This study assessed the effects of an aerobic training program on reaction time tasks that manipulated preparatory intervals (PI) to produce temporal preparation effects using short (1, 3, 5 s) and long (5, 7, 9 s) PI. Older adults were assigned to either a 3-month aerobic training group or to a control group. Individuals in the training group participated in an aerobic training program of three 60-min sessions per week. The control group did not receive any training. Results indicated that 12 weeks of aerobic training induced a significant improvement in cardiorespiratory capacity (VO2max estimate). All participants who completed the aerobic program showed improvement after training in the choice RT task, along with enhanced preparation, such that they maintained preparation over time more efficiently after the training program. Moreover, enhanced ability to use the short PI was observed but only in lower fit individuals. Results of the present study suggest that improving aerobic fitness may enhance attentional control mechanisms in older adults.
aging; aerobic training; task complexity; response preparation
The ability to voluntarily inhibit a single response is evident early in development, even as the ability to maintain an inhibitory “task set” continues to improve. To date, functional neuroimaging studies have detailed developmental changes in systems supporting inhibitory control exerted at the single-trial level, but changes underlying the ability to maintain an inhibitory task set remain little understood. Here we present findings from a functional magnetic resonance imaging (fMRI) study that characterizes the development of systems supporting both transient (trial-related) and sustained (task-set-related) activation during performance of the antisaccade (AS) task—an oculomotor test of inhibitory control (Hallett, 1978). Transient activation decreased from childhood to adolescence in regions known to support inhibitory processes and oculomotor control, likely reflecting less effortful response production. In contrast, sustained activation increased to adulthood in regions implicated in control. Our results suggest that development of the ability to maintain a task set is primary to the maturation of inhibitory control, and further, that this ability is still immature in adolescence.
Development; Cognition; Inhibition; Control; Eye movement; Oculomotor; Prefrontal cortex; fMRI
This study investigated the preparatory control of motor inhibition and motor execution using a stop signal task (SST) and functional magnetic resonance imaging (fMRI). In the SST, a frequent “go” signal triggered a prepotent response and a less frequent “stop” signal prompted the inhibition of this response. Preparatory control of motor inhibition and execution in the stop signal trials were examined by contrasting brain activation between stop success and stop error trials during the fore-period, in which participants prepared to respond to go or to stop. Results from 91 healthy adults showed greater activation in the right prefrontal cortex and inferior parietal lobule during preparatory motor inhibition. Preparatory motor execution activated bilateral putamen, primary motor cortices, posterior cingulate cortex, ventromedial prefrontal cortex, and superior temporal/intraparietal sulci. Furthermore, the extents of these inhibition and execution activities were inversely correlated across subjects. On the basis of a median split of the stop signal reaction time (SSRT), subjects with short SSRT showed greater activity in the right orbital frontal cortex during preparatory inhibition. These new findings suggest that the go and stop processes interact prior to target presentation in the SST, in accord with recent computational models of stop signal inhibition.
stop signal; inhibitory control; proactive; prefrontal; race model; go/no-go
The motor cortices are active during both movement and movement preparation. A common assumption is that preparatory activity constitutes a sub-threshold form of movement activity: a neuron active during rightwards movements becomes modestly active during preparation of a rightwards movement. We asked whether this pattern of activity is in fact observed. We found that it was not: at the level of a single neuron, preparatory tuning was weakly correlated with movement-period tuning. Yet somewhat paradoxically, preparatory tuning could be captured by a preferred direction in an abstract ‘space’ that described the population-level pattern of movement activity. In fact, this relationship accounted for preparatory responses better than did traditional tuning models. These results are expected if preparatory activity provides the initial state of a dynamical system whose evolution produces movement activity. Our results thus suggest that preparatory activity may not represent specific factors, and may instead play a more mechanistic role.
