The Experts below are selected from a list of 2085 Experts worldwide ranked by ideXlab platform
Carlo Alberto Marzi - One of the best experts on this subject based on the ideXlab platform.
-
Interhemispheric Transfer of spatial and semantic information: electrophysiological evidence.
Psychophysiology, 2013Co-Authors: Anna Dal Molin, Carlo Alberto Marzi, Marie T. Banich, Massimo GirelliAbstract:The goal of this study was to cast light on the existence of functional callosal channels for the Interhemispheric Transfer (IHT) of spatial and semantic information. To do so, we recorded event-related potentials in healthy humans while performing a primed odd-even discrimination task. Targets were visually presented numbers preceded by single-letter primes signaling the probable presentation of an odd or an even number. Primes and targets could appear either in the same or in different visual fields, thus requiring an IHT in the latter case. The P1 and N2 components were influenced by IHT of spatial information only, whereas the later N400 was influenced by IHT of both spatial and semantic information. This was not the case for the P3b, which was modulated by semantic validity only. These results provide novel evidence of the existence of a temporally separated Interhemispheric exchange of spatial and semantic information.
-
Interhemispheric Transfer and integration of imagined visual stimuli
Neuropsychologia, 2007Co-Authors: Silvia Savazzi, Francesca Mancini, Carlo Alberto MarziAbstract:We employed two reaction time paradigms to find out whether imagined visual stimuli can be integrated between the two cerebral hemispheres. In a first experiment we found that Interhemispheric Transfer time, as assessed with the Poffenberger paradigm, was much longer for imagined than visible stimuli and this suggests that the callosal site of Transfer is different in the two conditions. In a second experiment we found that Interhemispheric summation, as assessed with the redundant signal effect paradigm, was present for both visible and imagined stimuli and could be accounted for by a neural coactivation mechanism rather than by a probabilistic explanation. Taken together, these results support the view that that there is an equivalence between perceptual and imagery processes that goes beyond early processing stages and includes the Interhemispheric exchange of information.
-
Interhemispheric Transfer following callosotomy in humans: role of the superior colliculus.
Neuropsychologia, 2007Co-Authors: Silvia Savazzi, Mara Fabri, Guido Rubboli, Aldo Paggi, Carlo Alberto Tassinari, Carlo Alberto MarziAbstract:It is now common knowledge that the total surgical section of the corpus callosum (CC) and of the other forebrain commissures prevents Interhemispheric Transfer (IT) of a host of mental functions. By contrast, IT of simple sensorimotor functions, although severely delayed, is not abolished, and an important question concerns the pathways subserving this residual IT. To answer this question we assessed visuomotor IT in split-brain patients using the Poffenberger paradigm (PP), that is, a behavioral paradigm in which simple reaction time (RT) to visual stimuli presented to the hemifield ipsilateral to the responding hand is compared to stimuli presented to the contralateral hemifield, a condition requiring an IT. We tested the possibility that the residual IT is mediated by the collicular commissure interconnecting the two sides of the superior colliculus (SC). To this purpose, we used short-wavelength visual stimuli, which in neurophysiological studies in non-human primates have been shown to be undetectable by collicular neurons. We found that, in both totally and partially callosotomised patients, IT was considerably longer with S-cone input than with L-cone input or with achromatic stimuli. This was not the case in healthy participants in whom IT was not affected by color. These data clearly show that the SC plays an important role in IT of sensorimotor information in the absence of the corpus callosum.
