VII Facial - anterior 2/3 of tongue

IX Glossopharyngeal - posteiror 1/3 of tongue and posterior of mouth

X Vagus - from taste buds at base of tongue and the pharynx

receptor> G_OLF> adenyl cyclase III (ACIII)> ^[cAMP] > ^[Na][Ca] > depolarization

^[Ca]> Cl channels open > further depolarization

Ca exchanger hyperpolarizes

salty - Na moves through Na channel > depolarization

sour - H+ from weak acids blocks K channels > depolarization

sweet - GPCR>cAMP>blocks K channels> depolarization

Bitter - diverse pathways blocks K or activates Cl pump

Umami - mGluR opens cation channel > depolarization

secondary olfactory system

septum of nose

separate accessory olfactory bulb

separate parallel pathway

slites in mouth allow passage of odorants

amygdala and hippocampus activation

VNO involved in learning to copulate, responds to pheremones

different class of odorant receptors (VR1s, VR2s)

initiates behavior

modulates behavior (intensity, frequency, coordination)

necessary and sufficient for behavior

stimulation leads to full behavior

few identified - e.g. crayfish escape behavior, LG controls upward tailflip, MG controls backward tail flip

some have no EC

others can express complex behaviors in headless state

rely on internal and external sensory information

do not require external signals

external signals provide useful input stabilizing performance and correcting for disturbance

one muscle cell

each skeletal muscle recieves a single motor neuron input

Ia - fast, large diameter, fires early during contraction (dynamic)

II - slow, small diameter, fires during sustained contraction (static)

Ib - inhibitory, from Golgi tendon organ, activated by extrafusal fiber contraction (muscle force)

provide steady motion

match force with task

work with tendon organs to improve control

contract to provide continuous monitoring of muscle tension

co-activate with extrafusal fibers

motor units provide incremental increase in the number of motor muscle fibers put to work

depends on motor neuron input resistance (size principle)

small motor neurons innervate small muscle fibers

enables walking - opposite limb extended

provides postural support during withdrawal from a painful stimulus

can change the range or direction of a reflex

e.g. paw touch during swing vs stance phase of walking - produces opposite effects

network of neurons producing rhythmic sequence of actions

minimum elements - 2 or more autoactive neurons, mutual inhibition, fatigue

post-inhibitory rebound improves performance

if inhibited for awhile more excitable afterward

active much faster than normal after inhbition

lowering of threshold during inhibited state

example of CPG

movement of mouth triggers coordinated contraction of gastric mill and digestive tract by stomatogastric nerve

mutual inhbition

1 firest first (by chance) > inhibits 2

1 fatigues > stops inhibiting 2

2 fires (post inhibitory rebound) > inhibits 1

2 fatigues > stops inhibiting 1

Lateral corticospinal tract - distal limbs

Rubrospinal tract - extensors

ventral corticospinal tract - voluntary motor impulses

vesitbulospinal tracts - limbs and trunk (lateral), neck and upper trunk (medial)

reticulospinal tracts - limb extension

tectospinal tracts - neck/head orientation

fires just before movement

controls spinal neurons through pyramidal tracts and brainstem motor nuclei. Direction-sensitive neurons (anterograde vs retrograde)

involved in planning movements

lesions lead to thwarted behaviors

inhibits movement until ordered

substantia nigra produces dopamine (excitatory)

Cortex>neostriatum (substantia nigra)> globus pallidus (subthalamic nucleus)> thalamus> cortex

connections ancient (similar to shark, connection to premotor cortex)

involved in learned motor patterns, balance

removal alters coordinated movements

tasks involving recognition of temporal organization most affected

also involved in sensory processing, spatial mapping of body surface

Cerebellar cortex

cerebrocerebellum - lateral hemispheres

spinocerebrum - medial to the cerebrocerebellum

vestibulocerebellum - caudal-inferior lobes

Deep cerebellar nuclei (dentate, interpose, and fastigial nuclei)

cerebellar peduncles (superior, middle, inferior)

receives input directly from spinal cord

lateral part is concerned with movements of distal muscles

median strip (vermis) concerned with movements of proximal muscles including eye movements

floculus and nodulus

receives input from vestibular nuclei of the brainstem

primarily concerned with movement underlying posture and equilibrium, as well as vestibulo-ocular reflex

multicellular protuberances surrounded by local invaginations in the tongue epithelium that form a trench to concentrate tastants

fungiform (25%), circumvalate (50%), foliate (25%)

small units important for activities that require sustained muscular contraction

red fibers

large pale muscle fibers that generate more force

important for brief exertions that require large forces

has properties that lie between S and FF 

twice the force of S and are resistant to fatigue

receive input form the cerebellar cortex

cerebrocerebellum > dentate

spinocerebellum > fastigial

vestibulocerebellum > vestibular complex

efferent pathway

project to upper motor neurons of the superior colliculus

multiple afferent and efferent pathways

most complex