Interoceptive Attentiveness Induces Significantly More PFC Activation during a Synchronized Linguistic Task Compared to a Motor Task as Revealed by Functional Near-Infrared Spectroscopy

Abstract

Currently, there is little understanding of how interoceptive attentiveness (IA) affects brain responses during synchronized cognitive or motor tasks. This pilot study explored the effect of explicit IA manipulation on hemodynamic correlates of simple cognitive tasks implying linguistic or motor synchronization. Eighteen healthy participants completed two linguistic and motor synchronization tasks during explicit IA and control conditions while oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin variations were recorded by functional Near-Infrared Spectroscopy (fNIRS). The findings suggested that the brain regions associated with sustained attention, such as the right prefrontal cortex (PFC), were more involved when an explicit focus on the breath was induced during the cognitive linguistic task requiring synchronization with a partner, as indicated by increased O2Hb. Interestingly, this effect was not significant for the motor task. In conclusion, for the first time, this pilot research found increased activity in neuroanatomical regions that promote sustained attention, attention reorientation, and synchronization when a joint task is carried out and the person is focusing on their physiological body reactions. Moreover, the results suggested that the benefits of conscious concentration on physiological interoceptive correlates while executing a task demanding synchronization, particularly verbal alignment, may be related to the right PFC.

Keywords: PFC; cognitive tasks; fNIRS; interoceptive attentiveness; synchronization.

Figure 1

Experiment setup. (A) The experimental procedure with the synchronization tasks duration and timing of the instructions provided for the explicit IA and control conditions. (B) Example of the experimental setting with fNIRS device recording and the experimenter during the task execution (i.e., for the motor task).

Figure 2

fNIRS montage. Location of the sources (yellow) and detectors (green) of fNIRS montage. Sources were in the following positions: AF3-AF4, F5-F6. Detectors were placed on: AFF1h-AFF2h, F3-F4. A total of six channels (violet) have been acquired: Ch1 (AF3-F3), Ch2 (AF3-AFF1h), Ch3 (F5-F3), Ch4 (AF4-F4), Ch5 (AF4-AFF2h), Ch6 (F6-F4).

Figure 3

Hemodynamic signal time course for all channels under the four conditions. The figure shows the time course plots of O2Hb (red) and HHb signal (blue) for each channel when performing the following tasks: motor and linguistic tasks during the control condition and motor and linguistic tasks during the explicit IA condition.

Figure 4

fNIRS hemodynamic results. (A) The graph displays O2Hb modulation (D values) as a function of Condition, which is significantly increased for the explicit IA compared to the control condition. (B) The bar chart shows significantly higher O2Hb values in the right compared to left frontal areas in the explicit IA condition. (C) As the bar graph shows, significantly greater mean O2Hb values were found in the linguistic than the motor task in the explicit IA condition. All data are represented as mean ± SE; all asterisks (*) mark statistically significant differences, with p ≤ 0.05.