Visual Reaction Time Task Research Articles

Do fibromyalgia patients display hypervigilance for innocuous somatosensory stimuli? Application of a body scanning reaction time paradigm

This study tested the hypothesis that fibromyalgia patients display hypervigilance for somatosensory signals. Hypervigilance was operationalized as the detection of weak electrocutaneous stimuli. Innocuous electrical stimuli gradually increasing in strength were administered to one of four different body locations. A reaction time paradigm was used in which subjects had to respond as fast as possible to stimulus detection by pressing a button corresponding to the correct body location. The detection task was presented first under single task conditions and subsequently under dual task conditions, in combination with a second (visual) reaction time task. It was predicted that hypervigilance would be most prominent under dual task conditions, where subjects can choose to allocate attention selectively to one of the tasks. Questionnaires on general body vigilance, pain vigilance, pain related-fear and pain catastrophizing were also administered. Thirty female fibromyalgia patients were compared to 30 healthy controls matched on age, sex and educational level. No evidence for hypervigilance for innocuous signals was found: patients did not show superior detection of electrical stimuli either under single or dual task conditions. Also, no differences were found between patients and controls on the body vigilance questionnaire. Detection of electrical stimuli was, however, predicted by pain-related fear and pain vigilance.

ERP differences in visual attention processing between attention‐deficit hyperactivity disorder and control boys in the absence of performance differences

Event-related potentials (ERPs) were recorded during a visual two-choice reaction time (RT) task in attention-deficit hyperactivity disorder (ADHD) and control boys selected using strict inclusion and exclusion criteria. No group differences were found in mean RT and correct responses. Although early occipital ERPs were not affected in the ADHD group, the peak latency of early anterior ERPs (N1, P1, N2) was significantly delayed. ADHD showed a larger effect of stimulus type on the frontal negativity (N530) and the posterior late negativity (nSW) and a smaller effect of stimulus type on anterior N2 and posterior P3b amplitude. The development of N530 and P450 amplitude across blocks of five trials was analyzed using orthogonal polynomial trend analysis of variance software. In the control group, P450 amplitude to "frequent" stimuli reduced across blocks. In the ADHD group, N530 amplitude increased for "rare" stimuli across blocks. It is suggested that the ADHD group showed a lack of automatization of the categorization process with increasing time on task for which they compensated by controlled attentional processes.

Influence of the predicted time of stimuli eliciting movements on responses of tonically active neurons in the monkey striatum.

Changes in activity of tonically active neurons of the primate striatum are determined both by the behavioural significance of stimuli and the context in which stimuli are presented. We investigated how the responses of these neurons are modified by the temporal predictability of stimuli eliciting learned behavioural reactions. Single neurons were recorded from the caudate nucleus and putamen of two macaque monkeys performing a visual reaction time task under conditions in which the timing of the trigger stimulus was made more or less predictable. The monkeys' ability to predict the trigger onset was assessed by measuring arm movement reaction times and saccadic ocular reactions. Of 171 neurons responding to the unsignalled presentation of the trigger stimulus, 32% lost their response when an instruction cue preceded the trigger by a highly practised 1.5 s interval, and the response reappeared when this interval was varied randomly from 1 to 2.5 s or prolonged to 3 or 4. 5 s. Although 43% of the neurons remained responsive irrespective of task condition, the responses were stronger with longer intervals than with the accustomed 1.5 s interval. In addition, a number of neurons responding to the instruction lost their response when the trigger appeared more distant from the instruction. These findings demonstrate that neuronal responses to a movement-triggering signal become more numerous and pronounced when the degree of temporal predictability of that signal was decreased. We conclude that tonic striatal neurons are sensitive to temporal aspects of stimulus prediction.

Performance monitoring in a confusing world: Error-related brain activity, judgments of response accuracy, and types of errors.

