The Experts below are selected from a list of 2076 Experts worldwide ranked by ideXlab platform
Anne B Sereno - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of eye-position gain field populations determine geometry of visual space
Frontiers Media S.A., 2016Co-Authors: Sidney R. Lehky, Margaret E. Sereno, Anne B SerenoAbstract:We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal Cortex (AIT) in the ventral stream and Lateral Intraparietal Cortex (LIP) in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields). Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smaller spatial scales and smaller dispersions than in LIP. Thus we show that the geometry of eye-position visual space depends on the population characteristics of gain fields, and that differences in gain field characteristics for different cortical areas may underlie differences in the representation of space
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Characteristics of Eye-Position Gain Field Populations Determine Geometry of Visual Space
2015Co-Authors: Jody C. Culham, Patrizia Fattori, Sidney R. Lehky, Margaret E. Sereno, Anne B SerenoAbstract:We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal Cortex (AIT) in the ventral stream and Lateral Intraparietal Cortex (LIP) in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields). Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well-established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smalle
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shape selectivity in primate Lateral Intraparietal Cortex
Nature, 1998Co-Authors: Anne B Sereno, John H R MaunsellAbstract:The extrastriate visual Cortex can be divided into functionally distinct temporal and parietal regions, which have been implicated in feature-related ('what') and spatial ('where') vision, respectively. Neuropsychological studies of patients with damage to either the temporal or the parietal regions provide support for this functional distinction. Given the prevailing modular theoretical framework and the fact that prefrontal Cortex receives inputs from both temporal and parietal streams, recent studies have focused on the role of prefrontal Cortex in understanding where and how information about object identity is integrated with (or remains segregated from) information about object location. Here we show that many neurons in primate posterior parietal Cortex (the 'where' pathway) show sensory shape selectivities to simple, two-dimensional geometric shapes while the animal performs a simple fixation task. In a delayed match-to-sample paradigm, many neuronal units also show significant differences in delay-period activity, and these differences depend on the shape of the sample. These results indicate that units in posterior parietal Cortex contribute to attending to and remembering shape features in a way that is independent of eye movements, reaching, or object manipulation. These units show shape selectivity equivalent to any shown in the ventral pathway.
Kevan A. C. Martin - One of the best experts on this subject based on the ideXlab platform.
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Behavioral/Systems/Cognitive Pathways of Attention: Synaptic Relationships of Frontal Eye Field to V4, Lateral Intraparietal Cortex, and Area 46 in Macaque Monkey
2015Co-Authors: John C. Anderson, Henry Kennedy, Kevan A. C. MartinAbstract:The frontal eye field (FEF) of the primate neoCortex occupies a pivotal position in thematrix of inter-areal projections. In addition to its role in directing saccadic eyemovements, it is the source of an attentional signal thatmodulates the activity of neurons in extrastriate and parietal Cortex. Here, we tested the prediction that FEF preferentially excites inhibitory neurons in target areas during attentional modulation. Using the anterograde tracer biotinylated dextran amine, we found that the projections from FEF terminate in all cortical layers of area 46, Lateral Intraparietal area (LIP), and visual area V4. Axons in layer 1 spread extensively, those in layer 2/3 were most numerous, individual axons in layer 4 formed sprays of colLaterals, and those of the deep layers were the finest caliber and irregular. All labeled synapses were the typical asymmetric morphology of excitatory synapses of pyramidal neurons. Dendritic spines were the most frequent synaptic target in all areas (95 % inarea 46, 89 % inV4, 84 % inLIP, 78 % intrinsic local FEF). The remaining targetswere one soma and dendritic shafts, most of which showed characteristics of inhibitory neurons with smooth dendrites (5 % of all targets in area 46, 2% in V4, 9 % in LIP, and 13 % in FEF)
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Pathways of Attention: Synaptic Relationships of Frontal Eye Field to V4, Lateral Intraparietal Cortex, and Area 46 in Macaque Monkey
Journal of Neuroscience, 2011Co-Authors: John C. Anderson, Henry Kennedy, Kevan A. C. MartinAbstract:The frontal eye field (FEF) of the primate neoCortex occupies a pivotal position in the matrix of inter-areal projections. In addition to its role in directing saccadic eye movements, it is the source of an attentional signal that modulates the activity of neurons in extrastriate and parietal Cortex. Here, we tested the prediction that FEF preferentially excites inhibitory neurons in target areas during attentional modulation. Using the anterograde tracer biotinylated dextran amine, we found that the projections from FEF terminate in all cortical layers of area 46, Lateral Intraparietal area (LIP), and visual area V4. Axons in layer 1 spread extensively, those in layer 2/3 were most numerous, individual axons in layer 4 formed sprays of colLaterals, and those of the deep layers were the finest caliber and irregular. All labeled synapses were the typical asymmetric morphology of excitatory synapses of pyramidal neurons. Dendritic spines were the most frequent synaptic target in all areas (95% in area 46, 89% in V4, 84% in LIP, 78% intrinsic local FEF). The remaining targets were one soma and dendritic shafts, most of which showed characteristics of inhibitory neurons with smooth dendrites (5% of all targets in area 46, 2% in V4, 9% in LIP, and 13% in FEF).
