The Experts below are selected from a list of 5922 Experts worldwide ranked by ideXlab platform
Khader M. Hasan - One of the best experts on this subject based on the ideXlab platform.
-
decoding the Superior Parietal Lobule connections of the Superior longitudinal fasciculus arcuate fasciculus in the human brain
Neuroscience, 2014Co-Authors: Arash Kamali, Haris I. Sair, A. Radmanesh, Khader M. HasanAbstract:Abstract The temporo-Parietal (TP) white matter connections between the inferior Parietal Lobule and Superior temporal gyrus as part of the Superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) or middle longitudinal fasciculus (MdLF) have been studied in prior diffusion tensor tractography (DTT) studies. However, few studies have been focusing on the higher TP connections of the Superior Parietal Lobule with the temporal lobe. These higher TP connections have been shown to have a role in core processes such as attention, memory, emotions, and language. Our most recent study, for the first time, hinted to the possibility of a long white matter connection interconnecting the Superior Parietal Lobule (SPL) with the posterior temporal lobe in human brain which we call the SLF/AF TP-SPL and for a shorter abbreviation, the TP-SPL. We decided to further investigate this white matter connection using fiber assignment by continuous tracking deterministic tractography and high spatial resolution diffusion tensor imaging on 3T. Five healthy right-handed men (age range 24–37 years) were studied. We delineated the SPL connections of the SLF/AF TP bilaterally in five normal adult human brains. Using a high resolution DTT technique, we demonstrate for the first time, the trajectory of a long fiber bundle connectivity between the SPL and posterior temporal lobe, called the SLF/AF TP-SPL (or the TP-SPL), bilaterally in five healthy adult human brains. We also demonstrate the trajectory of the vertically oriented posterior TP connections, interconnecting the inferior Parietal Lobule (IPL) with the posterior temporal lobe (TP-IPL) in relation to the TP-SPL, arcuate fasciculus and other major language pathways. In the current study, for the first time, we categorized the TP connections into the anterior and posterior connectivity groups and subcategorized each one into the SPL or IPL connections.
-
Decoding the Superior Parietal Lobule connections of the Superior longitudinal fasciculus/arcuate fasciculus in the human brain.
Neuroscience, 2014Co-Authors: Arash Kamali, Haris I. Sair, A. Radmanesh, Khader M. HasanAbstract:Abstract The temporo-Parietal (TP) white matter connections between the inferior Parietal Lobule and Superior temporal gyrus as part of the Superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) or middle longitudinal fasciculus (MdLF) have been studied in prior diffusion tensor tractography (DTT) studies. However, few studies have been focusing on the higher TP connections of the Superior Parietal Lobule with the temporal lobe. These higher TP connections have been shown to have a role in core processes such as attention, memory, emotions, and language. Our most recent study, for the first time, hinted to the possibility of a long white matter connection interconnecting the Superior Parietal Lobule (SPL) with the posterior temporal lobe in human brain which we call the SLF/AF TP-SPL and for a shorter abbreviation, the TP-SPL. We decided to further investigate this white matter connection using fiber assignment by continuous tracking deterministic tractography and high spatial resolution diffusion tensor imaging on 3T. Five healthy right-handed men (age range 24–37 years) were studied. We delineated the SPL connections of the SLF/AF TP bilaterally in five normal adult human brains. Using a high resolution DTT technique, we demonstrate for the first time, the trajectory of a long fiber bundle connectivity between the SPL and posterior temporal lobe, called the SLF/AF TP-SPL (or the TP-SPL), bilaterally in five healthy adult human brains. We also demonstrate the trajectory of the vertically oriented posterior TP connections, interconnecting the inferior Parietal Lobule (IPL) with the posterior temporal lobe (TP-IPL) in relation to the TP-SPL, arcuate fasciculus and other major language pathways. In the current study, for the first time, we categorized the TP connections into the anterior and posterior connectivity groups and subcategorized each one into the SPL or IPL connections.
-
Tracing Superior longitudinal fasciculus connectivity in the human brain using high resolution diffusion tensor tractography.
