Trial-to-trial adjustments of speed-accuracy trade-offs in premotor and primary motor cortex.

Recent studies have shown that activity in sensorimotor structures varies depending on the speed-accuracy trade-off (SAT) context in which a decision is made. Here we tested the hypothesis that the same areas also reflect a more local adjustment of SAT established between individual trials, based on the outcome of the previous decision. Two monkeys performed a reaching decision task in which sensory evidence continuously evolves during the time course of a trial. In two SAT contexts, we compared neural activity in trials following a correct choice vs. those following an error. In dorsal premotor cortex (PMd), we found that 23% of cells exhibited significantly weaker baseline activity after error trials, and for ∼30% of these this effect persisted into the deliberation epoch. These cells also contributed to the process of combining sensory evidence with the growing urgency to commit to a choice. We also found that the activity of 22% of PMd cells was increased after error trials. These neurons appeared to carry less information about sensory evidence and time-dependent urgency. For most of these modulated cells, the effect was independent of whether the previous error was expected or unexpected. We found similar phenomena in primary motor cortex (M1), with 25% of cells decreasing and 34% increasing activity after error trials, but unlike PMd, these neurons showed less clear differences in their response properties. These findings suggest that PMd and M1 belong to a network of brain areas involved in SAT adjustments established using the recent history of reinforcement. NEW & NOTEWORTHY: Setting the speed-accuracy trade-off (SAT) is crucial for efficient decision making. Previous studies have reported that subjects adjust their SAT after individual decisions, usually choosing more conservatively after errors, but the neural correlates of this phenomenon are only partially known. Here, we show that neurons in PMd and M1 of monkeys performing a reach decision task support this mechanism by adequately modulating their firing rate as a function of the outcome of the previous decision.

Eye-to-Hand Coordination in Obstructive Sleep APNEA Syndrome: a Descriptive Study.

OBJECTIVE: Psychomotor slowdown was observed in individuals with Obstructive Sleep Apnea Syndrome (OSAS). Previous studies evaluated separately cognitive and motor reaction times, finding that OSAS individuals show a specific impairment in the latter. The present study investigates whether eye-to-hand coordination (EHC), a specific psychomotor ability, is compromised in OSAS. METHOD: The EHC was measured in 30 OSAS individuals who were matched with 30 healthy controls by the Two-Hand Coordination Test analyzing the speed, accuracy, and coordination; the role of these variables was investigated in predicting the group they belonged to. RESULTS: The OSAS participants showed poorer performance in the execution accuracy (t(55) = -3.36, d'Cohen = -0.89, p ≤ .001), which was also found to be the only predictor of the belonging to group (ß = 0.43 (0.18), p < .05). CONCLUSIONS: The OSAS individuals show impairments in EHC and in correcting their error (executive slowdown). This is the first investigation exploring EHC coordination in this population and contributes in understanding the psychomotor slowness characterizing OSAS.

Your error in my hand: An investigation of observational posterror slowing.

For human beings, monitoring others' errors is essential for efficient goal-directed behavior. Indeed, the mere observation of other individuals' errors provides a rich source of information that can be used to avoid potential errors and improve our performance without direct experience. Recent studies have outlined that vicarious experience of errors influences the observer's overt behavior. This observational posterror slowing (oPES) is supposed to reflect a strategic increase in control aimed at reducing the probability of an error. Because the consequences of error observation have been exclusively investigated by means of arbitrary button-press responses, which limit the investigation to premovement processes, it is unclear whether the observation of an error also influences the online control of goal-directed actions. In the present study, for the first time, we investigated the effect of error observation on the reach-to-grasp movement by means of kinematical analysis. The results revealed that error-observation effects are not confined to premovement processes-they also strategically affect spatial movement trajectories. Our findings add substantially to previous literature, showing that the oPES spreads to movement execution when a more realistic, ecologically valid task is employed.

Response time distribution parameters show posterror behavioral adjustment in mental arithmetic.

After making an error, we usually slow down before our next response. This phenomenon is known as the posterror slowing (PES) effect. It has been interpreted to be an indicator of posterror behavioral adjustments and, therefore, has been linked to cognitive control. However, contradictory findings regarding PES and posterror accuracy cast doubt on such a relation. To determine whether behavior is adjusted after making an error, we investigated other features of behavior, such as the distribution of response times (RT) in a mental arithmetic task. Participants performed an arithmetic task with (Experiments 1 and 2) and without (Experiment 1) an accuracy-tracking procedure. On both tasks, participants responded more slowly and less accurately after errors. However, the RT distribution was more symmetrical on posterror trials compared to postcorrect trials, suggesting that a change in processing mode occurred after making an error, thus linking cognitive control to error monitoring, even in cases when accuracy decreased after errors. These findings expand our understanding on how posterror behavior is adjusted in mental arithmetic, and we propose that the measures of the RT distribution can be further used in other domains of error-monitoring research.

The cost of errors: Perceived error detection in dual-task conditions.

Detecting that an error has been made can be crucial for the implementation of appropriate behavioral adjustments. Brain imaging studies indicate that error detection is not limited to response errors and that similar mechanisms are engaged even when behavioral control is not needed. The current study examines whether perceived error detection - the detection of erroneous stimuli that violate our expectations - requires central resources. In two experiments - using a dual-task design - we show that perceived error detection in the first task creates a bottleneck in information processing and delays the response selection of the second task. The results suggest that the requirement for central cognitive resources is a general feature of error detection because it is present even when the demand for behavioral control is low.