Brainstem auditory-evoked potentials in two meditative mental states

CONTEXT Practicing mental repetition of "OM" has been shown to cause significant changes in the middle latency auditory-evoked potentials, which suggests that it facilitates the neural activity at the mesencephalic or diencephalic levels. AIMS The aim of the study was to study the brainstem auditory-evoked potentials (BAEP) in two meditation states based on consciousness, viz. dharana, and dhyana. MATERIALS AND METHODS Thirty subjects were selected, with ages ranging from 20 to 55 years (M=29.1; ±SD=6.5 years) who had a minimum of 6 months experience in meditating "OM". Each subject was assessed in four sessions, i.e. two meditation and two control sessions. The two control sessions were: (i) ekagrata, i.e. single-topic lecture on meditation and (ii) cancalata, i.e. non-targeted thinking. The two meditation sessions were: (i) dharana, i.e. focusing on the symbol "OM" and (ii) dhyana, i.e. effortless single-thought state "OM". All four sessions were recorded on four different days and consisted of three states, i.e. pre, during and post. RESULTS The present results showed that the wave V peak latency significantly increased in cancalata, ekagrata and dharana, but no change occurred during the dhyana session. CONCLUSIONS These results suggested that information transmission along the auditory pathway is delayed during cancalata, ekagrata and dharana, but there is no change during dhyana. It may be said that auditory information transmission was delayed at the inferior collicular level as the wave V corresponds to the tectum.