The Experts below are selected from a list of 5550 Experts worldwide ranked by ideXlab platform
Gregor Rainer - One of the best experts on this subject based on the ideXlab platform.
-
phase locking of single neuron activity to theta oscillations during working memory in monkey Extrastriate Visual Cortex
Neuron, 2005Co-Authors: Gregory V Simpson, N K Logothetis, Gregor RainerAbstract:Working memory has been linked to elevated single neuron discharge in monkeys and to oscillatory changes in the human EEG, but the relation between these effects has remained largely unexplored. We addressed this question by measuring local field potentials and single unit activity simultaneously from multiple electrodes placed in Extrastriate Visual Cortex while monkeys were performing a working memory task. We describe a significant enhancement in theta band energy during the delay period. Theta oscillations had a systematic effect on single neuron activity, with neurons emitting more action potentials near their preferred angle of each theta cycle. Sample-selective delay activity was enhanced if only action potentials emitted near the preferred theta angle were considered. Our results suggest that Extrastriate Visual Cortex is involved in short-term maintenance of information and that theta oscillations provide a mechanism for structuring the recurrent interaction between neurons in different brain regions that underlie working memory.
-
working memory related theta 4 7hz frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, Gregory V Simpson, H Lee, N K LogothetisAbstract:Abstract Working memory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memory oscillations can also be observed in monkey Cortex. We indeed found working-memory related oscillations in the theta frequency band in monkey Visual Cortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding.
-
The Effect of Learning on the Function of Monkey Extrastriate Visual Cortex
PLoS biology, 2004Co-Authors: Gregor Rainer, H Lee, Nikos K. LogothetisAbstract:One of the most remarkable capabilities of the adult brain is its ability to learn and continuously adapt to an ever-changing environment. While many studies have documented how learning improves the perception and identification of Visual stimuli, relatively little is known about how it modifies the underlying neural mechanisms. We trained monkeys to identify natural images that were degraded by interpolation with Visual noise. We found that learning led to an improvement in monkeys' ability to identify these indeterminate Visual stimuli. We link this behavioral improvement to a learning-dependent increase in the amount of information communicated by V4 neurons. This increase was mediated by a specific enhancement in neural activity. Our results reveal a mechanism by which learning increases the amount of information that V4 neurons are able to extract from the Visual environment. This suggests that V4 plays a key role in resolving indeterminate Visual inputs by coordinated interaction between bottom-up and top-down processing streams.
-
Working-memory related theta (4–) frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, H Lee, Gregory V. Simpson, N K LogothetisAbstract:Workingmemory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memoryoscillations can also be observed in monkeyCortex. We indeed found working-memoryrelatedoscillations in the thetafrequency band in monkeyVisualCortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding
N K Logothetis - One of the best experts on this subject based on the ideXlab platform.
-
phase locking of single neuron activity to theta oscillations during working memory in monkey Extrastriate Visual Cortex
Neuron, 2005Co-Authors: Gregory V Simpson, N K Logothetis, Gregor RainerAbstract:Working memory has been linked to elevated single neuron discharge in monkeys and to oscillatory changes in the human EEG, but the relation between these effects has remained largely unexplored. We addressed this question by measuring local field potentials and single unit activity simultaneously from multiple electrodes placed in Extrastriate Visual Cortex while monkeys were performing a working memory task. We describe a significant enhancement in theta band energy during the delay period. Theta oscillations had a systematic effect on single neuron activity, with neurons emitting more action potentials near their preferred angle of each theta cycle. Sample-selective delay activity was enhanced if only action potentials emitted near the preferred theta angle were considered. Our results suggest that Extrastriate Visual Cortex is involved in short-term maintenance of information and that theta oscillations provide a mechanism for structuring the recurrent interaction between neurons in different brain regions that underlie working memory.
-
working memory related theta 4 7hz frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, Gregory V Simpson, H Lee, N K LogothetisAbstract:Abstract Working memory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memory oscillations can also be observed in monkey Cortex. We indeed found working-memory related oscillations in the theta frequency band in monkey Visual Cortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding.
-
Working-memory related theta (4–) frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, H Lee, Gregory V. Simpson, N K LogothetisAbstract:Workingmemory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memoryoscillations can also be observed in monkeyCortex. We indeed found working-memoryrelatedoscillations in the thetafrequency band in monkeyVisualCortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding
Gregory V Simpson - One of the best experts on this subject based on the ideXlab platform.
-
phase locking of single neuron activity to theta oscillations during working memory in monkey Extrastriate Visual Cortex
Neuron, 2005Co-Authors: Gregory V Simpson, N K Logothetis, Gregor RainerAbstract:Working memory has been linked to elevated single neuron discharge in monkeys and to oscillatory changes in the human EEG, but the relation between these effects has remained largely unexplored. We addressed this question by measuring local field potentials and single unit activity simultaneously from multiple electrodes placed in Extrastriate Visual Cortex while monkeys were performing a working memory task. We describe a significant enhancement in theta band energy during the delay period. Theta oscillations had a systematic effect on single neuron activity, with neurons emitting more action potentials near their preferred angle of each theta cycle. Sample-selective delay activity was enhanced if only action potentials emitted near the preferred theta angle were considered. Our results suggest that Extrastriate Visual Cortex is involved in short-term maintenance of information and that theta oscillations provide a mechanism for structuring the recurrent interaction between neurons in different brain regions that underlie working memory.
-
working memory related theta 4 7hz frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, Gregory V Simpson, H Lee, N K LogothetisAbstract:Abstract Working memory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memory oscillations can also be observed in monkey Cortex. We indeed found working-memory related oscillations in the theta frequency band in monkey Visual Cortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding.