Response inhibition, or the suppression of prepotent but contextually inappropriate behaviors, is essential to adaptive, flexible responding. Individuals with autism spectrum disorders (ASD) consistently show deficient response inhibition during antisaccades. In our prior functional MRI study, impaired antisaccade performance was accompanied by reduced functional connectivity between the frontal eye field (FEF) and dorsal anterior cingulate cortex (dACC), regions critical to volitional ocular motor control. Here we employed magnetoencephalography (MEG) to examine the spectral characteristics of this reduced connectivity. We focused on coherence between FEF and dACC during the preparatory period of antisaccade and prosaccade trials, which occurs after the presentation of the task cue and before the imperative stimulus. We found significant group differences in alpha band mediated coherence. Specifically, neurotypical participants showed significant alpha band coherence between the right inferior FEF and right dACC and between the left superior FEF and bilateral dACC across antisaccade, prosaccade, and fixation conditions. Relative to the neurotypical group, ASD participants showed reduced coherence between these regions in all three conditions. Moreover, while neurotypical participants showed increased coherence between the right inferior FEF and the right dACC in preparation for an antisaccade compared to a prosaccade or fixation, ASD participants failed to show a similar increase in preparation for the more demanding antisaccade. These findings demonstrate reduced long-range functional connectivity in ASD, specifically in the alpha band. The failure in the ASD group to increase alpha band coherence with increasing task demand may reflect deficient top-down recruitment of additional neural resources in preparation to perform a difficult task.
Autism; ASD; Connectivity; Alpha Synchrony; MEG
Attentional control involves the ability to allocate preparatory attention to improve subsequent stimulus processing and response selection. There is behavioral evidence to support the hypothesis that increased expectancy of stimulus and response conflict may decrease the subsequent experience of conflict during task performance. We used a cued Flanker and event-related fMRI design to separate processes involved in preparation from those involved in resolving conflict, and to identify the brain systems involved in these processes as well as the association between preparatory activity levels and activity related to subsequent conflict processing. Our results demonstrate that preparatory attentional allocation following a cue to the upcoming level of conflict is mediated by a network involving Dorsolateral Prefrontal Cortex (DLPFC) and the Intraparietal Sulcus (IPS). Informed preparation for conflict processing was associated with decreased Anterior Cingulate Cortex/preSupplementary Motor Area (ACC/preSMA) and IPS activity during the flanker target presentation, supporting their roles in conflict processing and visuospatial attention during the flanker task. Ventrolateral Prefrontal Cortex/Orbitofrontal Cortex (VLPFC/OFC) was active when specific strategic task rule and outcome information was available.
The goals of the study were to examine inhibitory deficits on the antisaccade task in 8- to 20-year olds with youth-onset psychosis or attention deficit/hyperactivity disorder (ADHD) and healthy controls and to examine if age-related changes in performance differed across groups. In addition to the conventional measures of performance, pupillary dilations were used to obtain estimates of phasic and tonic level of arousal. Results showed that the psychosis, but not the ADHD, group had elevated antisaccade error rates; however, variability of error rates was high in all groups. These inhibitory failures were accompanied by a lower level of momentary cognitive effort (as indexed by pupillary dilations). The largest differences between the control and clinical groups were found not in the expected indices of inhibition but in the probability of correcting inhibitory errors and in variability of antisaccade response times, which were correlated with each other. These findings did not appear to be attributable to a deficit in maintaining task instructions in mind in either disorder or lack of motivation in ADHD. Instead, results point to impairments in both clinical groups in sustaining attention on a trial-by-trial basis, resulting in deficits in self-monitoring. Thus, results show inhibitory deficits in the context of more general attentional impairments in both disorders.
schizophrenia; antisaccades; inhibition; pupillometry; eye movements
The authors used a predictable, externally cued task-switching paradigm
to investigate executive control in a severe closed-head injury (CHI)
population. Eighteen individuals with severe CHI and 18 controls switched
between classifying whether a digit was odd or even and whether a letter was a
consonant or vowel on every 4th trial. The target stimuli appeared in a circle
divided into 8 equivalent parts. Presentation of the stimuli rotated clockwise.
