Neuroscience Analysis of Occupational Performance (OCTH 455)
and
Neuroscience (PTRS 850)
Motor Systems Review: Question #4
The Question
Mr. Goldberg is your most recent client, and you have been discussing his case at the rehabilitation team meeting. One therapist reports that Mr. Goldberg is having trouble eating and dressing himself. Mr. Goldberg knocks things off the lunchtray when reaching for them, and when dressing his movements seem to be separate actions - they don't flow together smoothly. He then becomes frustrated that he can not dress as quickly as usual. Diagram the motor pathways which might be involved in the normal performance of tasks such as these, and indicate where the problems which produce the behavioral impairment might be.
The Reasoning
The boldface portions of the question are relevant to this particular answer.
- Knocking things over when reaching for them suggests a lack of fine control of motor movements. Impaired sensation, or impaired perception and integration of sensory information (e.g., proprioception and/or vision) may be one source of this problem. Another likely problem may be incoordination of the muscles supporting his reaching for the objects, suggestive of a cerebellar problem (or a problem with the cerebellar peducles). Sensory testing may be indicated, but first consider asking the therapist to more carefully describe how he is making the movement - is there a tremor whcih gets worse as he makes the movement but which isn't present when he is at rest?
- Dressing requires careful coordination of many muscles on both sides of the body. The cerebellum may be involved since the motor sequences for dressing are intact (suggesting the motor planning regions and motor output pathways are functional) but not smoothly coordinated. Since there does not appear to be any problem initiating movements or problems with excessive movements, the basal ganglia are not likely to be involved
- Frustration may suggest involvement of the limbic system, suggesting the possibility of damage in the thalamus which might produce these symptoms. A more simple explanation, however, is that Mr. Goldberg's frustration is a perfectly natural and appropriate response to functional limitations imposed by his condition.
The Answer
Lesion(s) of the cerebellum or of the superior cerebellar peduncle. Lesions of the left and right cerebellar hemispheres (cerebrocerebellum) disrupt motor planning and slow reaction time. Superior cerebellar peduncles convey cerebellar output to the red nucleus, VL nuc. Thalamus, and the reticular formation.
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