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Patrizia Fattori - One of the best experts on this subject based on the ideXlab platform.
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neural coding of action in three dimensions task and time invariant reference frames for visuospatial and motor related activity in Parietal Area v6a
The Journal of Comparative Neurology, 2020Co-Authors: Rossella Breveglieri, Kostas Hadjidimitrakis, Masoud Ghodrati, Marcello G P Rosa, Patrizia FattoriAbstract:Goal-directed movements involve a series of neural computations that compare the sensory representations of goal location and effector position, and transform these into motor commands. Neurons in posterior Parietal cortex (PPC) control several effectors (e.g., eye, hand, foot) and encode goal location in a variety of spatial coordinate systems, including those anchored to gaze direction, and to the positions of the head, shoulder, or hand. However, there is little evidence on whether reference frames depend also on the effector and/or type of motor response. We addressed this issue in macaque PPC Area V6A, where previous reports using a fixate-to-reach in depth task, from different starting arm positions, indicated that most units use mixed body/hand-centered coordinates. Here, we applied singular value decomposition and gradient analyses to characterize the reference frames in V6A while the animals, instead of arm reaching, performed a nonspatial motor response (hand lift). We found that most neurons used mixed body/hand coordinates, instead of "pure" body-, or hand-centered coordinates. During the task progress the effect of hand position on activity became stronger compared to target location. Activity consistent with body-centered coding was present only in a subset of neurons active early in the task. Applying the same analyses to a population of V6A neurons recorded during the fixate-to-reach task yielded similar results. These findings suggest that V6A neurons use consistent reference frames between spatial and nonspatial motor responses, a functional property that may allow the integration of spatial awareness and movement control.
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Preparatory activity for purposeful arm movements in the dorsomedial Parietal Area V6A: Beyond the online guidance of movement
Scientific Reports, 2018Co-Authors: Elisa Santandrea, Annalisa Bosco, Rossella Breveglieri, Claudio Galletti, Patrizia FattoriAbstract:Over the years, electrophysiological recordings in macaque monkeys performing visuomotor tasks brought about accumulating evidence for the expression of neuronal properties (e.g., selectivity in the visuospatial and somatosensory domains, encoding of visual affordances and motor cues) in the posterior Parietal Area V6A that characterize it as an ideal neural substrate for online control of prehension. Interestingly, neuroimaging studies suggested a role of putative human V6A also in action preparation; moreover, pre-movement population activity in monkey V6A has been recently shown to convey grip-related information for upcoming grasping. Here we directly test whether macaque V6A neurons encode preparatory signals that effectively differentiate between dissimilar actions before movement. We recorded the activity of single V6A neurons during execution of two visuomotor tasks requiring either reach-to-press or reach-to-grasp movements in different background conditions, and described the nature and temporal dynamics of V6A activity preceding movement execution. We found striking consistency in neural discharges measured during pre-movement and movement epochs, suggesting that the former is a preparatory activity exquisitely linked to the subsequent execution of particular motor actions. These findings strongly support a role of V6A beyond the online guidance of movement, with preparatory activity implementing suitable motor programs that subsequently support action execution.
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Neural activity in the medial Parietal Area V6A while grasping with or without visual feedback
Scientific Reports, 2016Co-Authors: Rossella Breveglieri, Annalisa Bosco, Claudio Galletti, Lauretta Passarelli, Patrizia FattoriAbstract:Recent works have reported that grasping movements are controlled not only by the dorsolateral visual stream, as generally thought, but also by the dorsomedial visual stream, and in particular by the medial posterior Parietal Area V6A. To date, the grasping activity of V6A neurons has been studied only in darkness. Here we studied the effect of visual feedback on grasp-related discharges of V6A neurons while the monkey was preparing and executing the grasping of a handle. We found that V6A grasping activity could be excited or inhibited by visual information. The neural population was divided into Visual, Motor, and Visuomotor cells. The majority of Visual and Visuomotor neurons did not respond to passive observation of the handle, suggesting that vision of action, rather than object vision, is the most effective factor. The present findings highlight the role of the dorsomedial visual stream in integrating visual and motor signals to monitor and correct grasping.
