NPB 110B

olfactory system

olfactory system

the sensory system for smell

olfactory receptor neurons

receptor cells that initiate the sense of smell

depolarizing current

inward

when chlorine leaves the cell...

creates a negative/inward current

how many receptor proteins does each ORN possess

one

how many odorants can each ORN respond to

many

each olfactory nerve projects

ipsilaterally to the olfactory bulb

gustatory system

the sensory system for taste

how many receptors can a taste receptor cell express for different tastants

several

salt and sour tastes are elicited by

ionic stimuli

sweet, umami, and bitter all act through

GPCRs

vestibular receptors

mechanoreceptors that detect fluid movement in the labyrinths of the inner ear

depolarization of vestibular hair cells is caused by

the stereocilia movement towards the kinocilium

hyperpolarization of vestibular hair cells is caused by

stereocilia movement away from the kinocilium

when short hairs tip in the direction of tall hairs

stimulates the firing of cranial nerve 8

when tall hairs tip in the direction of short hairs

inhibits the firing of cranial nerve 8

how many total semicircular canals

6

each semicircular canal responds to

angular head acceleration during rotation of the head in their plane

endolymph

high in K+ and low in Na+

otolith organs

utricle and saccule

otolith organs provide information about

linear acceleration and changes in head position relative to the forces of gravity

utricle lies

horizontally

saccule is oriented

vertically

which way are utricle hair cells are oriented

towards the striola

which way are saccule hair cells oriented

away from the striola

vestibular nerve has how many subdivisions

two

superior vestibular nerve

horizontal and anterior semicircular canals and utricle

inferior vestibular nerve

posterior semicircular canal and saccule

axons of the vestibular nerve synapse in the

vestibular nucleus

four major vestibular nuclei

superior nucleus, lateral nucleus, medial nucleus, descending nucleus

superior and medial nuclei receive input predominately from the

semicircular canals

lateral nucleus receives input mainly from the

canals and otolith organs

descending nucleus receives input from the

otolith organs and projects to the cerebellum and spinal cord

lateral and superior vestibular nuclei project to the

thalamus

from the thalamus, the vestibular neurons project to the

vestibular cortex

lateral vestibulospinal tract

Axons arising in the lateral vestibular nucleus that project ipsilaterally to facilitate lower motor neurons to extensor muscles and simultaneously inhibit lower motor neurons to flexor muscles via interneurons.

medial vestibulospinal tract

Axons arising in the medial vestibular nucleus that project bilaterally to the cervical and thoracic spinal cord. Affects the activity of lower motor neurons that control the neck and upper back muscles.

vestibulo-ocular reflex

Coordination of motion information with visual information that allows you to maintain your gaze on an object while you move

vestibulo-colic reflex

keeps the head still in space or on a level plane when you walk

vestibular spinal reflex

adjusts posture for rapid changes in position

basal ganglia and cerebellum have no direct connection to the

lower motor neurons

motor homunculus discovered by

Wilder Penfield

Edward Evarts findings

concluded that cells were muscle like; the force, not displacement of the wrist, correlates with neuron firing

Georgopolus Experiments

results show that cells are tuned to direction

individuals with lesions in the premotor cortex may have difficulty

performing movements in response to verbal commands

cerebellum function

coordination, balance, motor learning

Vestibulocerebellum

maintenance of balance, control of eye movements

Spinocerebellum

Enhances muscle tone and coordinates skilled, voluntary movements

lateral cerebellum

area of the cerebellum responsible for voluntary movement of extremities

caudate nucleus and putamen

receive input from the cerebral cortex and send output to the globus pallidus

globus pallidus

component of the basal ganglia that connects to the thalamus which relays information to the motor areas and the prefrontal cortex

Huntington's Disease

A human genetic disease caused by a dominant allele; characterized by uncontrollable body movements and degeneration of the nervous system; usually fatal 10 to 20 years after the onset of symptoms.

