Module 3 Discussion 2 Flashcards by Sara Richmond

Innervate the ends of intrafusal fibers

Gamma Motor neuron

How well did you know this?

Not at all

Perfectly

where does the gamma motor neuron receive information from

Receives info from cerebellum

How well did you know this?

Not at all

Perfectly

Function of gamma motor neuron

keep muscle spindle from reaching slack state

Keeps 1A sensory axons active to maintain stretch reflex

How well did you know this?

Not at all

Perfectly

_____________ is when the gamma neurons do not communicate with cerebellum → muscle goes slack

Hypotonia:

How well did you know this?

Not at all

Perfectly

Gamma Loop first step:

Muscle is stretched → 1A sensory axons send info to alpha motor neurons → extrafusal fibers contract

How well did you know this?

Not at all

Perfectly

Gamma loop second step:

Gamma motor neurons fire on intrafusal muscle fibers to cause them to contract

How well did you know this?

Not at all

Perfectly

Gamma loop third step:

Gamma motor neurons and alpha motor neurons fire simultaneously

How well did you know this?

Not at all

Perfectly

What does the third step avoid

Avoids hypotonia

How well did you know this?

Not at all

Perfectly

Gamma look step 4

Intrafusal muscle fibers will not be slack → 1A sensory neurons can fire due to another stimulus

How well did you know this?

Not at all

Perfectly

Located in tendon of extrafusal muscle intertwined with 1B sensory neurons

Golgi tendon organ

How well did you know this?

Not at all

Perfectly

Function of Golgi tendon organ

ensure muscle is not over contracting

How well did you know this?

Not at all

Perfectly

1B sensory axon detects when

muscle contracts

How well did you know this?

Not at all

Perfectly

1B synapses on

inhibitory interneuron in spinal cord

How well did you know this?

Not at all

Perfectly

Inhibitory interneuron synapses on alpha motor neuron

(using GABA)

How well did you know this?

Not at all

Perfectly

Alpha motor neuron stops firing when stimulated by Golgi tendon

Protects tendon and muscle from over contracting

How well did you know this?

Not at all

Perfectly

Muscle is stretched (extra/intrafusal muscle) by

extra weight

How well did you know this?

Not at all

Perfectly

1A afferent axons detect stretch and synapse with __________

alpha motor neurons

How well did you know this?

Not at all

Perfectly

Detect stretch via

mechanically gated channels

How well did you know this?

Not at all

Perfectly

Alpha motor neurons stimulate

extrafusal muscle fibers to contract

How well did you know this?

Not at all

Perfectly

Gamma motor neurons fire on

intrafusal muscle ends to contract intrafusal muscle fibers

How well did you know this?

Not at all

Perfectly

Keeps 1A sensory axons active
1B afferent axons in GTO detect extrafusal muscle contraction and synapse with inhibitory interneurons in spinal cord and then _____________

Inhibitory interneurons synapse on alpha motor neuron to prevent over contraction

How well did you know this?

Not at all

Perfectly

Uses inhibitory interneurons

reciprocal inhibition

How well did you know this?

Not at all

Perfectly

Excite a muscle and reciprocally inhibit its _____________ to allow for designated contraction

antagonist

How well did you know this?

Not at all

Perfectly

Add a weight in hand → muscle is lengthened

1A sensory axon detects stretch in biceps and fires on alpha motor neuron

Alpha motor neuron will fire to contract bicep
1A sensory axon also fires on inhibitory interneuron
Inhibitory interneuron synapses on alpha motor neuron in triceps (antagonist muscle) to prevent contraction
This overcomes the stretch reflex in the triceps

How well did you know this?

Not at all

Perfectly

Uses excitatory interneurons and means move leg away from pain

Flexor withdrawal reflex

In flexor withdrawal reflex: | __________ nociceptive axons detect pain

Aδ

In flexor withdrawal reflex: | Synapse on excitatory interneurons that synapse on alpha motor neurons to

contract flexor muscles

In flexor withdrawal reflex: | Synapse on inhibitory interneurons that synapse on

alpha motor neurons of extensor muscles

Cross extensor reflex: allow us

to be supported by other leg

During the cross extension reflex:

Extensor muscles are activated | Flexor muscles are inhibited

Aδ nociceptive axons that detected pain synapse _____________

on interneurons in opposite leg

Flexor withdrawal reflex + cross extensor reflex work together

So we can flex one limb to withdraw it from pain and extend other to stay standing on it

Cross extensor reflex is building block for

locomotion

Movement of single limb is a cycle of 2 phases in bipeds:

Phase 1: stance phase → both feet on ground | Phase 2: gait phase → one foot is off ground

___________ stance phase → both feet on ground

Phase 1:

Locomotion depends on

spinal cord neurons that exhibit a central pattern generator rhythm

____________gait phase → one foot is off ground

Phase 2:

___________ neurons that create action potentials on their ownNot dependent on sensory input or entirely on higher centers in brain

Central Pattern Generators (GPGs):

What experiment shows the central pattern generator

Cat lesion experiments

_____________: planning movement Highly dependent on sensory input (like knowing where you are) Sensory info reaches cerebral neocortex Strategizes with basal ganglia

Strategy

___________: issue instructions of movement Sends info to neurons in spinal cord on how to execute movement Primary motor cortex choose final movement Cerebellum (to contribute to past movements)

Tactics

_________ moving Coordinates muscles to actually move Brainstem and spinal cord (alpha motor neurons) send info to body

Execution:

