Handedness Development: A Model for Investigating the Development of Hemispheric Specialization and Interhemispheric Coordination

Abstract

The author presents his perspective on the character of science, development, and handedness and relates these to his investigations of the early development of handedness. After presenting some ideas on what hemispheric specialization of function might mean for neural processing and how handedness should be assessed, the neuroscience of control of the arms/hands and interhemispheric communication and coordination are examined for how developmental processes can affect these mechanisms. The author’s work on the development of early handedness is reviewed and placed within a context of cascading events in which different forms of handedness emerge from earlier forms but not in a deterministic manner. This approach supports a continuous rather than categorical distribution of handedness and accounts for the predominance of right-handedness while maintaining a minority of left-handedness. Finally, the relation of the development of handedness to the development of several language and cognitive skills is examined.

A Novel Perspective for Examining and Comparing Real and Virtual Test Tasks Performed by the Dominant and Non-Dominant Hand in Healthy Adults

“…Taking into account the above facts and in accordance with the proposal presented by Michel in his review [40], at least four basic methods of assessing human handedness can be distinguished. The first method is associated with the individual's narrative or self-identified handedness, e.g., "I'm right-handed/left-handed/mixed-handed" or "I use ambilateral hands".…”

“…A recent interesting large-scale (1,766,671 participants) genome-wide association study (GWAS) revealed that 48 genetic variants are statistically associated with different forms of self-identified handedness (41 left-handed and 7 mixed) [78]. However, as Michel indicated in his review [40], GWAS does not identify genes that are commonly found associated with handedness in other primate species or across different phases of human development, and these studies do not identify deep handedness homology. In addition, the author pointed out that genetics might have some influence on the initiation of the developmental trajectory of handedness, slightly affecting the probability of one form over another.…”

“…Control of hands is contralateral, the right hand is under the control of the left hemisphere and the left hand is under the control of the right hemisphere. Lateralization is a progressive process that develops with age [43] to include neuromotor development [40,44,45]. Various techniques are used to estimate lateralization, both in health [46][47][48] and disease [49,50].…”

“…Various techniques are used to estimate lateralization, both in health [46][47][48] and disease [49,50]. Not only traditional hand preference questionnaires are used to measure handedness, but most of all performance variables because, as the studies emphasize, they are more objective than questionnaires [40,51]. Scientists also suggest that handedness cannot be predicted with a single measure of manual performance, because the measurements are unreliable due to their subjectivity [40,52].…”

“…In humans, lateralization typically refers to a division of functional processing between two cerebral hemispheres, for instance left-hemisphere specialization for language and praxis and that of the right hemisphere for spatial attention, face recognition, and speech prosody is observed [34][35][36][37]. The phenomenon of handedness is an interesting example of functional asymmetry [38][39][40]. Approximately 75-90% of the human population prefer to use their right hand to realize a lot of tasks involving various levels of dexterity, and about 80% are right footed [41,42].…”