The error-related negativity (ERN) represents a neural response, recorded from scalp electrodes, that is associated with monitoring activities. It is most likely generated in the anterior cingulate cortex (ACC). Measures of the ERN, and of behavioral and perceived accuracy, were obtained from participants while they performed a visual 2-choice reaction time task under degraded stimulus conditions. Irrespective of behavioral accuracy, the amplitude of the ERN (measured at the time of the response) covaried with the perceived inaccuracy of the behavior (measured at the end of the trial). Errors due to premature responding (errors perceived as errors) were associated with large ERNs. Errors due to data limitations (errors about which there was uncertainty) were associated with smaller ERNs. These and other results are consistent with the proposal that performance monitoring, as manifested by the ERN, involves a comparison between representations of the appropriate response and the response actually made.

Performance monitoring in a confusing world: error-related brain activity, judgments of response accuracy, and types of errors.

The error-related negativity (ERN) represents a neural response, recorded from scalp electrodes, that is associated with monitoring activities. It is most likely generated in the anterior cingulate cortex (ACC). Measures of the ERN, and of behavioral and perceived accuracy, were obtained from participants while they performed a visual 2-choice reaction time task under degraded stimulus conditions. Irrespective of behavioral accuracy, the amplitude of the ERN (measured at the time of the response) covaried with the perceived inaccuracy of the behavior (measured at the end of the trial). Errors due to premature responding (errors perceived as errors) were associated with large ERNs. Errors due to data limitations (errors about which there was uncertainty) were associated with smaller ERNs. These and other results are consistent with the proposal that performance monitoring, as manifested by the ERN, involves a comparison between representations of the appropriate response and the response actually made.

Effect of the irrelevant location of the response signal on choice reaction time: an electromyographic study in humans.

Choice reaction time (RT) is shorter when the stimulus corresponds spatially to the response than when the stimulus does not, even when the stimulus location is irrelevant to the task. We used electromyographic measures to document that this effect is the result of a response conflict. The activity of the prime movers of two alternative responses was recorded during the performance of a visual RT task in which the irrelevant spatial correspondence between the stimuli and the responses was varied. Only the premotor component of RT was affected by the stimulus-response correspondence. Correct trials were distinguished according to whether or not the activation of the prime mover involved in the required response was preceded by an activation of the prime mover involved in the alternative response. Double muscular activation trials were more numerous for noncorresponding than for corresponding stimulus-response associations. Furthermore, these trials yielded longer RTs than the single muscular activation trials.

Topography of averaged electrical brain activity relating to interhemispheric dynamics in normal humans: where does the critical relay take place?

Interhemispheric relay time (IHRT) was investigated using a 16-electrode montage in 10 normal subjects during a simple visual reaction time task (Poffenberger paradigm). The P1 latency was the dependent measure. Response-locked components were separated from the stimulus-locked components based on the reaction times using a Woldorff-like filter. The issues of theoretical interest were the following: (1) does the responding hand modulate IHRT estimates as a function of electrode site, or stimulated field?; (2) what are the respective advantages of various pairs of symmetrical across-midline electrode sites for tracking IHRT?; and (3) what are the respective advantages of symmetrical vs. asymmetrical across-midline electrode site–pair configurations for tracking IHRT? There were significant lags attributable to IHRT in both evoked potential P1 latencies and in reaction times — but these were uncorrelated. The responding hand was not found to significantly modulate IHRT estimates derived from the P1 peak latency of response-corrected ERPs. Anterior sites yielded more precocious components and briefer estimates of IHRT which were closer to those observed in reaction time estimates. However, posterior leads yielded more reliable estimates. Various analyses suggested that IHRT can be tracked, very vaguely, with asymmetric configurations as well as symmetric ones, each for different reasons.