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mixed body hand reference frame for reaching in 3d space in macaque Parietal Area pec
Cerebral Cortex, 2016Co-Authors: Valentina Piserchia, Rossella Breveglieri, Claudio Galletti, Kostas Hadjidimitrakis, Federica Bertozzi, Patrizia FattoriAbstract:The neural correlates of coordinate transformations from vision to action are expressed in the activity of posterior Parietal cortex (PPC). It has been demonstrated that among the medial-most Areas of the PPC, reaching targets are represented mainly in hand-centered coordinates in Area PE, and in eye-centered, body-centered, and mixed body/hand-centered coordinates in Area V6A. Here, we assessed whether neurons of Area PEc, located between V6A and PE in the medial PPC, encode targets in body-centered, hand-centered, or mixed frame of reference during planning and execution of reaching. We studied 104 PEc cells in 3 Macaca fascicularis. The animals performed a reaching task toward foveated targets located at different depths and directions in darkness, starting with the hand from 2 positions located at different depths, one next to the trunk and the other far from it. We show that most PEc neurons encoded targets in a mixed body/hand-centered frame of reference. Although the effect of hand position was often rather strong, it was not as strong as reported previously in Area PE. Our results suggest that Area PEc represents an intermediate node in the gradual transformation from vision to action that takes place in the reaching network of the dorsomedial PPC.
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Multiple Representation of Reaching Space in the Medial Posterior Parietal Area V6A
Cerebral Cortex, 2014Co-Authors: Annalisa Bosco, Rossella Breveglieri, David H. Reser, Claudio Galletti, Patrizia FattoriAbstract:During foveal reaching, the activity of neurons in the macaque medial posterior Parietal Area V6A is modulated by both gaze and arm direction. In the present work, we dissociated the position of gaze and reaching targets, and studied the neural activity of single V6A cells while the eyes and reaching targets were arranged in different spatial configurations (peripheral and foveal combinations). Target position influenced neural activity in all stages of the task, from visual presentation of target and movement planning, through reach execution and holding time. The majority of neurons preferred reaches directed toward peripheral targets, rather than foveal. Most neurons discharged in both premovement and action epochs. In most cases, reaching activity was tuned coherently across action planning and execution. When reaches were planned and executed in different eye/target configurations, multiple analyses revealed that few neurons coded reaching actions according to the absolute position of target, or to the position of target relative to the eye. The majority of cells responded to a combination of both these factors. These data suggest that V6A contains multiple representations of spatial information for reaching, consistent with a role of this Area in forming cross-reference frame representations to be used by premotor cortex.
Matthew V Chafee - One of the best experts on this subject based on the ideXlab platform.
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Participation of primary motor cortical neurons in a distributed network during maze solution: representation of spatial parameters and time-course comparison with Parietal Area 7a.
Experimental Brain Research, 2004Co-Authors: David A. Crowe, Matthew V Chafee, Bruno B. Averbeck, Apostolos P. GeorgopoulosAbstract:Traditionally, primary motor cortex (M1) has been thought to be involved solely in planning and generating movements. Recent evidence suggests that the arm Area of M1 plays a role in other functions, such as the representation of serial order (Pellizzer et al. 1995, Science 269:702–705; Carpenter et al. 1999, Science 283:1752–1757) and spatial processing (Georgopoulos et al. 1989, Science 243:234–236). Previous studies of such cognitive processes have used tasks in which a directed arm movement was required, raising a question as to whether this brain Area is involved in cognitive processing per se, or whether such cognitive signals may be gated into the arm Area of M1 only when arm movements are required. To study this question, we developed a task that required a spatial analysis of a complex visual stimulus, but required no arm movement as a response. In this task, monkeys were shown an octagonal maze. After an imposed delay of 2 to 2.5 s, they indicated whether a path that emanated from the center of the maze exited at the perimeter (exit maze) or terminated within the maze (no-exit maze) by pressing a pedal with their left or right foot, respectively. We recorded from 785 cells from the arm Area of M1 from two monkeys during the delay period of the maze task. We found that cell activity was influenced by both the exit status and the direction of the path, beginning soon after the maze was displayed. This activity was not related to the activation of arm muscles, suggesting that the directional signals observed represented abstract spatial aspects of maze processing. Finally, we compared maze-related activity of M1 neurons with those recorded from posterior Parietal Area 7a, reported previously (Crowe et al. 2004). Interestingly, cells from each Area exhibited similar properties. Both the exit status and path direction were encoded by cells in M1 and 7a, although to different extents. An analysis of the time-course of the neural representation of these factors revealed that Area 7a and M1 begin to encode these factors at the same time, suggesting these brain Areas are part of a distributed system performing the spatial computations involved in maze solution.
