NEUR3101 Lecture Notes - Lecture 15: Euclidean Vector, Neural Coding, Upper Motor Neuron
3 levels of control
○
Organised serially and in parallel
○
Spinal cord, brain stem and forebrain
-
Receive sensory input
○
Basal ganglia
Action of the basal ganglia and cerebellum on cerebral cortex is via the relay
nuclei in the thalamus
□
Cerebellum
Are influenced by subcortical systems
○
All 3 levels:
-
Levels of the motor system
The brain stem modulates the action of spinal motor circuits
-
Cerebral cortex acts directly and indirectly on spinal motor neurons
○
Cerebral cortex acts on brain stem motor neurons through the corticobulbar tract
○
Cerebral motor neurons in the brain stem and the spinal cord
-
Cortical association areas (prefrontal, parietal and temporal)
○
Basal ganglia and the cerebellum via the thalamus
○
Motor cortex is influenced by both cortical and subcortical inputs
-
Basic features of central motor control
Descending Spinal Tracts
Motor neurons
Indirect connections with motoneurons regulate a larger number of muscles than do direct
connections. They may contribute to the organisation of multi
-
jointed movements such as
reaching and walking
-
Projections in the spinal cord
Motor cortical areas are organised somatotopically
○
There is, however, a large degree of overlap between cortical regions associated with
different body parts
○
Motor map (homunculus) is only loosely accurate
○
M1 cells that fire at greatest rates for activation of different muscles overlap considerably
○
Hence the clinical term "upper motor neuron"
□
Historically believed that M1 merely relayed commands from higher processing
centres to spinal cord
Now understood that considerable involvement in the executive control of movement
in M1
Clue to understanding how M1 "codes" movement is to study in detail the effects of
M1 projections on the spinal cord
What does it control?
○
Corticomotoneuronal call activity depends on the motor task
○
Monkey wrist extension / flexion experiment
Recordings made of the firing of individual M1 (corticospinal tract) neurons
How do M1 cells "code" force
○
Primary Motor Cortex (M1)
-
Motor cortex areas
Cortical Control of Movement
Monday, 11 June 2018 7:26 PM
Lecture 15 Page 1
Document Summary
Action of the basal ganglia and cerebellum on cerebral cortex is via the relay nuclei in the thalamus. The brain stem modulates the action of spinal motor circuits. Cerebral motor neurons in the brain stem and the spinal cord. Cerebral cortex acts directly and indirectly on spinal motor neurons. Cerebral cortex acts on brain stem motor neurons through the corticobulbar tract. Motor cortex is influenced by both cortical and subcortical inputs. Basal ganglia and the cerebellum via the thalamus. Indirect connections with motoneurons regulate a larger number of muscles than do direct connections. They may contribute to the organisation of multi-jointed movements such as reaching and walking. There is, however, a large degree of overlap between cortical regions associated with different body parts. M1 cells that fire at greatest rates for activation of different muscles overlap considerably. Historically believed that m1 merely relayed commands from higher processing centres to spinal cord.
