Week 13 - Cortical Motor Areas Flashcards
Complex/Volitional Movement
Motor output that is planned and refined by the motor cortex, basal ganglia and cerebullum
Where is the red nucleus located?
Midbrain
What cells are present in the red nucleus?
Rubrospinal cells
What do rubrospinal cells do?
Activate localized synergies especially in the distal libs and face
what are rubrospinal cells contrasted to?
Reticulospinal and vestibulospinal tracts that organise postural and locomotory synergies
What do rubrospinal cells cross and where do they end up
They cross the midline and end up in the intermediate zone - not directly to motor neurons
what do rubrospinal tracts descend in?
they descend in lateral white matter with corticospinal tract together in a way - because its also concerned with distal motor nuclei
synergy
group of muscles contracting together for a specific purpose
comparison of reticulospinal tracts synergies with rubrospinal tract synergies
reticulospinal tract synergies - widespread ( cover half the body) useful in generating postures
rubrospinal synergies - highly localized
where is the motor cortex located
precentral gyrus
descending axons - motor cortex-spinal cord
where do they go?
most of the descending axons from motor cortex to spinal cord (corticospinal) go to interneurons
what type of organization does the motor cortex have
somatotropic organization
proportions based on number of motor neurons in the area
where do axons with direct corticospinal synapses on motor neurons go?
distal limbs or speech motor nuclei
how do motor cortex axons end up in the spinal cord
the motor cortex axons porject to the brainstem, it then crosses the midline and travels via lateral white matter and ends up in the spinal cord.
multiple representation
single motor nuclei (muscles) represented in columns at many loci
what is each column in
a different neigbourhood (different adjacent columns)
what does each cortical locus represent
a different synergy; muscles which particpate in most synergies have the biggest representation
what do muscle synergies depend on
personal experiences
what is somethign that is also dependent on motor cortex synergies
language
when are motor maps laid out
development and at very early stages
what do thumb motor neurons have direct synaptic connections with
their corresponding neurons (thumbcorticomotorneural cells) in the motor cortex
precision grip
eg. holding a pencil
what happens to neural cells in motor cortex when precision grip is active
the neurons in motor cortex are active
power grip
holding a ball
what happens to neural cells in motor cortex when power grip is active
the neurons in motor cortex are inactive
motor field
how one corticospinal axon synapses with a set of motor nuclei, in more than one spinal segment
comment on activity of synapses in motor field
many synapses are silent
what do motor field help with
plasticity
only sensory input with direct access to motor cortex
propioceptors
cutaneous input
comes from somatosensory association areas, related to postural and motion information
premotor areas
they select motor cortical synergies into proper sequence for a given movement
propioceptive input
direct from thalamus and from somatic association cortex
what do premotor areas project to?
project into motor cortex but also with parallel routes to motor nuclei
what role do premotor areas have
pattern generation role for learned highly evolved movements
what sensory inputs does premotor cprtex process?
visual and auditory for cueing movment phases
eg. dorsal visual stream to dorsal half (spatial locations) and ventral visual stream to ventral half (object form –> shape of hand)
what recognizes enviornmental cues
sensory association areas recognize the cues and forward the signal to the frontal lobe (prefrontal and premotor cortex)
what triggers motor reactions
environmental cues
broca’s area
premotor zone for sequencing language elements for speech or writing-typing
where does brocas area get input from
wernicke’s area
how does the premotor cortex help with responses
it selects appropriate response synergies in motor cortex
preparatory activity
premotor neurons set up the motor cortex
not active during performance only active during the preparatoryphase
what happens if there is a delay in preparatory activity
premotor neurons maintain acitivyt until a go cue is given
where is the supplementary motor area located
medial wall of hemisphere
representation of somatic motor area
somatotopic representation of body but less detail than motor cortex
what does supplemetary motor cortex cotrol
bilateral coordination of limbs when different motions done on eahc side
what does supplementary motor area process
internal volitional signals that drive movements
where is the cingulate motor area located
singulate sulcus
what does the cingulate motor area process
emotional nd motivational drive to movmeents
