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BackgroundInhibitory control, or the ability to suppress planned but inappropriate prepotent actions in the current environment, plays an important role in the control of human performance. Evidence from empirical studies utilizing a sport-specific design has shown that athletes have superior inhibitory control. However, less is known about whether this superiority might (1) still be seen in a general cognitive task without a sport-related context; (2) be modulated differentially by different sporting expertise (e.g., tennis versus swimming).Methodology/Principal FindingsHere we compared inhibitory control across tennis players, swimmers and sedentary non-athletic controls using a stop-signal task without a sport-specific design. Our primary finding showed that tennis players had shorter stop-signal reaction times (SSRTs) when compared to swimmers and sedentary controls, whereas no difference was found between swimmers and sedentary controls. Importantly, this effect was further confirmed after considering potential confounding factors (e.g., BMI, training experience, estimated levels of physical activity and VO2max), indicative of better ability to inhibit unrequired responses in tennis players.Conclusions/SignificanceThis suggests that fundamental inhibitory control in athletes can benefit from open skill training. Sport with both physical and cognitive demands may provide a potential clinical intervention for those who have difficulties in inhibitory control.

The limits of human visual short-term memory (VSTM) have been well documented, and recent neuroscientific studies suggest that VSTM performance is associated with activity in the posterior parietal cortex. Here we show that artificially elevating parietal activity via positively charged electric current through the skull can rapidly and effortlessly improve people's VSTM performance. This artificial improvement, however, comes with an interesting twist: it interacts with people's natural VSTM capability such that low performers who tend to remember less information benefitted from the stimulation, whereas high performers did not. This behavioral dichotomy is explained by event-related potentials around the parietal regions: low performers showed increased waveforms in N2pc and contralateral delay activity (CDA), which implies improvement in attention deployment and memory access in the current paradigm, respectively. Interestingly, these components are found during the presentation of the test array instead of the retention interval, from the parietal sites ipsilateral to the target location, thus suggesting that transcranial direct current stimulation (tDCS) was mainly improving one's ability to suppress no-change distractors located on the irrelevant side of the display during the comparison stage. The high performers, however, did not benefit from tDCS as they showed equally large waveforms in N2pc and CDA, or SPCN (sustained parietal contralateral negativity), before and after the stimulation such that electrical stimulation could not help any further, which also accurately accounts for our behavioral observations. Together, these results suggest that there is indeed a fixed upper limit in VSTM, but the low performers can benefit from neurostimulation to reach that maximum via enhanced comparison processes, and such behavioral improvement can be directly quantified and visualized by the magnitude of its associated electrophysiological waveforms.

Transcranial magnetic stimulation (TMS) is now widely used as a 'virtual' lesion paradigm to investigate behavioural functions, but the mechanisms through which it influences neural processing are unclear. To understand the differential effects of TMS on spatially overlapping populations of neurons we manipulated the relative activity levels of visual neurons by adapting subjects to a range of visual stimuli. By applying TMS to the visual cortex representing the central visual field we have shown in two experiments that the behavioural and perceptual effects of TMS depend on the state of adaptation of the neural population stimulated by TMS. Specifically, we have demonstrated that within the stimulated area TMS perceptually facilitates the attributes encoded by the less active neural population. We have demonstrated the generality of this principle for both suprathreshold and subthreshold TMS as well as for colour and orientation-contingent colour using both subjective reports and psychophsyical measures. These findings can explain how TMS disrupts cognitive functions and therefore have implications for all studies which use TMS to disrupt behaviour.

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Recent physiological recording studies in monkeys have suggested that the frontal eye fields (FEFs) are involved in visual scene analysis even when eye movement commands are not required. We examined this proposed function of the human frontal eye fields during performance of visual search tasks in which difficulty was matched and eye movements were neither necessary nor required. Magnetic stimulation over FEF modulated performance on a conjunction search task and a simple feature search task in which the target was unpredictable from trial to trial, primarily by increasing false alarm responses. Simple feature search with a predictable target was not affected. The results establish that human FEFs are critical to visual selection, regardless of the need to generate a saccade command.

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Abstract& Frontal eye field (FEF) neurons discharge in response to behaviorally relevant stimuli that are potential targets for saccades. Distinct visual and motor processes have been dissociated in the FEF of macaque monkeys, but little is known about the visual processing capacity of FEF in humans. We used double-pulse transcranial magnetic stimulation [(d)TMS] to investigate the timing of target discrimination during visual conjunction search. We applied dual TMS pulses separated by 40 msec over the right FEF and vertex. These were applied in five timing conditions to sample separate time windows within the first 200 msec of visual processing. (d)TMS impaired search performance, reflected in reduced d 0 scores. This effect was limited to a time window between 40 and 80 msec after search array onset. These parameters correspond with single-cell activity in FEF that predicts monkeys' behavioral reports on hit, miss, false alarm, and correct rejection trials. Our findings demonstrate a crucial early role for human FEF in visual target discrimination that is independent of saccade programming. &