Biomedical subjects
Publications and source records attributed to D Galin.
The hypothesis of less direct interaction between hemispheres in young children was supported by a behavioral test. Fabric samples were compared with either the same hand (same hemisphere) or with opposite hands (between hemispheres). Crossed errors were a significantly larger proportion of total errors in 3-year-olds than in 5-year-olds.
Left-and right-handers have been reported to differ in lateral hemispheric specialization for cognition. We compared different methods of dividing subjects into handedness groups: preference(a 12-item questionnaire), performance(speed, strength, dexterity), and preference plus performance, and determined which method of handedness classification indicated the greatest group differences on EEG and dichotic measures of lateral specialization. All handedness measures were significantly intercorrelated. These handedness measures were significantly correlated with the dichotic test over the whole population but were significantly correlated with EEG asymmetry only in females. Scoring degree of handedness showed significant relationships to lateral specialization which were not seen when subjects were classified into discrete handedness groups. Ambidextrous subjects performed as well as right- or left-handers on unimanual tasks despite a lack of hand preference. The hand used for writing was shown to be too limited to be used as the sole index of handedness in studies related to cognition.
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At the start of this lecture, I invited you to indulge with me in a "dessert" of speculations. I hope it has been a sufficiency, not a surfeit. In summary, we have examined a hypothetical model of some dissociations of consciousness and the expression of unconscious symptoms in adults; we then explored some possible conditions that would account for the development of separate mental streams. In the course of this exploration we were led to question some basic assumptions about the unity of the self, and we proposed some possible mechanisms by which lateral specialization develops in children. This model of the development of lateral specialization has some implications for the study of evolution of the human brain and consciousness. It would seem useful to examine the relationship between the evolution of the commissural systems and the evolution of different capacities for consciousness. According to this model, the full development of lateral specialization depends upon the later myelination of the commissures, which makes possible the autonomy and competition between hemispheres. By this means, only minimal differences between hemispheres need to be specified genetically, since the rest of lateralization can be produced by progressive differentiation, through interactions with the environment. Thus man's eternal, internal struggle may be the price paid for the evolution of lateral specialization.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.