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neural activity in primate Parietal Area 7a related to spatial analysis of visual mazes
Cerebral Cortex, 2004Co-Authors: David A. Crowe, Matthew V Chafee, Bruno B. Averbeck, Apostolos P. GeorgopoulosAbstract:Cognitive psychological studies of humans and monkeys solving visual mazes have provided evidence that a covert analysis of the maze takes place during periods of eye fixation interspersed between saccades, or when mazes are solved without eye movements. We investigated the neural basis of this process in posterior Parietal cortex by recording the activity of single neurons in Area 7a during maze solution. Monkeys were required to determine from a single point of fixation whether a critical path through the maze reached an exit or a blind ending. We found that during this process the activity of approximately one in four neurons in Area 7a was spatially tuned to maze path direction. We obtained evidence that path tuning did not reflect a covert saccade plan insofar as the majority of neurons active during maze solution were not active on a delayed-saccade control task, and the minority that were active on both tasks did not exhibit congruent spatial tuning in the two conditions. We also obtained evidence that path tuning during maze solution was not due to the locations of visual receptive fields mapped outside the behavioral context of maze solution, in that receptive field centers and preferred path directions were not spatially aligned. Finally, neurons tuned to path direction were not present in Area 7a when a naive animal viewed the same visual maze stimuli but did not solve them. These data support the hypothesis that path tuning in Parietal cortex is not due to the lower level visual features of the maze stimulus, but rather is associated with maze solution, and as such, reflects a cognitive process applied to a complex visual stimulus.
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matching patterns of activity in primate prefrontal Area 8a and Parietal Area 7ip neurons during a spatial working memory task
Journal of Neurophysiology, 1998Co-Authors: Matthew V Chafee, Patricia S GoldmanrakicAbstract:Chafee, Matthew V. and Patricia S. Goldman-Rakic. Matching patterns of activity in primate prefrontal Area 8a and Parietal Area 7ip neurons during a spatial working memory task. J. Neurophysiol. 79...
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Matching patterns of activity in primate prefrontal Area 8a and Parietal Area 7ip neurons during a spatial working memory task
Journal of neurophysiology, 1998Co-Authors: Matthew V Chafee, Patricia S. Goldman-rakicAbstract:Single-unit recording studies of posterior Parietal neurons have indicated a similarity of neuronal activation to that observed in the dorsolateral prefrontal cortex in relation to performance of delayed saccade tasks. A key issue addressed in the present study is whether the different classes of neuronal activity observed in these tasks are encountered more frequently in one or the other Area or otherwise exhibit region-specific properties. The present study is the first to directly compare these patterns of neuronal activity by alternately recording from Parietal Area 7ip and prefrontal Area 8a, under the identical behavioral conditions, within the same hemisphere of two monkeys performing an oculomotor delayed response task. The firing rate of 222 posterior Parietal and 235 prefrontal neurons significantly changed during the cue, delay, and/or saccade periods of the task. Neuronal responses in the two Areas could be distinguished only by subtle differences in their incidence and timing. Thus neurons responding to the cue appeared earliest and were more frequent among the task-related neurons within Parietal cortex, whereas neurons exhibiting delay-period activity accounted for a larger proportion of task-related neurons in prefrontal cortex. Otherwise, the task-related neuronal activities were remarkably similar. Cue period activity in prefrontal and Parietal cortex exhibited comparable spatial tuning and temporal duration characteristics, taking the form of phasic, tonic, or combined phasic/tonic excitation in both cortical populations. Neurons in both cortical Areas exhibited sustained activity during the delay period with nearly identical spatial tuning. The various patterns of delay-period activity-tonic, increasing or decreasing, alone or in combination with greater activation during cue and/or saccade periods-likewise were distributed to both cortical Areas. Finally, similarities in the two populations extended to the proportion and spatial tuning of presaccadic and postsaccadic neuronal activity occurring in relation to the memory-guided saccade. The present findings support and extend evidence for a faithful duplication of receptive field properties and virtually every other dimension of task-related activity observed when Parietal and prefrontal cortex are recruited to a common task. This striking similarity attests to the principal that information shared by a prefrontal region and a sensory association Area with which it is connected is domain specific and not subject to hierarchical elaboration, as is evident at earlier stages of visuospatial processing.