Reaction time performance following unilateral striatal dopamine depletion and lesions of the subthalamic nucleus in the rat

The akinesia resulting from Parkinson's disease or striatal dopamine depletion in experimental animals can be ameliorated or reversed by inactivation of the subthalamic nucleus. This inactivation might be effective by restoring balance to the basal ganglia motor circuits. Alternatively, new movement-related deficits might be introduced which mask the original impairments (e.g. hyperkinesia might replace hypokinesia). In the present study, striatal dopamine depletion was effected unilaterally, in order to dissociate generalized effects, e. g. hyperkinesia, from response-specific initiation effects. Rats were trained in a lateralized visual reaction time task and then assigned to one of four groups: striatal dopamine depletion; cell body lesion of the subthalamic nucleus; combined striatal dopamine depletion and subthalamic nucleus lesion; or control. As expected, rats with striatal dopamine depletion exhibited slower reaction time and a bias to respond to the ipsilateral side. The subthalamic nucleus lesion resulted in no reaction time change (in particular, there was no evidence of faster reaction times), but there was an increase in anticipatory responding. The group with the combined striatal dopamine depletion and subthalamic nucleus lesion had no reaction time impairment. This group showed an increase in anticipatory errors and a contralateral response bias. These data demonstrate that lesions of the subthalamic nucleus do not merely cancel the akinesia which follows striatal dopamine depletion by the addition of a hyperkinetic impairment. Rather, there appears to be a change in the balance of the motor system.

Development of inhibitory control across the life span.

The stop-signal procedure was used to examine the development of inhibitory control. A group of 275 participants, 6 to 81 years of age, performed a visual choice reaction time (go) task and attempted to inhibit their responses to the go task when they heard a stop signal. Reaction times to the stop and go signals were used to assess performance in inhibition and response execution, respectively. Results indicated the speed of stopping becomes faster with increasing age throughout childhood, with limited evidence of slowing across adulthood. By contrast, strong evidence was obtained for age-related speeding of go-signal reaction time throughout childhood, followed by marked slowing throughout adulthood. Hierarchical regression confirmed that the age-related change in inhibitory control could not be explained by general speeding or slowing of responses. Findings are discussed in regard to the contrast between the development of inhibition and response execution and the utility of the stop-signal procedure.

Neural mechanisms of involuntary attention to acoustic novelty and change.

Behavioral and event-related brain potential (ERP) measures were used to elucidate the neural mechanisms of involuntary engagement of attention by novelty and change in the acoustic environment. The behavioral measures consisted of the reaction time (RT) and performance accuracy (hit rate) in a forced-choice visual RT task where subjects were to discriminate between odd and even numbers. Each visual stimulus was preceded by an irrelevant auditory stimulus, which was randomly either a "standard" tone (80%), a slightly higher "deviant" tone (10%), or a natural, "novel" sound (10%). Novel sounds prolonged the RT to successive visual stimuli by 17 msec as compared with the RT to visual stimuli that followed standard tones. Deviant tones, in turn, decreased the hit rate but did not significantly affect the RT. In the ERPs to deviant tones, the mismatch negativity (MMN), peaking at 150 msec, and a second negativity, peaking at 400 msec, could be observed. Novel sounds elicited an enhanced N1, with a probable overlap by the MMN, and a large positive P3a response with two different subcomponents: an early centrally dominant P3a, peaking at 230 msec, and a late P3a, peaking at 315 msec with a right-frontal scalp maximum. The present results suggest the involvement of two different neural mechanisms in triggering involuntary attention to acoustic novelty and change: a transient-detector mechanism activated by novel sounds and reflected in the N1 and a stimulus-change detector mechanism activated by deviant tones and novel sounds and reflected in the MMN. The observed differential distracting effects by slightly deviant tones and widely deviant novel sounds support the notion of two separate mechanisms of involuntary attention.