Participants performed the switching task at both a short (200 ms) and a long
(1,000 ms) preparatory interval. Although the participants with CHI exhibited
slower response times and greater switch costs, similar to controls, additional
preparatory time reduced the switch costs, and the switch costs were limited to
the 1st trial in the run. These findings indicate that participants with severe
CHI were able to take advantage of time to prepare for the task switch, and the
executive control processes involved in the switch costs were completed before
the 1st trial of the run ended.
closed-head injury; traumatic brain injury; executive functions; task switching; set shifting
The nature of immature reward processing and the influence of rewards on basic elements of cognitive control during adolescence are currently not well understood. Here, during functional magnetic resonance imaging, healthy adolescents and adults performed a modified antisaccade task in which trial-by-trial reward contingencies were manipulated. The use of a novel fast, event-related design enabled developmental differences in brain function underlying temporally distinct stages of reward processing and response inhibition to be assessed. Reward trials compared with neutral trials resulted in faster correct inhibitory responses across ages and in fewer inhibitory errors in adolescents. During reward trials, the blood oxygen level–dependent signal was attenuated in the ventral striatum in adolescents during cue assessment, then overactive during response preparation, suggesting limitations during adolescence in reward assessment and heightened reactivity in anticipation of reward compared with adults. Importantly, heightened activity in the frontal cortex along the precentral sulcus was also observed in adolescents during reward-trial response preparation, suggesting reward modulation of oculomotor control regions supporting correct inhibitory responding. Collectively, this work characterizes specific immaturities in adolescent brain systems that support reward processing and describes the influence of reward on inhibitory control. In sum, our findings suggest mechanisms that may underlie adolescents’ vulnerability to poor decision-making and risk-taking behavior.
adolescence; antisaccade; fMRI; response inhibition; reward
The ability to voluntarily inhibit responses to task irrelevant stimuli, which is a fundamental component of cognitive control, has a protracted development through adolescence. Prior human developmental imaging studies have found immaturities in localized brain activity in children and adolescents. However, little is known about how these regions integrate with age to form the distributed networks known to support cognitive control. In the present study, we used Granger Causality analysis to characterize developmental changes in effective connectivity underlying inhibitory control (antisaccade task) compared to reflexive responses (prosaccade task) in human participants. By childhood few top-down connectivity were evident with increased parietal interconnectivity. By adolescence connections from prefrontal cortex increased and parietal interconnectivity decreased in number. From adolescence to adulthood there was evidence of increased number and strength of frontal connections to cortical regions as well as subcortical regions. Taken together, results suggest that developmental improvements in inhibitory control may be supported by age related enhancements in top-down effective connectivity between frontal, oculomotor and subcortical regions.
Development; Cognitive Control; Oculomotor; connectivity; fMRI
Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that starts in childhood and frequently persists in adults. Several theories postulate deficits in ADHD that have effects across many executive functions or in more narrowly defined aspects, such as response inhibition. Electrophysiological studies on children, however, indicate that ADHD is not associated with a core deficit of response inhibition, as abnormal inhibitory processing is typically preceded or accompanied by other processing deficits. It is not yet known if this pattern of abnormal processing is evident in adult ADHD.
The objective of this paper was to investigate event-related potential indices of preparatory states and subsequent response inhibition processing in adults with ADHD. Two cued continuous performance tasks were presented to 21 adults meeting current criteria for adult ADHD and combined type ADHD in childhood, and 20 controls.
The ADHD group exhibited significantly weaker orienting attention to cues, cognitive preparation processes and inhibitory processing. In addition, we observed a strong correlation between the resources allocated to orienting to cues and the strength of the subsequent response strength control processes, suggesting that orienting deficits partly predict and determine response control deficits in ADHD.
These findings closely resemble those previously found in children with ADHD, which indicate that there is not a core response inhibition deficit in ADHD. These findings therefore suggest the possibility of developmental stability into adulthood of the underlying abnormal processes in ADHD.
