Exploring Human Sensory Cortex Using the New Oddball Design by Frequency-Tagging

Details

Supervisors

Nozaradan, Sylvie

Faculty

Faculté de médecine et médecine dentaire

Degree label

Master [180] en médecine

Abstract

As neuroscientific studies evolve, in vivo recording techniques such as electroencephalography (EEG) have improved the understanding of neuronal and cerebral function in recent years. But the electrophysiological recordings on the scalp revealed ongoing endogenous brain activity, unrelated to the stimulation generated by the environment. In order to overcome this limitation, the experimental method of frequency-tagging has been posited. This method consists in identifying the specific brain responses to the stimulation sets according to their expected frequencies and determined by the structure of the stimulus. Hence, frequency tags elicit steady-state evoked potentials (SS-EPs), which essentially means that the same frequency of stimulation can be found in brain responses. Frequency-tagging has a very important signal-to-noise ratio (SNR), which favors the exploration of cortical activities with better accuracy. On another hand, a new experimental design, known as the oddball paradigm, in which one stimulating item appears infrequently within series of standard stimulating items thus showing unexpected stimulatory events in a series of identical stimuli, induced larger stimulus-specific neuronal responses. Recently, several studies have attempted to combine the dual frequency-tagging / oddball paradigm approach thus benefiting from the double advantage of high signal-to-noise ratio responses and more objective identification of stimulation contrast response based on the expected frequency of the oddball occurrence. Intrigued by the discovery of new fields still little explored and with the aim of deepening already published works, we plan to forward in the same methodological line as a result of these works. Using 4 distint experiments, we study the new oddball design by frequency-tagging in two different sensory modalities (somatosensory cortex and auditory cortex) but each one based on vibration-type dynamic inputs.