-
Attention and Interhemispheric Transfer: A Behavioral and fMRI Study
Journal of cognitive neuroscience, 2005Co-Authors: Bruno Weber, Valerie Treyer, N. Oberholzer, T. Jaermann, Peter Boesiger, Peter Brugger, Marianne Regard, Alfred Buck, Silvia Savazzi, Carlo Alberto MarziAbstract:When both detections and responses to visual stimuli are performed within one and the same hemisphere, manual reaction times (RTs) are faster than when the two operations are carried out in different hemispheres. A widely accepted explanation for this difference is that it ref lects the time lost in callosal transmission. Interhemispheric Transfer time can be estimated by subtracting RTs for uncrossed from RTs for crossed responses (crossed – uncrossed difference, or CUD). In the present study, we wanted to ascertain the role of spatial attention in affecting the CUD and to chart the brain areas whose activity is related to these attentional effects on Interhemispheric Transfer. To accomplish this, we varied the proportion of crossed and uncrossed trials in different blocks. With this paradigm subjects are likely to focus attention either on the hemifield contralateral to the responding hand (blocks with 80% crossed trials) or on the ipsilateral hemifield (blocks with 80% uncrossed trials). We found an inverse correlation between the proportion of crossed trials in a block and the CUD and this effect can be attributed to spatial attention. As to the imaging results, we found that in the crossed minus uncrossed subtraction, an operation that highlights the neural processes underlying Interhemispheric Transfer, there was an activation of the genu of the corpus callosum as well as of a series of cortical areas. In a further commonality analysis, we assessed those areas which were activated specifically during focusing of attention onto one hemifield either contra- or ipsilateral to the responding hand. We found an activation of a number of cortical and subcortical areas, notably, parietal area BA 7 and the superior colliculi. We believe that the main thrust of the present study is to have teased apart areas important in Interhemispheric transmission from those involved in spatial attention.
-
Interhemispheric Transfer and laterality effects in simple visual reaction time in schizophrenics.
Cognitive neuropsychiatry, 2002Co-Authors: Vincenzo Florio, Carlo Miniussi, Angelo Maravita, Sabrina Fossella, Carlo Alberto MarziAbstract:Introduction. There is evidence that schizophrenics have an abnormal corpus callosum and an abnormal pattern of cerebral asymmetries. We investigated whether there are corresponding functional abnormalities in Interhemispheric Transfer (IT) and laterality effects. Methods. Medicated schizophrenic patients and matched controls were tested in the Poffenberger paradigm, that is, a simple manual reaction time (RT) paradigm with laterally presented visual stimuli designed to provide a behavioural estimate of IT. By subtracting RT averaged across the uncrossed hand-hemifield conditions, from RT averaged across the crossed hand-hemifield conditions, one can obtain an estimate of IT time. Results. In schizophrenic patients the difference between crossed and uncrossed conditions was 0 because of an unusually prolonged RT in the uncrossed condition right hand/ right field. A broadly similar result has been obtained previously in the tactile modality (Ditchfield & Hemsley, 1990) and is consistent with a left hemisphere impairment. This effect was still present when the patients were retested about 2 years later. Conclusions. These results demonstrate the existence in schizophrenic patients of a consistent slowing down of simple visuomotor responses subserved by the left hemisphere.
Carlo Miniussi - One of the best experts on this subject based on the ideXlab platform.
-
Interhemispheric Transfer and laterality effects in simple visual reaction time in schizophrenics.
Cognitive neuropsychiatry, 2002Co-Authors: Vincenzo Florio, Carlo Miniussi, Angelo Maravita, Sabrina Fossella, Carlo Alberto MarziAbstract:Introduction. There is evidence that schizophrenics have an abnormal corpus callosum and an abnormal pattern of cerebral asymmetries. We investigated whether there are corresponding functional abnormalities in Interhemispheric Transfer (IT) and laterality effects. Methods. Medicated schizophrenic patients and matched controls were tested in the Poffenberger paradigm, that is, a simple manual reaction time (RT) paradigm with laterally presented visual stimuli designed to provide a behavioural estimate of IT. By subtracting RT averaged across the uncrossed hand-hemifield conditions, from RT averaged across the crossed hand-hemifield conditions, one can obtain an estimate of IT time. Results. In schizophrenic patients the difference between crossed and uncrossed conditions was 0 because of an unusually prolonged RT in the uncrossed condition right hand/ right field. A broadly similar result has been obtained previously in the tactile modality (Ditchfield & Hemsley, 1990) and is consistent with a left hemisphere impairment. This effect was still present when the patients were retested about 2 years later. Conclusions. These results demonstrate the existence in schizophrenic patients of a consistent slowing down of simple visuomotor responses subserved by the left hemisphere.
-
Pathways of Interhemispheric Transfer in normals and in a split-brain subject. A positron emission tomography study.