Brain structure & function, 2013Co-Authors: Arash Kamali, Adam E. Flanders, Joshua Brody, Jill V. Hunter, Khader M. HasanAbstract:The major language pathways such as Superior longitudinal fasciculus (SLF) pathways have been outlined by experimental and diffusion tensor imaging (DTI) studies. The SLF I and some of the Superior Parietal Lobule connections of the SLF pathways have not been depicted by prior DTI studies due to the lack of imaging sensitivity and adequate spatial resolution. In the current study, the trajectory of the SLF fibers has been delineated on five healthy human subjects using diffusion tensor tractography on a 3.0-T scanner at high spatial resolution. We also demonstrate for the first time the trajectory and connectivity of the SLF fibers in relation to other language pathways as well as the Superior Parietal Lobule connections of the language circuit using high spatial resolution DTI in the healthy adult human brain.
Claudio Galletti - One of the best experts on this subject based on the ideXlab platform.
-
Structural connectivity and functional properties of the macaque Superior Parietal Lobule
Brain Structure and Function, 2019Co-Authors: Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Claudio GallettiAbstract:Despite the consolidated belief that the macaque Superior Parietal Lobule (SPL) is entirely occupied by Brodmann’s area 5, recent data show that macaque SPL also hosts a large cortical region with structural and functional features similar to that of Brodmann’s area 7. According to these data, the anterior part of SPL is occupied by a somatosensory-dominated cortical region that hosts three architectural and functional distinct regions (PE, PEci, PEip) and the caudal half of SPL by a bimodal somato-visual region that hosts four areas: PEc, MIP, PGm, V6A. To date, the most studied areas of SPL are PE, PEc, and V6A. PE is essentially a high-order somatomotor area, while PEc and V6A are bimodal somatomotor–visuomotor areas, the former with predominant somatosensory input and the latter with predominant visual input. The functional properties of these areas and their anatomical connectivity strongly suggest their involvement in the control of limb movements. PE is suggested to be involved in the preparation/execution of limb movements, in particular, the movements of the upper limb; PEc in the control of movements of both upper and lower limbs, as well as in their interaction with the visual environment; V6A in the control of reach-to-grasp movements performed with the upper limb. In humans, SPL is traditionally considered to have a different organization with respect to macaques. Here, we review several lines of evidence suggesting that this is not the case, showing a similar structure for human and non-human primate SPLs.
-
Receptor density pattern confirms and enhances the anatomic-functional features of the macaque Superior Parietal Lobule areas
Brain Structure and Function, 2019Co-Authors: Daniele Impieri, Claudio Galletti, Karl Zilles, Lucija Rapan, Nicole Schubert, Nicola Palomero-gallagherAbstract:The macaque monkey Superior Parietal Lobule (SPL) is part of a neuronal network involved in the integration of information from visual and somatosensory cortical areas for execution of reaching and grasping movements. We applied quantitative in vitro receptor autoradiography to analyse the distribution patterns of 15 different receptors for glutamate, GABA, acetylcholine, serotonin, dopamine, and adenosine in the SPL of three adult male Macaca fascicularis monkeys. For each area, mean (averaged over all cortical layers) receptor densities were visualized as a receptor fingerprint of that area. Multivariate analyses were conducted to detect clusters of areas according to the degree of (dis)similarity of their receptor organization. Differences in regional and laminar receptor distributions confirm the location and extent of areas V6, V6Av, V6Ad, PEc, PEci, and PGm as found in cytoarchitectonic and functional studies, but also enable the definition of three subdivisions within area PE. Receptor densities are higher in supra- than in infragranular layers, with the exception of kainate, M_2, and adenosine receptors. Glutamate and GABAergic receptors are the most expressed in all areas analysed. Hierarchical cluster analyses demonstrate that SPL areas are organized in two groups, an organization that corresponds to the visual or sensory-motor characteristics of those areas. Finally, based on present results and in the framework of our current understanding of the structural and functional organization of the primate SPL, we propose a novel pattern of homologies between human and macaque SPL areas.