Optimizing outcomes involves rapidly and continuously adjusting behavior based on context. While most behavioral studies focus on immediate task conditions, responses to events are also influenced by recent history. We used magnetoencephalography and a saccadic paradigm to investigate the neural bases of 2 trial history effects that are well characterized in the behavioral eye movement literature: task-switching and the prior-antisaccade effect. We found that switched trials were associated with increased errors and transient increases in activity in the frontal eye field (FEF) and anterior cingulate cortex early in the preparatory period. These activity changes are consistent with active reconfiguration of the task set, a time-limited process that is triggered by the instructional cue. Following an antisaccade versus prosaccade, there was increased activity in the FEF and prefrontal cortex that persisted into the preparatory period of the subsequent trial, and saccadic latencies were prolonged. We attribute these effects to persistent inhibition of the ocular motor response system from the prior antisaccade. These findings refine our understanding of how trial history interacts with current task demands to adjust responses. Such dynamic modulations of neural activity and behavior by recent experience are at the heart of adaptive flexible behavior.
antisaccade; frontal eye field; magnetoencephalography; saccade; task-switching
The generation of saccades is influenced by the level of "preparatory set activity" in cortical oculomotor areas. This preparatory activity can be examined using the gap-paradigm in which a temporal gap is introduced between the disappearance of a central fixation target and the appearance of an eccentric target.
Ten healthy subjects made horizontal pro- or antisaccades in response to lateralized cues after a gap period of 200 ms. Single-pulse transcranial magnetic stimulation (TMS) was applied to the dorsolateral prefrontal cortex (DLPFC), frontal eye field (FEF), or supplementary eye field (SEF) of the right hemisphere 100 or 200 ms after the disappearance of the fixation point. Saccade latencies were measured to probe the disruptive effect of TMS on saccade preparation. In six individuals, we gave realistic sham TMS during the gap period to mimic auditory and somatosensory stimulation without stimulating the cortex.
TMS to DLPFC, FEF, or SEF increased the latencies of contraversive pro- and antisaccades. This TMS-induced delay of saccade initiation was particularly evident in conditions with a relatively high level of preparatory set activity: The increase in saccade latency was more pronounced at the end of the gap period and when participants prepared for prosaccades rather than antisaccades. Although the "lesion effect" of TMS was stronger with prefrontal TMS, TMS to FEF or SEF also interfered with the initiation of saccades. The delay in saccade onset induced by real TMS was not caused by non-specific effects because sham stimulation shortened the latencies of contra- and ipsiversive anti-saccades, presumably due to intersensory facilitation.
Our results are compatible with the view that the "preparatory set" for contraversive saccades is represented in a distributed cortical network, including the contralateral DLPFC, FEF and SEF.
Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental disorder that starts in childhood and frequently persists in adults. In a comparison of adults with ADHD and a matched control sample, we previously showed that abnormal inhibitory processing is typically preceded or accompanied by other processing deficits in adult ADHD. We now compare these data further to additional data from first-degree relatives (fathers) of children with ADHD to identify whether this pattern of abnormal processing shares familial influences with ADHD in adults.
Using a family design, we compared 20 fathers of children with the combined subtype of ADHD with 21 adults with ADHD combined subtype and 20 controls in event-related potential indices of preparatory states and subsequent response inhibition processing as elicited by a cued continuous performance task.
Fathers of children with ADHD exhibited significantly weaker orienting attention to cues and inhibitory processing than the controls but not the ADHD sample.
These findings provide evidence for the familial association of attentional orienting and response inhibition processes with ADHD in adults and indicate a familial and neurobiological link between ADHD in children and adults.