Kenneth H. Britten - One of the best experts on this subject based on the ideXlab platform.
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Parietal Area vip causally influences heading perception during pursuit eye movements
The Journal of Neuroscience, 2011Co-Authors: Tao Zhang, Kenneth H. BrittenAbstract:The ventral intraParietal Area (VIP) of the macaque monkey brain is a multimodal Area with visual, vestibular, somatosensory, and eye movement-related responses. The visual responses are strongly directional, and VIP neurons respond well to complex optic flow patterns similar to those found during self-motion. To test the hypothesis that visual responses in VIP directly contribute to the perception of self-motion direction, we used electrical microstimulation to perturb activity in VIP while animals performed a two-alternative heading discrimination task. Microstimulation systematically biased monkeys' choices in a direction consistent with neuronal preferences at the stimulation site, and these effects were larger while the animal was making smooth pursuit eye movements. From these results, we conclude that VIP is causally involved in the perception of self-motion from visual cues and that this involvement is gated by ongoing motor behavior.
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extrastriate Area mst and Parietal Area vip similarly represent forward headings
Journal of Neurophysiology, 2010Co-Authors: James B Maciokas, Kenneth H. BrittenAbstract:Many studies have documented the involvement of medial superior temporal extrastriate Area (MST) in the perception of heading based on optic flow information. Furthermore, both heading perception and the responses of MST neurons are relatively stable in the presence of eye movements that distort the retinal flow information on which perception is based. Area VIP in the posterior Parietal cortex also contains a robust representation of optic flow cues for heading. However, the studies in the two Areas were frequently conducted using different stimuli, making quantitative comparison difficult. To remedy this, we studied MST using a family of random dot heading stimuli that we have previously used in the study of VIP. These stimuli simulate observer translation through a three-dimensional cloud of points, and a range of forward headings was presented both with and without horizontal smooth pursuit eye movements. We found that MST neurons, like VIP neurons, respond robustly to these stimuli and partially compensate for the presence of pursuit. Quantitative comparison of the responses revealed no substantial difference between the heading responses of MST and VIP neurons or in their degree of pursuit tolerance.
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Parietal Area VIP Neuronal Responses to Heading Stimuli Are Encoded in Head-Centered Coordinates
Neuron, 2004Co-Authors: Tao Zhang, Hilary W. Heuer, Kenneth H. BrittenAbstract:The ventral intraParietal Area (VIP) is a multimodal Parietal Area, where visual responses are brisk, directional, and typically selective for complex optic flow patterns. VIP thus could provide signals useful for visual estimation of heading (self-motion direction). A central problem in heading estimation is how observers compensate for eye velocity, which distorts the retinal motion cues upon which perception depends. To find out if VIP could be useful for heading, we measured its responses to simulated trajectories, both with and without eye movements. Our results showed that most VIP neurons very strongly signal heading direction. Furthermore, the tuning of most VIP neurons was remarkably stable in the presence of eye movements. This stability was such that the population of VIP neurons represented heading very nearly in head-centered coordinates. This makes VIP the most robust source of such signals yet described, with properties ideal for supporting perception.
Rossella Breveglieri - One of the best experts on this subject based on the ideXlab platform.