-
Sensory properties of the caudal aspect of the macaque’s Superior Parietal Lobule
Brain Structure and Function, 2018Co-Authors: Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Rossella Breveglieri, Sofia Briganti, Claudio GallettiAbstract:In the Superior Parietal Lobule (SPL), the anterior part (area PE) is known to process somatosensory information, while the caudalmost part (areas V6Av and V6) processes visual information. Here we studied the visual and somatosensory properties of the areas PEc and V6Ad located in between the somatosensory and visual domains of SPL. About 1500 neurons were extracellularly recorded in 19 hemispheres of 12 monkeys ( Macaca fascicularis ). Visual and somatosensory properties of single neurons were generally studied separately, while in a subpopulation of neurons, both the sensory properties were tested. Visual neurons were more represented in V6Ad and somatosensory neurons in PEc. The visual neurons of these two areas showed similar properties and represented a large part of the contralateral visual field, mostly the lower part. In contrast, somatosensory neurons showed remarkable differences. The arms were overrepresented in both the areas, but V6Ad represented only the upper limbs, whereas PEc both the upper and lower limbs. Interestingly, we found that in both the areas, bimodal visual–somatosensory cells represented the proximal part of the arms. We suggest that PEc is involved in locomotion and in the control of hand/foot interaction with the objects of the environment, while V6Ad is in the control of the object prehension specifically performed with the upper limbs. Neuroimaging and lesion studies from literature support a strict homology with humans.
-
Thalamo-cortical projections to the macaque Superior Parietal Lobule areas PEc and PE.
The Journal of comparative neurology, 2018Co-Authors: Daniele Impieri, Michela Gamberini, Lauretta Passarelli, Marcello G. P. Rosa, Claudio GallettiAbstract:The exposed surface of the Superior Parietal Lobule in macaque brain contains two architectonically defined areas named PEc and PE. The aim of the present study is the characterization of thalamic afferents of these two areas. For this purpose, retrograde neuronal tracers were injected, or placed in crystal form, in areas PEc and PE. We found that the two areas show a similar pattern of thalamic inputs, mainly originating from Lateral Posterior (LP), Pulvinar (Pul), Ventral Posterior Lateral (VPL), and Ventral Lateral (VL) nuclei, all structures known to be involved in visual, somatosensory, and/or sensorimotor processing. Minor afferents were observed from the Centromedian/Parafascicular complex (CM/PF), Central Lateral (CL), Ventral Anterior (VA), and Medial Dorsal (MD) nuclei. LP and VL were more strongly connected to PEc than to PE, while the other main thalamic inputs to the two areas showed slight differences in strength. The part of the Pul mostly connected with areas PEc and PE was the Medial Pul. No labeled cells were found in the retinotopically organized Lateral and Inferior Pul. In the somatotopically organized VPL and VL nuclei, labeled neurons were mainly found in regions likely to correspond to the trunk and limb representations (in particular the legs). These findings are in line with the sensory-motor nature of areas PEc and PE, and with their putative functional roles, being them suggested to be involved in the preparation and control of limb interaction with the environment, and in locomotion.
-
sensory properties of the caudal aspect of the macaque s Superior Parietal Lobule
Brain Structure & Function, 2017Co-Authors: Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Rossella Breveglieri, Sofia Briganti, Claudio GallettiAbstract:In the Superior Parietal Lobule (SPL), the anterior part (area PE) is known to process somatosensory information, while the caudalmost part (areas V6Av and V6) processes visual information. Here we studied the visual and somatosensory properties of the areas PEc and V6Ad located in between the somatosensory and visual domains of SPL. About 1500 neurons were extracellularly recorded in 19 hemispheres of 12 monkeys (Macaca fascicularis). Visual and somatosensory properties of single neurons were generally studied separately, while in a subpopulation of neurons, both the sensory properties were tested. Visual neurons were more represented in V6Ad and somatosensory neurons in PEc. The visual neurons of these two areas showed similar properties and represented a large part of the contralateral visual field, mostly the lower part. In contrast, somatosensory neurons showed remarkable differences. The arms were overrepresented in both the areas, but V6Ad represented only the upper limbs, whereas PEc both the upper and lower limbs. Interestingly, we found that in both the areas, bimodal visual–somatosensory cells represented the proximal part of the arms. We suggest that PEc is involved in locomotion and in the control of hand/foot interaction with the objects of the environment, while V6Ad is in the control of the object prehension specifically performed with the upper limbs. Neuroimaging and lesion studies from literature support a strict homology with humans.
Arash Kamali - One of the best experts on this subject based on the ideXlab platform.
