Assessing the Impact of the NeuroCatch Platform 2 Stimulus Tone Volume

Electroencephalography (EEG) signals have been collected and studied since the early 1970s as a non-invasive way of assessing brain function. As early as the 1930s, a derivative of the raw EEG signal - event-related potentials (ERPs) - were computed. These scalp-recorded ERPs are the brain's response to a stimulus of interest (e.g. a flashing checkerboard or an angry face). The size, timing, and topographical location of ERP components lend insight into the timing and complexity of various cognitive processes. At NeuroCatch Inc. (NCI), research is primarily focused on three ERP components: the N100, P300 and N400, associated with different attention abilities (sensory processing, target detection \& semantic processing). The N100 is a negative-going deflection around 100 ms post stimulus onset. This particular ERP component indexes sensory stimulus at a pre-attentive level, or in other words, the acknowledgement by the brain that information has entered the system. Whereas the P300 - a positive-going deflection around 300 ms - indexes an early stage of attentional processing. This component is particularly sensitive to context updating or target identification (the brain's 'Ah-ha!' response). Finally, the N400 is a negative-going deflection peaking around 400 ms post stimulus. This component is measured in situations of semantic violations (e.g. 'The pizza was too hot to … lamp"), thus indexing one of the highest-order cognitive functions: language processing. Each of the three ERP components have been studied in academic laboratories for multiple decades and prototypical values for their timing (latency) and size (amplitude) have become widely accepted. To elicit the ERP components of interest in this study (N100, P300, N400), proprietary auditory stimulus sequences will be administered using the NeuroCatch Platform 2, an investigational medical device. Each sequence consists of tones and word pairs to elicit the various components of interest. Standard tones (lower volume, low pitch) make up most of the tones in the sequence, with deviant tones (higher volume, higher pitch) inserted in random intervals. The difference in volume and pitch between the standard tones and deviant tones, coupled with the "unexpected" nature of the deviant tone, is what drives the N100 and P300 responses. NeuroCatch Platform 2 consists of a computerized acquisition software which presents the stimulus, acquires the data and presents the amplitude and latency values of the ERP components (N100, N400, P300). This protocol is intended to assess the effect of changing the standard tone volume in the NeuroCatch Platform 2 auditory tone sequences on the elicited ERP responses.