PSYCH 454 Lecture Notes - Lecture 19: Corticospinal Tract, Skeletal Muscle, Rubrospinal Tract
24 May 2018
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Lect 19: Part 2
Neural activity just before movement onset varies less from trial-to trial
●How response of population of neurons in motor cortex evolves, compared with activity
at start of movement preparation
●Plot is called “state-space” - population of neurons evolves through neurons for single
trial
○Plot the activities of neuron 1, 2 and 3 throughout movement plan
○Evolution of neural activity in PMA for single trial
●different types of movements occupy different state-spaces of population activity
○If you didn’t converge on optimal subspace (went off path/abnormal route) =
longer reaction time of movement
●“In summary: goal of dynamical systems theory: motor systems act as machine to
generate particular pattern of activity to drive muscle movements”
Plasticity of Motor cortex (M1)
●More cells that control particular action→ finer
the control
○More cells in motor cortex devoted to hand movements and facial
expressions=we have relatively fine control
●Finer motor control can result from training
○Evidence suggests more of motor cortex may be recruited
●After lesion:
○Changes in motor cortex after peripheral lesions (ex: lesion nerve innervating
muscle of snout of rat)
■Before lesion: cells in motor cortex controlled whiskers
■After lesion: same part of motor cortex that used to controlled controlled
whiskers, now moves forelimbs
●Motor cortex → “plastic”
○Representation of movements in motor cortex can change
○This plasticity may occur not only after lesions, but under normal conditions
(learning through experience)
Descending tracts of Spinal Tract
●How areas in motor cortex project down to spinal cord,
to eventually control LMN and skeletal muscle
●2 major pathways: (start of name = origin of tract)
○Lateral pathways: voluntary motor control
■Corticospinal tract: descends from motor
cortex and goes to spinal tract
Document Summary
Neural activity just before movement onset varies less from trial-to trial. How response of population of neurons in motor cortex evolves, compared with activity at start of movement preparation. Plot is called state-space - population of neurons evolves through neurons for single trial. Plot the activities of neuron 1, 2 and 3 throughout movement plan. Evolution of neural activity in pma for single trial. Different types of movements occupy different state-spaces of population activity. If you didn"t converge on optimal subspace (went off path/abnormal route) = longer reaction time of movement. In summary: goal of dynamical systems theory : motor systems act as machine to generate particular pattern of activity to drive muscle movements . More cells that control particular action finer the control. More cells in motor cortex devoted to hand movements and facial expressions=we have relatively fine control. Finer motor control can result from training. Evidence suggests more of motor cortex may be recruited.