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neural coding of action in three dimensions task and time invariant reference frames for visuospatial and motor related activity in Parietal Area v6a
The Journal of Comparative Neurology, 2020Co-Authors: Rossella Breveglieri, Kostas Hadjidimitrakis, Masoud Ghodrati, Marcello G P Rosa, Patrizia FattoriAbstract:Goal-directed movements involve a series of neural computations that compare the sensory representations of goal location and effector position, and transform these into motor commands. Neurons in posterior Parietal cortex (PPC) control several effectors (e.g., eye, hand, foot) and encode goal location in a variety of spatial coordinate systems, including those anchored to gaze direction, and to the positions of the head, shoulder, or hand. However, there is little evidence on whether reference frames depend also on the effector and/or type of motor response. We addressed this issue in macaque PPC Area V6A, where previous reports using a fixate-to-reach in depth task, from different starting arm positions, indicated that most units use mixed body/hand-centered coordinates. Here, we applied singular value decomposition and gradient analyses to characterize the reference frames in V6A while the animals, instead of arm reaching, performed a nonspatial motor response (hand lift). We found that most neurons used mixed body/hand coordinates, instead of "pure" body-, or hand-centered coordinates. During the task progress the effect of hand position on activity became stronger compared to target location. Activity consistent with body-centered coding was present only in a subset of neurons active early in the task. Applying the same analyses to a population of V6A neurons recorded during the fixate-to-reach task yielded similar results. These findings suggest that V6A neurons use consistent reference frames between spatial and nonspatial motor responses, a functional property that may allow the integration of spatial awareness and movement control.
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Preparatory activity for purposeful arm movements in the dorsomedial Parietal Area V6A: Beyond the online guidance of movement
Scientific Reports, 2018Co-Authors: Elisa Santandrea, Annalisa Bosco, Rossella Breveglieri, Claudio Galletti, Patrizia FattoriAbstract:Over the years, electrophysiological recordings in macaque monkeys performing visuomotor tasks brought about accumulating evidence for the expression of neuronal properties (e.g., selectivity in the visuospatial and somatosensory domains, encoding of visual affordances and motor cues) in the posterior Parietal Area V6A that characterize it as an ideal neural substrate for online control of prehension. Interestingly, neuroimaging studies suggested a role of putative human V6A also in action preparation; moreover, pre-movement population activity in monkey V6A has been recently shown to convey grip-related information for upcoming grasping. Here we directly test whether macaque V6A neurons encode preparatory signals that effectively differentiate between dissimilar actions before movement. We recorded the activity of single V6A neurons during execution of two visuomotor tasks requiring either reach-to-press or reach-to-grasp movements in different background conditions, and described the nature and temporal dynamics of V6A activity preceding movement execution. We found striking consistency in neural discharges measured during pre-movement and movement epochs, suggesting that the former is a preparatory activity exquisitely linked to the subsequent execution of particular motor actions. These findings strongly support a role of V6A beyond the online guidance of movement, with preparatory activity implementing suitable motor programs that subsequently support action execution.
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Neural activity in the medial Parietal Area V6A while grasping with or without visual feedback
Scientific Reports, 2016Co-Authors: Rossella Breveglieri, Annalisa Bosco, Claudio Galletti, Lauretta Passarelli, Patrizia FattoriAbstract:Recent works have reported that grasping movements are controlled not only by the dorsolateral visual stream, as generally thought, but also by the dorsomedial visual stream, and in particular by the medial posterior Parietal Area V6A. To date, the grasping activity of V6A neurons has been studied only in darkness. Here we studied the effect of visual feedback on grasp-related discharges of V6A neurons while the monkey was preparing and executing the grasping of a handle. We found that V6A grasping activity could be excited or inhibited by visual information. The neural population was divided into Visual, Motor, and Visuomotor cells. The majority of Visual and Visuomotor neurons did not respond to passive observation of the handle, suggesting that vision of action, rather than object vision, is the most effective factor. The present findings highlight the role of the dorsomedial visual stream in integrating visual and motor signals to monitor and correct grasping.
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mixed body hand reference frame for reaching in 3d space in macaque Parietal Area pec
Cerebral Cortex, 2016Co-Authors: Valentina Piserchia, Rossella Breveglieri, Claudio Galletti, Kostas Hadjidimitrakis, Federica Bertozzi, Patrizia FattoriAbstract:The neural correlates of coordinate transformations from vision to action are expressed in the activity of posterior Parietal cortex (PPC). It has been demonstrated that among the medial-most Areas of the PPC, reaching targets are represented mainly in hand-centered coordinates in Area PE, and in eye-centered, body-centered, and mixed body/hand-centered coordinates in Area V6A. Here, we assessed whether neurons of Area PEc, located between V6A and PE in the medial PPC, encode targets in body-centered, hand-centered, or mixed frame of reference during planning and execution of reaching. We studied 104 PEc cells in 3 Macaca fascicularis. The animals performed a reaching task toward foveated targets located at different depths and directions in darkness, starting with the hand from 2 positions located at different depths, one next to the trunk and the other far from it. We show that most PEc neurons encoded targets in a mixed body/hand-centered frame of reference. Although the effect of hand position was often rather strong, it was not as strong as reported previously in Area PE. Our results suggest that Area PEc represents an intermediate node in the gradual transformation from vision to action that takes place in the reaching network of the dorsomedial PPC.