H Lee - One of the best experts on this subject based on the ideXlab platform.
-
working memory related theta 4 7hz frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, Gregory V Simpson, H Lee, N K LogothetisAbstract:Abstract Working memory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memory oscillations can also be observed in monkey Cortex. We indeed found working-memory related oscillations in the theta frequency band in monkey Visual Cortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding.
-
The Effect of Learning on the Function of Monkey Extrastriate Visual Cortex
PLoS biology, 2004Co-Authors: Gregor Rainer, H Lee, Nikos K. LogothetisAbstract:One of the most remarkable capabilities of the adult brain is its ability to learn and continuously adapt to an ever-changing environment. While many studies have documented how learning improves the perception and identification of Visual stimuli, relatively little is known about how it modifies the underlying neural mechanisms. We trained monkeys to identify natural images that were degraded by interpolation with Visual noise. We found that learning led to an improvement in monkeys' ability to identify these indeterminate Visual stimuli. We link this behavioral improvement to a learning-dependent increase in the amount of information communicated by V4 neurons. This increase was mediated by a specific enhancement in neural activity. Our results reveal a mechanism by which learning increases the amount of information that V4 neurons are able to extract from the Visual environment. This suggests that V4 plays a key role in resolving indeterminate Visual inputs by coordinated interaction between bottom-up and top-down processing streams.
-
Working-memory related theta (4–) frequency oscillations observed in monkey Extrastriate Visual Cortex
Neurocomputing, 2004Co-Authors: Gregor Rainer, H Lee, Gregory V. Simpson, N K LogothetisAbstract:Workingmemory has been linked to elevated activity in single neurons in monkeys, as well as to oscillatory phenomena in the human EEG. To understand the relation between these findings, we explore here whether working-memoryoscillations can also be observed in monkeyCortex. We indeed found working-memoryrelatedoscillations in the thetafrequency band in monkeyVisualCortex, which were correlated to monkeys’ behavioral performance on a contrast discrimination task. We discuss possible functional interpretations of this finding
B. Rörig - One of the best experts on this subject based on the ideXlab platform.
-
Long‐range horizontal connections between supragranular pyramidal cells in the Extrastriate Visual Cortex of the rat
The Journal of comparative neurology, 1994Co-Authors: H. Lohmann, B. RörigAbstract:In this study, we examined the morphological structure and synaptic physiology of long-range axon projections among supragranular pyramidal cells in the Extrastriate Visual Cortex of the rat. Intra- and extracellular recordings from layer II/III pyramidal cells were performed in brain slices of area 18a following extracellular stimulation of either the underlying white matter or within layer II/III. Neurons were injected with biocytin for two-dimensional reconstruction of their axon arborizations. The conduction velocity of afferent fibers (0.58 m/s) was twice as high as that of intracortical tangential fibers (0.28 m/s). Layer II/III cells were mainly di- or polysynaptically driven by afferent activation, but predominantly monosynaptically driven from intracortical stimulation sites. The afferent as well as intracortically evoked postsynaptic potentials showed a very similar time course and shape. From both stimulation sites, suprathreshold action potentials could be elicited. The current threshold for a postsynaptic response and the slope and width of excitatory postsynaptic potentials (EPSPs) increased with the distance of lateral stimulation. The morphological properties of layer II/III pyramidal cell axon collaterals closely corresponded to the electrophysiological results. Long-range intraareal axon collaterals could be followed up to 1 mm within the supragranular layers. Their length-distance distribution showed an inverse relationship to the threshold currents of EPSPs. Pyramidal cells exhibited regularly spaced patches of horizontal axon collaterals with an interpatch distance of about 250 microns. We concluded that the supragranular horizontal network in the Extrastriate Visual Cortex of the rat is qualitatively very similar to that of cats and monkeys. However, quantitative differences exist in its spatial extent and physiological characteristics.
-
long range horizontal connections between supragranular pyramidal cells in the Extrastriate Visual Cortex of the rat
The Journal of Comparative Neurology, 1994Co-Authors: H. Lohmann, B. RörigAbstract:In this study, we examined the morphological structure and synaptic physiology of long-range axon projections among supragranular pyramidal cells in the Extrastriate Visual Cortex of the rat. Intra- and extracellular recordings from layer II/III pyramidal cells were performed in brain slices of area 18a following extracellular stimulation of either the underlying white matter or within layer II/III. Neurons were injected with biocytin for two-dimensional reconstruction of their axon arborizations. The conduction velocity of afferent fibers (0.58 m/s) was twice as high as that of intracortical tangential fibers (0.28 m/s). Layer II/III cells were mainly di- or polysynaptically driven by afferent activation, but predominantly monosynaptically driven from intracortical stimulation sites. The afferent as well as intracortically evoked postsynaptic potentials showed a very similar time course and shape. From both stimulation sites, suprathreshold action potentials could be elicited. The current threshold for a postsynaptic response and the slope and width of excitatory postsynaptic potentials (EPSPs) increased with the distance of lateral stimulation. The morphological properties of layer II/III pyramidal cell axon collaterals closely corresponded to the electrophysiological results. Long-range intraareal axon collaterals could be followed up to 1 mm within the supragranular layers. Their length-distance distribution showed an inverse relationship to the threshold currents of EPSPs. Pyramidal cells exhibited regularly spaced patches of horizontal axon collaterals with an interpatch distance of about 250 microns. We concluded that the supragranular horizontal network in the Extrastriate Visual Cortex of the rat is qualitatively very similar to that of cats and monkeys. However, quantitative differences exist in its spatial extent and physiological characteristics.
