Brain-Computer Interfaces for Augmentative and Alternative Communication: A Tutorial

Abstract

Purpose: Brain-computer interfaces (BCIs) have the potential to improve communication for people who require but are unable to use traditional augmentative and alternative communication (AAC) devices. As BCIs move toward clinical practice, speech-language pathologists (SLPs) will need to consider their appropriateness for AAC intervention.

Method: This tutorial provides a background on BCI approaches to provide AAC specialists foundational knowledge necessary for clinical application of BCI. Tutorial descriptions were generated based on a literature review of BCIs for restoring communication.

Results: The tutorial responses directly address 4 major areas of interest for SLPs who specialize in AAC: (a) the current state of BCI with emphasis on SLP scope of practice (including the subareas: the way in which individuals access AAC with BCI, the efficacy of BCI for AAC, and the effects of fatigue), (b) populations for whom BCI is best suited, (c) the future of BCI as an addition to AAC access strategies, and (d) limitations of BCI.

Conclusion: Current BCIs have been designed as access methods for AAC rather than a replacement; therefore, SLPs can use existing knowledge in AAC as a starting point for clinical application. Additional training is recommended to stay updated with rapid advances in BCI.

Figure 1.

From left to right, example visual displays for the following BCIs: P300 grid speller, RSVP P300, SSVEP, and motor-based (SMR with keyboard). For the P300 grid, each row and column are highlighted until a letter is selected. In the RSVP, each letter is displayed randomly, sequentially in the center of the screen. For the SSVEP, this example uses four flickering stimuli (at different frequencies) to represent the cardinal directions, which are used to select individual grid items. This can also be done with individual flicker frequencies for all 36 items with certain technical considerations. For the motor-based BCI, this is an example of a binary-selection virtual keyboard; imagined right hand movements select the right set of letters. RSVP = rapid serial visual presentation; SSVEP = steady state visually evoked potential; SMR = sensorimotor rhythm; BCI = brain–computer interfaces. Copyright © Tobii Dynavox. Reprinted with permission.

Figure 2.

From left to right, examples of how existing BCI paradigms can be applied to page sets from current AAC devices: P300 grid, SSVEP, motor based (with icon grid). For the P300 grid interface, a row or column is highlighted until a symbol is selected (here, it is yogurt). For the SSVEP, either directional (as shown here) or individual icons flicker at specified strobe rates to either move a cursor or directly select an item. For motor based, the example shown here uses attempted or imagined left hand movements to advance the cursor and right hand movements to choose the currently selected item. SSVEP = steady state visually evoked potential; SMR = sensorimotor rhythm; BCI = brain–computer interfaces; AAC = augmentative and alternative communication. Copyright © Tobii Dynavox. Reprinted with permission.