Postural motor programming in paraplegic patients during rehabilitation

One of the basic aims in the rehabilitation of thoracic spinal cord injured (SCI) patients concerns the regaining of sitting posture control. This implies the development of new postural strategies requiring the adjustment of motor programming processes. The aim of this study was to investigate the time course of postural reorganization during active, clinical rehabilitation of thoracic SCI patients with different SCI levels. Thus changes in motor programming in sitting balance control were investigated in two groups of complete low or high thoracic SCI patients. At several stages during the rehabilitation process an experiment was held in which sitting posture was perturbed systematically using submaximal reaching movements over four reaching distances. This bimanual reaching task was presented as a visual precue choice reaction time (RT) task in which reaching distance (i.e. grade of postural perturbation) was precued. Results indicated that in both high and low thoracic SCI patients RTs in movements involving postural perturbation became shorter during the course of the rehabilitation period. However, low thoracic SCI patients were generally slower in the programming of balance perturbing movements than high thoracic SCI patients, a phenomenon that did not change over time. Furthermore, initial differences in RTs as a function of grade of postural perturbation disappeared in both groups in the course of the rehabilitation phase. Precue benefit, equally large for both groups, did not change as a function of rehabilitation time. It is concluded that the observed phenomena signify the gradual development of new central postural control processes in both SCI groups during rehabilitation. Low thoracic SCI patients, having more residual sensorimotor functions, seem to adopt more complex strategies in maintaining and restoring sitting balance that take longer to specify and to programme. High thoracic SCI patients seem to rely on simpler strategies using more passive postural support.

Unilateral Lesions of the Dorsal Striatum in Rats Disrupt Responding in Egocentric Space

Rats were trained in a specially designed, multichoice operant chamber on a visual choice reaction time task designed to assess performance on each side of the rat's body. The task required animals to sustain a nose poke in a central hole, until a brief light stimulus was presented in either of two holes that were located on the same side of the box. Once the rats were trained to perform the task to both sides independently they received unilateral injections of quinolinic acid into the dorsal striatum. Postoperatively, lesioned animals were impaired when performing the task on the side contralateral to the lesion. The time taken to initiate contralateral responses was increased. Contralateral responses were also exclusively biased toward the nearer of the two response locations, regardless of the location of the stimulus. This was interpreted as a specific impairment in generating responses in contralateral space. In contrast, no comparable deficit was seen when the animals performed the task on the side ipsilateral to the lesion. Additional postoperative challenges, in which response options were presented bilaterally, showed this response deficit to be defined in egocentric coordinates, with the severest response deficits for the most contralateral locations.

Deficits in response initiation, but not attention, following excitotoxic lesions of posterior parietal cortex in the rat

Damage to posterior parietal cortex in humans is known to cause hemineglect, and specifically difficulty in disengaging attention in tests of covert orienting. Aspirative lesions of a region of cortex in rats which is thought to be homologous to primate posterior parietal cortex has also been reported to cause what appears to be multimodal neglect. In order to make an assessment of the nature of this disorder, a variety of tests were employed: (1) a test of somatosensory neglect after Schallert et al. (Pharmacol. Biochem. Behav., 16 (1982) 455–462); (2) a skilled paw-reaching test after Whishaw et al. (Brain 109 (1986) 805–843); (3) a visual reaction time task with peripheral cues analogous to Posner's test of covert orienting (Q. J. Exp. Psychol., 32 (1980) 3–25). Following the posterior parietal lesion there was a global increase in reaction time of responses made contralateral to the lesion in the reaction time task, but there was no evidence of a deficit in covert orienting. There was also no evidence of somatosensory neglect. There was a decrease in the number of attempted reaches with the contralateral paw and a tendency to spend a smaller proportion of time in the contralateral half of the reaching cage.

Working memory impairments in traumatic brain injury: evidence from a dual-task paradigm

Although many individuals with traumatic brain injury (TBI) perform well on standard neuropsychological tests, they often exhibit marked functional difficulties. The functions which are impaired seem to be analogous to the role of the central executive system (CES) in Baddeley's [ Working Memory, 1986, Oxford University Press, New York] widely accepted model of working memory. The purpose of this study was to investigate CES function in individuals with TBI with a dual-task paradigm. We studied 25 non-demented persons who were at various stages in their recovery from severe TBI and compared their performance on a dual-task paradigm to a group of age-matched controls. Our dual-task paradigm measured performance on a simple visual reaction time task both alone (baseline) and during concurrent tasks of articulation or digit span. Subjects were also assessed with other neuropsychological tests of executive function. TBI patients had slower reaction times on the primary task when performed alone ( P < 0.05) and greater decrements in performance during dual-task conditions ( P < 0.01). They also exhibited significantly greater deficits than control subjects on other measures of executive function. Although correlations between dual-task performance and other executive measures were quite low, principle components analysis suggested that a common factor does exist between these measures. These findings support the conclusion that TBI patients have a working memory impairment that is due to dysfunction of the CES and which may be related to executive function deficits as measured by standard neuropsychological testing.