Experimental brain research, 1999Co-Authors: Carlo Alberto Marzi, Daniela Perani, Giancarlo Tassinari, A. Colleluori, Angelo Maravita, Carlo Miniussi, Eraldo Paulesu, Paola Scifo, F. FazioAbstract:We studied with PET the intra- and Interhemispheric pathways subserving a simple, speeded-up visuomotor task. Six normal subjects and one patient with a complete section of the corpus callosum (M.E.) underwent regional cerebral blood flow (rCBF) measurements under conditions of lateralized tachistoscopic visual presentations in a simple manual reaction time paradigm. Confirming previous behavioural findings, we found that on average crossed hand and/or hemifield conditions, i.e. those requiring an Interhemispheric Transfer of information, yielded a longer RT than uncrossed conditions. This difference (0.7 ms) was dramatically larger (45.6 ms) in the callosum-sectioned patient M.E. In normal subjects the cortical areas selectively activated in uncrossed and crossed conditions were different. In the former condition, most activation foci were anterior to the ventral anterior commissure (VAC) plane, whereas in the latter there was a prevalent parietal and occipital activation. This shows that a simple model in which the cortical visuo-motor pathways are similar in the intra- and the Interhemispheric condition, with an extra callosal route for the latter, is too simplistic. Furthermore, these results suggest that the bulk of visuomotor Interhemispheric Transfer takes place through the widespread callosal fibres interconnecting the parietal cortices of the two hemispheres. The pattern of activation in the two crossing conditions was markedly different in M.E., in whom Interhemispheric Transfer might take place via his intact anterior commissure or subcortical commissures.
-
Transcranial magnetic stimulation selectively impairs Interhemispheric Transfer of visuo-motor information in humans
Experimental brain research, 1998Co-Authors: Carlo Alberto Marzi, Angelo Maravita, Carlo Miniussi, Laura Bertolasi, G.p. Zanette, Jc Rothwell, Jerome N. SanesAbstract:We investigated the cerebral cortical route by which visual information reaches motor cortex when visual signals are used for manual responses. Subjects responded unimanually to photic stimuli delivered to the hemifield ipsilateral or contralateral to the moving hand. On some trials, trans-cranial magnetic stimulation (TMS) was applied unilaterally over the occiput, with the aim of stimulating extrastriate visual areas and thereby modifying transmission of visual input. In association with the side of a visual stimulus and a motor response, TMS could change inter- or intra-hemispheric transmission needed to convey visual information to motor areas. Reaction time differences following TMS suggested that TMS exerted an inhibitory effect only when visuo-motor information had to be Transferred Interhemispherically. This result reinforces evidence for an extrastriate pathway of Interhemispheric Transfer of visuomotor information.
-
Interhemispheric Transfer of visual information in humans: the role of different callosal channels.
Archives italiennes de biologie, 1997Co-Authors: A. E. Ipata, Massimo Girelli, Carlo Miniussi, Carlo Alberto MarziAbstract:We have assessed the Interhemispheric transmission time (IHTT) by electrophysiological means in normal subjects performing a visuomotor reaction time task. We subtracted the latency of ERP components (P1 and N1) evoked by lateralized visual stimuli presented to the ipsilateral hemifield (indirect-callosal pathway) from the latency of the same components evoked by stimulation of the contralateral hemifield (direct pathway). Estimates of IHTT ranged between 5.77 msec and 12.54 depending upon the type of component and the location of the electrode sites. More anterior locations yielded shorter values of IHTT, and overall IHTT tended to be 7 msec shorter for the N1 component than for the P1 component. Moreover, there was an asymmetric IHTT for N1 in central sites with shorter latencies in the direction right-to-left hemisphere than in the opposite direction. Taken together, these results are in keeping with the idea that Interhemispheric Transfer of visuomotor information does not occur at the level of the primary visual areas but at more anterior cortical areas. The shorter IHTT for the N1 component suggests the involvement of the callosal connections between the inferotemporal areas of the two hemispheres.
Veit Roessner - One of the best experts on this subject based on the ideXlab platform.