-
decoding the Superior Parietal Lobule connections of the Superior longitudinal fasciculus arcuate fasciculus in the human brain
Neuroscience, 2014Co-Authors: Arash Kamali, Haris I. Sair, A. Radmanesh, Khader M. HasanAbstract:Abstract The temporo-Parietal (TP) white matter connections between the inferior Parietal Lobule and Superior temporal gyrus as part of the Superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) or middle longitudinal fasciculus (MdLF) have been studied in prior diffusion tensor tractography (DTT) studies. However, few studies have been focusing on the higher TP connections of the Superior Parietal Lobule with the temporal lobe. These higher TP connections have been shown to have a role in core processes such as attention, memory, emotions, and language. Our most recent study, for the first time, hinted to the possibility of a long white matter connection interconnecting the Superior Parietal Lobule (SPL) with the posterior temporal lobe in human brain which we call the SLF/AF TP-SPL and for a shorter abbreviation, the TP-SPL. We decided to further investigate this white matter connection using fiber assignment by continuous tracking deterministic tractography and high spatial resolution diffusion tensor imaging on 3T. Five healthy right-handed men (age range 24–37 years) were studied. We delineated the SPL connections of the SLF/AF TP bilaterally in five normal adult human brains. Using a high resolution DTT technique, we demonstrate for the first time, the trajectory of a long fiber bundle connectivity between the SPL and posterior temporal lobe, called the SLF/AF TP-SPL (or the TP-SPL), bilaterally in five healthy adult human brains. We also demonstrate the trajectory of the vertically oriented posterior TP connections, interconnecting the inferior Parietal Lobule (IPL) with the posterior temporal lobe (TP-IPL) in relation to the TP-SPL, arcuate fasciculus and other major language pathways. In the current study, for the first time, we categorized the TP connections into the anterior and posterior connectivity groups and subcategorized each one into the SPL or IPL connections.
-
Decoding the Superior Parietal Lobule connections of the Superior longitudinal fasciculus/arcuate fasciculus in the human brain.
Neuroscience, 2014Co-Authors: Arash Kamali, Haris I. Sair, A. Radmanesh, Khader M. HasanAbstract:Abstract The temporo-Parietal (TP) white matter connections between the inferior Parietal Lobule and Superior temporal gyrus as part of the Superior longitudinal fasciculus/arcuate fasciculus (SLF/AF) or middle longitudinal fasciculus (MdLF) have been studied in prior diffusion tensor tractography (DTT) studies. However, few studies have been focusing on the higher TP connections of the Superior Parietal Lobule with the temporal lobe. These higher TP connections have been shown to have a role in core processes such as attention, memory, emotions, and language. Our most recent study, for the first time, hinted to the possibility of a long white matter connection interconnecting the Superior Parietal Lobule (SPL) with the posterior temporal lobe in human brain which we call the SLF/AF TP-SPL and for a shorter abbreviation, the TP-SPL. We decided to further investigate this white matter connection using fiber assignment by continuous tracking deterministic tractography and high spatial resolution diffusion tensor imaging on 3T. Five healthy right-handed men (age range 24–37 years) were studied. We delineated the SPL connections of the SLF/AF TP bilaterally in five normal adult human brains. Using a high resolution DTT technique, we demonstrate for the first time, the trajectory of a long fiber bundle connectivity between the SPL and posterior temporal lobe, called the SLF/AF TP-SPL (or the TP-SPL), bilaterally in five healthy adult human brains. We also demonstrate the trajectory of the vertically oriented posterior TP connections, interconnecting the inferior Parietal Lobule (IPL) with the posterior temporal lobe (TP-IPL) in relation to the TP-SPL, arcuate fasciculus and other major language pathways. In the current study, for the first time, we categorized the TP connections into the anterior and posterior connectivity groups and subcategorized each one into the SPL or IPL connections.
-
Tracing Superior longitudinal fasciculus connectivity in the human brain using high resolution diffusion tensor tractography.
Brain structure & function, 2013Co-Authors: Arash Kamali, Adam E. Flanders, Joshua Brody, Jill V. Hunter, Khader M. HasanAbstract:The major language pathways such as Superior longitudinal fasciculus (SLF) pathways have been outlined by experimental and diffusion tensor imaging (DTI) studies. The SLF I and some of the Superior Parietal Lobule connections of the SLF pathways have not been depicted by prior DTI studies due to the lack of imaging sensitivity and adequate spatial resolution. In the current study, the trajectory of the SLF fibers has been delineated on five healthy human subjects using diffusion tensor tractography on a 3.0-T scanner at high spatial resolution. We also demonstrate for the first time the trajectory and connectivity of the SLF fibers in relation to other language pathways as well as the Superior Parietal Lobule connections of the language circuit using high spatial resolution DTI in the healthy adult human brain.