Unilateral striatal lesions impair response execution on a lateralised choice reaction time task

A novel lateralised reaction time task is described and used to evaluate the effects of d-amphetamine injections and unilateral dorso-striatal lesions in rats. The task involves a two-lever Skinner box adaptation of the nine-hole box visual choice reaction time task first developed by Carli et al. d-Amphetamine had a dose dependent effect on nearly all aspects of task performance. Low and the intermediate doses of d-amphetamine speeded reaction time and movement time, and abolished the delay-dependent pattern of responding in the task. The highest dose of amphetamine disrupted the animals' ability to perform reliably, the task contingencies. Unilateral lesions in the dorsal neostriatum resulted in an increase of error trials, produced a bias to respond towards the ipsilateral side, and decreased the accuracy of responding to contralateral stimuli. The overall mean reaction time to contralateral stimuli was not influenced by the lesions, but the movement time was increased selectively when responding to contralateral stimuli. The data suggest that striatal activation by amphetamine increases motor readiness, which can enhance reaction time performance at the cost of increased errors due to anticipation of cue presentation, in particular at long holding delays. Conversely, striatal lesions induce lateralised defects in executive, rather than sensory, processes, and impair the animals' ability to execute movement towards the contralateral side.

Role of the Striatum, Cerebellum, and Frontal Lobes in the Learning of a Visuomotor Sequence

This study was designed to examine the role of the striatum, cerebellum, and frontal lobes in the implicit learning of a visuomotor sequence. The performance of patients with idiopathic Parkinson's disease (PD), with damage to the cerebellum, or with a circumscribed lesion to the frontal lobes was thus compared to that of separate groups of matched normal control subjects on an adapted version of the Repeated Sequence Test. This paradigm consists of a visual reaction-time task with a fixed embedded sequence of finger movements to be performed based on presentation of visual stimuli. Subjects received four blocks of trials (i.e., 40 presentations of a 10-item sequence) per day over 6 training days. Following the last experimental session, subjects were also given two tests measuring their declarative knowledge of the sequence. Only PD patients with a bilateral striatal-dysfunction or patients with lesions to the cerebellum failed to improve their performance in the last three training sessions, hence suggesting an impairment late in the acquisition process. Further analyses revealed that such impairment was mainly implicit in nature, and that it could not be ascribed to a general decline in cognitive functioning, to mood disturbances, or to the severity of the motor symptoms. By contrast, the level of declarative knowledge of the sequence did not differ between the three clinical groups and their respective groups of normal subjects. These findings suggest that, unlike declarative memory, the incremental acquisition of a new visuomotor skill depends upon the integrity of both the striatum and the cerebellum, but not of the frontal lobes.

The Effects of Alpha-2 Agonist, Medetomidine and its Antagonist, Atipamezole on Reaction and Movement Times in a Visual Choice Reaction Time Task in Monkeys

Alpha-2 adrenoceptor agonists have been shown to improve the working memory task performance of aged monkeys. Suggestions offered to explain this finding include improved short-term memory processing, slight sedation, and decreased distractiveness. Although sedation is evident at high doses, it may also contribute to the working memory task performance at low doses. The aim of the present work was to find out whether the positive effects of an alpha-2 agonist, medetomidine, on working memory performance could be explained by its sedative effects. This was accomplished by measuring the reaction and movement times of monkeys performing a visual choice reaction time task under the influence of medetomidine or its antagonist atipamezole. In the task a trial began with the monkey holding a central pad. After a short period one of two lateral light emitting diodes was turned on for 300 ms and the monkeys were trained to release the central bar and touch either of the bars, situated below the diodes, depending on the location of the stimulus. The reaction and movement times were significantly longer than on saline control only at the highest dose of medetomidine (10.0 μg/kg). At the lowest dose of atipamezole (0.01 mg/kg), the reaction times were significantly shorter than on saline control. The results of this study demonstrate that low doses of medetomidine, which have earlier been shown to improve working memory performance, do not induce sedation as measured by reaction and movement times.

