Biomedical subjects

Emmanuel Procyk

Publications and source records attributed to Emmanuel Procyk.

4 recordsLinked to original sources

PubMed2006

Modulation of dorsolateral prefrontal delay activity during self-organized behavior.

The regulation of cognitive activity relies on the flexibility of prefrontal cortex functions. To study this mechanism we compared monkey dorsolateral prefrontal activity in two different spatial cognitive tasks: a delayed response task and a self-organized problem-solving task. The latter included two periods, a search by trial and error for a correct response, and a repetition of the response once discovered. We show that (1) delay activity involved in the delayed task also participates in self-generated responses during the problem-solving task and keeps the same location preference, and (2) the amplitude of firing and the strength of spatial selectivity vary with task requirement, even within search periods while approaching the correct response. This variation is dissociated from pure reward probability, but may have a link with uncertainty because the selectivity dropped when reward predictability was maximal. Overall, we show that spatially tuned delay activity of prefrontal neurons reflects the varying level of engagement in control between different spatial cognitive tasks and during self-organized behavior.

Animals↗

PubMed2005

Anterior cingulate error-related activity is modulated by predicted reward.

Learning abilities depend on detection and exploitation of errors. In primates, this function involves the anterior cingulate cortex. However, whether anterior cingulate error-related activity indicates occurrence of inappropriate responses or results from other computations is debated. Here we have tested whether reward-related parameters modulate error-related activity of anterior cingulate neurons. Recordings in monkeys performing stimulus-reward associations and preliminary data obtained with a problem-solving task revealed major properties of error-related unit activity: (i) their amplitude varies with the amount of predicted reward or the proximity to reward delivery; (ii) they appear both after execution and performance errors; (iii) they do not indicate which error occurred or which correction to make; and (iv), importantly, the activity of these neurons also increases following an external signal indicating the necessity to shift response. Hence, we conclude that anterior cingulate 'error' activity might represent a negative deviation from a predicted goal, and does not only reflect error detection but signals events interrupting potentially rewarded actions.

Action Potentials↗

PubMed2004

The primate working memory networks.

Working memory has long been associated with the prefrontal cortex, since damage to this brain area can critically impair the ability to maintain and update mnemonic information. Anatomical and physiological evidence suggests, however, that the prefrontal cortex is part of a broader network of interconnected brain areas involved in working memory. These include the parietal and temporal association areas of the cerebral cortex, cingulate and limbic areas, and subcortical structures such as the mediodorsal thalamus and the basal ganglia. Neurophysiological studies in primates confirm the involvement of areas beyond the frontal lobe and illustrate that working memory involves parallel, distributed neuronal networks. In this article, we review the current understanding of the anatomical organization of networks mediating working memory and the neural correlates of memory manifested in each of their nodes. The neural mechanisms of memory maintenance and the integrative role of the prefrontal cortex are also discussed.

Animals↗

PubMed2003

Reward anticipation, cognition, and electrodermal activity in the conditioned monkey.

In the present report, we examine electrodermal activity (skin conductance responses, SCRs) in monkeys trained to perform target-selection (TS) tests. In each test, the animal was presented in successive trials with the same two unequally rewarded targets on a touch screen. The probabilistic contingencies of the rewards associated with each target rendered the selection of the best difficult. Our findings revealed SCRs time-locked to the arm movements toward the rewarded targets, occurring after the target touches. Parameters of the SCRs were stable when the uncertainty of the choices and of the outcomes varied. The results support the hypothesis that the physiological processes indexed by the SCRs are the correlate of anticipatory appetitive behavior. In contrast, there is no evidence that the SCRs reflect cognitive processes associated with the detection of the best target.

Animals↗