Date Published: March 14, 2019
Publisher: Public Library of Science
Author(s): Mahboobeh Dehghan Nayyeri, Markus Burgmer, Bettina Pfleiderer, Patricia Souza Brocardo.
Studies on cross-modal interaction have demonstrated attenuated as well as facilitated effects for both neural responses as well as behavioral performance. The goals of this pilot study were to investigate possible cross-modal interactions of tactile stimulation on visual working memory and to identify possible neuronal correlates by using functional magnetic resonance imaging (fMRI). During fMRI, participants (n = 12 females, n = 12 males) performed a verbal n-back task (0-back and 2-back tasks) while tactile pressure to the left thumbnail was delivered. Participants presented significantly lower behavioral performances (increased error rates, and reaction times) during the 2-back task as compared to the 0-back task. Task performance was independent of pressure in both tasks. This means that working memory performance was not impacted by a low salient tactile stimulus. Also in the fMRI data, no significant interactions of n-back x pressure were observed. In conclusion, the current study found no influence of tactile pressure on task-related brain activity during n-back (0-back and 2-back) tasks.
The ability to maintain focus on task-relevant information in the presence of interference protects our limited cognitive resources from becoming overloaded. Therefore cognitive control is needed to bridge the gap between the processing of distracting sensory information and goal-directed action . Studies on cross-modal interaction, including vision and tactile sensation [2, 3], have demonstrated inhibitory as well as facilitated effects for both, neural responses in higher sensory association and primary sensory cortices, as well as behavioral performance. Similarly, tactile stimulation of the index finger can induce the perceptual suppression of visual stimuli when tactile and visual information are spatially and temporally consistent .
The goal of this fMRI study was to investigate the possible influence of low salient tactile stimuli (pressure) on performance and related brain activity in a working memory task. To do so, healthy participants were asked to perform a visual n-back paradigm (0-back, 2-back) combined with pressure as a sensory stimulus.
The study sample of 24 participants with 12 female and 12 male young medical students is rather small and homogenous. Consequently, this study needs to be considered a pilot study to investigate potential differences in brain activity in response to tactile stimulation during a visual working memory task. The number of participants might have been too small to measure subtle differences.