Dataset Information

Response inhibition and response monitoring in a saccadic countermanding task in schizophrenia.

ABSTRACT: Cognitive control deficits are pervasive in individuals with schizophrenia (SZ) and are reliable predictors of functional outcome, but the specificity of these deficits and their underlying neural mechanisms have not been fully elucidated. The objective of the present study was to determine the nature of response inhibition and response monitoring deficits in SZ and their relationship to symptoms and social and occupational functioning with a behavioral paradigm that provides a translational approach to investigating cognitive control.Seventeen patients with SZ and 16 demographically matched healthy control subjects participated in a saccadic countermanding task. Performance on this task is approximated as a race between movement generation and inhibition processes; this race model provides an estimate of the time needed to cancel a planned movement. Response monitoring can be assessed by reaction time adjustments on the basis of trial history.Saccadic reaction time was normal, but patients required more time to inhibit a planned saccade. The latency of the inhibitory process was associated with the severity of negative symptoms and poorer occupational functioning. Both groups slowed down significantly after correctly cancelled and erroneously noncancelled stop signal trials, but patients slowed down more than control subjects after correctly inhibited saccades.These results suggest that SZ is associated with a difficulty in inhibiting planned movements and an inflated response adjustment effect after inhibiting a saccade. Furthermore, behavioral results are consistent with potential abnormalities in frontal and supplementary eye fields in patients with SZ.

SUBMITTER: Thakkar KN

PROVIDER: S-EPMC3006077 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Response inhibition and response monitoring in a saccadic countermanding task in schizophrenia.

Thakkar Katharine N KN Schall Jeffrey D JD Boucher Leanne L Logan Gordon D GD Park Sohee S

Biological psychiatry 20101023 1

<h4>Background</h4>Cognitive control deficits are pervasive in individuals with schizophrenia (SZ) and are reliable predictors of functional outcome, but the specificity of these deficits and their underlying neural mechanisms have not been fully elucidated. The objective of the present study was to determine the nature of response inhibition and response monitoring deficits in SZ and their relationship to symptoms and social and occupational functioning with a behavioral paradigm that provides ...[more]

PMID: 20970778

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Project description:Adaptation of saccades can be induced by different error signals, such as retinal position errors, prediction errors, or reinforcement learning. Recently, we showed that a shift in the spatial goal of a perceptual task can induce saccadic adaptation, in the absence of a bottom-up position error. Here, we investigated whether this top-down effect is mediated by the visibility of the task-relevant object, by reinforcement due to the feedback about the perceptual judgment or by a target selection mechanism. Participants were asked to discriminate visual stimuli arranged in a vertical compound. To induce adaptation, the discrimination target was presented at eccentric locations in the compound. In the first experiment, we compared adaptation with an easy and difficult discrimination. In the second experiment, we compared adaptation when feedback about the perceptual task was valid and when feedback was provided but was unrelated to performance. In the third experiment, we compared adaptation with instructions to fixate one of the elements in the compound-target selection-to the perceptual task condition-target selection and discrimination. To control for a bottom-up stimulus effect, we ran a fourth experiment in which the only instruction was to look at the compound. The saccade amplitude data were fitted by a two-state model distinguishing between an immediate and a gradual error correction process. We replicated our finding that a perceptual task can drive adaptation of saccades. Adaptation showed no effect of feedback reliability, nor an effect of the perceptual task beyond target selection. Adaptation was induced by a top-down signal since it was absent when there was no target selection instruction and no perceptual task. The immediate error correction was larger for the difficult than for the easy condition, suggesting that task difficulty affects mainly voluntary saccade targeting. In addition, the repetition of experiments one week later increased the magnitude of the gradual error correction. The results dissociate two distinct components of adaptation: an immediate and a gradual error correction. We conclude that perceptual-task induced adaptation is most likely due to top-down target selection within a larger object.

Project description:Differences in inhibitory ability between older (64-79 years, N = 24) and younger adults (18-26 years, N = 24) were investigated using a diffusion model analysis. Participants performed a task-switching paradigm that allows assessing n-2 task repetition costs, reflecting inhibitory control on the level of tasks, as well as n-1 response-repetition costs, reflecting inhibitory control on the level of responses. N-2 task repetition costs were of similar size in both age groups. Diffusion model analysis revealed that for both younger and older adults, drift rate parameters were smaller in the inhibition condition relative to the control condition, consistent with the idea that persisting task inhibition slows down response selection. Moreover, there was preliminary evidence for task inhibition effects in threshold separation and non-decision time in the older, but not the younger adults, suggesting that older adults might apply different strategies when dealing with persisting task inhibition. N-1 response-repetition costs in mean RT were larger in older than younger adults, but in mean error rates tended to be larger in younger than older adults. Diffusion-model analysis revealed longer non-decision times in response repetitions than response switches in both age groups, consistent with the idea that motor processes take longer in response repetitions than response switches due to persisting response inhibition of a previously executed response. The data also revealed age-related differences in overall performance: Older adults responded more slowly and more accurately than young adults, which was reflected by a higher threshold separation parameter in diffusion model analysis. Moreover, older adults showed larger non-decision times and higher variability in non-decision time than young adults, possibly reflecting slower and more variable motor processes. In contrast, overall drift rate did not differ between older and younger adults. Taken together, diffusion model analysis revealed differences in overall performance between the age groups, as well as preliminary evidence for age differences in dealing with task inhibition, but no evidence for an inhibitory deficit in older age.

Dataset Information

Response inhibition and response monitoring in a saccadic countermanding task in schizophrenia.

Publications

Response inhibition and response monitoring in a saccadic countermanding task in schizophrenia.

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