William T Newsome - One of the best experts on this subject based on the ideXlab platform.
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integration of sensory and reward information during perceptual decision making in Lateral Intraparietal Cortex lip of the macaque monkey
PLOS ONE, 2010Co-Authors: Alan E Rorie, James L Mcclelland, William T NewsomeAbstract:Single neurons in cortical area LIP are known to carry information relevant to both sensory and value-based decisions that are reported by eye movements. It is not known, however, how sensory and value information are combined in LIP when individual decisions must be based on a combination of these variables. To investigate this issue, we conducted behavioral and electrophysiological experiments in rhesus monkeys during performance of a two-alternative, forced-choice discrimination of motion direction (sensory component). Monkeys reported each decision by making an eye movement to one of two visual targets associated with the two possible directions of motion. We introduced choice biases to the monkeys' decision process (value component) by randomly interleaving balanced reward conditions (equal reward value for the two choices) with unbalanced conditions (one alternative worth twice as much as the other). The monkeys' behavior, as well as that of most LIP neurons, reflected the influence of all relevant variables: the strength of the sensory information, the value of the target in the neuron's response field, and the value of the target outside the response field. Overall, detailed analysis and computer simulation reveal that our data are consistent with a two-stage drift diffusion model proposed by Diederich and Bussmeyer [1] for the effect of payoffs in the context of sensory discrimination tasks. Initial processing of payoff information strongly influences the starting point for the accumulation of sensory evidence, while exerting little if any effect on the rate of accumulation of sensory evidence.
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monkeys play the odds
Nature, 1999Co-Authors: Philippe Grangier, James M Nichols, William T NewsomeAbstract:Animals -- like humans -- are thought to make decisions based on the expected size and probability of rewards. A neural correlate of this behaviour has now been demonstrated by experiments in which rhesus monkeys have to switch their gaze to a particular target for a juice reward. The number of signals fired by neurons in the Lateral Intraparietal Cortex is found to vary depending on the size of the expected reward.
Sidney R. Lehky - One of the best experts on this subject based on the ideXlab platform.
