The Experts below are selected from a list of 273 Experts worldwide ranked by ideXlab platform
Michael S. Gazzaniga - One of the best experts on this subject based on the ideXlab platform.
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Split-Brain, Split-Mind
The Neurology of Conciousness, 2015Co-Authors: Nicole Marinsek, Michael S. Gazzaniga, Michael B MillerAbstract:The corpus callosum anatomically and functionally connects the two cerebral Hemispheres. Despite its important role in interhemispheric communication however, severing the corpus callosum produces few—if any—noticeable cognitive or behavioral abnormalities. Incredibly, split-brain patients do not report any drastic changes in their conscious experience even though nearly all interhemispheric communication ceases after surgery. Extensive research has shown that both Hemispheres remain conscious following disconnection and the conscious experience of each Hemisphere is private and independent of the other. Additionally, the conscious experiences of the Hemispheres appear to be qualitatively different, such that the consciousness of the left Hemisphere is more enriched than the right. In this chapter, we offer explanations as to why split-brain patients feel unified despite possessing dual conscious experiences and discuss how the divided consciousness of split-brain patients can inform current theories of consciousness.
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Attention in Split-Brain Patients
Neurobiology of Attention, 2007Co-Authors: Todd C Handy, Michael S. GazzanigaAbstract:ABSTRACT Attention can take many different forms in human information processing, yet one question central to all domains of attention research concerns understanding how our attentional capacities are controlled. Accordingly, the study of attentional functioning in split-brain patients has long focused on investigating the degree to which attention is independently controlled in the two cerebral Hemispheres. In particular, severing the corpus callosum disrupts the ability of the two Hemispheres to directly communicate, and as a result, the Hemispheres can no longer coordinate their operations in a strategic and organized manner. As a result, each Hemisphere in the split-brain patient is thus believed to function in a relatively independent manner, a condition that is ideal for examining the laterality of attentional control processes. For example, if a split-brain patient is given a visual search task to perform, at least three different results may be obtained, each of which is informative regarding the implementation of attentional control processes in cortex. If each Hemisphere can independently search the display elements in the contralateral visual hemifield, it would suggest that the control processes mediating visual search exist in parallel within each Hemisphere. Conversely, if only one of the two Hemispheres shows an ability to perform visual search, it would support the proposal that control processes are lateralized to that Hemisphere. Finally, if the split-brain patient is unable to perform the visual search task, it would be consistent with the idea that attentional processes underlying visual search are distributed—or integrated—across the two cerebral Hemispheres.
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Mike or me? Self-recognition in a split-brain patient
Nature Neuroscience, 2002Co-Authors: David J. Turk, Michael S. Gazzaniga, Todd F. Heatherton, William M. Kelley, Margaret G. Funnell, C. Neil MacraeAbstract:A split-brain patient (epileptic individual whose corpus callosum had been severed to minimize the spread of seizure activity) was asked to recognize morphed facial stimuli—presented separately to each Hemisphere—as either himself or a familiar other. Both Hemispheres were capable of face recognition, but the left Hemisphere showed a recognition bias for self and the right Hemisphere a bias for familiar others. These findings suggest a possible dissociation between self-recognition and more generalized face processing within the human brain.
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Language and speech capacity of the right Hemisphere
Neuropsychologia, 2002Co-Authors: Michael S. Gazzaniga, Steven A. HillyardAbstract:Abstract Right Hemisphere language and speech capacity was further analyzed in brain-bisected patients. The results indicate that little or no syntactic capability exists in the right Hemisphere. The only semantic dimension that was comprehended in a series of pictorial-verbal matching tests was the affirmative-negative. Moreover, earlier indications of a right Hemisphere speech capacity could not be confirmed. Differences in verbal reaction time to visual stimuli projected to right and left Hemispheres were alternatively interpreted as consequences of subcortical transfer mechanisms or cross-cuing strategies.
Susana Agusti - One of the best experts on this subject based on the ideXlab platform.
