Distribution of brain stem responses to acoustic stimuli over the human scalp

Responses to acoustic stimuli are generated in neurons of nuclei on both sides of the brain stem. In order to determine whether there are electrode positions which can be used to record activity predominantly generated in the neurons of nuclei of one side, the distribution of brain stem responses to acoustic stimuli over the human scalp was investigated. The response is found to be maximum at the vertex, and diminishes gradually toward the nasion, inion and the mastoid process. There are no significant differences between responses to ipsi- and contralateral stimulation. It follows that there are no electrode positions, which can be used to record the activity generated in the neurons of nuclei of one side. There are, however, indications that monolateral pathology of brain stem nuclei may be detectable by comparing responses to stimuli presented on the right, the left and bilaterally.