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Characteristics of eye-position gain field populations determine geometry of visual space
Frontiers Media S.A., 2016Co-Authors: Sidney R. Lehky, Margaret E. Sereno, Anne B SerenoAbstract:We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal Cortex (AIT) in the ventral stream and Lateral Intraparietal Cortex (LIP) in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields). Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smaller spatial scales and smaller dispersions than in LIP. Thus we show that the geometry of eye-position visual space depends on the population characteristics of gain fields, and that differences in gain field characteristics for different cortical areas may underlie differences in the representation of space
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Characteristics of Eye-Position Gain Field Populations Determine Geometry of Visual Space
2015Co-Authors: Jody C. Culham, Patrizia Fattori, Sidney R. Lehky, Margaret E. Sereno, Anne B SerenoAbstract:We have previously demonstrated differences in eye-position spatial maps for anterior inferotemporal Cortex (AIT) in the ventral stream and Lateral Intraparietal Cortex (LIP) in the dorsal stream, based on population decoding of gaze angle modulations of neural visual responses (i.e., eye-position gain fields). Here we explore the basis of such spatial encoding differences through modeling of gain field characteristics. We created a population of model neurons, each having a different eye-position gain field. This population was used to reconstruct eye-position visual space using multidimensional scaling. As gain field shapes have never been well-established experimentally, we examined different functions, including planar, sigmoidal, elliptical, hyperbolic, and mixtures of those functions. All functions successfully recovered positions, indicating weak constraints on allowable gain field shapes. We then used a genetic algorithm to modify the characteristics of model gain field populations until the recovered spatial maps closely matched those derived from monkey neurophysiological data in AIT and LIP. The primary differences found between model AIT and LIP gain fields were that AIT gain fields were more foveally dominated. That is, gain fields in AIT operated on smalle
John C. Anderson - One of the best experts on this subject based on the ideXlab platform.
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Behavioral/Systems/Cognitive Pathways of Attention: Synaptic Relationships of Frontal Eye Field to V4, Lateral Intraparietal Cortex, and Area 46 in Macaque Monkey
2015Co-Authors: John C. Anderson, Henry Kennedy, Kevan A. C. MartinAbstract:The frontal eye field (FEF) of the primate neoCortex occupies a pivotal position in thematrix of inter-areal projections. In addition to its role in directing saccadic eyemovements, it is the source of an attentional signal thatmodulates the activity of neurons in extrastriate and parietal Cortex. Here, we tested the prediction that FEF preferentially excites inhibitory neurons in target areas during attentional modulation. Using the anterograde tracer biotinylated dextran amine, we found that the projections from FEF terminate in all cortical layers of area 46, Lateral Intraparietal area (LIP), and visual area V4. Axons in layer 1 spread extensively, those in layer 2/3 were most numerous, individual axons in layer 4 formed sprays of colLaterals, and those of the deep layers were the finest caliber and irregular. All labeled synapses were the typical asymmetric morphology of excitatory synapses of pyramidal neurons. Dendritic spines were the most frequent synaptic target in all areas (95 % inarea 46, 89 % inV4, 84 % inLIP, 78 % intrinsic local FEF). The remaining targetswere one soma and dendritic shafts, most of which showed characteristics of inhibitory neurons with smooth dendrites (5 % of all targets in area 46, 2% in V4, 9 % in LIP, and 13 % in FEF)
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Pathways of Attention: Synaptic Relationships of Frontal Eye Field to V4, Lateral Intraparietal Cortex, and Area 46 in Macaque Monkey
Journal of Neuroscience, 2011Co-Authors: John C. Anderson, Henry Kennedy, Kevan A. C. MartinAbstract:The frontal eye field (FEF) of the primate neoCortex occupies a pivotal position in the matrix of inter-areal projections. In addition to its role in directing saccadic eye movements, it is the source of an attentional signal that modulates the activity of neurons in extrastriate and parietal Cortex. Here, we tested the prediction that FEF preferentially excites inhibitory neurons in target areas during attentional modulation. Using the anterograde tracer biotinylated dextran amine, we found that the projections from FEF terminate in all cortical layers of area 46, Lateral Intraparietal area (LIP), and visual area V4. Axons in layer 1 spread extensively, those in layer 2/3 were most numerous, individual axons in layer 4 formed sprays of colLaterals, and those of the deep layers were the finest caliber and irregular. All labeled synapses were the typical asymmetric morphology of excitatory synapses of pyramidal neurons. Dendritic spines were the most frequent synaptic target in all areas (95% in area 46, 89% in V4, 84% in LIP, 78% intrinsic local FEF). The remaining targets were one soma and dendritic shafts, most of which showed characteristics of inhibitory neurons with smooth dendrites (5% of all targets in area 46, 2% in V4, 9% in LIP, and 13% in FEF).
