Electroence phalography Cross-Entropy Analysis of Brain Responses Expressed Towards Appetitive Stimuli: A Pilot Study
1. Problem Statement
Brain responses to situations involving appetitivestimuli are indicative of organismic states of preparation for consummatory responses. While it has been shown that anterior alpha asymmetry in the frontal area of the brain as measured with electroencephalography (EEG)is associated with approach behavior and motivation to wards appetitive stimuli (Gable & Harmon-Jones, 2008; Wacker, Chavanon, Leue, &Stemmler, 2008; Prause et al., 2014; Renaud et al., 2019) to our knowledge no cross-entropy investigation of this phenomenon was done yet.
Fifteen (15) male participants were immersed in a virtual environment simulating appetitive stimuli for a 2-minute period as well as in a control environment with comparable geometry but presenting no appetitive stimuli as such. Orders of presentation were counterbalanced to avoid sequence effects.
A 64 electrodes EEG cap was used with a Brain Amp amplifier, installed following the 10-20 convention. Artefacts and eye-movements were manually removed from the EEG digital tracing. The sample rate was of 500 Hz and the impedance was kept under 25 Ω. Electrodes were referenced at Fpz and the recordings were re-referenced with the means of left and right mastoids. Fast Fourier Transforms were applied to the data to obtain power (mV2) of frequencies (1 to 30 Hz) in each 1 s epoch (Oberman et al., 2005). Time-series expressing power of the Alpha (8-13 Hz) band was isolated from electrodes FP1FP2F7F3F4F8 (frontal area).
Cross-entropy between the right frontal hemisphere area (F8F4FP2) and the left frontal hemisphere (F7F3FP1) area will be performed using time-series analysis with the R software. Experimental and control conditions will be compared using repeated measures ANOVAs.
Analyzes are in progress. Results will be ready for the conference and the paper to be submitted.
It is expected that the degree of asynchronismin the brain frontal area will be significantly different between the experimental and the control conditions. These results may be useful in the development of a brain computer interface, especially for biomedical applications in psychiatry.
Keywords - Appetitive Stimuli, Consummatory Response, Virtual Reality, Electroence Phalography, Entropy.