Key Symptoms of Huntingtons Disease

chorea - abnormal involuntary writhing movements

Parkinson's disease

a progressive disease that destroys brain cells and is identified by muscular tremors, slowing of movement, and partial facial paralysis

muscle spindles

transducers of muscle length and located in parallel

Golgi tendon organs

located in series and transducers of muscle force

the role of gamma motor neurons

regulate the gain of muscle spindles so they can operate efficiently at any length of the parent muscle

motor neurons innervating axial (proximal) musculature are located

medially

motor neurons innervating the distal musculature are located more

laterally

corticospinal tract

90% of the fibers cross at lower medulla

pontine reticulospinal tract

excitatory synpase on leg extensors and arm flexors

medullary reticulospinal tract

inhibitory synapse

lesion of corticopinal tract

substantial deficit in the control and coordination of fine finger movements

lesion of the vestibulospinal and reticulospinal tracts

severe postural deficits

lesion in spinal cord

loss of all descending input and normal neurologic reflexes

monosynaptic component

an excitatory loop from the spindle to the alpha motor neuron back to the muscle containing the spindle

disynaptic component

from the spindle to inhibitory interneurons to the alpha motor neuron innervating the antagonistic muscle

what kind of feedback loop does the stretch reflex operate as

negative

ALS

caused by the degeneration of the alpha motor neurons and their input from the cortex

myasthenia gravis

the acetylcholine that is released at the neuromuscular junction fails to consistently elicit an action potential in the muscle fiber because the body is making antibodies against the receptors.

Facilitation

a very brief, rapid increase in synaptic strength, lasting only tens to hundreds of milliseconds

augmentation

an increase in synaptic strength, lasting several seconds

depression

a decrease in synaptic strength, lasting several seconds

Post-tetanic potentiation

an increase in strength lasting minutes

long term potentiation

an increase in synaptic strength that lasts for hours or longer

long term depression

a decrease in synaptic strength that lasts for hours or longer

facilitation is a

presynaptic event

NMDA glutamate receptors are permeable to ___ but blocked by ___

Ca2+, Mg2+

Habituation in Sea Hares

over many trials, touching the siphon no longer causes the gill to contract vigorously

Sensitization

response elicited by a noxious stimulus to other non-noxious stimuli

During habituation of the gill-withdrawal reflex in Aplysia

transmission at the glutamatergic synapse between the sensory and motor neuron is depressed

during sensitization

there is a recruitment of additional neurons

Hebb's postulate

coordinated activity of presynaptic and postsynaptic neuron strengthens the synapse

strabismus

condition where the eyes deviate when looking at the same object

Broca's area

Controls language expression - an area of the frontal lobe, usually in the left hemisphere, that directs the muscle movements involved in speech.

Wernicke's area

controls language reception - a brain area involved in language comprehension and expression; usually in the left temporal lobe

Broca's aphasia

condition resulting from damage to Broca's area, causing the affected person to be unable to speak fluently, to mispronounce words, and to speak haltingly

Wernicke's aphasia

condition resulting from damage to Wernicke's area, causing the affected person to be unable to understand or produce meaningful language, able to speak fluently

in this type of aphasia, the patient is aware of the deficit

broca's aphasia

in this type of aphasia, the patient is unaware of the deficit

wernicke's aphasia

conduction aphasia

arises from lesions to the pathways connecting broca's and wernicke's

declarative memory

the cognitive information retrieved from explicit memory; knowledge that can be declared

nondeclarative memory

A subsystem within Long term memory which consists of skills we acquire through repetition and practice

operant conditioning

a type of learning in which behavior is strengthened if followed by a reinforcer or diminished if followed by a punisher

classical conditioning

a type of learning in which one learns to link two or more stimuli and anticipate events

Pavlovian conditioning

A type of learning in which a neutral stimulus acquires the ability to evoke a response that was originally evoked by another stimulus.

Henry Gustav Molaison

His working memory and his ability to form long-term procedural memories was intact. He could learn new motor skills, despite not being able to remember learning them.

Priming

the activation, often unconsciously, of certain associations, thus predisposing one's perception, memory, or response

episodic memory

the collection of past personal experiences that occurred at a particular time and place

semantic memory

a network of associated facts and concepts that make up our general knowledge of the world