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 attention effects on the brain stem auditory frequency-following response (FFR) elicited by a periodic tone. Young adult subjects heard a repetitive auditory stimulus while detecting infrequent target stimuli in either an auditory or visual detection task. Five channels of high frequency electroencephalographic (EEG) activity were recorded along the scalp midline with the center electrode positioned at the vertex. The FFR was elicited by the repetitive tone during both tasks. There were significant individual differences in the electrode sites yielding maximum response amplitudes, but overall FFR amplitudes were significantly larger during the auditory attention task. These results suggest that selective attention in humans can modify signal processing in sensory (afferent) pathways at the level of the brain stem. This may reflect top-down perceptual preprocessing mediated by extensive descending (efferent) pathways that originate in the cortex. Overall, the FFR appears to be a robust indicator of early auditory neural processing and shows effects not seen in brain stem auditory evoked response studies employing transient (click) acoustic stimuli.

Distortion product otoacoustic emissions (DPOAE) and automated auditory brainstem response (AABR) screening were conducted in infants at a distant hospital using remote computing. Eighteen males and twelve females ranging in age from 11 -45 days were tested. Both DPOAE and AABR data were recorded using an integrated test system which was connected to the computer network at the Utah Valley Regional Medical Center. Using a broadband Internet connection, an examiner at Utah State University, 200 km away, could control the DPOAE and the ABR equipment. Identical hearing screening results were obtained for face-to-face and telemedicine trials with all infants. The DPOAE means for face-to-face and telemedicine trials were not significantly different at any frequency. In an analysis of variance, there was no significant difference for the test method (F ¼ 0.8, P . 0.05). These results indicate that remote computing is a feasible telemedicine method for providing DPOAE and ABR hearing screening services to infants in rural communities.

Biological systems can remain unchanged for several hundred years at cryogenic temperatures. In several hundred years, current rapid scientific and technical progress should lead to the ability to reverse any biological damage whose reversal is not forbidden by physical law. We therefore explore whether contemporary people facing terminal conditions might be preserved well enough today for their eventual recovery to be compatible with physical law. The ultrastructure of the brain can now be excellently preserved by vitrification, and solutions needed for vitrification can now be distributed through organs with retention of organ viability after transplantation. Current law requires a few minutes of cardiac arrest before cryopreservation of terminal patients, but dogs and cats have recovered excellent brain function after 16-60 min of complete cerebral ischemia. The arrest of biological time as a bridge to engineered negligible senescence, therefore, appears consistent with current scientific and medical knowledge.