Functional Equivalence of Imagined vs. Real Performance of an Inhibitory Task: An EEG/ERP Study

Early neuroimaging and electrophysiological studies suggested that motor imagery recruited a different network than motor execution. However, several studies have provided evidence for the involvement of the same circuits in motor imagery tasks, in the absence of overt responses. The present study aimed to test whether imagined performance of a stop-signal task produces a similar pattern of motor-related EEG activity than that observed during real performance. To this end, mu and beta eventrelated desynchronization (ERD) and the Lateralized Readiness Potential (LRP) were analyzed. The study also aimed to clarify the functional significance of the Stop-N2 and Stop-P3 event-related potential (ERPs) components, which were also obtained during both real and imagined performance. The results showed a common pattern of brain electrical activity, and with a similar time course, during covert performance and overt execution of the stop-signal task: presence of LRP and Stop-P3 in the imagined condition and identical LRP onset, and similar mu and beta ERD temporal windows for both conditions. These findings suggest that a similar inhibitory network may be activated during both overt and covert execution of the task. Therefore, motor imagery may be useful to improve inhibitory skills and to develop new communicating systems for Brain-Computer Interface (BCI) devices based on inhibitory signalsThis research was funded by Spanish Ministerio de Economía y Competitividad (Reference PSI2013-43594-R). AJG-V was supported by a research grant from the Fundación Ramón DominguezS

Perceptual consequences of reflexive eye movements: effects of exogenous attention and frontal stimulation

This thesis investigated the visual perceptual consequences of reflexive eye movements in humans. A multimodal approach involving the modulation of exogenous attention, and the perturbation of the right frontal eye field (rFEF), explored visual perceptual and oculomotor control functions. Stimulation of the rFEF by TMS and the presentation of stimuli (cues) in order to orient attention, were combined with the measurement of brain activity with EEG, and eye tracking. These methods allowed the investigation of brain function and cognitive processing during a task combining visually driven eye movements with visual motion discrimination. Perturbation of the rFEF provided evidence of dissociable roles in visual perception, shown by a facilitatory effect during involuntary eye movements and an inhibitory effect during eye movement suppression. The rFEF TMS effect at the behavioral level was accompanied by posterior alpha power modulation. Not only the visual perceptual but also the oculomotor control function of the rFEF were affected by TMS, as shown by the reduction in eye movement velocity. The modulation of attention by the presentation of cue stimuli led to effects that were not dependent on eye movements: a facilitatory effect of exogenous orienting of attention was observed when the motion discrimination task was performed simultaneously with the generation of reflexive eye movements, and again also during movement suppression. The effect of attention was reflected in EEG correlates of early visual perceptual processing. Taken together, these results allow generalization to real-world contexts or clinical conditions where visual perception may be compromised by involuntary or pathological eye movements, highlighting the fact that even during reflexive movements the potential involvement of attention is essential for understanding cognitive processing

Specific Contributions of Ventromedial, Anterior Cingulate, and Lateral Prefrontal Cortex for Attentional Selection and Stimulus Valuation

Functional clusters of neurons in the monkey prefrontal and anterior cingulate cortex are involved in guiding attention to the most valuable objects in a scene