Patrizia Fattori - One of the best experts on this subject based on the ideXlab platform.
-
Structural connectivity and functional properties of the macaque Superior Parietal Lobule
Brain Structure and Function, 2019Co-Authors: Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Claudio GallettiAbstract:Despite the consolidated belief that the macaque Superior Parietal Lobule (SPL) is entirely occupied by Brodmann’s area 5, recent data show that macaque SPL also hosts a large cortical region with structural and functional features similar to that of Brodmann’s area 7. According to these data, the anterior part of SPL is occupied by a somatosensory-dominated cortical region that hosts three architectural and functional distinct regions (PE, PEci, PEip) and the caudal half of SPL by a bimodal somato-visual region that hosts four areas: PEc, MIP, PGm, V6A. To date, the most studied areas of SPL are PE, PEc, and V6A. PE is essentially a high-order somatomotor area, while PEc and V6A are bimodal somatomotor–visuomotor areas, the former with predominant somatosensory input and the latter with predominant visual input. The functional properties of these areas and their anatomical connectivity strongly suggest their involvement in the control of limb movements. PE is suggested to be involved in the preparation/execution of limb movements, in particular, the movements of the upper limb; PEc in the control of movements of both upper and lower limbs, as well as in their interaction with the visual environment; V6A in the control of reach-to-grasp movements performed with the upper limb. In humans, SPL is traditionally considered to have a different organization with respect to macaques. Here, we review several lines of evidence suggesting that this is not the case, showing a similar structure for human and non-human primate SPLs.
-
Sensory properties of the caudal aspect of the macaque’s Superior Parietal Lobule
Brain Structure and Function, 2018Co-Authors: Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Rossella Breveglieri, Sofia Briganti, Claudio GallettiAbstract:In the Superior Parietal Lobule (SPL), the anterior part (area PE) is known to process somatosensory information, while the caudalmost part (areas V6Av and V6) processes visual information. Here we studied the visual and somatosensory properties of the areas PEc and V6Ad located in between the somatosensory and visual domains of SPL. About 1500 neurons were extracellularly recorded in 19 hemispheres of 12 monkeys ( Macaca fascicularis ). Visual and somatosensory properties of single neurons were generally studied separately, while in a subpopulation of neurons, both the sensory properties were tested. Visual neurons were more represented in V6Ad and somatosensory neurons in PEc. The visual neurons of these two areas showed similar properties and represented a large part of the contralateral visual field, mostly the lower part. In contrast, somatosensory neurons showed remarkable differences. The arms were overrepresented in both the areas, but V6Ad represented only the upper limbs, whereas PEc both the upper and lower limbs. Interestingly, we found that in both the areas, bimodal visual–somatosensory cells represented the proximal part of the arms. We suggest that PEc is involved in locomotion and in the control of hand/foot interaction with the objects of the environment, while V6Ad is in the control of the object prehension specifically performed with the upper limbs. Neuroimaging and lesion studies from literature support a strict homology with humans.
-
sensory properties of the caudal aspect of the macaque s Superior Parietal Lobule
Brain Structure & Function, 2017Co-Authors: Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Rossella Breveglieri, Sofia Briganti, Claudio GallettiAbstract:In the Superior Parietal Lobule (SPL), the anterior part (area PE) is known to process somatosensory information, while the caudalmost part (areas V6Av and V6) processes visual information. Here we studied the visual and somatosensory properties of the areas PEc and V6Ad located in between the somatosensory and visual domains of SPL. About 1500 neurons were extracellularly recorded in 19 hemispheres of 12 monkeys (Macaca fascicularis). Visual and somatosensory properties of single neurons were generally studied separately, while in a subpopulation of neurons, both the sensory properties were tested. Visual neurons were more represented in V6Ad and somatosensory neurons in PEc. The visual neurons of these two areas showed similar properties and represented a large part of the contralateral visual field, mostly the lower part. In contrast, somatosensory neurons showed remarkable differences. The arms were overrepresented in both the areas, but V6Ad represented only the upper limbs, whereas PEc both the upper and lower limbs. Interestingly, we found that in both the areas, bimodal visual–somatosensory cells represented the proximal part of the arms. We suggest that PEc is involved in locomotion and in the control of hand/foot interaction with the objects of the environment, while V6Ad is in the control of the object prehension specifically performed with the upper limbs. Neuroimaging and lesion studies from literature support a strict homology with humans.
