EXSS 380: MIDTERM 1
52 Cards in this Set
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supraspinal structures
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cerebral cortex, cerebellum and brain stem
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cerebrum
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largest part of the mature brain, controls higher brain functions including: interpreting sensory info, initiating muscle contraction and movement, storing memory, reasoning, intelligence
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cerebral cortex
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folds of tissue called gyri
shallow grooves between = sulci
deep grooves between = fissures
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somatosensory area
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sensation of touch, pain, temperature, and proprioception
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somatosensory association area
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integration and interpretation of somatosensory information
shape, texture, relative orientation of body segments
memory storage for comparison of sensory information
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primary motor area
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voluntary contraction of specific muscles or muscle groups
coding of force and direction of movement
important for generation of skilled and accurate movements
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premotor and supplementary motor area
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memory banks for learned activities
communicate w. primary motor are to generate learned, complex, sequential activities
contraction of specific muscles in a specific sequence
writing, walking
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homunculus
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spatial organization of somatosensory and motor function of cortical areas
size of representative area dependent on function
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motor cortex inputs
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spinal cord
cerebellum
cortical areas
cortico-cortical projections to primary motor area from: premotor area, somatosensory area, somatosensory association area
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motor cortex outputs
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basal ganglia
cerebellum
red nucleus
reticular formation
spinal cord
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basal ganglia
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brain structure involved in initiation and coordination of voluntary movement
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red nucleus
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midbrain structure involved in coordination of muscle contractions
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reticular formation
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part of brain stem involved in sensory and motor relay and regulation of muscle tone
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spinal cord
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corticospinal tract
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brain stem
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contains a network of nuclei and neuronal tracts involved in sensory and motor relay
midbrain, pons, medulla oblongata
various respiratory and cardiac centers
origin of cranial nerves
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cerebral hemisphere dominance
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cross over effect (decussation)
most spinal tracts cross over at medulla oblongata
left cerebral hemisphere - right side
right cerebral hemisphere - left side
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cerebellum
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large mass of tissue located posterior to brain stem
2nd largest mass in brain to cerebrum
functions to compare intended and observed motion - sensory input to cerebellum integrated and sent to cerebral cortex for correction of movement
highly involved in skilled movements
primary bra…
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inputs to cerbellum
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receives info about goals, commands, and feedback signals associated with planning and execution of movement from: cortex, brain stem, spinal cord
comparison of intended motion and actual events
occurs while a motion is in progress and during repetitions of the same movement
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outputs of cerebellum
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cerebral cortex - informs primary and premotor areas concerning inhibition or excitation of various pathways
brain stem nuclei
spinal cord - no direct connection to motorneurons
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lesions in cerebellum
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decomposition of movement
movements become sequential rather than smoothly coordinated
suggests a role in planning and programming of movements
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basal ganglia functions
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refinement of motor commands
movement sequencing
scaling of movement amplitude and velocity
movement initiation
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symptoms of parkinsons
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bradykinesia - slowness of movement and prolonged reaction time
tremor - involuntary movements
rigidity - increased muscle tone and resistance to external forces
postural deficits - decreased postural stability
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spinal cord
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continuation of distal brain
foramen magnum to superior border of 2nd lumbar vertebra
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laminar organization of spinal cord
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layered
butterfly or H pattern of gray within white matter
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gray matter in the spinal cord
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receives and integrates info
gray color due to lack of myelination
posterior horns
anterior horns
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white matter in the spinal cord
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myelinated axons of motor and sensory neurons
3 major longitudinal columns - posterior, lateral, and anterior columns
columns contain tracts - ascending(sensory) and descending (motor)
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spinal nerves