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Multiple Representation of Reaching Space in the Medial Posterior Parietal Area V6A
Cerebral Cortex, 2014Co-Authors: Annalisa Bosco, Rossella Breveglieri, David H. Reser, Claudio Galletti, Patrizia FattoriAbstract:During foveal reaching, the activity of neurons in the macaque medial posterior Parietal Area V6A is modulated by both gaze and arm direction. In the present work, we dissociated the position of gaze and reaching targets, and studied the neural activity of single V6A cells while the eyes and reaching targets were arranged in different spatial configurations (peripheral and foveal combinations). Target position influenced neural activity in all stages of the task, from visual presentation of target and movement planning, through reach execution and holding time. The majority of neurons preferred reaches directed toward peripheral targets, rather than foveal. Most neurons discharged in both premovement and action epochs. In most cases, reaching activity was tuned coherently across action planning and execution. When reaches were planned and executed in different eye/target configurations, multiple analyses revealed that few neurons coded reaching actions according to the absolute position of target, or to the position of target relative to the eye. The majority of cells responded to a combination of both these factors. These data suggest that V6A contains multiple representations of spatial information for reaching, consistent with a role of this Area in forming cross-reference frame representations to be used by premotor cortex.
Claudio Galletti - One of the best experts on this subject based on the ideXlab platform.
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Preparatory activity for purposeful arm movements in the dorsomedial Parietal Area V6A: Beyond the online guidance of movement
Scientific Reports, 2018Co-Authors: Elisa Santandrea, Annalisa Bosco, Rossella Breveglieri, Claudio Galletti, Patrizia FattoriAbstract:Over the years, electrophysiological recordings in macaque monkeys performing visuomotor tasks brought about accumulating evidence for the expression of neuronal properties (e.g., selectivity in the visuospatial and somatosensory domains, encoding of visual affordances and motor cues) in the posterior Parietal Area V6A that characterize it as an ideal neural substrate for online control of prehension. Interestingly, neuroimaging studies suggested a role of putative human V6A also in action preparation; moreover, pre-movement population activity in monkey V6A has been recently shown to convey grip-related information for upcoming grasping. Here we directly test whether macaque V6A neurons encode preparatory signals that effectively differentiate between dissimilar actions before movement. We recorded the activity of single V6A neurons during execution of two visuomotor tasks requiring either reach-to-press or reach-to-grasp movements in different background conditions, and described the nature and temporal dynamics of V6A activity preceding movement execution. We found striking consistency in neural discharges measured during pre-movement and movement epochs, suggesting that the former is a preparatory activity exquisitely linked to the subsequent execution of particular motor actions. These findings strongly support a role of V6A beyond the online guidance of movement, with preparatory activity implementing suitable motor programs that subsequently support action execution.
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Neural activity in the medial Parietal Area V6A while grasping with or without visual feedback
Scientific Reports, 2016Co-Authors: Rossella Breveglieri, Annalisa Bosco, Claudio Galletti, Lauretta Passarelli, Patrizia FattoriAbstract:Recent works have reported that grasping movements are controlled not only by the dorsolateral visual stream, as generally thought, but also by the dorsomedial visual stream, and in particular by the medial posterior Parietal Area V6A. To date, the grasping activity of V6A neurons has been studied only in darkness. Here we studied the effect of visual feedback on grasp-related discharges of V6A neurons while the monkey was preparing and executing the grasping of a handle. We found that V6A grasping activity could be excited or inhibited by visual information. The neural population was divided into Visual, Motor, and Visuomotor cells. The majority of Visual and Visuomotor neurons did not respond to passive observation of the handle, suggesting that vision of action, rather than object vision, is the most effective factor. The present findings highlight the role of the dorsomedial visual stream in integrating visual and motor signals to monitor and correct grasping.
