Detecting the user mental states from the NIRS-measured hemodynamic signals

There is a need to develop brain-computer interface (BCI) systems that are able to remain stable in varying psychophysiological conditions (such as during times of mental fatigue) that can disrupt user capability. Attention resources are finite and how a gradual decrease in attention across time – the so-called time-on-task (TOT) effect – can influence neural signals is yet to be identified. This present study investigated in fifteen male volunteers (i) the time course of cortico-spinal excitability through single-pulse transcranial magnetic stimulation; and (ii) the changes in activity of pre-motor, primary motor, prefrontal cortex and right parietal areas by means of near-infrared spectroscopy (NIRS), during a sustained attention reaction task (RT) of 30 min duration. Applicability of using NIRS-measured cortical activity in order to classify subject attentional state during the sustained attention task was further tested in a sample of 7 subjects

From face processing to face recognition: Comparing three different processing levels

International audienc

Adaptation of motor activity to lapses in attention.

Sustained attention is fundamental for cognition and when impaired, impacts negatively on important contemporary living skills. Degradation in sustained attention is characterized by the time-on-task (TOT) effect, which manifests as a gradual increase in reaction time (RT). The TOT effect is accompanied by changes in relative brain activity patterns in attention-related areas, most noticeably in the prefrontal cortex (PFC) and the right parietal areas. However, activity changes in task-relevant motor structures have not been confirmed to date. This article describes an investigation of such motor-related activity changes as measured with 1) the time course of corticospinal excitability (CSE) through single-pulse transcranial magnetic stimulation; and 2) the changes in activity of premotor (PMC), primary motor (M1), PFC, and right parietal areas by means of near-infrared spectroscopy, during a sustained attention RT task exhibiting the TOT effect. Our results corroborate established findings such as a significant increase (P < 0.05) in lateral prefrontal and right parietal areas activity after the emergence of the TOT effect but also reveal adaptations in the form of motor activity changes--in particular, a significant increase in CSE (P < 0.01) and in primary motor area (M1) activity (P < 0.05)