Hamilton, Charles Robert (1964) Studies on adaptation to deflection of the visual field in split-brain monkeys and man. Dissertation (Ph.D.), California Institute of Technology. http://resolver.caltech.edu/CaltechETD:etd-09172002-135454
Experiments were performed with split-brain monkeys and human subjects to investigate several questions concerning the ability of higher mammals to compensate for errors in reaching produced by optical rearrangements of the visual field. The aim of these experiments was to determine 1) if the adaptive process or effect could be localized to or associated with particular structures or regions of the brain, 2) if the adaptive changes are made in visual, motor, or proprioceptive elements of coordination, and 3) how the process and effect of adaptation compare with other types of learning and memory.
Subjects were required to practice localizing movements with specified combinations of eyes and limbs while looking through prisms that deflected their visual field. They then were tested for transfer of the acquired adaptation to unpracticed members of the body. Normal monkeys and monkeys with differing degrees of midline section of the cerebral and midbrain commissures and of other structures showed normal adaptive ability with all eye-hand combinations and possessed no deficits when tested for interocular transfer. Normal reaching also appeared to be unaffected by split-brain surgery. Monkeys and human subjects did not transfer the acquired compensations from the practiced to the unpracticed arm in several experiments, although partial transfer to unpracticed members was found with human subjects in certain situations. The adaptive effects did not require vision for a return toward normal coordination.
It was concluded that the adaptive process is not organized completely at cortical levels and that subcortical centers are involved in reaching with both normal and adapted coordination. The effect of adaptation seems best described as recalibrations in position sense of particular limbs of the body. Under some conditions these alterations seem to be restricted to the level of the particular joints that were practiced during adaptation, while under other conditions generalization to unpracticed members was observed. The critical factor for the occurrence of generalization appears to be the kind or amount of movement rather than differences in visual stimulation. Adaptation differs from other forms of sensory and motor learning by the presence of interocular transfer in split-brain monkeys and by the complete absence of intermanual transfer in monkeys and man under some conditions.
|Item Type:||Thesis (Dissertation (Ph.D.))|
|Degree Grantor:||California Institute of Technology|
|Thesis Availability:||Public (worldwide access)|
|Defense Date:||20 April 1964|
|Default Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Imported from ETD-db|
|Deposited On:||18 Sep 2002|
|Last Modified:||26 Dec 2012 03:01|
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