Facilitation effects of an auditory accessory stimulus on visual reaction time

Visual reaction time (RT) is reduced when the visual stimulus is paired with an auditory stimulus. This auditory stimulus is accessory in the sense that subjects need not to pay attention to it in the visual RT task. This study examined how the facilitation effect of the auditory accessory stimulus changes with varying the stimulus onset asynchrony (SOA) between the two stimuli, and their intensities. The results showed that RTs are reduced as the visual stimulus is preceded by the auditory stimulus. Furthermore, RTs are transiently reduced when the two stimuli are presented at the same time. The magnitude of this facilitation is directly proportional to the intensity of the auditory stimulus and is inversely proportional to that of the visual stimulus. These findings suggest that there are two different kinds of facilitation effects on visual RTs made by the auditory accessory stimulus.

The influence of cardiac phase on reaction time depending on heart period length and on stimulus and response laterality

The aim of this study was twofold: (1) to reinvestigate the question of cardiac cycle time effect on sensorimotor performance, and (2) to examine the dependence of this effect on stimulus and response laterality. Thirty-eight right-handed subjects performed a simple visual reaction time task, where stimuli were presented randomly to the right or to the left of the fixation point, or centrally. Half of the responses were given by the right hand, and the other half by the left hand. The stimuli occurred at either 150- or 600-msec delays from the R wave of the electrocardiogram, that is, during the systolic or diastolic part of the cardiac cycle, respectively. For right stimuli and right-hand responses, the reaction time was marginally longer for systolic than for diastolic stimuli. No such effect emerged for central and left stimuli and for left-hand responding. This result suggested—albeit weakly—that the sensorimotor functions of the left cerebral hemisphere might be influenced to a greater extent by the physiological changes accompanying cardiac activity than those of the right hemisphere. Additionally, it was shown that in females characterized by long heart periods, the reaction time was longer for stimuli presented during systole than for stimuli presented during diastole, but the opposite was true in females with short heart periods. In males, a similar but nonsignificant tendency was found. This result does not contradict the Laceys’ (1970) baroreceptor hypothesis. The limitations of this and similar approaches are discussed.

CNV, PINV and probe-evoked potentials in schizophrenics

Distractibility and temporal modulation of attention in schizophrenics were studied using a visual reaction time task with additional auditory probe stimuli during the forewarning period or between trials. The probes were thought to exert a distracting influence, especially on schizophrenics, and at the same time they generated auditory EPs which allowed to track the modulation of cortical excitability during response preparation. The midline distribution of the terminal contingent negative variation (tCNV) and the amplitude of the postimperative negative variation (PINV) were clearly different in 20 DSM III-R schizophrenics, as compared with 20 alcoholics and 20 normal controls. In schizophrenics, the more frontal distribution of the tCNV was associated with a higher degree of psychopathology (measured with the Brief Psychiatric Rating Scale) and with delayed reactions. Probes between trials reduced tCNV and PINV in all subjects alike. However, this effect could not be attributed to distraction, because reaction times were faster in these trials, possibly due to an alerting effect of the auditory probes. The N100 and P300 amplitudes to probes in the forewarning period, i.e., during the negative potential shift of the CNV, were significantly enhanced in all groups. Apparently there is a state of increased cortical excitability during the CNV which is not selectively “tuned” toward relevant stimuli. In schizophrenia, the temporal and topographical regulation of this excitability is disturbed.