Inhibitory mechanisms are critically involved in goal-directed behaviors. To gain further insight into how such mechanisms shape motor representations during response preparation, motor evoked potentials (MEPs) elicited by transcranial magnetic stimulation (TMS) and H-reflexes were recorded from left hand muscles during choice reaction time tasks. The imperative signal, which indicated the required response, was always preceded by a preparatory cue. During the post-cue delay period, left MEPs were suppressed when the left hand had been cued for the forthcoming response, suggestive of a form of inhibition specifically directed at selected response representations. H-reflexes were also suppressed on these trials, indicating that the effects of this inhibition extend to spinal circuits. In addition, left MEPs were suppressed when the right hand was cued, but only when left hand movements were a possible response option before the onset of the cue. Notably, left hand H-reflexes were not modulated on these trials, consistent with a cortical locus of inhibition that lowers the activation of task-relevant, but non-selected responses. These results suggest the concurrent operation of two inhibitory mechanisms during response preparation: one decreases the activation of selected responses at the spinal level, helping to control when selected movements should be initiated by preventing their premature release; a second, upstream mechanism helps to determine what response to make during a competitive selection process.
cognitive control; competition; corticospinal excitability; decision-making; response selection; transcranial magnetic stimulation; H-reflex
Advance preparation has been shown to improve the efficiency of conflict resolution. Yet, with little empirical work directly linking preparatory neural activity to the performance benefits of advance cueing, it is not clear whether this relationship results from preparatory activation of task-specific networks, or from activity associated with general alerting processes. Here, fMRI data were acquired during a spatial Stroop task in which advance cues either informed subjects of the upcoming relevant feature of conflict stimuli (spatial or semantic) or were neutral. Informative cues decreased reaction time (RT) relative to neutral cues, and cues indicating that spatial information would be task-relevant elicited greater activity than neutral cues in multiple areas, including right anterior prefrontal and bilateral parietal cortex. Additionally, preparatory activation in bilateral parietal cortex and right dorsolateral prefrontal cortex predicted faster RT when subjects responded to spatial location. No regions were found to be specific to semantic cues at conventional thresholds, and lowering the threshold further revealed little overlap between activity associated with spatial and semantic cueing effects, thereby demonstrating a single dissociation between activations related to preparing a spatial versus semantic task-set. This relationship between preparatory activation of spatial processing networks and efficient conflict resolution suggests that advance information can benefit performance by leading to domain-specific biasing of task-relevant information.
attention; cognitive control; advance preparation; feature biasing; conflict; Stroop
Prospective memory (PM) research typically examines the ability to remember to execute delayed intentions but often ignores the ability to forget finished intentions. We had participants perform (or not perform; control group) a PM task and then instructed them that the PM task was finished. We later (re)presented the PM cue. Approximately 25% of participants made a commission error, the erroneous repetition of a PM response following intention completion. Comparisons between the PM groups and control group suggested that commission errors occurred in the absence of preparatory monitoring. Response time analyses additionally suggested that some participants experienced fatigue across the ongoing task block, and those who did were more susceptible to making a commission error. These results supported the hypothesis that commission errors can arise from the spontaneous retrieval of finished intentions and possibly the failure to exert executive control to oppose the PM response.
Prospective memory; commission errors; spontaneous retrieval; fatigue; forgetting; executive control
Cognitive control is required for correct performance on antisaccade tasks, including the ability to inhibit an externally driven ocular motor repsonse (a saccade to a peripheral stimulus) in favor of an internally driven ocular motor goal (a saccade directed away from a peripheral stimulus). Healthy humans occasionally produce errors during antisaccade tasks, but the mechanisms associated with such failures of cognitive control are uncertain. Most research on cognitive control failures focuses on post-stimulus processing, although a growing body of literature highlights a role of intrinsic brain activity in perceptual and cognitive performance. The current investigation used dense array electroencephalography and distributed source analyses to examine brain oscillations across a wide frequency bandwidth in the period prior to antisaccade cue onset. Results highlight four important aspects of ongoing and preparatory brain activations that differentiate error from correct antisaccade trials: (i) ongoing oscillatory beta (20–30Hz) power in anterior cingulate prior to trial initiation (lower for error trials), (ii) instantaneous phase of ongoing alpha-theta (7Hz) in frontal and occipital cortices immediately before trial initiation (opposite between trial types), (iii) gamma power (35–60Hz) in posterior parietal cortex 100 ms prior to cue onset (greater for error trials), and (iv) phase locking of alpha (5–12Hz) in parietal and occipital cortices immediately prior to cue onset (lower for error trials). These findings extend recently reported effects of pre-trial alpha phase on perception to cognitive control processes, and help identify the cortical generators of such phase effects.
