Module 5 - Movement Flashcards
what sensations are a part of somatosensory system
pain, touch, pressure, temperature, balance
what three structures is the somatosensory system associated with
cerebrum, brainstem, spinal cord
what system is somatosensory connected with?
motor system via spinal cord
afferent
info transfer from outside of body inwards via somatic nervous system
efferent
info transfer from inside of body outwards via central nervous system
what type of nerve fibre bundle is found in CNS
tracts
what type of nerve fibre bundle is found outside CNS
nerves
general steps of afferent pathway
sensory receptors - sensory neurons - posterior root - cns
general steps of efferent pathway
cns - motor neurons - anterior root - muscles
what two portions make up neocortex
sensory and motor cortex
what layers make up the sensory and motor cortex
1-3 = integrative functions
4 = sensory input (afferent)
5-6 = output to other parts of brain (efferent)
differences in layer 4 between sensory and motor cortex
thick in sensory, thin in motor
differences in layer 5 between sensory and motor cortex
thick in motor, thin in sensory
what are the five categories that make up the spinal cord (in order from top to bottom)
cranial nerves (C1-C8)
thoracic (T1-T12)
lumbar (L1-L5)
sacral (S1-S5)
coccygeal segment
what are the categories that make up the spinal cord called?
dermatomes
two main characteristics of frontal lobe organization
hierarchical and parallel
what was the first early motor theory
feedback
-wait for feedback about movement, then proceed with next
lahey motor sequence theory
believed that feedback took too long
motor sequences - one movement held in the ready, while another movement occurred
how do motor sequences occur
prefrontal cortex: movement/behaviour is planned
premotor cortex: info received from prefrontal, and movement coordinated
primary motor cortex: movement is executed
what could damage do prefrontal cortex result in
rule-breaking
what could damage to primary motor cortex result in
difficulty talking, and moving
why is frontal lobe hierarchical and parallel?
hierarchical: movement occurs in a sequence consisting of action in different regions; blood flow increases in regions of use
parallel: movement/planning can occur independently of each other
where does blood flow occur in brain for simple movement
sensory and motor cortex
where does blood flow occur for motor sequence
premotor cortex
where does blood flow occur for complex movement
prefrontal, parietal, and temporal cortex
describe Hess’ experiment
implanted electrodes into brains of dogs/cats to elicit species typical behaviour
determined that stimulation of certain areas of brainstem results in STB
cerebral palsy (location of injury, cause, and symptoms)
-brainstem injury (typically before/after birth due to lack of oxygen, genetic defects, etc)
-results in rigidity, dykinesia, spacisitiy, difficulty with passive movements
two main types of spinal cord injuries
parapeligia (injury below cervical region = no sensation in legs)
quadripeligia (injury to cervical region = no sensation in arms and legs)
where is there no sensation as result of spinal cord injury
site of cut downwards
nanotechnology
use of small tools (nanovesicles) to improve acute effects of spinal cord injuries
what is scratch reflex
automatic reflex of limb to remove a stimulus from body
itching causes reflex
Fritsch and Hitzig discovery
used electrical stim on the neocortex of dogs and produced movement in limbs, paws, and mouth
demonstrated that neocortex contributes to movement
Penfield discovery
used elec stim on neocortex and produced twitches in different areas
came up with homunculus to demonstrate bodily areas associated with different parts of motor cortex (topographic organization)
- huge hands, lips, and mouth because high association
how did recent discoveries disprove penfield
used longer/more intense electrical stim
came up with the idea of movement categories in primary motor cortex and premotor cortex instead of homunculus
conclusion was position point theory
what four movement categories are associated with premotor cortex
ascend, descend, jump
reach to clasp
defense posture
hand movement towards mouth
what three movement categories are associated with primary motor cortex
chew
hand movement in distal space
hand movement in central space
position point theory
states that the motor cortex allows body parts to move using a map of where the parts are able to move in space
Evarts experiment
trained monkeys to use wrist to lift weights and implanted electrode in wrist to record neural activity
neural activity continued (and increased at certain points) throughout which demonstrated neurons contribute to execution, force, and planning of movement
Schieber experiment
demonstrated that motor neurons are involved in motor planning, withholding movement, and even mental imagery of movement
Nudo experiment
