Somatosensory Event-Related Potential as an Electrophysiological Correlate of Endogenous Spatial Tactile Attention: Prospects for Electrotactile Brain-Computer Interface for Sensory Training

Abstract

Tactile attention tasks are used in the diagnosis and treatment of neurological and sensory processing disorders, while somatosensory event-related potentials (ERP) measured by electroencephalography (EEG) are used as neural correlates of attention processes. Brain-computer interface (BCI) technology provides an opportunity for the training of mental task execution via providing online feedback based on ERP measures. Our recent work introduced a novel electrotactile BCI for sensory training, based on somatosensory ERP; however, no previous studies have addressed specific somatosensory ERP morphological features as measures of sustained endogenous spatial tactile attention in the context of BCI control. Here we show the morphology of somatosensory ERP responses induced by a novel task introduced within our electrotactile BCI platform i.e., the sustained endogenous spatial electrotactile attention task. By applying pulsed electrical stimuli to the two proximal stimulation hotspots at the user’s forearm, stimulating sequentially the mixed branches of radial and median nerves with equal probability of stimuli occurrence, we successfully recorded somatosensory ERPs for both stimulation locations, in the attended and unattended conditions. Waveforms of somatosensory ERP responses for both mixed nerve branches showed similar morphology in line with previous reports on somatosensory ERP components obtained by stimulation of exclusively sensory nerves. Moreover, we found statistically significant increases in ERP amplitude on several components, at both stimulation hotspots, while sustained endogenous spatial electrotactile attention task is performed. Our results revealed the existence of general ERP windows of interest and signal features that can be used to detect sustained endogenous tactile attention and classify between spatial attention locations in 11 healthy subjects. The current results show that features of N140, P3a and P3b somatosensory ERP components are the most prominent global markers of sustained spatial electrotactile attention, over all subjects, within our novel electrotactile BCI task/paradigm, and this work proposes the features of those components as markers of sustained endogenous spatial tactile attention in online BCI control. Immediate implications of this work are the possible improvement of online BCI control within our novel electrotactile BCI system, while these finding can be used for other tactile BCI applications in the diagnosis and treatment of neurological disorders by employing mixed nerve somatosensory ERPs and sustained endogenous electrotactile attention task as control paradigms.

Event-related potential evidence for tactile orientation processing in the human brain

“…In the present study, we investigated brain activity during tactile orientation adaptation using an ERP experiment. Our results extended previous findings (Jones and Forster 2012 , 2013 ; Juravle et al 2016 ; Gherri et al 2023 ; Novičić and Savić 2023 ) by revealing that the tactile orientation adaptation effect occurred across the whole brain starting from 60 (i.e., N60) to 300 ms (i.e., N120, P300). Furthermore, we found that the adaptation-related N60 component occurred around the contralateral central-parietal areas, which may reflect orientation processing in the somatosensory areas.…”

“…Second, distributed negative activity across ipsilateral and contralateral frontal sites (FC5/6, F7/8 electrodes) occurred at 120 ms. These electrodes were close to and over somatosensory areas, similar to the selection of electrodes in previous somatosensory ERP studies (Forster et al 2009 ; Jones and Forster 2012 ; Novičić and Savić 2023 ). Third, the scalp topography also showed that the parietal lobe area was broadly distributed (P3/4, P7/8 electrodes) at approximately 300 ms, which is responsible for tactile perception according to Gottlieb ( 2007 ) and (Chen et al 2019 ).…”

ERP evidence of attentional somatosensory processing and stimulus-response coupling under different hand and arm postures

“…Previous studies demonstrated that attention facilitated behavioral performance in individual sensory modalities. Furthermore, attentional increases were noted in the amplitude of early and middle latency components of event-related brain potentials (ERPs) elicited by somatosensory stimulation (Desmedt and Robertson, 1977;Garcia-Larrea et al, 1995;Eimer et al, 2002;van Velzen et al, 2002;Valeriani et al, 2003;Kida et al, 2004b,c;Forster and Eimer, 2005;Kida et al, 2006;Gherri and Eimer, 2008;Press et al, 2008;Adler et al, 2009;Keil et al, 2017;Novicic and Savic, 2023;Savic et al, 2023). Auditory spatial selective attention exerts two types of effects on N1 amplitude: the superimposition of another negativity (processing negativity, PN, or its negative difference between attended and unattended channels, Nd) and the enhancement of N1 itself (Hillyard et al, 1973;Naatanen et al, 1978;Naatanen, 2000), and visual spatial attention also exerts both of these effects on amplitudes in the N1-P2 latency range (Johannes et al, 1995;Hillyard and Anllo-Vento, 1998).…”

Editorial: Global excellence in brain-computer interfaces: Europe

“…BCI applications and use case scenarios are diverse but still constrained to several application domains: replacing functions that were lost due to injury or disease [e.g., communication in severely disabled (Savić et al, 2021 ; Vansteensel et al, 2023 )]; restoring the lost functions [e.g., though controlled electrical stimulation of muscles in paralysis (Benabid et al, 2019 )]; improving affected functions [e.g., BCI-based therapeutic interventions post-stroke (Nojima et al, 2022 )]; enhancing the functions [e.g., neuromodulation of attention, memory, workload, motor skills (Sciaraffa et al, 2022 ; Novičić and Savić, 2023 )]; and using BCI technology as research tools to study brain functions (Brunner et al, 2015 ). BCIs may not only serve the medical field and healthcare and could be applied in other areas, such as entertainment, gaming, education, ergonomics, marketing, and more (Falk et al, 2023 ; Soekadar et al, 2023 ).…”