Scientific validation of the Tomatis® effect: EEG recordings of sound encoding from brainstem to cerebral cortex Project acronym: Tomatis-ABR-PILOT Project duration: 6 months Principal investigator: Carles Escera
Summary
The present research proposal aims at demonstrating that the so-called “Tomatis effect”, the reeducation of the auditory system, relies on an actual modification of sound encoding along the auditory pathway, fromc brainstem to cerebral cortex. For that purpose, in this pilot phase a preliminary sample of 12 healthy participants will be blind assigned to either a “Tomatis Group” (TG) or a “Control Group” (CG). Participants of the TG will receive 13 two-hour listening sessions following a TOMATIS® listening program. Participants in the CG will also receive 15 two-hour listening sessions of the same musical pieces used in the TOMATIS® program presented through the same TOMATIS® device, but the musical pieces will not be processed with the Tomatis Gating system and the bone conductor output will be switched off. Brain activity related to the encoding of sound features will be recorded in the two groups before and after the listening sessions, and their responses will be compared. In particular, we will record the complex Auditory Brainstem Response (cABR) or Frequency Following Response (FFR), which is the biological signature of sound encoding at the level of the inferior colliculus in the ascending auditory pathway along the brainstem. It is extracted from the electroencephalogram (EEG) by averaging the brain EEG responses to circa 1000 stimulus presentations, and it has been show to track plastic changes in the auditory brainstem during both shortterm and long-term learning. Also we will record the mismatch negativity (MMN) cortical auditory evoked potential that reflects the violation of an acoustic regularity encoded in the auditory cortex. It is also extracted from the EEG by averaging the responses to a smaller number of stimulus, circa 100-200. The specific aims of this pilot phase of the project is to assess the feasibility of the proposed approach to demonstrate 1) that the TOMATIS® listening method, as implemented usual in clinical routine (phase 1: 15 twohour training sessions) improves sound encoding in the auditory brainstem by comparing the cABR elicited to a complex sound in a group of participants fulfilling the TOMATIS® training with that of a control group, and 2) that the TOMATIS® listening method, as implemented usual in clinical routine improves sound encoding in the auditory cortex, and the detection of rare sounds violating expectations based on acoustic regularity. This will be achieved by comparing the MMN elicited deviant auditory stimuli occurring in a sequence of otherwise repetitive stimulation (“standard” tones). The Cognitive Neuroscience Research Group, lead by Prof. Carles Escera at the University of Barcelona has a consolidated experience in the investigation of the cerebral mechanisms of auditory perception by means of auditory evoked potentials, in particular with the MMN, an his research has revealed a series of potential clinical applications of this evoked potentials. Also, his recent results with the cABR have demonstrated that the human inferior colliculus is involved in regularity encoding and deviance detection. It is expected that this pilot project will set the bases for the future understanding of the mechanisms operating the so-called “Tomatis effect” by Carles Escera, University of Barcelona version FINAL. 06/03/2014