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The neural selection and control of saccades by the frontal eye field.
- Philos. Trans. R. Soc. Lond. B Biol. Sci.
, 2002
"... Recent research has provided new insights into the neural processes that select the target for and control the production of a shift of gaze. Being a key node in the network that subserves visual processing and saccade production, the frontal eye eld (FEF) has been an effective area in which to mon ..."
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Cited by 48 (3 self)
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Recent research has provided new insights into the neural processes that select the target for and control the production of a shift of gaze. Being a key node in the network that subserves visual processing and saccade production, the frontal eye eld (FEF) has been an effective area in which to monitor these processes. Certain neurons in the FEF signal the location of conspicuous or meaningful stimuli that may be the targets for saccades. Other neurons control whether and when the gaze shifts. The existence of distinct neural processes for visual selection and saccade production is necessary to explain the exibility of visually guided behaviour.
A Model of the Go/No-Go Task
"... In this article, the first explicit, theory-based comparison of 2-choice and go/no-go variants of 3 experimental tasks is presented. Prior research has questioned whether the underlying core-information processing is different for the 2 variants of a task or whether they differ mostly in response de ..."
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Cited by 41 (11 self)
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In this article, the first explicit, theory-based comparison of 2-choice and go/no-go variants of 3 experimental tasks is presented. Prior research has questioned whether the underlying core-information processing is different for the 2 variants of a task or whether they differ mostly in response demands. The authors examined 4 different diffusion models for the go/no-go variant of each task along with a standard diffusion model for the 2-choice variant (R. Ratcliff, 1978). The 2-choice and the go/no-go models were fit to data from 4 lexical decision experiments, 1 numerosity discrimination experiment, and 1 recognition memory experiment, each with 2-choice and go/no-go variants. The models that assumed an implicit decision criterion for no-go responses produced better fits than models that did not. The best model was one in which only response criteria and the nondecisional components of processing changed between the 2 variants, supporting the view that the core information on which decisions are based is not different between them.
Signal transformations from cerebral cortex to superior colliculus for the generation of saccades. Vision Research
, 2001
"... The ability of primates to make rapid and accurate saccadic eye movements for exploring the natural world is based on a neuronal system in the brain that has been studied extensively and is known to include multiple brain regions extending throughout the neuraxis. We examined the characteristics of ..."
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Cited by 14 (0 self)
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The ability of primates to make rapid and accurate saccadic eye movements for exploring the natural world is based on a neuronal system in the brain that has been studied extensively and is known to include multiple brain regions extending throughout the neuraxis. We examined the characteristics of signal flow in this system by recording from identified output neurons of two cortical regions, the lateral intraparietal area (LIP) and the frontal eye field (FEF), and from neurons in a brainstem structure targeted by these output neurons, the superior colliculus (SC). We compared the activity of neurons in these three populations while monkeys performed a delayed saccade task that allowed us to quantify visual responses, motor activity, and intervening delay activity. We examined whether delay activity was related to visual stimulation by comparing the activity during interleaved trials when a target was either present or absent during the delay period. We examined whether delay activity was related to movement by using a Go/Nogo task and comparing the activity during interleaved trials in which a saccade was either made (Go) or not (Nogo). We found that LIP output neurons, FEF output neurons, and SC neurons can all have visual responses, delay activity, and presaccadic bursts; hence in this way they are all quite similar. However, the delay activity tended to be more related to visual stimulation in the cortical output neurons than in the SC neurons. Complementing this, the delay activity tended to be more related to movement in the SC neurons than in the cortical output neurons. We conclude, first, that the signal flow leaving the cortex represents activity at nearly every stage of visuomotor transformation, and second, that there
Prefrontal neurons coding suppression of specific saccades
- Neuron
, 2004
"... tients with frontal lobe damage. Despite the clinical im-portance of suppression, most studies of the frontal ..."
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Cited by 8 (0 self)
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tients with frontal lobe damage. Despite the clinical im-portance of suppression, most studies of the frontal
Effects of electrical microstimulation in monkey frontal eye field on saccades to remembered targets
, 2005
"... Abstract Spatially selective delay activity in the frontal eye field (FEF) is hypothesized to be part of a mechanism for the transformation of visual signals into instructions for voluntary movements. To understand the linkage between FEF activity and eye movement planning, we recorded neuronal res ..."
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Cited by 4 (1 self)
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Abstract Spatially selective delay activity in the frontal eye field (FEF) is hypothesized to be part of a mechanism for the transformation of visual signals into instructions for voluntary movements. To understand the linkage between FEF activity and eye movement planning, we recorded neuronal responses of FEF neurons while monkeys performed a memory-saccade task. We then electrically stimulated the same sites during the memory-delay epoch of the task. The stimulation currents used were subthreshold for evoking saccades during a gap-fixation task. Microstimulation resulted in changes in the spatial and temporal components of saccade parameters: an increase in latency, and a shift in amplitude and direction. We performed a vector analysis to determine the relative influence of the visual cue and electrical stimulus on the memory-saccade. In general, the memory-saccade was strongly weighted toward the visual cue direction, yet the electrical stimulus introduced a consistent bias away from the receptive/movement field of the stimulation site. The effects of sub-threshold stimulation were consistent with a combination of vector subtraction and averaging, but not with vector summation. Vector subtraction may play a role in spatial updating of movement plans for memory-guided saccades when eye position changes during the memory period.
