for

learning

Stage 3

slow waves, delta waves, deeply relaxed body, slow heart and respiration, decreased muscle tension, growth hormone secretion at peak

delta waves

high amplitude, low frequency, 1 hZ frequency

what are delta waves important for

learning and synaptic pruning

what are delta waves generated by

highly synced neural activity

REM stage

desynced activity, EEG similar to waking stage, eyes move rapidly, relaxed muscles, increased temp/heart rate/respiration/cortical firing rate, dreams

what are sleep stages categorized by

EEG and peripheral physiology

approximately how many sleep cycles do we go per night

4 to 6

4 functions of sleep

energy conservation, ecological adaptation, body restoration, memory consolidation

reactivation process

process associated with memory consolidation

fatal familial insomnia (FFI)

mutation in DRNP gene, baby insomnia, eventual death

adenosine

neuromodulator, cellular metabolism byproduct, negative feedback loop for sleep, increases sleep drive

what does adenosine bind to

metabotropic receptors

what do drugs blocking adenosine receptors do

increase wakefulness

orexin

promotes wakefulness, high during day and low when we sleep

what does loss of orexin cause

narcolepsy

symptoms of narcolepsy

cataplexy, low orexin levels, daytime sleepiness, sleep paralysis

Type I narcolepsy

cataplexy present, low orexin levels

Type II narcolepsy

cataplexy not present, typical orexin levels

narcolepsy treatments

behavioral, wakefulness promoting agents, typical stimulants

subdivisions of somatosensory receptors

dorsal columnar, spinothalamic

dorsal columnar system

pressure/touch control, mild-moderate pressure detected

spinothalamic

pain/temperature control, excessive pressure detected

difference between dorsal columnar and spinothalamic division

takes different routes to brain

types of touch

constant pressure/static, vibration, stretch, pain/temperature

2-point discrimination threshold

a way to determine sensitivity of an area

touch receptor transduction

receptor responds to pressure, cell membrane stretched, mechanically gated ion channels open, cell depolarizes

types of touch receptors

pacinian corpuscle, mercel's disk, ruffini's disk, free nerve endings

pacinian corpuscle

rapidly adapting, responds to vibration and pressure (high frequency), low activation threshold, large receptor field, dorsal columnar system

mercel's disk

slowly adapting, responding to light/static touch, small receptor field, dorsal columnar system

ruffini's corpuscle

slowly adapting, responds to stretch, dorsal columnar system

free nerve endings

rapidly adapting, responds to pain, spinothalamic system

dorsal root ganglion (DRT)

holds cell bodies of somatosensory cells for the dorsal column system

how do axons of somatosensory cells project

ascend ipsilaterally to dorsal columnar nuclei in the caudal medulla

ipsilaterally

same side

where does dorsal columnar system cross the midlines

medulla oblangata

where does spinothalamic system cross the midline

spinal cord

the deeper you go...

the larger the receptor fields

what is dorsal columnar system important for

mechanosensation

another name for dorsal columnar system

medial lemniscal pathway

what activates spinothalamic system

too much mechanosensation

brown-sequard syndrome

damaged left thoracic spinal cord, sensations lost in right left because of crossing since neural path is blocked

sensitized pain means

tissue damage

when cells are damaged or dead, the released chemicals activate what

nociceptive neurons

what kind of path is pain

descending control

where does the spinothalamic tract send a collateral to

PAG

where does the PAG project to

raphe nuclei

raphe nuclei

inhibit pain neurons

what is the PAG innervated by

amygdala, cortex, hypothalamus

what do descending pain modulators synapse on

peptidergic neurons

local pain modulation pathway

a) AB fiber mechanoreceptor; b) C fiber (noireceptor); c) PAG); inhibitory circuit neurons; dorsal horn projection neurons

mechanostimulation causes AB fibers to release

inhibitory transmitters to reduce pain

exogenous pain control

antinflammatories, opiates

antinflammatories

inhibits prostoglandin production to prevent inflammation and swelling

opiates

reduce internal pain sensation in brain, activates opioid receptors in spinal cord, binds to enkaphalin

what part of the brain is the somatosensory cortex located in

parietal lobe

how is the somatosensory cortex organized

topographically

what is the somatosensory sometimes called

homunculus

cortical plasiticity

with experience, representations of specific areas can change

another name for spinothalamic system

anterolateral

what does stimulating mechanoreceptors do

inhibit pain

inhibitory local circuit neuron

interneurons

what controls local control of pain

mechanoreceptors

what do lower motor neurons send axons to and drive

skeletal muscles

where are upper motor neurons located

cortex

___ motor neuron synapses on ___________ muscle fibers

1; multiple

nicotinic transmission path

motor neuron fires; acetylcholine released; binds to nicotinic receptors on muscle fibers

3 types of muscles

fast-fatigueable, fast-fatigue resistant, slow

fast-fastigue muscles

lot of oxygen, lots of force at once, successive activation lowers exerted force, lots of simultaneous activation of motor neurons activates muscle, sprinting, jumping

fast-fatigue resistant

for activities with middle force

slow muscles

no oxygen, little force for long time periods, standing, balancing

with experience, what changes between fast and slow fibers

the ratio of fast and slow muscles

muscle spindles

responds to passive stretch and not contraction

golgi tendon organs

tells how much force is a muscle is applying, responds to contraction and not passive stretch, high activity threshold

what does muscle contraction decrease

baseline activity levels

extensor muslces

extend/open joints

flexor muscles

flex/close joints