Semantic Classical Conditioning and Brain-Computer Interface Control: Encoding of Affirmative and Negative Thinking

Abstract

The aim of the study was to investigate conditioned electroencephalography (EEG) responses to factually correct and incorrect statements in order to enable binary communication by means of a brain-computer interface (BCI). In two experiments with healthy participants true and false statements (serving as conditioned stimuli, CSs) were paired with two different tones which served as unconditioned stimuli (USs). The features of the USs were varied and tested for their effectiveness to elicit differentiable conditioned reactions (CRs). After acquisition of the CRs, these CRs to true and false statements were classified offline using a radial basis function kernel support vector machine. A mean single-trial classification accuracy of 50.5% was achieved for differentiating conditioned “yes” versus “no” thinking and mean accuracies of 65.4% for classification of “yes” and 68.8% for “no” thinking (both relative to baseline) were found using the best US. Analysis of the area under the curve of the conditioned EEG responses revealed significant differences between conditioned “yes” and “no” answers. Even though improvements are necessary, these first results indicate that the semantic conditioning paradigm could be a useful basis for further research regarding BCI communication in patients in the complete locked-in state.

Brain communication in the locked-in state

“…The proposed 'extinction of goal directed thinking effect' (Birbaumer et al, 2012) prevents semantic conditioning because the motivated intention to anticipate a 'yes' or 'no' answer after the conditioning stimulus is attenuated or extinguished (Perky, 1910) and may also be responsible for the inconsistent results. Another explanation of the results concerns the aversive stimulus anticipation after an affirmative statement that may retroactively block processing of affirmative representations; alternatively, no aversive stimulus or an aversive stimulus after negative statements and/or positive stimuli such as harmonic sounds and/or statements of significant others could be used as unconditioned stimulus; however, auditory stimuli were used as unconditioned stimulus in the past in this procedure described here without significant above-chance classification accuracies (Furdea et al, 2012;Ruf et al, 2013). It is also possible that the selected slow wave and frequency bands (Fig.…”

“…After extensive testing in healthy samples (Furdea et al, 2012;De Massari et al, 2013;Ruf et al, 2013), this 'reflexive' classical conditioning paradigm was applied in this study online with patients with amyotrophic lateral sclerosis (two of them in a lockedin state, one in a completely locked-in state) to allow basic communication (i.e. responding to yes-no statements).…”

Prediction of brain-computer interface aptitude from individual brain structure

“…It is also possible to control a BCI by performing motor imagery of different body parts such as hands or feet which causes event-related desynchronization (ERD) and event-related synchronization (ERS) of the sensorimotor rhythm (SMR) (also referred to as μ-rhythm) (Pfurtscheller and da Silva, 1999; Neuper et al, 2003; Kübler et al, 2005). Novel approach utilize the principles of semantic classical conditioning to establish a communication channel (Furdea et al, 2012; De Massari et al, 2013; Ruf et al, 2013). …”

Covert Intention to Answer to Self-Referential Questions Is Represented in Alpha-Band Local and Interregional Neural Synchronies

“…An alternative approach is necessary, which does not involve volitional and highly cognitive efforts. For example, Birbaumer and colleagues suggested an approach based on classical conditioning [5, 48, 49]. They tried to associate language stimuli with unpleasant sensory stimuli so that cortical responses to these nonlanguage stimuli are conditioned according to the language stimuli [5, 48, 49].…”