Effects of handedness and sex on the morphology of the corpus callosum: A study with brain magnetic resonance imaging. Brain & Cognition, 16, 41-61
Neurological Clinic, C.H.U. Timone, Marseilles, France. Brain and Cognition
(Impact Factor: 2.48).
06/1991; 16(1):41-61. DOI: 10.1016/0278-2626(91)90084-L
In view of conflicting data in the existing literature, we examined 53 normal subjects using a handedness questionnaire and callosal area measurements obtained from midsagittal MRI images. The callosum was found to be significantly larger in nonconsistent right-handers (NCRH), especially in its anterior half and especially for males. A significant hand x sex interaction, favoring consistent right-handed (CRH) females, was also found for the posterior midbody, a region known to house interhemispheric fibers connecting the right and left posterior association cortices. These results (1) confirm Witelson's (1985) first findings on postmortem specimens; (2) validate a dichotomy between CRH and NCRH rather than simply considering the writing hand, as was the case in most other similar studies; and (3) suggest that at least two different sex-related--probably hormonal--factors may be acting during the callosal development, one explaining the larger anterior half in NCRH males and the other the larger posterior midbody in CRH females.
Available from: John D Jasper
- "A growing body of research indicates that consistent (strong)handedness (i.e., exclusive use of the right hand for virtually all manual activities requiring fine motor control) is associated with decreased access to processes localized to the right hemisphere (RH), including episodic memory retrieval (e.g., Lyle, McCabe, & Roediger, 2008; Propper, Christman, & Phaneuf, 2005), body image representation (e.g., Christman, Bentle, & Niebauer, 2007; Niebauer, Aselage, & Schutte, 2002), and belief updating (e.g., Christman, Henning, Geers, Propper, & Niebauer, 2008; Jasper, Prothero, & Christman, 2009). This decreased access to RH processing is presumed to reflect the presence of (i) a smaller corpus callosum in strongly right-handed people (e.g., Clarke & Zaidel, 1994; Denenberg, Kertesz, & Cowell, 1991; Habib et al., 1991; Luders et al., 2010; Witelson & Goldsmith, 1991) and, subsequently, decreased RH activation in strongly righthanded people (e.g., Flor-Henry & Koles, 1982; Papousek & Schulter, 1999; Propper, Pierce, Geisler, Christman, & Bellorado, 2012). This idea that consistent (strong) right-versus inconsistent (mixed)-handedness is associated with decreased versus increased access to RH processing, respectively, has recently been extended to issues involving risk perception. "
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ABSTRACT: Two methodological variants of Kahneman and Tversky's Asian disease scenario were investigated. One variant involved replacing the “all-or-none” outcome scenarios of the risky choice with “most-or-some” scenario outcomes, and the second variant involved replacing the negative domain of lives lost with a positive domain of jobs created. In addition, the effects of strength of handedness, a variable related to individual differences in risk perception, were examined. Results indicated that standard framing effects were obtained across both domains, with a decrease in risky choice under the gain domain. Scenario type also interacted with handedness, such that the all-or-none scenario yielded framing effects for consistent (strong)-handers only, whereas the most-or-some scenario yielded framing effects for inconsistent (mixed)-handers only (consistent-handers are those who use the same hand exclusively for almost all activities). These results demonstrate that framing effects are strongly influenced by the presence versus absence of extreme/absolute outcomes and that individuals (in this case, decision makers with varying degrees of handedness strength) are differentially sensitive to different pieces of information.
Available from: PubMed Central
- "Personal handedness has also been used as a behavioral marker for hemispheric interaction as several studies have found that mixed or inconsistent handed individuals have a relatively larger corpus callosum compared to right-handed individuals (e.g., Witelson, 1985; Denenberg et al., 1991; Habib et al., 1991; Clarke and Zaidel, 1994). The larger size of the corpus callosum subsequently provides a basis for greater hemispheric interaction (Christman, 1993, 1995; Niebauer et al., 2002). "
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ABSTRACT: Performing a sequence of fast saccadic horizontal eye movements has been shown to facilitate performance on a range of cognitive tasks, including the retrieval of episodic memories. One explanation for these effects is based on the hypothesis that saccadic eye movements increase hemispheric interaction, and that such interactions are important for particular types of memory. The aim of the current research was to assess the effect of horizontal saccadic eye movements on the retrieval of both episodic autobiographical memory (event/incident based memory) and semantic autobiographical memory (fact based memory) over recent and more distant time periods. It was found that saccadic eye movements facilitated the retrieval of episodic autobiographical memories (over all time periods) but not semantic autobiographical memories. In addition, eye movements did not enhance the retrieval of non-autobiographical semantic memory. This finding illustrates a dissociation between the episodic and semantic characteristics of personal memory and is considered within the context of hemispheric contributions to episodic memory performance.
Available from: Michael C Corballis
- "Because there is also evidence that left handed individuals are overly represented in sporting activities, especially in those in which individuals are pitted against each other (Aggleton & Wood, 1990; Grouios, Tsorbatzoudis, Alexandris, & Barkoukis, 2000; Holtzen, 2000), we included an almost equal number of right-and left-handed individuals, to assess the possibility that differences in callosal function might be due to handedness rather than sporting activity per se. Some studies have suggested that the size of the CC may vary as a function of handedness, but evidence as to the direction of the effect is conflicting: Some have suggested that the CC is larger in left-than in right-handed individuals (e.g., Habib et al., 1991; Witelson, 1985, 1989; Witelson & Goldsmith, 1991), and Cherbuin and Brinkman (2006) reported interhemispheric transfer to be faster in left-than in right-handed individuals. To assess callosal function, we follow the procedure used by Patston et al. (2007), using the simple reaction-time paradigm first devised by Poffenberger (1912), which provides a measure of ITT. "
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ABSTRACT: ABSTRACT The authors' aim was to compare interhemispheric transfer time between 2 groups: highly skilled sportsmen and control subjects. Left- and right-handed individuals were included in the study. The Poffenberger paradigm was used to measure the crossed-uncrossed difference, representing the time to transfer information from one hemisphere to the other. No difference in laterality was found, but the results revealed a greater crossed-uncrossed difference in the skilled sportsmen than in the controls. The authors suggest that this may be due to more highly developed within-hemisphere integration of inputs and outputs, at the expense of cross-hemisphere integration.
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