removed digit area on monkey
when using better hand, cortical map for that area decreased and grew larger in other areas
when forced to use bad hand, cortical map improved
led to constraint induced therapy
Constraint induced therapy
being forced to use injured limb to regain cortical map/movement
good for stroke victims
success depends on frustration of dominant hand
what are cortiospinal tracts
main efferent pathways from the cortex to brain to spinal cord
two main ones: lateral and ventral that cross at pyramids
emerge from ventral surface of brainstem forming pyramidal tracts
axons cross to opposite side
what does lateral corticospinal tracts do
synapses with motor and interneurons that innervate that limbs and digits of the body
what do anterior corticospinal tracts do
synapses with interneurons that innervate the trunk of the body
what are interneurons responsible for and what do they project to
complex body movements (ie. those with joints)
project to motor neurons
what are motor neurons responsible for and what do they project to
whole body movements
carry nervous system commands to muscles
project to muscles
what do corticospinal tracts project to
motor and interneuronsal
what are anterior horns
neurons that jut out from spinal cord
contains neurons and interneurons
where are motor neuron cell bodies located in spinal cord
anterior horn
where are interneurons located in spinal cord
adjacent and medial to motor neurons in anterior horn
what do flexor muscles do
biceps
move muscles closer to body
uses flexor motor neurons
what do extensor muscles do
triceps
move muscles away from body
uses extensor motor neurons
what neurotransmitter is involved with controlling muscles
acetylcholine
describe basal ganglia
collection of nuclei connected with neocortex
modulates activity of cortical systems, association/habit learning, motivation/emotion, motor control
big role in voluntary movement
what 3 nuclei make up basal ganglia
caudate nucleus, putamen, and globus pallidus (internal and external)
what 2 nuclei make up the striatum? where is it located?
caudate nucleus and putamen (in basal ganglia)
where is subthalamuc nucleus located
below the basal ganglia
where is the substantial nigra located
midbrain
what are the three main connections of basal ganglia
1) all regions of cortex project to basal ganglia
2) basal ganglia projects to motor cortex via the thalamus
3) received dopamine from substantia nigra
what are the two main types of basal ganglia disorders and examples of them
hypokinetic = too little force, lack of dopamine connections, pausicity of movement, rigidity, difficulty initiating movement (Parkinsons)
hyperkinetic = too much force, excessive and involuntary movement (Tourettes or Huntingtons)
how two force and basal ganglia activity relate
higher basal ganglia activity = higher force
what is volume control theory
states that basal ganglia can influence movement based on its two pathways: direct and indirect
describe direct path of volume control theory
inhibitory:
inhibited globus pallidus - allowing thalamus to produce movement and circuits
if dominant = over amplified movement
describe indirect path of volume control theory
excitatory:
excites global pallidus - inhibiting thalamus to produce movement
if dominant = no movement
characteristics of cerebellum
10% of brain
important for motor skills
more neurons and folds than actual cortex
sits atop of brainstem
2 hemispheres
contains a flocullus region
describe two hemispheres of cerebellum and where they project to
medial = controls face and body midline, damage disrupts balance + eye movement
lateral = associated with hand, limb, and feet movement, damage disrupts movement in those areas
both hems project to other brain regions
describe layers of cerebellum
3 layers total
2nd layer consists of purkinge cells that are the output cells of the cerebellum
in general, what does damage to cerebellum cause
difficulty in making accurate movements
how does cerebellum produce accurate movements
compares message for intended movement with actual movement
sends error message to cortex to improve movement
main characteristics of somatosensory system
creates sensation which allows movement to occur
consists of somatosensory receptors and vestibular system
what is vestibular system
creates sensations of balance and head movement
only part of somatosensory that is confined to an organ (ear)
where are somatosensory receptors located
all over body (skin, muscles, joints etc)
describe body hair somatosensory receptors
body hair attached to the dendrites of neurons
what are the two types of skin
glabrous: hairless, high sensitivity, lips/tongue/hands/feet
hairy: hair, low sensitivity, arms/back/legs
describe density of somatosensory receptors
low = arms, legs, and back
high = hands, feet, lips, and tongue (high sensitivity)
what are three main types of somatosensory receptors and what do they correspond with?
