RECORDING OF AUDITORY MIDDLE LATENCY EVOKED POTENTIALS DURING THE PRACTICE OF MEDITATION WITH THE SYLLABLE "OM"
Shirley Telles, and Desiraju T. Department of Neurophysiology, National Institute of Mental Health & Neuro Sciences, Bangalore (Accepted August 3, 1993)
Abstract: Middle latency auditory evoked potentials were examined in 7 proficient subjects during the practice of meditation on the syllable "Om", to determine whether these potentials would differ significantly from those recorded during the baseline state without practicing meditation. Similar records were also obtained in 7 "naive" subjects, matched for age, before and during a control period which involved sitting with eyes closed, and with no special instructions for focusing their thoughts. There was considerable inter-subject variability in the different components. However, during meditation there was a small but significant reduction in the peak latency of the Nb wave (the maximum negativity occurring between 35 and 65 msec). This reduction was observed consistently during the 3 repeat sessions of each subject, while the "naive" subjects did not show this change. These results suggest that the inter-subject variability of middle latency auditory evoked potentials precludes using them as the method of choice for assessing the effects of meditation. The small but consistent decrease in the Nb wave peak latency, indicates that the middle latency auditory evoked potentials do change with meditation. However, the variability of the potentials may mask subtle changes.
It is reported1 that near field or long latency auditory evoked potentials (AEPs) showed no consistent change with Transcendental Meditation (TM). Another study2 reported a reduction in far field (short latency) wave V peak latency following meditation. As It is known that far field AEPs alter with meditation, while near field/long latency potentials do not change, the present study was undertaken to assess the effects of meditation on middle latency AEPs. Such data can help in understanding how neural processing at various levels could change differently during a meditation practice in which thoughts are focused on a word or phrase without conscious effort to do so (i.e., meditation on the syllable "Om"), which is the principle that is also followed in transcendental meditation (TM).