Motor Systems Flashcards
What are components of the hierarchical control of movement?
Neocortex - contributed to our conscious control of movement, while the brain stem and spinal cord are involved in performing the more automatic actions we make. Normally functions together as a whole.
What did Hughlings-Jackson (19th century) suggest?
The nervous system is organised in layers, with higher levels controlling complex behaviour by acting through lower levels. Since each nervous system developed at different times, each must have some functional independence. Adapted from evolutionary theory.
What did Karl Lashley (1950s) suggest?
Movements for skilled actions are performed quickly to rely on feedback. Movement modules preprogrammed by the brain and produced as a motor sequence. Complex behaviours require selecting and executing multiple movement sequences. As one sequence is executed, the next sequence is being prepared.
What is the role of the prefrontal cortex?
Planning of movements, specifying the goal (e.g. deciding to play with iPhone).
What is the role of the premotor cortex?
Organises motor sequences (e.g. select movements appropriate to the context of the action). The premotor cortex produces complex movement sequences appropriate to the task. Select movements appropriate to the context of the action.
What is the role of the primary motor cortex?
Produces specific, skilled movements.
What did Roland, 1993 find?
Blood flow increases in the hand area of the primary somatosensory and primary motor cortex when subjects use a finger to push a lever. Blood flow increases in the premotor cortex when subjects perform a sequence of movements. Blood flow also increases in the prefrontal, temporal, and parietal cortex when subjects use a finger to find a route through a maze. Oxygen is delivered to neurons by haemoglobin in capillary red blood cells. When neuronal activity increases there is an increased demand for oxygen and the local response is an increase in blood flow to regions of increased neural activity.
What did Fritsch and Hitzig (1870) find?
Electrical stimulation of a dog’s cortex produced movement of mouth, limbs and paws.
What did Wilder Penfield (1930s) find?
Used electrical stimulation to map the cortices of human patients who were about to undergo neurosurgery. Confirmed the role of primary motor cortex in producing movement in humans.
What is the homunculus?
Representation of the human body in the sensory or motor cortex; also any topographical representation of the body by a neural area.
What is topographic organisation?
Neural spatial representation of the body or areas of the sensory world perceived by a sensory organ. The parts of the motor cortex that control the hands, fingers, lips, and tongue are disproportionately larger than parts of the motor cortex that control other areas.
What did Michael Graziano (2006) find?
Used more precise stimulation in the motor cortex. Electrical stimulation in conscious non-human primates elicits recognisable actions. These behaviors weren’t just simple muscle twitches. Instead they were complex, involved many joints in coordination, and often resembled meaningful actions such as putting the hand to the mouth and opening the mouth, making a defensive gesture as if to ward off an impend ing impact, or reaching outward and shaping the hand as if to grasp an object.
What did Nudo et al. (1996) find?
Damaged part of the motor cortex that controlled the hand in monkeys. Without rehabilitation, the hand area of the motor cortex became smaller, whereas the elbow and shoulder area became larger. Monkeys lost most ability to move the hand. With rehabilitation, the hand area of the motor cortex retained its size, and monkeys retained some ability to move hand. This may explain recovery after stroke in humans.
What are corticospinal tracts?
Bundle of nerve fibres directly connecting the cerebral cortex to the spinal cord. Branches at the brainstem into opposite-side lateral tract that controls movement of limbs and digits, and a same-side ventral tract that informs movement of the trunk. Also called the pyramidal tract.
What is the lateral corticospinal tract?
Branches at the brainstem level, crossing over to the opposite side of the brain and spinal cord. Moves the digits and limbs on the opposite side of the body.
