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Neurobiology of Adult Brain Disorders > Neuromodulation of the Central Nervous System > Flashcards

Neuromodulation of the Central Nervous System Flashcards

1
Q

Name the six components of the central nervous system

A

Spinal cord, brain stem, cerebellum, midbrain, diencephalon, and cerebrum

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2
Q

Name the components of the brainstem

A

medulla, pons, and midbrain

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3
Q

What is the function of the medulla?

A

digestion, breathing, heart rate control

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4
Q

What is the function of the pons?

A

movement of information from hemispheres to the cerebellum

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5
Q

What is the function of the cerebellum?

A

motor tasks, learning, force-range of movement

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6
Q

What is the function of the midbrain?

A

sensory-motor functions, eye movement, visual-auditory reflexes

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7
Q

What are the two components of the diencephalon?

A

thalamus and the hypothalamus

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8
Q

What is included in the cerebrum?

A

cerebral cortex, basal ganglia, hippocampus, and amygdaloid nuclei

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9
Q

The medial lemniscus links __ receptors and __ __ for all modalities-sensations except __

A

sensory, cerebral cortex
smell

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10
Q

Sensory decussation occurs at the ___

A

medulla

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11
Q

Fibers that originate in the primary motor cortex and terminate in the __ horn of the __ __ constitute a significant part of the __ tract engaged in ___

A

ventral; spinal cord
corticospinal
movement

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12
Q

Describe the descending lateral corticospinal pathway

A

In the cerebral cortex (primary motor cortex) thru internal capsule
Down to midbrain (cerebral peduncle)
Pons
Medulla
Medulla/ spinal cord junction - pyramidal decussation to contralateral side)
Lateral corticospinal tract
Spinal cord to lateral motor muscle

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13
Q

Describe the ascending pathway of sensation

A

Sensation in thru dorsal root ganglion to medulla
Medulla - sensory decussation to contralateral side
Pons (medulla + pons = medial laminiscus)
Midbrain
Ventral posterior lateral nucleus
Somatosensory cortex

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14
Q

__, __, and __ are involved in the control of simple tasks, including walking

A

motor cortex, brain stem, and spinal cord

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15
Q

The right lobe receives signals from the __ side of the body

A

left

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16
Q

Sensory information regulates __

A

movement

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17
Q

Reflexes are __ and __ based on the task

A

flexible and adapted

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18
Q

Reflexes are integrated by centrally generated __ commands into __, __ movements

A

motor
complex, adaptive

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19
Q

Where do the sensory stimuly for spinal reflexes arise from?

A

receptors in muscles, joints, and skin

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20
Q

The neural circuitry responsible for the motor response is contained where?

A

Entirely within the spinal cord

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21
Q

What are two types of spinal reflex pathways?

A

Polysynaptic and monosynaptic

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22
Q

Spinal reflexes produce __ patterns of __ contraction

A

coordinated; muscle

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23
Q

Cutaneous reflexes produce __ movements that serve __ and __ functions

A

complex
protective; postural

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24
Q

The __-__ reflex is purely spinal

A

flexion-withdrawal

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25
Q

The stretch reflex is purely __, it __ the muscle lengthening

A

spinal; resists

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26
Q

What are Renshaw cells?

A

interneurons whose primary role is recurrent inhibition of the same motor neurons which they are excited by

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27
Q

Modulation of spinal reflexes is __ dependent

A

task

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28
Q

Neural signalign in reflex pathways is adjusted according to the __ __

A

motor task

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29
Q

The state of the reflex pathways for any task is referred to as?

A

The function set; establishment unknown

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30
Q

Sensory input from a localized source generally produces ___ reflex responses in __ __ at once, some of which may be __ from the stimulus

A

coordinated; many muscles
distant

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31
Q

Supraspinal centers play an important role in __ and __ spinal reflexes, even to the extent of __ __ when appropriate

A

modulating; adapting
reversing movements

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32
Q

Local spinal circuits contribute to the __ of __ responses

A

coordination; reflex

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33
Q

T/F: la fibers make indirect connections to the alpha motorneurons

A

False! Direct connections

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34
Q

La fibers from a muscle __ not only the __ innervating the __ (homonymous) muscle, but also those innervating __ (heteronymous) muscles with a __ __ action

A

excite
motor neurons
same; other
similar mechanical

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35
Q

What is the basis for reciprocal innervation?

A

disynaptic inhibitory pathway

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36
Q

Explain the disynaptic inhibitory pathway in lamends terms

A

When a muscle is stretched, its antagonists relax

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37
Q

Divergence in reflex pathways __ __ inputs and __ __ movements

A

amplifies sensory
coordinates muscle

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38
Q

In all reflex pathways in the spinal cord, the __ neurons form divergent connections with a __ number of target neurons through extensive __ __

A

sensory
large
axonal branching

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39
Q

T/F: Stimulation of a small number of sensory axons from a small area of skin is sufficient to cause contractions of widely distributed muscles and thus to produce a coordinated motor pattern

A

true

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40
Q

Individual la axons make __ synapses with all __ __ neurons innervating the medial gastrocnemius of the cat-autogenic excitation