-
Overlapping representations for reach depth and direction in caudal Superior Parietal Lobule of macaques.
Journal of neurophysiology, 2015Co-Authors: Kostas Hadjidimitrakis, Rossella Breveglieri, Claudio Galletti, Giulia Dal Bo, Patrizia FattoriAbstract:Reaching movements in the real world have typically a direction and a depth component. Despite numerous behavioral studies, there is no consensus on whether reach coordinates are processed in separate or common visuomotor channels. Furthermore, the neural substrates of reach depth in Parietal cortex have been ignored in most neurophysiological studies. In the medial posterior Parietal area V6A, we recently demonstrated the strong presence of depth signals and the extensive convergence of depth and direction information on single neurons during all phases of a fixate-to-reach task in 3-dimensional (3D) space. Using the same task, in the present work we examined the processing of direction and depth information in area PEc of the caudal Superior Parietal Lobule (SPL) in three Macaca fascicularis monkeys. Across the task, depth and direction had a similar, high incidence of modulatory effect. The effect of direction was stronger than depth during the initial fixation period. As the task progressed toward arm movement execution, depth tuning became more prominent than directional tuning and the number of cells modulated by both depth and direction increased significantly. Neurons tuned by depth showed a small bias for far peripersonal space. Cells with directional modulations were more frequently tuned toward contralateral spatial locations, but ipsilateral space was also represented. These findings, combined with results from neighboring areas V6A and PE, support a rostral-to-caudal gradient of overlapping representations for reach depth and direction in SPL. These findings also support a progressive change from visuospatial (vergence angle) to somatomotor representations of 3D space in SPL.
-
Cortical Connections of Parietal Field PEc in the Macaque: Linking Vision and Somatic Sensation for the Control of Limb Action
Cerebral cortex (New York N.Y. : 1991), 2010Co-Authors: Sophia Bakola, Michela Gamberini, Lauretta Passarelli, Patrizia Fattori, Claudio GallettiAbstract:The cortical projections to the caudal part of the Superior Parietal Lobule (area PEc) were studied in 6 cynomolgus monkeys using fluorescence tracers. Significant numbers of labeled cells were found in a restricted network of Parietal, mesial, and frontal areas. Quantitative analysis demonstrated that approximately 30% of the total projection neurons originated in the adjacent areas of the dorsocaudal part of the Superior Parietal Lobule (areas PE and V6A). The medial bank of the intraParietal sulcus, inferior Parietal Lobule, and frontal lobe (mainly the dorsocaudal part of premotor area F2) each contributed approximately 15% of the projection neurons. About 15% of the labeled neurons were located in the posterior cingulate area (PEci) and another 10% in other areas of the mesial surface of the hemisphere. Based on these data, we suggest that PEc processes information about the position of the limbs. The specific anatomical links between PEc and motor and premotor areas that host a representation of the lower limbs, together with the link with vestibular cortex and with areas involved in the analysis of optic flow and spatial navigation, imply a role for PEc in locomotion and coordinated limb movement in the environment.
Norihiro Sadato - One of the best experts on this subject based on the ideXlab platform.
-
Brain networks involved in tactile speed classification of moving dot patterns: the effects of speed and dot periodicity.
Scientific reports, 2017Co-Authors: Jiajia Yang, Takanori Kochiyama, Ryo Kitada, Kai Makita, Yuta Araki, Norihiro SadatoAbstract:Humans are able to judge the speed of an object’s motion by touch. Research has suggested that tactile judgment of speed is influenced by physical properties of the moving object, though the neural mechanisms underlying this process remain poorly understood. In the present study, functional magnetic resonance imaging was used to investigate brain networks that may be involved in tactile speed classification and how such networks may be affected by an object’s texture. Participants were asked to classify the speed of 2-D raised dot patterns passing under their right middle finger. Activity in the Parietal operculum, insula, and inferior and Superior frontal gyri was positively related to the motion speed of dot patterns. Activity in the postcentral gyrus and Superior Parietal Lobule was sensitive to dot periodicity. Psycho-physiological interaction (PPI) analysis revealed that dot periodicity modulated functional connectivity between the Parietal operculum (related to speed) and postcentral gyrus (related to dot periodicity). These results suggest that texture-sensitive activity in the primary somatosensory cortex and Superior Parietal Lobule influences brain networks associated with tactually-extracted motion speed. Such effects may be related to the influence of surface texture on tactile speed judgment.