nociception = pain, temperature, itch
apsis = fine touch and pressure
proprioception = body awareness
what are two types of receptors + what do they do
rapidly adapting = neurons activate when stimulus starts/ends
slowly adapting - neurons detect is stimulus is still occurring and only activate if sensory event is present
characteristics of posterior root ganglion neurons
dendrites carry somatosensory info to CNS
cell bodies are located outside the cord
contains a single long dendrite where only tip is responsible to stimulation
every spinal cord segment is flanked by __
posterior root ganglion that contain different types of neurons
what type of info do small axons with little myelination carry?
nociceptive info (pain, temperature, and itch)
what type of info do large axons with lots of myelination carry?
haptic info (touch and pressure)
proprioceptive info (location and movement)
do large or small axons carry info faster?
large
what is deafferation?
loss of incoming sensory input due to damage of sensory fibres (ganglion cells in posterior root ganglia)
lots of difficulty with movement
what could result from proprioceptive disruption
not knowing where limbs are in space
hard to move
what are two main somatosensory pathways to brain
posterior spinothalamic
anterior spinothalamic tract
what is the posterior spinothalamic tract
haptic-proprioceptive axons
carries fine touch and pressure fibres to brain
what is the anterior spinothalamic tract
nociceptive axons
pathway from cord to thalamus
carries info about pain/temp to brain
what 3 relay neurons are required for posterior spinothalamic tract?
posterior root ganglia neurons
posterior column nuclei neurons
thalamic neurons
what 3 relay neurons are required for anterior spinothalamic tract
posterior root neurons
spinal cord grey matter
ventrolateral thalamic neurons
where does hapsis/proprioception damage occur?
side of body where injury occurred
where does nocieption damage occur?
on opposite side of body from injury, below where injury occurred
where does damage to all somatosensory receptors occur?
on opposite side
what is the monosynaptic reflex?
formed by a single synapse between a sensory and motor neuron
simplest reflexes
ex. knee jerk
what is a multisynaptic reflex
formed by somatosensory neurons making multiple connections with both interneurons and motor neurons
what is central pain
pain in a part of body that is not obviously injured
ex. phantom limb
what is phantom limb
sensations felt in limb that is lost
illusions that originate in brain
treated with opiods/injections or counterillusions
when is pain reduced
in fight/flight situations
theory is that endogenous opioids are generated (which reduce pain)
what is gate theory
interactions between touch and pain paths influence pain perception
when is pain reduced/gained in gate theory
haptic-proprioceptive stimulation can reduce pain perception, and absence of stimulation can increase pain through interactions at a pain gate
what improves pain
activities that activate haptic and proprioceptive fibres to close pain gates
why do opioids help with pain
gate uses endogenous opiod as inhibitor neurotransmitter.
therefore opioids relieve pain by acting like it
what causes pins and needles
sitting too long in one position that results in loss of oxygen from reduced blood flow
this deactivates large militated axons that carry touch/pressure info
sensory info flows in pain/temperature pathway instead leading to sensation
where are there additional pain gates
brainstem and cortex
could be why there is cognitive effects with pain
can pain be reduced with gray matter
yes, with periaqueductal gray matter through activation via electrical stimulation
what is referred pain
pain felt in one of internal organs that can be felt on surface of body
