Neurobiology Final

the apex of the cochlea in the scala vestibuli

Where do pressure waves ascend to?

the base within the scala tympani

Where do pressure waves descend?

pushes hair cells against the tectorial membrane

Basilar membrane movement does what?

turning pressure waves into changes in membrane potential

Auditory system general purpose?

opens Ca2+ channels, driving neurotransmitter release

K+ influx opens what channels and drives what?

acetylcholine as a neurotransmitter

What does the efferent synapse of a hair cell release?

inward

In a hair cell, the driving force on K+ at apical surface is what direction?

outward

In a hair cell, the driving force on K+ at basal surface is what direction?

gain control mechanism

A process by which hair cells adjust their sensitivity to sound stimuli, enabling them to maintain functionality across a range of sound intensities.

tonotopy

The spatial arrangement of where auditory signals are transmitted, received, and perceived.

in the cochlea and human auditory cortex

Where is there tonotopy?

at the first cochlear nucleus in the auditory pathway

where do we have encoding of intensity and frequency?

superior olivary complex (MSO + LSO)

Different nuclei in what complex encodes information about time and intensity?

MSO: medial superior olive

Which part of SOC encodes time?

LSO: lateral superior olive

Which part of SOC encodes intensity?

motor control

interaction between sensory input and motor input

volition

The process of making a conscious choice or decision to perform an action, often involving voluntary control over movement.

sensory feedback

The dynamic process that allows for corrections in movement and modification to the motor program to improve in the future 

unconscious processing

What occurs when the motor system performs some movements automatically without higher order control (walking) ?

adaptability

The ability of the nervous system to adjust and change in response to experience or environmental conditions, enhancing learning and motor performance.

Thalamus

Where do the 4 levels and 2 side loops interact with each other?

basic motor functions

What is the role of the spinal cord as the first level of the motor control hierarchy?

generate adaptive muscle force

How do spinal circuits contribute to movement?

low-level execution

How does the spinal cord assist the motor cortex?

skeletal, contraction

What do alpha motor neurons innervate and what is their effect?

acetylcholine

What neurotransmitter do alpha motor neurons release at the neuromuscular junction?

action potential trigger

What happens when acetylcholine binds to receptors on muscle fibers?

muscle contraction

What do action potentials in muscle fibers lead to?

anterior (ventral) horn

Where are motor neurons that control limbs and the body located?

brainstem motor nuclei

Where are motor neurons that control the head and facial muscles found?

motor neurons

What is the only pathway through which the nervous system communicates with muscles?

multiple input integration

Why do motor neurons have highly branched dendritic trees?

neuron pool

What is a group of neurons for one muscle?

1:1

What is the ratio between a muscle and its motor neuron pool?

motor unit

What is a neuron plus its fibers?

fibers per motor neuron

What does the innervation ratio describe in motor units?

delicate movement

What kind of movement is associated with a small innervation ratio?

coarse movement

What kind of movement is associated with a high innervation ratio?

rate code

How do motor neurons signal the amount of force a muscle should exert?

Max contraction with no further increase despite more APs.

What is tetanus in the context of muscle contraction?

Small neurons fire before large ones.

What is the size principle in motor neuron recruitment?

Lower membrane surface area and fewer ion channels.

Why do small motor neurons fire before large ones?

motor neuron size

What determines the type of muscle fiber a motor neuron innervates?

Slow-twitch (low force, long duration).

What type of muscle fibers do small motor neurons innervate?

Fast-twitch, fatigue-resistant.

What type of muscle fibers do intermediate motor neurons innervate?

Fast-twitch, fatigable (high force, short duration).

What type of muscle fibers do large motor neurons innervate?

motor control

how the brain processes sensory input to construct detailed representation of external environment

homeostasis

adjust control of motor system (output) based on sensory input

movement

dynamic process that requires constant interaction between sensory input and motor output 

muscle receptors

provide sensory information about muscles and limbs

muscle spindles

What detects change in muscle length and rate of change of length (velocity) of muscle

muscle spindle details

6-8 intrafusal fibers with stretch recepors

open and close as a function of the length of the intrafusal fiber

what do stretch receptors do?

Golgi tendon organs

What detects changes in the magnitude of force applied to the muscle?

Nuclear chain, static nuclear bag, dynamic nuclear bag fibers

3 types of muscle spindle fibers

nuclear chain fibers

nuclei aligned in a single row in the center of the fiber

static nuclear bag fibers

nuclei form a spindle

dynamic nuclear bag fibers

similar morphology to static bag fibers because they signal rate of change of muscle length)

Group 1A

afferents wrap around the center of all types of intrafusal fibers. specialized endings.

Group 2

afferents innervate the ends of the nuclear chain fibers and static bag fibers at flower spray endings

extrafusal fibers

fibers that stretch and then contract to produce force

No, spindle fibers stretch along with the muscle fibers but when muscle fibers contract, spindle fibers don’t.

Do spindles stretch and then contract with extrafusal muscle fibers?

myotatic reflex

A reflexive contraction of a muscle in response to its own stretch, involved in maintaining stability and posture.

reciprocal inhibition

A neural process that inhibits the opposing muscle group when a muscle contracts, allowing smooth and coordinated movements.

flexor reflex

initiatedby pain receptors and coordinates activity at multiple joints (group 3 afferent activation —> excitatory interneurons —> alpha motor neurons —> muscle contraction)

crossed extension reflex

coordinates activity of other half of body while primary side reacts

hypersensitive flexor reflex

facilitates reflex when anticipating unpleasant sensory experience

suppressed flexor reflex

inhibits reflex when sensory stimulus initiates reflex (putting up with pain instead of reacting)

corticospinal

controls motor neurons and interneurons in the spinal cord

corticobulbar

controls brainstem nuclei that innervate cranial muscles

alpha (efferent) motor neurons

neurons that directly innervate skeletal muscles to produce movement.

gamma motor neurons

neurons that innervate contractile components at the ends of intrafusal fibers (spindles)

declarative memory

long term memory (knowing what) has conscious component and includes memories of facts and events

nondeclarative

long term memory (knowing how) includes memories that don’t have conscious component, like memories for skills and habits

glutamatergic excitatory synapse between the sensory neuron and motor neuron

What specific synapse causes muscle contraction? (glutamatergic..)

learning

a change in the strength of existing synaptic connections

short term memory

Type of memory that involved second messenger systems, 5HT binding, modulation of membrane ion channels, and cyclic amp as a secondary messenger

long term memory

type of memory that involves changes in protein synthesis and gene regulation, physical changes in neuron, changes in varicosities, growth of new processes and formation of synapses, and gene expression regulating proteins

excitatory

What type of receptor is glutamate?

flexor-extensor rule

motor neurons that innervate flexor muscles are located posterior to motor neurons that innervate extensor muscles

proximal-distal rule

motor neurons that innervate distal muscles (branch) are located lateral to motor neurons that innervate proximal muscles (trunk)