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Hemispheric Specialization (hemispheric + specialization)
Selected AbstractsTask-dependent modulation of functional connectivity between hand motor cortices and neuronal networks underlying language and music: a transcranial magnetic stimulation study in humansEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2007R. Sparing Abstract Although language functions are, in general, attributed to the left hemisphere, it is still a matter of debate to what extent the cognitive functions underlying the processing of music are lateralized in the human brain. To investigate hemispheric specialization we evaluated the effect of different overt musical and linguistic tasks on the excitability of both left and right hand motor cortices using transcranial magnetic stimulation (TMS). Task-dependent changes of the size of the TMS-elicited motor evoked potentials were recorded in 12 right-handed, musically naive subjects during and after overt speech, singing and humming, i.e. the production of melody without word articulation. The articulation of meaningless syllables served as control condition. We found reciprocal lateralized effects of overt speech and musical tasks on motor cortex excitability. During overt speech, the corticospinal projection of the left (i.e. dominant) hemisphere to the right hand was facilitated. In contrast, excitability of the right motor cortex increased during both overt singing and humming, whereas no effect was observed on the left hemisphere. Although the traditional concept of hemispheric lateralization of music has been challenged by recent neuroimaging studies, our findings demonstrate that right-hemisphere preponderance of music is nevertheless present. We discuss our results in terms of the recent concepts on evolution of language and gesture, which hypothesize that cerebral networks mediating hand movement and those subserving language processing are functionally linked. TMS may constitute a useful tool to further investigate the relationship between cortical representations of motor functions, music and language using comparative approaches. [source] Detection of animals in natural images using far peripheral visionEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2001Simon J. Thorpe Abstract It is generally believed that the acuity of the peripheral visual field is too poor to allow accurate object recognition and, that to be identified, most objects need to be brought into foveal vision by using saccadic eye movements. However, most measures of form vision in the periphery have been done at eccentricities below 10° and have used relatively artificial stimuli such as letters, digits and compound Gabor patterns. Little is known about how such data would apply in the case of more naturalistic stimuli. Here humans were required to categorize briefly flashed (28 ms) unmasked photographs of natural scenes (39° high, and 26° across) on the basis of whether or not they contained an animal. The photographs appeared randomly in nine locations across virtually the entire extent of the horizontal visual field. Accuracy was 93.3% for central vision and decreased almost linearly with increasing eccentricity (89.8% at 13°, 76.1% at 44.5° and 71.2% at 57.5°). Even at the most extreme eccentricity, where the images were centred at 70.5°, subjects scored 60.5% correct. No evidence was found for hemispheric specialization. This level of performance was achieved despite the fact that the position of the image was unpredictable, ruling out the use of precued attention to target locations. The results demonstrate that even high-level visual tasks involving object vision can be performed using the relatively coarse information provided by the peripheral retina. [source] Infant-holding biases in mothers and affective symptoms during pregnancy and after deliveryINFANT AND CHILD DEVELOPMENT, Issue 2 2009Jacques Vauclair Abstract Several authors have reported that participants have a leftward bias when holding a newborn or young infant. Our study of mothers met before and after their infant's birth sought to ascertain whether particular combinations of affective symptoms (depression, anxiety) and holding positions (horizontal versus vertical) were related to holding-side biases. Our results showed that (a) mothers displayed a significant leftward (71%) holding bias, (b) mothers with affective symptoms held their newborn on the right side and more frequently in the vertical position, and (c) hemispheric specialization for perceiving visual emotions had no significant effect on the holding-side biases of new mothers. These results suggest that maternal affective symptoms have a dominant effect on the determination of holding-side preferences, when associated with a particular holding position. Copyright © 2008 John Wiley & Sons, Ltd. [source] A neuropsychological dimension for anchoring effectsJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 5 2005John D. Jasper Abstract Previous research has shown that strength of handedness predicts differences in sensory illusions, Stroop interference, episodic memory, and beliefs about body image and the origin of species. Recent evidence also suggests handedness differences in the susceptibility to information framing and persuasion. The present paper extends this line of work to decision anchoring effects. In Experiment 1, 131 introductory psychology students responded to 12 real-world knowledge questions after being given random, uninformative high or low anchors. Results indicated that "strong-handers" showed larger anchoring effects than "mixed-handers." In Experiment 2, 89 introductory psychology students responded to 6 real-world knowledge questions in a modified, two-step anchoring task in which participants were given a credible source for the anchored information and asked to give pre- and post-anchor estimates. In contrast to Experiment 1, results revealed that mixed- and strong-handers were affected similarly by anchoring. In Experiment 3, 158 students were asked to estimate the answer to one of two versions of 8! (8,×,7,×,6,×,5,×,4,×,3,×,2,×,1 or 1,×,2,×,3,×,4,×,5,×,6,×,7,×,8),a multiplication problem in which the high and low anchors are inherently informative. Here, mixed-handers showed larger anchoring effects than strong-handers. A theory centered around the notion of hemispheric specialization and the communication between the two halves of the brain as well as arguments about the informativeness of anchors, metacognition, and recent theorizing in the anchoring literature are used to account for these data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Brief communication: Locomotor limb preferences in captive chimpanzees (Pan troglodytes): Implications for morphological asymmetries in limb bonesAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 1 2008William D. Hopkins Abstract Understanding the evolutionary origins of hemispheric specialization remains a topic of considerable interest in a variety of scientific disciplines. Whether nonhuman primates exhibit population-level limb preferences continues to be a controversial topic. In this study, limb preferences for ascending and descending locomotion were assessed as a means of examining the hypothesis that asymmetries in forelimb bones might be attributed to asymmetries in posture. The results indicated that captive chimpanzees showed a population-level leftward asymmetry in descending locomotion but no group bias for ascending locomotion. The results are consistent with previous behavioral studies in captive chimpanzees as well as studies on skeletal asymmetries of the forelimbs of chimpanzees. Am J Phys Anthropol, 2008. © 2008 Wiley-Liss, Inc. [source] Multiple measures of laterality in Garnett's bushbaby (Otolemur garnettii)AMERICAN JOURNAL OF PRIMATOLOGY, Issue 3 2010David B. Hanbury Abstract Behavioral laterality, a common measure of hemispheric specialization of the brain, has been examined in multiple tasks across several species of prosimian primates; however, there is inconsistency among findings between and within species that leaves many questions about laterality unanswered. Most studies have employed few measures of laterality, most commonly handedness. This study examined multiple measures of laterality within subjects in 17 captive-born Garnett's bushbabies (Otolemur garnettii) to assess the consistency of lateralized behaviors and to examine possible influences such as age, posture, novelty, and arousal to elucidate the relations between direction and strength of laterality. We measured reaching, turning bias, scent marking, tail wrapping, leading foot, side-of-mouth preference, and hand use in prey capture. Because autonomic arousal has been invoked as a determinant of strength of lateralization, we included multiple tasks that would allow us to test this hypothesis. All subjects were significantly lateralized on simple reaching tasks (P<0.01) and tail wrapping (P<0.01). Moreover, the number of animals lateralized on turning (P<0.01), leading limb (P<0.05), mouth use (P<0.01), and prey capture (P<0.01) was greater than would be expected by chance alone. There was consistency in the strength and direction of hand biases across different postures. Tasks requiring hand use were more strongly lateralized than tasks not involving hand use (P<0.001). The data do not support the assumption that arousal (as subjectively categorized) or novelty strengthens lateralized responding. The results of this study are discussed in terms of the effects of arousal, posture, and age on lateralized behavior. Am. J. Primatol. 72:206,216, 2010. © 2009 Wiley-Liss, Inc. [source] | ||||||||||