Exam Two - Locomotion Flashcards
What are the structures of the nervous system that control locomotion
- central pattern generator
- peripheral receptors and afferents
- locomotor regions in the brainstem
- cerebral cortex
basic neural mechanisms underlying movement include…
- convergence/divergence
- reciprocal innervation/inhibition
- central program pattern generators
- sensory reflexes
divergence
allows one neuron to communicate with many other neurons in a network
convergence
allows a neuron to receive input from many neurons in a network
reciprocal innervation/inhibition
when one set of muscles receives a signal for a reflex action, the antagonistic set of muscles receives a simultaneous signal that inhibits action
CPG are…
neuronal networks in which interconnected excitatory and inhibitory neurons produce an oscillating, rhythmic output in the absence of sensory feedback.
CPGs play an important part in motor behavior such as..
breathing, swimming, and locomotion
What concept is a hard-wired property of neuronal networks and involves both UMN and LMN?
reciprocal innervation
describe the two pathways sensory neurons take during the knee-jerk reflex
1 - sensory neurons send signal to spinal cord, from where motor neurons relay the info to quads, causing it to contract and jerk the leg
2 - sensory neurons also synapse with interneurons which send inhibitory signals via other motor neurons to the hamstring causing it to relax
A _______- is defined as a neural circuit that can produce self-sustained patterns of repetitive rhythmic outputs to the muscles involved in the rhythmic behavior in the absence of sensory input
CPG
The CPG for locomotion is in the ____________
spinal cord
locomotor CPG _________ require higher brain centers
does not
The CPG for locomotion is in the ___________ part of the ________ spinal cord
ventral, lumbar
The spinal CPG for locomotion consists of both…
rhythm (clock) and pattern generating subunits
the CPG for locomotion is controlled by neuron groups in ____________
lamina VII (7)
___________________ in the ventral grey matter (mostly lamina 7) regulate locomotor rhythms by communicating to each other across the midline to coordinate behavior
bilateral projecting interneurons
The activity of the locomotor CPG is modulated via sensory…
feedback and sensory input
the activity of the locomotor CPG is modulated via these descending tracts…
corticospinal
rubrospinal
reticulospinal
vestibulospinal
CPG receives input from what two pathways?
proprioceptive and exteroceptive
____________ feedback determines the magnitude and timing of CPG activity
local
____________ feedback regulates intensity and coordinates CPG activity with other motor acts
long loop
CPG activity itself can modulate incoming sensory feedback, via __________ of the afferent pathways
presynaptic inhibition
___________________ to CPG: return signal in response to rhythmic muscle movement, conveys a continuous measurement of the output
sensory feedback
What are the 3 nuclei of the reticular formation
midline (raphe)
medial
lateral
midline raphe nuclei of reticular formation is responsible for…
- consciousness and alertness
- ascending projections for arousal and attention
medial nuclei of reticular formation is responsible for…
intrinsic connections for control of eye movement, swallowing, and brainstem reflexes
lateral nuclei of reticular formation is responsible for…
descending projections for control of muscle tone, respiration, and arterial pressure
What are the three monoamine projections to the spinal cord
serotonin pathway
noradrenaline pathway
dopamine pathway
______________ neurons of the raphe nuclei are involved in the control of sleep-awake cycle and control circadian rhythm via connection to the suprachiasmatic nucleus
serotoninergic
The raphe nuclei are also involved in __________ by inhibiting neurons in the dorsal horn of the SC that are involved in tranmission.
controlling pain
subset of serotonergic neurons controls the activity of SC neurons associated with….
locomotor CPG
SSRI are used to treat depression and mood disorders AND can cause…
muscle fatigue
locus coeruleus (LC) part of RF is a major wakefulness ___________ nucleus, due to ______ prjections to the cerebral cortex, thalamus, tegmental nucleus, and _______ projections to sleep-promoting GABAnergic neurons of the basal forebrain and ventrolateral preoptic area
promoting
excitatory
inhibitory
LC activation _______ alterness
enhances
LC involved in control of __________, direct projections to the SC and autonomic nuclei of brainstem
autonomic functions
LC activation increases ___________ activity and decreases __________ activity
sympathetic
parasympathetic
_____________ controls behavioral flexibility, posture and balance, arousal of cortex, attention, memory, and emotions
Locus coeruleus (LC)
_________ pathways are projection neurons that synthesize and use dopamine as NT
dopaminergic
_______________ control pain response in SC, prime neurons for pain hypersensitivity following injury
descending dopaminergic systems
_____ controls the “stepping networks” in the SC
domapine
hypothalamo-spinal projections of the dopaminergic system control __________ networks in the brainstem and SC (CPG)
locomotor
________ pathways are involved in learning, reward, and motivation
dopaminergic
dysfunction of __________ pathways and nuclei are associated with disorders like parkinson’s disease, ADHD, addiction, and restless leg syndrome
dopaminergic
locomotor function is strongly affected by
neuromodulation
What are the 3 most common somatic reflexes discussed?
- stretch (knee-jerk) patellar
- withdrawal (flexor)
- crossed-extensor
What is an involuntary, relatively short-latency, and stereotyped motor response set into motion by an environmental stimulus?
reflex