A

excitatory
homonymous motor

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41
Q

T/F: convergence of inputs on Ib interneurons decreases flexibility of reflex responses

A

False, increases flexibility

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42
Q

Describe how the convergence of inputs on Ib interneurons increases reflex response flexibility

A

Ib inhibitory interneuron receives input from tendon organs, muscle spindles, joint and cutaneous receptors, and descending pathways

action of Ib sensory fibers on extensor motor neurons is REVERSED from Inhbition to excitation when walking is initiated

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43
Q

T/F: Central motor commands and cognitive processes can alter synaptic transmission in spinal reflex pathways

A

true

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44
Q

__ and __ of synaptic transmission in spinal reflex pathways can be altered during __ acts

A

strength; sign
behavioral

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45
Q

The __ of the __ reflex declines as we progress from standing to walking to running (__-__ reflex reversal)

A

strength monosynaptic
state-dependent

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46
Q

What are the three sites in the reflex pathway which central neurons can regulate the strength of spinal reflexes?

A

Synaptic transmission can be modified at
1. alpha motor neurons
2. interneurons in all reflex circuits EXCEPT monosynaptic pathways
3. presynaptic terminals of the afferent fibers

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47
Q

Gamma motor neurons adjust the __ of __ spindles

A

sensitivity; muscle

48
Q

Where do gamma motor neurons innervate?

A

the intrafusal muscle fibers of muscle spindles

49
Q

The __ of the intrafusal fibers by the __ motor neurons keeps the spindle under __, maintaining the __ __ of the Ia fibers within an optimal range for signaling changes in __

A

contraction; gamma
tension
firing rate
length

50
Q

What is the function of the alpha-gamma co-activation?

A

stabilizes the sensitivity of the muscle spindles, used in many voluntary movements

51
Q

What else, aside from axons of gamma motor neurons, innervate the intrafusal fibers?

A

axon collaterals of alpha motor neurons

52
Q

Define beta axons

A

axons that innervate both intrafusal and extrafusal muscle fibers

53
Q

Reflexes involving limb movements are mediated through __ and __ pathways

A

spinal; suprapinal

54
Q

What does M1 represent?

A

short-latency, monosynaptic, spinal

55
Q

MC is for __; subcortical is for __

A

distal; proximal

56
Q

What does M2 represent?

A

long-latency, long-loop pathway involving motor cortex

57
Q

Reflexes of the limbs are mediated by __ __ pathways and __ __ pathways that involve the __ cortex

A

spinal reflex; long-loop
motor

58
Q

What happens in Klippel-Fell syndrome?

A

Motor response is generated at both sides of the body

59
Q

What do co-activation of alpha and gamma motor neurons by a cortical motor command allow for?

A

Feedback from muscle spindles to reinforce activation in the alpha motor neurons

60
Q

The discharge rate in the Ia sensory fiber of a spindle increases during __ __ of a finger

A

slow flexion

61
Q

The increase of a discharge rate in the Ia sensory fiber of a simple is dependent on?

A

The alpha-gamma co-activation

62
Q

If the gamma motor neurons were not active, the spindle would __, and its discharge rate would __ as the muscle __

A

slacken, decrease, shortened

63
Q

When are alpha and gamma motor neurons co-activated?

A

During voluntary movements

64
Q

Damage to the CNS produces characteristic alterations In __ __ and __ __

A

reflex response; muscle tone

65
Q

Interruption of descending pathways to the spinal cord frequently produces __

A

spasticity

66
Q

What happens during transection of the spinal cord in humans?

A

A period of spinal shock followed by hyperreflexia

67
Q

Define cell body

A

metabolic center of the cell
nucleus with genes and endoplasmic reticiulum that synthesizes the proteins
aka soma

68
Q

Define the function of the dendrites

A

receive incoming signals from other cells

69
Q

Define the function of axons

A

carries signals to other neurons

70
Q

What is the size of axons?

A

0.1 mm to 2m

71
Q

Where can presynaptic terminals terminate?

A

dendrites, soma, or axons

72
Q

What are the 9 categories of perception?

A

Vision
Smell
Taste
Touch
Thermal senses
Pain
Hearing
Balance
Proprioception

73
Q

Define a reflex

A

coordinated, involuntary motor response initiated by a stimulus applied to peripheral receptors

74
Q

The actual response evoked by a reflex is dependent on?

A

The mechanisms that set the strength and pattern of responses according to the task and the behavioral state, or functional set

75
Q

T/F: modification of synaptic transmission in spinal reflex pathways by descending signals from the brain is thought to be an important factor

A

True

76
Q

Many groups of __ in spinal reflex pathways are also involved in producing __ __ such as walking and transmitting voluntary commands from the __

A

interneurons
complex movements
brain

77
Q

Why does injury to or disease of the CNS often result in significant alternations in the strength of spinal reflexes?