-
fine motor skills and Interhemispheric Transfer in treatment naive male children with tourette syndrome
Developmental Medicine & Child Neurology, 2012Co-Authors: Judith Buse, Julia M. August, Nathalie Bock, Denise Dörfel, Aribert Rothenberger, Veit RoessnerAbstract:Aim This study addressed whether Tourette syndrome is associated with an impairment of fine motor skills or altered Interhemispheric Transfer. We additionally investigated the association between Interhemispheric Transfer and size of the corpus callosum. Method The sample, a subsample of our larger neuroimaging sample, included 27 treatment-naive males with ‘pure’ Tourette syndrome (age range 10y 2mo–14y 4mo; mean age 11y 10mo, SD 1y 2mo) and 26 matched healthy comparison children (age range 10y 2mo–14y 4mo; mean age 11y 10mo, SD 1y 1mo). A finger tapping task and the Purdue Pegboard were used to assess fine motor skills. Interhemispheric Transfer time (ITT) was measured with the Poffenberger paradigm. The neuroanatomical data were derived from our previous neuroimaging study. Results ITT was negatively correlated with the size of callosal subregion 3 (r=−0.366, p=0.028), indicating that a shorter ITT was associated with a larger corpus callosum. Interpretation Our findings support the assumption that previously reported impairment of motor skills in Tourette syndrome does not directly result from tics but from other factors such as medication or comorbidities. Following the assumption that callosal subregion 3 in Tourette syndrome grows as a consequence of tic performance over years, our preliminary results suggest that this growth might accelerate Interhemispheric Transfer in Tourette syndrome.
-
Fine motor skills and Interhemispheric Transfer in treatment‐naive male children with Tourette syndrome
Developmental medicine and child neurology, 2012Co-Authors: Judith Buse, Julia M. August, Nathalie Bock, Denise Dörfel, Aribert Rothenberger, Veit RoessnerAbstract:Aim This study addressed whether Tourette syndrome is associated with an impairment of fine motor skills or altered Interhemispheric Transfer. We additionally investigated the association between Interhemispheric Transfer and size of the corpus callosum. Method The sample, a subsample of our larger neuroimaging sample, included 27 treatment-naive males with ‘pure’ Tourette syndrome (age range 10y 2mo–14y 4mo; mean age 11y 10mo, SD 1y 2mo) and 26 matched healthy comparison children (age range 10y 2mo–14y 4mo; mean age 11y 10mo, SD 1y 1mo). A finger tapping task and the Purdue Pegboard were used to assess fine motor skills. Interhemispheric Transfer time (ITT) was measured with the Poffenberger paradigm. The neuroanatomical data were derived from our previous neuroimaging study. Results ITT was negatively correlated with the size of callosal subregion 3 (r=−0.366, p=0.028), indicating that a shorter ITT was associated with a larger corpus callosum. Interpretation Our findings support the assumption that previously reported impairment of motor skills in Tourette syndrome does not directly result from tics but from other factors such as medication or comorbidities. Following the assumption that callosal subregion 3 in Tourette syndrome grows as a consequence of tic performance over years, our preliminary results suggest that this growth might accelerate Interhemispheric Transfer in Tourette syndrome.
Angelo Maravita - One of the best experts on this subject based on the ideXlab platform.
-
Interhemispheric Transfer and laterality effects in simple visual reaction time in schizophrenics.
Cognitive neuropsychiatry, 2002Co-Authors: Vincenzo Florio, Carlo Miniussi, Angelo Maravita, Sabrina Fossella, Carlo Alberto MarziAbstract:Introduction. There is evidence that schizophrenics have an abnormal corpus callosum and an abnormal pattern of cerebral asymmetries. We investigated whether there are corresponding functional abnormalities in Interhemispheric Transfer (IT) and laterality effects. Methods. Medicated schizophrenic patients and matched controls were tested in the Poffenberger paradigm, that is, a simple manual reaction time (RT) paradigm with laterally presented visual stimuli designed to provide a behavioural estimate of IT. By subtracting RT averaged across the uncrossed hand-hemifield conditions, from RT averaged across the crossed hand-hemifield conditions, one can obtain an estimate of IT time. Results. In schizophrenic patients the difference between crossed and uncrossed conditions was 0 because of an unusually prolonged RT in the uncrossed condition right hand/ right field. A broadly similar result has been obtained previously in the tactile modality (Ditchfield & Hemsley, 1990) and is consistent with a left hemisphere impairment. This effect was still present when the patients were retested about 2 years later. Conclusions. These results demonstrate the existence in schizophrenic patients of a consistent slowing down of simple visuomotor responses subserved by the left hemisphere.
-
Pathways of Interhemispheric Transfer in normals and in a split-brain subject. A positron emission tomography study.
