Responses to Task-Irrelevant Visual Features by Primate  Prefrontal Neurons

Lauwereyns, Johan; Sakagami, Masamichi; Tsutsui, Ken; Kobayashi, Shunsuke; Koizumi, Masashi; Hikosaka, Okihide

doi:10.1152/jn.2001.86.4.2001

Cited by 55 publications

(43 citation statements)

References 31 publications

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“…This idea is consistent with data showing task-dependent changes in background or undriven activity in high-order cortical areas (Sakagami & Niki, 1994;Lauwereyns et al, 2001;Port, Kruse, Lee, & Georgopoulas, 2001). Although it is not surprising that widespread excitation can produce drastic changes in a network, the generality of this effect is not intuitively obvious.…”

Section: Discussionsupporting

confidence: 90%

“…When we need to remember a phone number announced on the radio, some neural process in the brain enables our short-term memory; without the context information indicating that it is important to store it, the same number vanishes promptly from the mind. In the motor realm, this is a classic problem that neurophysiologists have studied using go versus no-go paradigms (see, e.g., Schultz & Romo, 1992;Lauwereyns et al, 2001;Sommer & Wurtz, 2001). In these tasks, a subject performs one of several possible motor actions in response to a presented stimulus, but the movement is contingent on a separate cue giving either a go or a no-go instruction.…”

Section: Introductionmentioning

confidence: 99%

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Background Synaptic Activity as a Switch Between Dynamical States in a Network

Salinas

2003

Neural Computation

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A bright red light may trigger a sudden motor action in a driver crossing an intersection: stepping at once on the brakes. The same red light, however, may be entirely inconsequential if it appears, say, inside a movie theater. Clearly, context determines whether a particular stimulus will trigger a motor response, but what is the neural correlate of this? How does the nervous system enable or disable whole networks so that they are responsive or not to a given sensory signal? Using theoretical models and computer simulations, I show that networks of neurons have a built-in capacity to switch between two types of dynamic state: one in which activity is low and approximately equal for all units, and another in which different activity distributions are possible and may even change dynamically. This property allows whole circuits to be turned on or off by weak, unstructured inputs. These results are illustrated using networks of integrate-and-fire neurons with diverse architectures. In agreement with the analytic calculations, a uniform background input may determine whether a random network has one or two stable firing levels; it may give rise to randomly alternating firing episodes in a circuit with reciprocal inhibition; and it may regulate the capacity of a center-surround circuit to produce either self-sustained activity or traveling waves. Thus, the functional properties of a network may be drastically modified by a simple, weak signal. This mechanism works as long as the network is able to exhibit stable firing states, or attractors.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Background Synaptic Activity as a Switch Between Dynamical States in a Network

Salinas

2003

Neural Computation

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“…For example, a neuron active in conjunction with planning rightward saccades will begin to fire not only in response to a target flashed in the right visual field but also in response to a foveal digitized image instructing the monkey to make a rightward saccade (Olson et al 2000). Similar effects of training were observed in other oculomotor areas (Bichot et al 1996;Grunewald et al 1999;Horwitz et al 2004a;Lauwereyns et al 2001;Toth and Assad 2002). The present study, however, is the first to have shown that training monkeys to attend to locations as defined with respect to a particular reference frame induces neurons to represent locations relative to that frame.…”

Section: Discussionsupporting

confidence: 72%

Impact of Experience on the Representation of Object-Centered Space in the Macaque Supplementary Eye Field

Moorman¹,

Olson²

2007

Journal of Neurophysiology

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Many neurons in the macaque supplementary eye field (SEF) exhibit object-centered spatial selectivity, firing at different rates when the monkey plans a saccade to the left or right end of a horizontal bar. Is this property natural to the SEF or is it a product of specialized training in the laboratory? To answer this question, we monitored the activity of single SEF neurons in two monkeys before and after training to select eye-movement targets by an object-centered rule. During stage 1, the monkeys performed a color delayed-match-to-sample (DMS) task in which a red or green central cue dictated an eye movement to the matching end of a horizontal bar. Many neurons at this stage exhibited object-centered spatial selectivity. During stage 2, the monkeys performed a color-conditional object-centered task in which a green or red central cue instructed an eye movement to the left or right end of a gray bar. More neurons exhibited object-centered spatial selectivity during this stage than during stage 1. During stage 3, the monkeys again performed the color DMS task. The fraction of neurons exhibiting object-centered spatial selectivity remained at a level comparable to that observed during stage 2 and above that observed during stage 1. Thus object-centered spatial selectivity was present before training on an object-centered rule, was enhanced as a product of object-centered training, and outlasted active use of an object-centered rule. We conclude that neural representations of object-centered space, naturally present in the primate brain, can be sharpened by training.

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“…Various neurophysiological studies have explored changes in neuronal properties as functions of multiple sensory cues in the spirit of the task proposed here (White and Wise, 1999;Lauwereyns et al, 2001;Wallis and Miller, 2003). Some of those results are consistent with context-dependent variations in gain but, because the paradigms were not designed to assess this, confounding factors are inevitable.…”

Section: Experimental Predictionsmentioning

confidence: 67%

Fast Remapping of Sensory Stimuli onto Motor Actions on the Basis of Contextual Modulation

Salinas¹

2004

J. Neurosci.

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Higher organisms can establish complex associations between sensory events and motor responses. More remarkable than their complexity, however, is that the resulting sensory-motor maps can be selectively interchanged. For example, a person who speaks English and Spanish can read aloud "con once, sin once," going effortlessly from one language to the other. What is the neural basis of this capacity? Here, a network model is presented in which multiple maps between sensory stimuli and motor actions are possible, but only one of them, depending on behavioral context, is implemented at any given time. The key is a nonlinear representation in which the gain of sensory responses is regulated by context information. Neuronal responses can indeed show variations in gain, as has been documented in the case of proprioceptive signals such as eye and head position, which can modulate visually triggered activity. However, in contrast to these, the contextual cues used here need not bear any relationship to the physical attributes of the stimuli; in particular, spatial location is irrelevant. The model thus postulates the existence of sensory neurons that are nonlinearly modulated by arbitrary context signals, a plausible and testable prediction. The proposed mechanism allows a network of neurons to effectively change the functional connectivity between its inputs and outputs and may partially explain how animals can quickly adapt their behavior to varying environmental conditions.

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Responses to Task-Irrelevant Visual Features by Primate Prefrontal Neurons

Cited by 55 publications

References 31 publications

Background Synaptic Activity as a Switch Between Dynamical States in a Network

Background Synaptic Activity as a Switch Between Dynamical States in a Network

Impact of Experience on the Representation of Object-Centered Space in the Macaque Supplementary Eye Field

Fast Remapping of Sensory Stimuli onto Motor Actions on the Basis of Contextual Modulation

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