A

role of supraspinal centers in spinal reflex pathways

78
Q

Neurons receive both __ and __ inputs via __ receptors in the __ __

A

excitatory, inhibitory
ionotropic
postsynaptic membrane

79
Q

What applies to the synaptic connection between the __ __ and the __ __ also applies to the CNS but is also more __ __ __

A

motor neuron; skeletal muscle
complex non specific

80
Q

T/F: Muscle fibers are innervated by many motor neurons

A

False, only one

81
Q

T/F: spinal cord motor neurons receive connections from hundreds/ thousands of other neurons

A

true

82
Q

Muscle fibers receive only __; central neurons receive __/__ inputs

A

excitatory
excitatory/ inhibitory

83
Q

All synaptic actions on muscle fibers are mediated only by __ which activates only __ type of __ __ __ ___

A

ACh; one
specific ionotropic-metabotropic receptors

84
Q

What is a role of central neurons?

A

they integrate diverse inputs into a single coordinated activity

85
Q

T/F: every action potential in the motor neuron produces an action potential in the muscle fiber

A

true

86
Q

How many excitatory neurons must fire together to produce a synaptic potential?

A

50-100 excitatory

87
Q

Tendon tap does not produce __ __ of the muscle spindle afferents, thus __ stimulation is preferred

A

synchronized depolarization
electrical

88
Q

Unitary EPSP =

A

one sensory neuron

89
Q

Increasing the current results in __ __ of sensory __ fibers and the ___ of neurons produced by the EPSP becomes larger

A

synchronized activation
afferent
depolarization

90
Q

Stimulation of __ __-__ neuron produces IPSPs in the motor neurons that ___ the flexor muscle, which is __ to the extensor

A

extensor stretch-receptor
innervate
antagonistic

91
Q

The hyperpolarizating action is mediated by an __ __, known as, reciprocal Ia ___ ___, and the circuit constitutes the __ unit for physiological alternated __ __

A

inhibitory interneuron (IN)
inhibitory interneuron
phasic movement

92
Q

Central synaptic inhibition is __ in most neurological disorders

A

decreased

93
Q

T/F: Experience refines sensory-motor function

A

true

94
Q

The shape of myelin can be __ dependent

A

experience

95
Q

Formation of new myelin was found to be required for…

A

motor learning in adult mice

96
Q

How do ballerinas differ from typically developing people?

A

significantly faster long-latency neuromuscular responses than controls
Significantly more consistent in muscle activation
Superior postural control mechanism
Spinal H-reflexes are smaller

97
Q

Name three impacts of the CNS after spinal cord injury (SCI)

A

impaired function of spinal circuitry and corticospinal drive
impaired processing of afferent input by spinal circuits
decline in transmission of uninjured fibers

98
Q

Most rehabilitation interventions of SCI rely heavily on __ __ __ __ because of the weak or impaired __ -_

A

compromised spared neuronal pathways
synaptic connections

99
Q

Name three efforts of rehabilitation after SCI

A

development of targeted neuromodulation interventions
use neuromodulation as a biomarker of motor recovery
use a combination of training interventions to optimize recovery

100
Q

The spinal cord serves as a hub center that integrates and translates __, __, and __ neuronal signals

A

descending, ascending, segmental

101
Q

T/F: Transspinal evoked potentials (TEPs) are not similar in animals and humans

A

False - they are similar

102
Q

Describe the TEP recruitment curve

A

sigmoid shape as the MEP, M-wave, H-reflex

103
Q

Soleus TEPs have nearly the __ __ of soleus H-reflexes in both animals and humans

A

half latency

104
Q

Define orthodromic

A

flow of current on afferent inputs and efferent output signals

105
Q

Define antidromic

A

flow of current on afferents following transspinal stimulation

106
Q

Transspinal stimulation __ motor evoked potentials (MEPs) during __

A

depresses; walking

107
Q

At the step that transspinal stimulation occurs, locomotor EMG activity is completely __ but fully recovers at the step __ __ __

A

suppressed
after transspinal stimulation

108
Q

TEPs are likely the result of both __ and __-__ neurons events

A

synaptic; non-synaptic events

109
Q

Describe four synaptic/ non-synaptic neuronal events that TEPs are likely the result of

A
  1. antidromic discharges of muscle afferents
  2. primary afferent depolarization-induced spikes that propagate orthodromic to afferent terminals that subsequently depolarize alpha neurons
  3. activation of spinal interneuronal circuits including recurrent and reciprocal Ia inhibition
  4. orthodromic excitation of motor axons
110
Q

T/F: transspinal stimulation is a promising neuromodulation modality

A

true

111
Q

The CNS __ and __ continuously based on __ __ and __

A

adapts; reorganizes
motor experience; use

112
Q

Reorganization occurs in a __-__ manner throughout the neuro-axis (__,__,__)

A

task-dependent
cortex, cerebellum, spinal cord

113
Q

What is the key to neuroplasticity?

A

proprioceptive feedback

114
Q

Describe self-reported changes and clinical assessment outcomes for cervicothoracic and thoracolumbar transspinal stimulation

A

increased voluntary muscle strength, sweating returned, decrease in leg spasms and decrease in ankle clonus

115
Q

Describe self-reported changes and clinical assessment outcomes for thoracolumbar transspinal stimulation

A

improved bladder control, improvement in pain, increased walking distance

116
Q
A

Neurobiology of Adult Brain Disorders (10 decks)

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