Strategy stage: | Sensory info reaches

cerebral neocortex

Strategy stage: | Cerebral cortex Strategizes with

basal ganglia

Tactics stage: Sends info to neurons in _______on how to execute movement movements)

spinal cord

Tactics Stage: | ____________choose final movement

Primary motor cortex

Tactics Stage: | ___________ (to contribute to past movements)

Cerebellum

Control movement of distal muscles | EX: corticospinal tract, rubrospinal tract

Lateral pathways

Control postural muscles | EX: vestibulospinal tract, tectospinal tract, pontine reticulospinal tract, medullary reticulospinal tract

Ventromedial pathways

``` Originates in the primary motor cortex Travels through… internal capsule and cerebral peduncles (midbrain) decussates in pyramids of medulla Terminates in the spinal cord ```

cortico spinal tract

Cortico spinal tract

primary motor cortex -> internal capsule -> cerebral peduncles (midbrain) -> pyramids fo medulla-> spinal cord

``` Parallel to the corticospinal tract Receives input from frontal cortex Originates and decussates in red nucleus Travels through: Midbrain Medulla Terminates in spinal cord ```

rubrospinal tract

Path of rubiospinal tract

frontal cortex-> red nucleus -> midbrain-> midbrain -> medulla -> Spinal cord

Lesioning lateral pathways: | ____________→ can’t move joints independently

Loss of fractional movement

Lesioning lateral pathways: | Voluntary movement was _________________

fragmented (slower, less accurate)

Lesioning lateral pathways: | Postural muscles were ________

unaffected (b/c from ventromedial pathways)

__________________________ | Symptoms similar to lateral pathways, but it recovers due to compensation of rubrospinal tract

Lesions to the corticospinal tract alone

Lesions to the corticospinal tract alone: | Permanent deficit in

distal flexors and fractional movement

Lesions to rubrospinal tract reverse recovery →

permanent damage

Motor control comes from the

motor cortex

__________ aka M1 aka motor cortex The actual execution of movement Somatotopy. A certain area of the cortex controls a certain part of the body

Area 4

``` ______________ SMA (supplementary motor area) Planning of movement PMA (premotor area) Planning of movement ```

Area 6

Somatosensory cortex (Parietal lobe (area 3b)) aids

motor control

____________ Is the SMA and the PMA

Area 6

___________________ | Located in medial parts of Area 6

Supplementary motor area (SMA)

________________ Located in lateral part of Area 6 Contains mirror neurons: respond when a movement is executed, imagined, and observed

Premotor area (PMA)

Contains ______________respond when a movement is executed, imagined, and observed Enable us to understand actions and intentions of others

mirror neurons:

Perhaps dysfunction of ___________is related to autism

mirror neurons

___________ Planning of movement + strategy Active right before execution of movement and when movement is observed Activity stops shortly after action is initiated Firing is highly specific to activity observed

SMA + PMA:

Communicates with body via brainstem and spinal cord Pyramidal neurons in layer V (Betz cells) Cell bodies are in cortex Project out and synapse directly on alpha motor neurons or indirectly with interneurons Active when a movement is executed Receive inputs from area 6 (SMA/PMA), 3, 1, 2 (parietal lobe) and thalamus

Area 4 aka primary motor cortex

what cells are in area 4 or primary motor cortex

Pyramidal neurons in layer V (Betz cells)

Project out and synapse directly on

alpha motor neurons or indirectly with interneurons

Active when a movement is executed | Receive inputs from area 6 (SMA/PMA), 3, 1, 2 (parietal lobe) and thalamus

area 4

Implant electrode in vivo (primates) | Train monkey to move joystick in a certain direction based on light

Coding of M1 Neuronal Function

Burst of activity occurs immediately before and during movement

Activity correlated with force and direction of movement

All individual neurons have “broad tuning” for direction All neurons can fire in a wide range of directions with various force Neurons have a prefered movement There’s a population of neurons firing per direction =___________

NOT just one direction per neuron

A population of neurons in motor cortex is active for

every movement

Activity of a single neuron represents a “vote” for a direction of movement

Neurons have a preference for specific directions

Resulting movement is an average of _____________

“votes” of the neurons

One neuron has different direction _______

preference than another

___________mportant for planning a movement (proprioception/strategy)

Parietal Lobe

Parietal Lobe: Sends info to______________________

primary somatosensory cortex (area 3b)

Parietal Lobe Receives input from _____________ Neurons responsive to ________________

ventral posterior nucleus of thalamus | somatosensory stimuli only

Parietal Lobe | Lesions impair __________

somatic sensation

PET studies: ____________ | Subject move finger = blood to ________

change in blood flow | areas 5, 6, 7, 4

Subject thinks about moving finger = blood to ______________ Subject move finger = blood to ________________ Subject thinks about moving finger = blood to ___________

area 6PET studies: change in blood flow areas 5, 6, 7, 4 area 6

Certain areas of the motor cortex are ____________

“malleable”

Cortex can reorganize to innervate a ______________

different target

Whisker experiment: motor neurons innervating whiskers were

lesioned

Motor neurons were remapped and innervated

forelimb and periocular muscles

If you learn an instrument, can reorganize

motor innervation

Regulates motor control

basal ganglia

2 functions, but likes doing 1 at a time of basal ganglia →

grouping/chunking: | Action selection

General circuitry: Motor cortex sends excitatory info to 1. _________ to process 1. _________ send inhibitory info to 2. __________ or 3. ____________ 2. ___________ sends excitatory info 3. _____________ 3. ___________ sends excitatory info to 4. ____________

basal ganglia superior colliculus or thalamus superior colliculus to thalamus Thalamus to motor cortex

Module 3 Discussion 2 Flashcards

(94 cards)