antisaccades; alpha; phase; frontal; parietal; EEG
We investigated whether attention shifts and eye movement preparation are mediated by shared control mechanisms, as claimed by the premotor theory of attention. ERPs were recorded in three tasks where directional cues presented at the beginning of each trial instructed participants to direct their attention to the cued side without eye movements (Covert task), to prepare an eye movement in the cued direction without attention shifts (Saccade task) or both (Combined task). A peripheral visual Go/Nogo stimulus that was presented 800 ms after cue onset signalled whether responses had to be executed or withheld. Lateralised ERP components triggered during the cue–target interval, which are assumed to reflect preparatory control mechanisms that mediate attentional orienting, were very similar across tasks. They were also present in the Saccade task, which was designed to discourage any concomitant covert attention shifts. These results support the hypothesis that saccade preparation and attentional orienting are implemented by common control structures. There were however systematic differences in the impact of eye movement programming and covert attention on ERPs triggered in response to visual stimuli at cued versus uncued locations. It is concluded that, although the preparatory processes underlying saccade programming and covert attentional orienting may be based on common mechanisms, they nevertheless differ in their spatially specific effects on visual information processing.
Spatial attention; Eye movements; Attentional control; Vision; Event-related brain potentials
We investigated whether attention shifts and eye movement preparation are mediated by shared control mechanisms, as claimed by the premotor theory of attention. ERPs were recorded in three tasks where directional cues presented at the beginning of each trial instructed participants to direct their attention to the cued side without eye movements (Covert task), to prepare an eye movement in the cued direction without attention shifts (Saccade task), or both (Combined task). A peripheral visual Go/Nogo stimulus that was presented 800 ms after cue onset signalled whether responses had to be executed or withheld. Lateralised ERP components triggered during the cue-target interval, which are assumed to reflect preparatory control mechanisms that mediate attentional orienting, were very similar across tasks. They were also present in the Saccade task, which was designed to discourage any concomitant covert attention shifts. These results support the hypothesis that saccade preparation and attentional orienting are implemented by common control structures. There were however systematic differences in the impact of eye movement programming and covert attention on ERPs triggered in response to visual stimuli at cued versus uncued locations. It is concluded that although the preparatory processes underlying saccade programming and covert attentional orienting may be based on common mechanisms, they nevertheless differ in their spatially specific effects on visual information processing.
Spatial attention; Eye movements; Attentional control; Vision; Event-related brain potentials
The human orbitofrontal cortex (OFC) plays a critical role in adapting behavior according to the context provided by expected outcomes of actions. However, several aspects of this function are still poorly understood. In particular, it is unclear to what degree any subdivisions of the OFC are specifically engaged when negatively valenced outcomes are expected, and to what extent such areas might be involved in preparatory active control of behavior. We examined these issues in two complementary functional magnetic resonance imaging (fMRI) studies in which we simultaneously and independently manipulated monetary incentives for correct performance, and demands for active preparation of cognitive control. In both experiments, preparation for performance was associated with lateral PFC activity in response to high incentives, regardless of their valence, as well as in response to increased task demands. In contrast, areas of the OFC centered around the lateral orbital sulcus responded maximally to negatively perceived prospects, even when such prospects were associated with decreases in preparatory cognitive control. These results provide direct support for theoretical models which posit that the OFC contributes to behavioral regulation by representing the value of anticipated outcomes, but does not implement active control aimed at avoiding or pursuing outcomes. Furthermore, they provide additional converging evidence that the lateral OFC is involved in representing specifically the affective impact of anticipated negative outcomes.
