Motor areas Flashcards
Identifying the roles of the motor areas of the brain and how motor issues are caused from damage
How were the cortical areas identified initially?
They are anatomically distinct
What are the primary motor areas?
M1/motor cortex/area 4
What are the large cells in layer V of the motor cortex?
Cortical spinal cells, which are distinguishing features of the motor cortex and are common in all animals
Why is the primary motor area regarded so?
Is the area where movement can be elicited with the lowest threshold of stimulation
How can you map somatotophy?
Electrodes; transcranial magnetic stimulation; neuroimaging
Is the somatotophy in all humans the same?
No, has same general pattern but each person has variations
What is the relationship between the motor cortex and movement?
Very close; fire around 5-100ms before movement
What does the motor cortex control in movement?
Force, direction, extent, speed
What are the non-primary motor areas?
Pre-motor cortex/lateral area 6; supplementary motor cortex/medial area 6; cingulate motor areas/areas 23 and 24
What do the PMA and SMA control?
Complex patterns and sequences of movements; movement selection and preparation; target encoding
What are the main inputs for the PMA and SMA?
From other motor areas
What is the difference in stimulation of PMA/SMA and M1?
Need higher thresholds of stimulation to PMA/SMA to produce movement
What is the difference in output of SMA and M1?
Output from SMA to weaker neurones markedly weaker than M1
What cortex has longest latency?
PMA/SMA
How much larger is PMA and SMA than M1?
6 times larger
What is the focus of the pre-motor cortex?
Set-related neuronal activity; movement planning
What is the focus of the supplementary motor cortex?
Bimanual tasks
What occurs when cortical damage occurs?
Loss of voluntary movements; weakness; paralysis
What does the basal ganglia control?
Movement regulation; skill learning; habit formation; reward systems
How do the pathways of the basal ganglia work together?
Both start at cortex; normally balanced
What are the differences between the two pathways?
Direct has an excitatory effect on cortex, indirect has an inhibitory effect on cortex; direct is pro-movement, indirect is anti-movement
What happens when someone suffers from hyperkinetic disorders?
Shifted towards direct pathway; unwanted movements initiated involuntarily; e.g. Huntington’s
What happens when someone suffers from hypokinetic disorders?
Shifted towards indirect pathway; cannot initiate movement; e.g. Parkinson’s
What is the ratio of input:output of cerebellum?
40:1
What is the structure of the cerebellum?
Crystalline, simple, three layers, 5 kinds of cells
What are the 5 kinds of cells in the cerebellum?
Inhibitory stellate Basket Purkinje Golgi Excitatory granule
What are the inputs to the cerebellum?
Only has 2; one is inferior cerebellar peduncle
What are the outputs of the cerebellum?
Mainly motor; superior cerebellar peduncle to motor cortex and red nuclei; inferior cerebellar peduncle to vestibular nuclei
What are the motor deficits caused by cerebellum damage?
Delayed movement; range of movement errors (e.g. touching nose); patterned movement errors
