Language Laterality in Left-Handed Aphasics

Goodglass, Harold; Quadfasel, F. A.

doi:10.1093/brain/77.4.521

Cited by 317 publications

(63 citation statements)

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“…The two-loci model of Levy & Nagylaki (1972) is inconsistent with the observation that left-handers tend towards ambilaterality, whereas right-handers show almost complete specialization of the hemispheres (Goodglass & Quadfasel 1954;Subirana 1964). If full expression of the alleles occurs only when a dominant allele is present at both loci, this problem is solved.…”

Section: Explanatory Power Of Genetic Modelsmentioning

confidence: 95%

Epigenesis of behavioural lateralization in humans and other animals

Schaafsma

Riedstra

Pfannkuche

et al. 2008

Phil. Trans. R. Soc. B

107

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Despite several decades of research, the epigenesis of behavioural and brain lateralization is still elusive, although its knowledge is important in understanding developmental plasticity, function and evolution of lateralization, and its relationship with developmental disorders. Over the last decades, it has become clear that behavioural lateralization is not restricted to humans, but a fundamental principle in the organization of behaviour in vertebrates. This has opened the possibility of extending descriptive studies on human lateralization with descriptive and experimental studies on other vertebrate species. In this review, we therefore explore the evidence for the role of genes and environment on behavioural lateralization in humans and other animals. First, we discuss the predominant genetic models for human handedness, and conclude that their explanatory power alone is not sufficient, leaving, together with ambiguous results from adoption studies and selection experiments in animals, ample opportunity for a role of environmental factors. Next, we discuss the potential influence of such factors, including perinatal asymmetrical perception induced by asymmetrical head position or parental care, and social modulation, both in humans and other vertebrates, presenting some evidence from our own work on the domestic chick. We conclude that both perinatal asymmetrical perception and later social modulation are likely candidates in influencing the degree or strength of lateralization in both humans and other vertebrates. However, in most cases unequivocal evidence for this is lacking and we will point out further avenues for research.

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Section: Explanatory Power Of Genetic Modelsmentioning

confidence: 95%

Epigenesis of behavioural lateralization in humans and other animals

Schaafsma

Riedstra

Pfannkuche

et al. 2008

Phil. Trans. R. Soc. B

107

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“…Moreover, the eventual handedness of these older infants is unknown, and the incidence of left-hemisphere speech dominance among adult left-handers is only 60070 (e.g., Goodglass & Quadfasel, 1954). An estimated 7070-lOOJo population proportion of left-handers suggests that perhaps 2 of the 24 older infants will become left-handed, only one of whom might show a speech REA.…”

Section: Methodological Considerationsmentioning

confidence: 99%

Development of infant ear asymmetries for speech and music

Best

Hoffman

Glanville

1982

Perception & Psychophysics

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Groups of 2-, 3-, and 4-month olds were tested for dichotic ear differences in memory-based phonetic and music timbre discriminations. A right-ear advantage for speech and a left-ear advantage (LEA) for music were found in the 3-and 4-month-olds. However, the 2-month-olds showed only the music LEA, with no reliable evidence of memory-based speech discrimination by either hemisphere. Thus, the responses of all groups to speech contrasts were different from those to music contrasts, but the pattern of the response dichotomy in the youngest group deviated from that found in the older infants. It is suggested that the quality or use of lefthemisphere phonetic memory may change between 2 and 3 months, and that the engagement of right-hemisphere specialized memory for musical timbre may precede that for left-hemisphere phonetic memory. Several directions for future research are suggested to determine whether infant short-term memory asymmetries for speech and music are attributable to acoustic factors, to different modes or strategies in perception, or to structural and dynamic properties of natural sound sources.The existence of a neurobiological dichotomy in human auditory perception, which distinguishes at least some qualities of spoken language from most nonlinguistic auditory events, is strongly implied by the pattern and incidence of functional cerebral asymmetries in adults, particularly as revealed through dichotic ear advantages (e.g.,

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“…In contrast, four of eight (50%) lefthanders had a rightward asymmetry, one (12.5%) had equal measures, and three of eight (37.5%) had a leftward asymmetry. Whereas most right-handers have language lateralized to the left hemisphere, left-handers are more anomalous (27)(28)(29)(30)(31)(32). Since the pars triangularis constitutes a portion of Broca's area (Brodmann's area 45), which is important in speech-language production, and because our data suggest that asymmetries of the pars triangularis may be associated with lateralized speech-language functions, further anatomic studies with neurobehavioral correlation of speech-language dominance seemed warranted.…”

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confidence: 99%

Pars triangularis asymmetry and language dominance.

Foundas

Leonard

Gilmore

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

138

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The pars triangularis is a portion of Broca's area. The convolutions that form the inferior and caudal extent of the pars triangularis include the anterior horizontal and anterior ascending rami of the sylvian fissure, respectively. To learn if there are anatomic asymmetries of the pars triangularis, these convolutions were measured on volumetric magnetic resonance imaging scans of 11 patients who had undergone selective hemispheric anesthesia (Wada testing) to determine hemispheric speech and language lateralization. Of the 10 patients with language lateralized to the left hemisphere, 9 had a leftward asymmetry of the pars triangularis. The 1 patient with language lateralized to the right hemisphere had a significant rightward asymmetry of the pars triangularis. Our data suggest that asymmetries of the pars triangularis may be related to speech-language lateralization.Paul Broca (1) described eight right-handed patients who lost the facility of speech and were found to have left hemispheric lesions. Broca (1) thought that the left third frontal convolution, including pars triangularis, was critical for speech. Although subsequent studies have demonstrated that left-sided lesions restricted to the third frontal convolution are probably associated with only transient loss of speech (2, 3) lesions of the right third frontal convolution rarely produce any speech deficits. These observations suggest that although the left inferior frontal lobe appears to be important in speech production, other undamaged areas can either compensate or substitute for this area. Both cortical stimulation (4, 5) and functional imaging studies (6-9) have provided support for the role of the left inferior frontal lobe in speech production. Wernicke (10) demonstrated that a lesion in the posterior portion of the left superior temporal lobe produced a syndrome different from that described by Broca (1). Whereas Broca's patients lost the capacity to speak fluently but retained comprehension, Wernicke's patients retained the ability to speak fluently but were impaired at comprehending speech. Subsequently, morphological cerebral asymmetries in the posterior superior temporal speech region (planum temporale) were demonstrated on postmortem brains (11-15), with a predominant leftward asymmetry of the planum temporale. However, consistent asymmetries of the inferior frontal region have been more difficult to demonstrate on postmortem studies (13,(16)(17)(18). Therefore, the distinctive morphological asymmetries of the planum temporale have been thought to be the neuroanatomical substrate for speech and language. Furthermore, the planum temporale constitutes part of cytoarchitectonic areas TA and TB, which are auditory association cortices important in higher order processing of auditory language input. However, direct evidence supporting this structurefunction relationship has been lacking.With the advent of three-dimensional volumetric magnetic resonance imaging (MRI), in vivo quantitative analysis of the The publication costs of this ...

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Language Laterality in Left-Handed Aphasics

Cited by 317 publications

References 0 publications

Epigenesis of behavioural lateralization in humans and other animals

Epigenesis of behavioural lateralization in humans and other animals

Development of infant ear asymmetries for speech and music

Pars triangularis asymmetry and language dominance.

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