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named for level where they exit the spinal cord
above for cervical region - spinal nerve C1 passes above C1 vertebrae, 8 cervical spinal nerves; 7 cervical certebrae, C8 unmatched
below for all other regions of the spinal column
spinal nerve T12 exits the spinal col…
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spinal nerves - two distinct attachments to spinal cord
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dorsal root - sensory
ventral root - motor
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dorsal root ganglia
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grouping of sensory nerve cell bodies
t-shaped
output to CNS
input to PNS
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ventral root
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output to skeletal muscle
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reflexes
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monosynaptic
oligosynaptic
polysynaptic
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monosynaptic
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sensory neuron sends message directly to motor neuron
i.e. no interneurons included in arc
ex: knee-jerk reflex - "patellar tendon reflex"
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oligosynaptic
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two to three interneurons included in arc
ex: reciprocal inhibition reflex
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polysynaptic
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more than three interneurons included in arc
ex: stepping on a tack - "flexion withdrawal reflex"
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latency in reflex arc
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time course from stimulus onset to response onset
defined by: conduction delay - dependent on nerve conduction velocity -- myelination, axonal length, axonal diameter. central delay - dependent on # synapses
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monosynaptic reflex loop for reflex arc
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afferent = 10ms
central = .5 ms/synapse
efferent = 10 ms
other factors
MT compliance
EMD
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monosynaptic reflexes
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spinal stretch reflex
spindle - Ia afferent - alpha-mn
homonymous (agonist) and heteronymous (synergist) alpha-mn
tendon-tap (t-reflex)
muscle stretch induced via reflex hammer
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flexion-withdrawal reflex
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typically induced by nocioceptors and/or cutaneous baroreceptors
produces coordinated withdrawal from a stimulus via flexion at multiple limbs
latencies organized to synchronize movement
also induces crossed-extensor reflex
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presynaptic inhibition
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decrease sensitivity to selective inputs without affecting sensitivity to others - affects specific axonal branches
net effect is a reduction of the amount of neurotransmitter across synaptic cleft - decreases synaptic potential
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postsynaptic inhibition
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inhibition of the postsynaptic membrane
inhibitory neuron produces IPSP
postsynaptic membrane less susceptible to depolarization
decrease sensitivity to all stimuli
examples: reciprocal, autogenic, recurrent inhibitions
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reciprocal inhibition
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postsynaptic in nature
Ia afferent branches after entering spinal cord
homonymous alpha-mn
collaterals to synergist alph-mn
Ia inhibitory interneuron
spindle inhibits antagonist via Ia inhibitory interneuron
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autogenic inhibition
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postsynaptic in nature
Ib afferent synapses with Ib inhibitory interneuron in spinal cord
Ib inhibitory interneuron projects onto homonymous alpha-mn
GTO inhibits agonist
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recurrent inhibition
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mediated by a spinal neuron - renshaw cell
agonist alpha-mn projects onto RC
RC has inhibitory projections on: agonist alpha-mn, agonist Ia inhibitory interneuron
negative feedback loop
stabilization of agonist alpha-mn firing rate
regulates strength of reciprocal inhibition
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electromyogram
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electrical signal associated with muscle contraction
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EMG is the sum
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of all active motor units
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physiological variables provided by EMG
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temporal - time based events related to muscle contraction
level of muscle activity - indicative of force under specific experimental conditions
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EMG Temporal Measures
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temporal variables
on vs. off
latency - relative to an external/internal event
duration of activation - absolute, standardized to cyclical motion
recruitment order
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amplitude measurement
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how active is the muscle (m.u. recruitment and rate coding)
often used to predict muscle force
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EMG vs. tension
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highly correlated during isometric contraction
poorly correlated during: dynamic movements, fatigue, comparisons between different joint angles
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EMG amplitude dependent on physiological factors
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# of active m.u.s
firing frequencies of active m.u.s
fiber type
fiber diameter
fiber depth and location
adipose tissue thickness - lowpass filter
muscle mechanics
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isometric
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typically expressed as a percentage of maximum voluntary isometric contraction
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dynamic
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emg activity may be standardized with respect to a control condition
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EXSS 380: MIDTERM 1