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contrasting sensitivity of marine biota to uv b radiation between southern and northern Hemispheres
Estuaries and Coasts, 2015Co-Authors: Susana Agusti, Moira Llabres, Beatriz Carreja, Miriam Fernandez, Carlos M DuarteAbstract:The asymmetries between Hemispheres in stratospheric ozone concentration and atmospheric aerosols, leading to differences in incident ultraviolet B (UV-B) radiation, were examined in order to resolve the differential forcing of adaptation and selection of marine organisms under elevated UV-B radiation. This analysis was based on a meta-analysis including 2,060 experimental assessments of responses of marine organisms from the Northern and Southern Hemispheres to UV-B. Stratospheric ozone concentration in spring and summer decreased by 11.0 % in the Southern and 2.7 % in the Northern between 1970 and 2012, indicating higher UV-B incidence on the Southern Hemisphere. The ratio of studies on UV-B radiation impacts performed in the Southern against the Northern Hemisphere was 0.34 indicating higher research effort in the Northern Hemisphere. Responses of marine biota to UV-B indicated significantly more resistance of marine organisms tested from the Southern Hemisphere (P < 0.01) to UV-B radiation. Marine plants (angiosperm, macroalgae and microalgae) showed no significant differences in UV-B sensitivity between Hemispheres, but the family Ulvaceae, showed significantly more resistance to UV-B for organisms tested from the Southern Hemisphere (P < 0.005). Echinodermata tested from the Southern Hemisphere were more resistant to UV-B (P < 0.005), as well as early stages of marine organisms (P < 0.001). Responses at the molecular and cellular level and demographic levels showed lower UV-B effects in the organisms tested from the Southern Hemisphere. The results obtained suggest that marine organisms from the Southern Hemisphere tend to be more resistant to UV-B radiation than those in the Northern Hemisphere.
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Contrasting Sensitivity of Marine Biota to UV-B Radiation Between Southern and Northern Hemispheres
Estuaries and Coasts, 2015Co-Authors: Susana Agusti, Moira Llabres, Beatriz Carreja, Miriam Fernandez, Carlos M DuarteAbstract:The asymmetries between Hemispheres in stratospheric ozone concentration and atmospheric aerosols, leading to differences in incident ultraviolet B (UV-B) radiation, were examined in order to resolve the differential forcing of adaptation and selection of marine organisms under elevated UV-B radiation. This analysis was based on a meta-analysis including 2,060 experimental assessments of responses of marine organisms from the Northern and Southern Hemispheres to UV-B. Stratospheric ozone concentration in spring and summer decreased by 11.0 % in the Southern and 2.7 % in the Northern between 1970 and 2012, indicating higher UV-B incidence on the Southern Hemisphere. The ratio of studies on UV-B radiation impacts performed in the Southern against the Northern Hemisphere was 0.34 indicating higher research effort in the Northern Hemisphere. Responses of marine biota to UV-B indicated significantly more resistance of marine organisms tested from the Southern Hemisphere ( P
C. Neil Macrae - One of the best experts on this subject based on the ideXlab platform.
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Mike or me? Self-recognition in a split-brain patient
Nature Neuroscience, 2002Co-Authors: David J. Turk, Michael S. Gazzaniga, Todd F. Heatherton, William M. Kelley, Margaret G. Funnell, C. Neil MacraeAbstract:A split-brain patient (epileptic individual whose corpus callosum had been severed to minimize the spread of seizure activity) was asked to recognize morphed facial stimuli—presented separately to each Hemisphere—as either himself or a familiar other. Both Hemispheres were capable of face recognition, but the left Hemisphere showed a recognition bias for self and the right Hemisphere a bias for familiar others. These findings suggest a possible dissociation between self-recognition and more generalized face processing within the human brain.
Carlos M Duarte - One of the best experts on this subject based on the ideXlab platform.