Experimental brain research, 1999Co-Authors: Carlo Alberto Marzi, Daniela Perani, Giancarlo Tassinari, A. Colleluori, Angelo Maravita, Carlo Miniussi, Eraldo Paulesu, Paola Scifo, F. FazioAbstract:We studied with PET the intra- and Interhemispheric pathways subserving a simple, speeded-up visuomotor task. Six normal subjects and one patient with a complete section of the corpus callosum (M.E.) underwent regional cerebral blood flow (rCBF) measurements under conditions of lateralized tachistoscopic visual presentations in a simple manual reaction time paradigm. Confirming previous behavioural findings, we found that on average crossed hand and/or hemifield conditions, i.e. those requiring an Interhemispheric Transfer of information, yielded a longer RT than uncrossed conditions. This difference (0.7 ms) was dramatically larger (45.6 ms) in the callosum-sectioned patient M.E. In normal subjects the cortical areas selectively activated in uncrossed and crossed conditions were different. In the former condition, most activation foci were anterior to the ventral anterior commissure (VAC) plane, whereas in the latter there was a prevalent parietal and occipital activation. This shows that a simple model in which the cortical visuo-motor pathways are similar in the intra- and the Interhemispheric condition, with an extra callosal route for the latter, is too simplistic. Furthermore, these results suggest that the bulk of visuomotor Interhemispheric Transfer takes place through the widespread callosal fibres interconnecting the parietal cortices of the two hemispheres. The pattern of activation in the two crossing conditions was markedly different in M.E., in whom Interhemispheric Transfer might take place via his intact anterior commissure or subcortical commissures.
-
Transcranial magnetic stimulation selectively impairs Interhemispheric Transfer of visuo-motor information in humans
Experimental brain research, 1998Co-Authors: Carlo Alberto Marzi, Angelo Maravita, Carlo Miniussi, Laura Bertolasi, G.p. Zanette, Jc Rothwell, Jerome N. SanesAbstract:We investigated the cerebral cortical route by which visual information reaches motor cortex when visual signals are used for manual responses. Subjects responded unimanually to photic stimuli delivered to the hemifield ipsilateral or contralateral to the moving hand. On some trials, trans-cranial magnetic stimulation (TMS) was applied unilaterally over the occiput, with the aim of stimulating extrastriate visual areas and thereby modifying transmission of visual input. In association with the side of a visual stimulus and a motor response, TMS could change inter- or intra-hemispheric transmission needed to convey visual information to motor areas. Reaction time differences following TMS suggested that TMS exerted an inhibitory effect only when visuo-motor information had to be Transferred Interhemispherically. This result reinforces evidence for an extrastriate pathway of Interhemispheric Transfer of visuomotor information.
Jed A Meltzer - One of the best experts on this subject based on the ideXlab platform.
-
Interhemispheric Transfer of semantic information facilitates bilateral word recognition
Journal of Experimental Psychology: General, 2020Co-Authors: Ronald Chu, Steve Joordens, Jed A MeltzerAbstract:Language comprehension is left-lateralized but with variable contributions from the right hemisphere. When both hemispheres are stimulated simultaneously using divided visual field presentation, performance may be enhanced or hindered depending on the complexity of the task, and these effects may relate to independent processing in both hemispheres or to information Transfer between hemispheres. Simultaneous stimulation of both hemispheres is thought to suppress Interhemispheric interactions, but information Transfer may nonetheless occur. Studies with simultaneous bilateral displays have demonstrated that semantic information from the contralateral visual field (and hemisphere) can facilitate relatedness judgments and lexical decisions. The current study extends this line of research by assessing semantic information Transfer in a bilateral word identification task. Task manipulations involving directed spatial attention and asymmetric primes (e.g., ATOM → BOMB) were used to isolate automatic priming as opposed to top-down processing. The results revealed 2 main findings: (a) Interhemispheric priming in the form of improved word recognition occurred specifically in conditions designed to isolate automatic Transfer of semantic information, that is, in the attended visual field for the target word in asymmetric prime pairs, and (b) there is evidence for an asymmetrical Transfer of semantic information, in that the subordinate left visual field-right hemisphere benefited more from such Transfer. Together, these results demonstrate evidence for automatic Interhemispheric Transfer of semantic information, even under conditions of simultaneous bilateral display. (PsycInfo Database Record (c) 2020 APA, all rights reserved).