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Cerebral asymmetries: complementary and independent processes.

Badzakova-Trajkov G, Häberling IS, Roberts RP, Corballis MC - PLoS ONE (2010)

Bottom Line: Most people are right-handed and left-cerebrally dominant for speech, leading historically to the general notion of left-hemispheric dominance, and more recently to genetic models proposing a single lateralizing gene.This hypothetical gene can account for higher incidence of right-handers in those with left cerebral dominance for speech.It remains unclear how this dominance relates to the right-cerebral dominance for some nonverbal functions such as spatial or emotional processing.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Auckland, Auckland, New Zealand. g.badzakova@auckland.ac.nz

ABSTRACT
Most people are right-handed and left-cerebrally dominant for speech, leading historically to the general notion of left-hemispheric dominance, and more recently to genetic models proposing a single lateralizing gene. This hypothetical gene can account for higher incidence of right-handers in those with left cerebral dominance for speech. It remains unclear how this dominance relates to the right-cerebral dominance for some nonverbal functions such as spatial or emotional processing. Here we use functional magnetic resonance imaging with a sample of 155 subjects to measure asymmetrical activation induced by speech production in the frontal lobes, by face processing in the temporal lobes, and by spatial processing in the parietal lobes. Left-frontal, right-temporal, and right-parietal dominance were all intercorrelated, suggesting that right-cerebral biases may be at least in part complementary to the left-hemispheric dominance for language. However, handedness and parietal asymmetry for spatial processing were uncorrelated, implying independent lateralizing processes, one producing a leftward bias most closely associated with handedness, and the other a rightward bias most closely associated with spatial attention.

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Related in: MedlinePlus

Scatter plots showing the relationships between the three functional asymmetries plotted for each handedness group separately.
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pone-0009682-g002: Scatter plots showing the relationships between the three functional asymmetries plotted for each handedness group separately.

Mentions: The degree of lateralisation on each of the tasks based on handedness (right-handers, left-handers) is visually presented in Figure 2 where three scatter plots show the relationships between the three tasks (word generation and landmark; word generation and faces; landmark and faces). Although all possible patterns of cerebral lateralization were observed, most subjects showed the ‘typical’ cerebral asymmetry pattern, with word generation lateralizing to the left, and landmark and faces lateralizing to the right. A small number of subjects showed a complete reversal of the cerebral asymmetry pattern, and others had both tasks lateralized to same hemisphere.


Cerebral asymmetries: complementary and independent processes.

Badzakova-Trajkov G, Häberling IS, Roberts RP, Corballis MC - PLoS ONE (2010)

Scatter plots showing the relationships between the three functional asymmetries plotted for each handedness group separately.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2837380&req=5

pone-0009682-g002: Scatter plots showing the relationships between the three functional asymmetries plotted for each handedness group separately.
Mentions: The degree of lateralisation on each of the tasks based on handedness (right-handers, left-handers) is visually presented in Figure 2 where three scatter plots show the relationships between the three tasks (word generation and landmark; word generation and faces; landmark and faces). Although all possible patterns of cerebral lateralization were observed, most subjects showed the ‘typical’ cerebral asymmetry pattern, with word generation lateralizing to the left, and landmark and faces lateralizing to the right. A small number of subjects showed a complete reversal of the cerebral asymmetry pattern, and others had both tasks lateralized to same hemisphere.

Bottom Line: Most people are right-handed and left-cerebrally dominant for speech, leading historically to the general notion of left-hemispheric dominance, and more recently to genetic models proposing a single lateralizing gene.This hypothetical gene can account for higher incidence of right-handers in those with left cerebral dominance for speech.It remains unclear how this dominance relates to the right-cerebral dominance for some nonverbal functions such as spatial or emotional processing.

View Article: PubMed Central - PubMed

Affiliation: Department of Psychology, University of Auckland, Auckland, New Zealand. g.badzakova@auckland.ac.nz

ABSTRACT
Most people are right-handed and left-cerebrally dominant for speech, leading historically to the general notion of left-hemispheric dominance, and more recently to genetic models proposing a single lateralizing gene. This hypothetical gene can account for higher incidence of right-handers in those with left cerebral dominance for speech. It remains unclear how this dominance relates to the right-cerebral dominance for some nonverbal functions such as spatial or emotional processing. Here we use functional magnetic resonance imaging with a sample of 155 subjects to measure asymmetrical activation induced by speech production in the frontal lobes, by face processing in the temporal lobes, and by spatial processing in the parietal lobes. Left-frontal, right-temporal, and right-parietal dominance were all intercorrelated, suggesting that right-cerebral biases may be at least in part complementary to the left-hemispheric dominance for language. However, handedness and parietal asymmetry for spatial processing were uncorrelated, implying independent lateralizing processes, one producing a leftward bias most closely associated with handedness, and the other a rightward bias most closely associated with spatial attention.

Show MeSH
Related in: MedlinePlus