-
The neural substrates associated with attentional resources and difficulty of concurrent processing of the two verbal tasks
Neuropsychologia, 2012Co-Authors: Kei Mizuno, Hiroki C. Tanabe, Norihiro Sadato, Masaaki Tanaka, Yasuyoshi WatanabeAbstract:The kana pick-out test has been widely used in Japan to evaluate the ability to divide attention in both adult and pediatric patients. However, the neural substrates underlying the ability to divide attention using the kana pick-out test, which requires participants to pick out individual letters (vowels) in a story while also reading for comprehension, thus requiring simultaneous allocation of attention to both activities, are still unclear. Moreover, outside of the clinical area, neuroimaging studies focused on the mechanisms of divided attention during complex story comprehension are rare. Thus, the purpose of the present study, to clarify the neural substrates of kana pick-out test, improves our current understanding of the basic neural mechanisms of dual task performance in verbal memory function. We compared patterns of activation in the brain obtained during performance of the individual tasks of vowel identification and story comprehension, to levels of activation when participants performed the two tasks simultaneously during the kana pick-out test. We found that activations of the left dorsal inferior frontal gyrus and Superior Parietal Lobule increase in functional connectivity to a greater extent during the dual task condition compared to the two single task conditions. In contrast, activations of the left fusiform gyrus and middle temporal gyrus, which are significantly involved in picking out letters and complex sentences during story comprehension, respectively, were reduced in the dual task condition compared to during the two single task conditions. These results suggest that increased activations of the dorsal inferior frontal gyrus and Superior Parietal Lobule during dual task performance may be associated with the capacity for attentional resources, and reduced activations of the left fusiform gyrus and middle temporal gyrus may reflect the difficulty of concurrent processing of the two tasks. In addition, the increase in synchronization between the left dorsal inferior frontal gyrus and Superior Parietal Lobule in the dual task condition may induce effective communication between these brain regions and contribute to more attentional processing than in the single task condition, due to greater and more complex demands on voluntary attentional resources.
-
Tactile–visual integration in the posterior Parietal cortex: A functional magnetic resonance imaging study
Brain research bulletin, 2007Co-Authors: Satoru Nakashita, Daisuke N. Saito, Takanori Kochiyama, Manabu Honda, Hiroki C. Tanabe, Norihiro SadatoAbstract:To explore the neural substrates of visual-tactile crossmodal integration during motion direction discrimination, we conducted functional magnetic resonance imaging with 15 subjects. We initially performed independent unimodal visual and tactile experiments involving motion direction matching tasks. Visual motion discrimination activated the occipital cortex bilaterally, extending to the posterior portion of the Superior Parietal Lobule, and the dorsal and ventral premotor cortex. Tactile motion direction discrimination activated the bilateral parieto-premotor cortices. The left Superior Parietal Lobule, intraParietal sulcus, bilateral premotor cortices and right cerebellum were activated during both visual and tactile motion discrimination. Tactile discrimination deactivated the visual cortex including the middle temporal/V5 area. To identify the crossmodal interference of the neural activities in both the unimodal and the multimodal areas, tactile and visual crossmodal experiments with event-related designs were also performed by the same subjects who performed crossmodal tactile-visual tasks or intramodal tactile-tactile and visual-visual matching tasks within the same session. The activities detected during intramodal tasks in the visual regions (including the middle temporal/V5 area) and the tactile regions were suppressed during crossmodal conditions compared with intramodal conditions. Within the polymodal areas, the left Superior Parietal Lobule and the premotor areas were activated by crossmodal tasks. The left Superior Parietal Lobule was more prominently activated under congruent event conditions than under incongruent conditions. These findings suggest that a reciprocal and competitive association between the unimodal and polymodal areas underlies the interaction between motion direction-related signals received simultaneously from different sensory modalities.
