We needed to be able to measure the effects of illness, lesion, drugs,
etc. on different levels of the neuraxis in humans. Therefore, we
established the capacity for recording the midlatency auditory P50
evoked potential, whose amplitude is a measure of level of arousal and
thus assesses brainstem-thalamus processes (5). The use of paired
auditory stimuli allows us to measure habituation to repetitive
stimulation, or sensory gating, a process disturbed in a number of
diseases (5). We also developed the capacity to measure reaction time (RT)
using a Psychomotor Vigilance Task (6) to derive the prototypical
measure of attention and thalamocortical processes (7). Finally, we
developed the capacity to measure frontal lobe blood flow using near
infrared spectroscopy, which provides an economical indicator for the
use of more expensive methods such as PET. We established a satellite
facility for spinal reflex testing in spinal cord injury and other
patient populations.
P50 potential amplitude. A. The
amplitude of the P50 potential is on the x-axis, and the
frequency of occurrence is shown on the Y-axis. The
distribution of P50 potential amplitudes in Ex-Term adolescents
(dark line) was unimodal, whereas the distribution of P50
potential amplitudes in Ex-Preterm adolescents appeared to have
three peaks (gray line). A test of Variance revealed a
significant difference between the two distributions (p<0.005).
A Mann-Whitney-U test of the two distributions revealed that
they were statistically different (P<0.01). B. Mean
amplitude of the P50 potential for all Ex-Term (open bar) and
Ex-Preterm (filled bar) adolescents demonstrating no difference
in amplitude when all Ex-Preterm subjects were pooled. The
multimodal distribution of P50 amplitudes among Ex-Preterm
subjects showed the presence of three peaks falling below the 33rd
, between the 33rd and 67th, and above the
67th percentiles. Comparisons between High (vertical
stripes), Medium (horizontal stripes) and Low (diagonal stripes)
amplitude peaks of Ex-Preterm adolescents showed significant
differences between peaks at **p<0.01
P50 potential amplitude. A. The
amplitude of the P50 potential is on the x-axis, and the
frequency of occurrence is shown on the Y-axis. The
distribution of P50 potential amplitudes in Ex-Term adolescents
(dark line) was unimodal, whereas the distribution of P50
potential amplitudes in Ex-Preterm adolescents appeared to have
three peaks (gray line). A test of Variance revealed a
significant difference between the two distributions (p<0.005).
A Mann-Whitney-U test of the two distributions revealed that
they were statistically different (P<0.01). B. Mean
amplitude of the P50 potential for all Ex-Term (open bar) and
Ex-Preterm (filled bar) adolescents demonstrating no difference
in amplitude when all Ex-Preterm subjects were pooled. The
multimodal distribution of P50 amplitudes among Ex-Preterm
subjects showed the presence of three peaks falling below the 33rd
, between the 33rd and 67th, and above the
67th percentiles. Comparisons between High (vertical
stripes), Medium (horizontal stripes) and Low (diagonal stripes)
amplitude peaks of Ex-Preterm adolescents showed significant
differences between peaks at **p<0.01