Gary Cloyd Galbraith

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The human brain stem frequency-following response (FFR) registers phase-locked neural activity to cyclical auditory stimuli. We show that the FFR can be elicited by word stimuli, and when speech-evoked FFTs are reproduced as auditory stimuli they are heard as intelligible speech. Stimuli were 10 high- and 10 low-probability words drawn from normative verbal(More)
The human brainstem frequency-following response (FFR) registers phase-locked neural activity to periodic auditory stimuli. FFR waveforms were extracted from the electroencephalogram by averaging responses to repeated auditory stimulation. Two channels of data were simultaneously recorded from horizontally (electrodes placed in ear canals) and vertically(More)
In 2 separate experiments the brain-stem frequency-following response (FFR) was recorded to a pure tone (200 Hz) and complex "missing fundamental" (MF) stimuli differing in temporal fine structure and envelope modulation depth. FFRs were simultaneously recorded in 2 channels with horizontal and vertical dipole orientations. Horizontal electrodes were(More)
Special analysis of EEG signals was performed for 15 subjects engaged in three motor tasks of differing difficulty. A measure of average weighted coherence (C) was computed between the six possible combinations of four scalp areas: Oz, C3, C4 and Fz. In all subjects, regardless of task, scalp recordings over cortical areas known to have relatively dense(More)
Normal sensory transduction requires the efficient disposal of acid (H+) generated by neuronal and sensory receptor activity. Multiple highly sensitive transport mechanisms have evolved in prokaryotic and eukaryotic organisms to maintain acidity within strict limits. It is currently assumed that the multiplicity of these processes provides a biological(More)
Reaction time (RT), discrimination sensitivity (d'), and the brainstem frequency-following response (FFR) were recorded in 32 subjects performing a selective attention task. Auditory stimuli were a 400 Hz pure tone and a complex "missing fundamental" (MF) presented dichotically to separate ears (channels). In two tasks, infrequent target stimuli were either(More)
Frequency-following responses (FFRs) were elicited by English long vowels (female /a/ and male /e/) in a dichotic listening task. Stimuli were simultaneous and of equal duration, but differing spectra permitted unique identification of vowel components in the compound FFR. Horizontal and vertical montage FFRs were recorded with putative origins in the(More)
Speech stimuli played in reverse are perceived as unfamiliar and alien-sounding, even though phoneme duration and fundamental voicing frequency are preserved. Although language perception ultimately resides in the neocortex, the brain stem plays a vital role in processing auditory information, including speech. The present study measured brain stem(More)
Selective attention modifies long-latency cortical event-related potentials. Amplitudes are typically enhanced and/or latencies reduced when evoking stimuli are attended. However, there is controversy concerning the effects of selective attention on short-latency brain stem evoked potentials. The objective of the present study was to assess possible(More)
In the auditory system, cortical event-related potential amplitudes are enhanced during selective attention within the auditory channel. In the case of brainstem responses, however, the results are less clear since only a few studies have reported attention effects. Nearly all of these studies have used click stimuli to elicit the brainstem auditory evoked(More)