Galbraith's research deals with the human brainstem frequency-following response (FFR). The FFR, recorded from scalp electrodes via the non-invasive electroencephalogram, registers the response of brainstem neurons to tones and complex auditory stimuli. Galbraith’s laboratory is currently studying FFRs in normal infants, using linguistic and tonal stimuli. This research may explain the neural substrates of preference for the mother's voice, as well as the developmental sequence in processing complex auditory information. By studying auditory brainstem development in non-delayed infants we should better understand re-ceptive communication disorders in developmentally delayed persons.
In studies of young adults, Galbraith's laboratory recently reported a significant relationship between brainstem processing of an auditory signal and simple motor reaction time (RT). Early temporal processing of the stimulus was assessed by the FFR. Results showed that FFR amplitudes differed when individual trials were selectively averaged according to whether RT was fast or slow. This finding is the first demonstration of early brainstem evoked responses correlating with much later motor responses.
Galbraith has also collaborated in a recent study of interhemispheric transfer in individuals with agenesis or commissurotomy of the corpus callosum. Visual evoked potentials recorded over left and right hemispheres (electrodes placed on the scalp), showed significantly greater latency variability, and decreased signal/noise ratios, in cross-hemisphere transmission. This study used unique analysis procedures developed by Galbraith.