reward; cognitive control; prefrontal cortex; inhibition; incentives
Movements are universally, sometimes frustratingly, variable. When such variability causes error, we typically assume that something went wrong during the movement. The same assumption is made by recent and influential models of motor control. These posit that the principal limit on repeatable performance is neuro-muscular noise that corrupts movement as it occurs. An alternative hypothesis is that movement variability arises before movements begin, during motor preparation. We examined this possibility directly by recording the preparatory activity of single cortical neurons during a highly-practiced reach task. Small variations in preparatory neural activity were predictive of small variations in the upcoming reach. Effect magnitudes were such that at least half of the observed movement variability likely had its source during motor preparation. Thus, even for a highly-practiced task, the ability to repeatedly plan the same movement limits our ability to repeatedly execute the same movement.
The neural mechanisms underlying different forms of preparatory control were examined using event-related fMRI. Preparatory brain activation was monitored in relation to different types of advance information: (1) random task cues indicating which of two possible tasks to perform upon subsequent target presentation, (2) task-ambiguous target stimuli, or 3) targets for which the correct response could be pre-determined. Three types of activation pattern were observed in different brain regions. First, more posterior regions of lateral prefrontal cortex (LPFC) and parietal cortex were activated by both advance task cues and advance targets, but with increased and more sustained activation for the latter. Second, more anterior regions of LPFC and parietal cortex were selectively activated by advance targets. Importantly, in these regions preparatory activation was not further modulated by the availability of advance response information. In contrast, preparatory activation in a third set of brain regions, including medial frontal cortex, reflected the utilization of advance response information, but by only a subset of participants. These results suggest three types of preparatory control: attentional (stimulus-oriented), intentional (action-oriented), and a possibly strategic component that might determine inter-individual differences in response readiness. Notably, the absence of regions selectively or even preferentially activated during cue-based preparation argues against certain conceptualizations of task-selective attention under cued task switching conditions.
The human cognitive system is equipped with various processes for dealing with everyday challenges. One of such processes is the inhibition of currently irrelevant goals or mental task-sets, which can be seen as a response to the critical event of information overflow in the cognitive system and challenging the cognitive system’s ability to keep track of ongoing demands. In two experiments, we investigate the flexibility of the inhibitory process by inserting rare non-critical events (25% of all trials), operationalized as univalent stimuli (i.e., unambiguous stimuli that call for only one specific task in a multitasking context), and by introducing the possibility to prepare for an upcoming task (Experiment 2). We found that the inhibitory process is not influenced by a cue informing subjects about the upcoming occurrence of a univalent stimulus. However, the introduction of univalent stimuli allowed preparatory processes to modify the impact of the inhibitory process. Therefore, our results suggest that inhibitory processes are engaged in a rather global manner, not taking into account variations in stimulus valence, which we took as operationalization of critical, conflict-inducing events in the ongoing stream of information processing. However, rare uncritical events, such as univalent stimuli that do not cause conflict and interference in the processing stream, appear to alter the way the cognitive system can take advantage of preparatory processes.
cognitive control; multitasking; interference
We investigated whether both the contingent negative variation (CNV), an event-related potential index of preparatory brain activity, and event-related oscillatory EEG activity differentiated Go and NoGo trials in a delayed response task. CNV and spectral power (4–100 Hz) were calculated from EEG activity in the preparatory interval in 16 healthy adult participants. As previously reported, CNV amplitudes were higher in Go compared to NoGo trials. In addition, event-related spectral power of the Go condition was reduced in the theta to low gamma range compared to the NoGo condition, confirming that preparing to respond is associated with modulation of event-related spectral activity as well as the CNV. Altogether, the impact of the experimental manipulation on both slow event-related potentials and oscillatory EEG activity may reflect coordinated dynamic changes in the excitability of distributed neural networks involved in preparation.