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mixed body hand reference frame for reaching in 3d space in macaque Parietal Area pec
Cerebral Cortex, 2016Co-Authors: Valentina Piserchia, Rossella Breveglieri, Claudio Galletti, Kostas Hadjidimitrakis, Federica Bertozzi, Patrizia FattoriAbstract:The neural correlates of coordinate transformations from vision to action are expressed in the activity of posterior Parietal cortex (PPC). It has been demonstrated that among the medial-most Areas of the PPC, reaching targets are represented mainly in hand-centered coordinates in Area PE, and in eye-centered, body-centered, and mixed body/hand-centered coordinates in Area V6A. Here, we assessed whether neurons of Area PEc, located between V6A and PE in the medial PPC, encode targets in body-centered, hand-centered, or mixed frame of reference during planning and execution of reaching. We studied 104 PEc cells in 3 Macaca fascicularis. The animals performed a reaching task toward foveated targets located at different depths and directions in darkness, starting with the hand from 2 positions located at different depths, one next to the trunk and the other far from it. We show that most PEc neurons encoded targets in a mixed body/hand-centered frame of reference. Although the effect of hand position was often rather strong, it was not as strong as reported previously in Area PE. Our results suggest that Area PEc represents an intermediate node in the gradual transformation from vision to action that takes place in the reaching network of the dorsomedial PPC.
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Multiple Representation of Reaching Space in the Medial Posterior Parietal Area V6A
Cerebral Cortex, 2014Co-Authors: Annalisa Bosco, Rossella Breveglieri, David H. Reser, Claudio Galletti, Patrizia FattoriAbstract:During foveal reaching, the activity of neurons in the macaque medial posterior Parietal Area V6A is modulated by both gaze and arm direction. In the present work, we dissociated the position of gaze and reaching targets, and studied the neural activity of single V6A cells while the eyes and reaching targets were arranged in different spatial configurations (peripheral and foveal combinations). Target position influenced neural activity in all stages of the task, from visual presentation of target and movement planning, through reach execution and holding time. The majority of neurons preferred reaches directed toward peripheral targets, rather than foveal. Most neurons discharged in both premovement and action epochs. In most cases, reaching activity was tuned coherently across action planning and execution. When reaches were planned and executed in different eye/target configurations, multiple analyses revealed that few neurons coded reaching actions according to the absolute position of target, or to the position of target relative to the eye. The majority of cells responded to a combination of both these factors. These data suggest that V6A contains multiple representations of spatial information for reaching, consistent with a role of this Area in forming cross-reference frame representations to be used by premotor cortex.
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Multiple aspects of neural activity during reaching preparation in the medial posterior Parietal Area v6a
Journal of Cognitive Neuroscience, 2014Co-Authors: Rossella Breveglieri, Claudio Galletti, Giulia Dal Bo, Kostas Hadjidimitrakis, Patrizia FattoriAbstract:The posterior Parietal cortex is involved in the visuomotor transformations occurring during arm-reaching movements. The medial posterior Parietal Area V6A has been shown to be implicated in reaching execution, but its role in reaching preparation has not been sufficiently investigated. Here, we addressed this issue exploring the neural correlates of reaching preparation in V6A. Neural activity of single cells during the instructed delay period of a foveated Reaching task was compared with the activity in the same delay period during a Detection task. In this latter task, animals fixated the target but, instead of performing an arm reaching movement, they responded with a button release to the go signal. Targets were allocated in different positions in 3-D space. We found three types of neurons: cells where delay activity was equally spatially tuned in the two tasks Gaze cells, cells spatially tuned only during reaching preparation Set cells, and cells influenced by both gaze and reaching preparation signals Gaze/Set cells. In cells influenced by reaching preparation, the delay activity in the Reaching task could be higher or lower compared with the Detection task. All the Set cells and a minority of Gaze/Set cells were more active during reaching preparation. Most cells modulated by movement preparation were also modulated with a congruent spatial tuning during movement execution. Present results highlight the convergence of visuospatial information, reach planning and reach execution signals on V6A, and indicate that visuospatial processing and movement execution have a larger influence on V6A activity than the encoding of reach plans.