Neurally Plausible Reinforcement Learning of Working Memory Tasks
"... A key function of brains is undoubtedly the abstraction and maintenance of information from the environment for later use. Neurons in association cortex play an important role in this process: by learning these neurons become tuned to relevant features and represent the information that is required ..."
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Cited by 3 (0 self)
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A key function of brains is undoubtedly the abstraction and maintenance of information from the environment for later use. Neurons in association cortex play an important role in this process: by learning these neurons become tuned to relevant features and represent the information that is required later as a persistent elevation of their activity [1]. It is however not well known how such neurons acquire these task-relevant working memories. Here we introduce a biologically plausible learning scheme grounded in Reinforcement Learning (RL) theory [2] that explains how neurons become selective for relevant information by trial and error learning. The model has memory units which learn useful internal state representations to solve working memory tasks by transforming partially observable Markov decision problems (POMDP) into MDPs. We propose that synaptic plasticity is guided by a combination of attentional feedback signals from the action selection stage to earlier processing levels and a globally released neuromodulatory signal. Feedback signals interact with feedforward signals to form synaptic tags at those connections that are responsible for the stimulus-response mapping. The neuromodulatory signal interacts with tagged synapses to determine the sign and strength of plasticity. The learning scheme is generic because it can train networks in different tasks, simply by varying inputs and rewards. It explains how neurons in association cortex learn to 1) temporarily store task-relevant information in non-linear stimulus-response mapping tasks [1, 3, 4] and 2) learn to optimally integrate probabilistic evidence for perceptual decision making [5, 6]. 1
Human frontal eye fields and spatial priming of pop-out
- J. Cogn. Neurosci
, 2007
"... & ‘‘Priming of pop-out’ ’ is a form of implicit memory that facilitates detection of a recently inspected search target. Re-peated presentation of a target’s features or its spatial position improves detection speed (feature/spatial priming). This study investigated a role for the human frontal ..."
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Cited by 3 (0 self)
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& ‘‘Priming of pop-out’ ’ is a form of implicit memory that facilitates detection of a recently inspected search target. Re-peated presentation of a target’s features or its spatial position improves detection speed (feature/spatial priming). This study investigated a role for the human frontal eye fields (FEFs) in the priming of color pop-out. To test the hypothesis that the FEFs play a role in short-term memory storage, transcranial magnetic stimulation (TMS) was applied during the intertrial interval. There was no effect of TMS on either spatial or fea-ture priming. To test whether the FEFs are important when a saccade is being programmed to a repeated target color or location, TMS was applied during the search array. TMS over the left but not the right FEFs abolished spatial priming, but had no effect on feature priming. These findings dem-onstrate functional specialization of the left FEFs for spatial priming, and distinguish this role from target discrimination and saccade-related processes. The results suggest that the left FEFs integrate a spatial memory signal with an evolving saccade program, which facilitates saccades to a recently in-spected location. &
SUMMARY
"... Although the bandwidth of access networks is rapidly increasing with the latest techniques such as DSL and FTTH, the access link bandwidth remains a bottleneck, especially when users activate multiple network applications simultaneously. Furthermore, since the throughput of a standard TCP connection ..."
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Cited by 1 (0 self)
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Although the bandwidth of access networks is rapidly increasing with the latest techniques such as DSL and FTTH, the access link bandwidth remains a bottleneck, especially when users activate multiple network applications simultaneously. Furthermore, since the throughput of a standard TCP connection is dependent on various network parameters, including round-trip time and packet loss ratio, the access link bandwidth is not shared among the network applications according to the user’s demands. In this thesis, we present a new management scheme of access link resources for effective utilization of the access link bandwidth and control of the TCP connection’s throughput. Our proposed scheme adjusts the total amount of the receive socket buffer assigned to TCP connections to avoid congestion at the access network, and assigns it to each TCP connection according to characteristics in consideration of QoS. The control objectives of our scheme are (1) to protect short-lived TCP connections from the bandwidth occupation by long-lived TCP connections, and (2) to differentiate the throughput of the long-lived TCP connections according to the upper-layer application’s demands. One of the results obtained from the simulation experiments is that our proposed scheme can reduce the delay of short-lived document transfer perceived by the receiver host by up to about 90%, while a high utilization of access link bandwidth is maintained. Copyright # 2006 John Wiley & Sons, Ltd.
iii
, 2013
"... Uncertainty, generalization, and neural representation of relevant variables for decision making ..."
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Uncertainty, generalization, and neural representation of relevant variables for decision making