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contrasting sensitivity of marine biota to uv b radiation between southern and northern Hemispheres
Estuaries and Coasts, 2015Co-Authors: Susana Agusti, Moira Llabres, Beatriz Carreja, Miriam Fernandez, Carlos M DuarteAbstract:The asymmetries between Hemispheres in stratospheric ozone concentration and atmospheric aerosols, leading to differences in incident ultraviolet B (UV-B) radiation, were examined in order to resolve the differential forcing of adaptation and selection of marine organisms under elevated UV-B radiation. This analysis was based on a meta-analysis including 2,060 experimental assessments of responses of marine organisms from the Northern and Southern Hemispheres to UV-B. Stratospheric ozone concentration in spring and summer decreased by 11.0 % in the Southern and 2.7 % in the Northern between 1970 and 2012, indicating higher UV-B incidence on the Southern Hemisphere. The ratio of studies on UV-B radiation impacts performed in the Southern against the Northern Hemisphere was 0.34 indicating higher research effort in the Northern Hemisphere. Responses of marine biota to UV-B indicated significantly more resistance of marine organisms tested from the Southern Hemisphere (P < 0.01) to UV-B radiation. Marine plants (angiosperm, macroalgae and microalgae) showed no significant differences in UV-B sensitivity between Hemispheres, but the family Ulvaceae, showed significantly more resistance to UV-B for organisms tested from the Southern Hemisphere (P < 0.005). Echinodermata tested from the Southern Hemisphere were more resistant to UV-B (P < 0.005), as well as early stages of marine organisms (P < 0.001). Responses at the molecular and cellular level and demographic levels showed lower UV-B effects in the organisms tested from the Southern Hemisphere. The results obtained suggest that marine organisms from the Southern Hemisphere tend to be more resistant to UV-B radiation than those in the Northern Hemisphere.
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Contrasting Sensitivity of Marine Biota to UV-B Radiation Between Southern and Northern Hemispheres
Estuaries and Coasts, 2015Co-Authors: Susana Agusti, Moira Llabres, Beatriz Carreja, Miriam Fernandez, Carlos M DuarteAbstract:The asymmetries between Hemispheres in stratospheric ozone concentration and atmospheric aerosols, leading to differences in incident ultraviolet B (UV-B) radiation, were examined in order to resolve the differential forcing of adaptation and selection of marine organisms under elevated UV-B radiation. This analysis was based on a meta-analysis including 2,060 experimental assessments of responses of marine organisms from the Northern and Southern Hemispheres to UV-B. Stratospheric ozone concentration in spring and summer decreased by 11.0 % in the Southern and 2.7 % in the Northern between 1970 and 2012, indicating higher UV-B incidence on the Southern Hemisphere. The ratio of studies on UV-B radiation impacts performed in the Southern against the Northern Hemisphere was 0.34 indicating higher research effort in the Northern Hemisphere. Responses of marine biota to UV-B indicated significantly more resistance of marine organisms tested from the Southern Hemisphere ( P
James A. Reggia - One of the best experts on this subject based on the ideXlab platform.
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Hemispheric Specialization and Independence for Word Recognition: A Comparison of Three Computational Models.
Brain and Language, 2004Co-Authors: Scott A. Weems, James A. ReggiaAbstract:Two findings serve as the hallmark for hemispheric specialization during lateralized lexical decision. First is an overall word advantage, with words being recognized more quickly and accurately than non-words (the effect being stronger in response latency). Second, a right visual field advantage is observed for words, with little or no hemispheric differences in the ability to identify non-words. Several theories have been proposed to account for this difference in word and non-word recognition, some by suggesting dual routes of lexical access and others by incorporating separate, and potentially independent, word and non-word detection mechanisms. We compare three previously proposed cognitive theories of hemispheric interactions (callosal relay, direct access, and cooperative Hemispheres) through neural network modeling, with each network incorporating different means of interhemispheric communication. When parameters were varied to simulate left Hemisphere specialization for lexical decision, only the cooperative Hemispheres model showed both a consistent left Hemisphere advantage for word recognition but not non-word recognition, as well as an overall word advantage. These results support the theory that neural representations of words are more strongly established in the left Hemisphere through prior learning, despite open communication between the Hemispheres during both learning and recall.
