Pain-related evoked potentials are modulated across the cardiac cycle

Evidence suggests that the arterial baroreceptors modulate pain. To examine whether cortical processing of nociception is modulated by natural variations in arterial baroreceptor stimulation during the cardiac cycle, peak-to-peak amplitudes of the N2–P2 pain-related potential and pain ratings were recorded in response to noxious laser stimulation at different times during the cardiac cycle in 10 healthy males. Significant variations in the N2–P2 amplitudes occurred across the cardiac cycle, with smaller amplitudes midcycle, indicating that cortical processing of nociception was attenuated during systole compared to diastole. Pain ratings did not vary across the cardiac cycle. These data support the hypothesis that arterial baroreceptors modulate the processing of nociception during each cardiac cycle

Stimulus.

<p>A, Stimulus. B, Relative spectral distribution of the light source.</p

VEFs induced by bright light.

<p>A, Top view of MEG waveforms of a representative subject in Experiment 1. B, Location of the estimated dipole in the eye superimposed on a subject’s own MR image. C, Grand-averaged source strength waveforms of retinal activity.</p

Effects of the yellow lens on VEF topography.

<p>Comparison of VEF topographies following a bright light stimulation between colorless and yellow lenses in a representative subject. Topographies for the recorded MEG signals (upper panel) and the model (lower panel) are shown. Note the similar topographies at early latencies, but lack of a clear quadrupole pattern distribution for the colorless lens condition at 150–160 ms. B, Dipole location for dipoles estimated in the fusiform gyrus region superimposed on a subject’s MR image.</p

Correlation between b-wave latency and transmittance at 450 nm.

<p>A, Grand-averaged source strength waveforms of retinal activity in Experiment 2. The averaged waveforms of both eyes are shown. B, Relationship between the mean peak latency of retinal activity (b-wave) and transmittance of color lenses. C, Correlation coefficient plotted against wavelength.</p

Spectral transmittance curves of color lenses.

<p>A colorless lens and four color lenses were used. Luminous transmittances for the color lenses were adjusted to an optical density of 70% of the light source.</p

Latency in Experiment 1 and 2.

<p>Latency in Experiment 1 and 2.</p

Inhibition in the Human Auditory Cortex - Table 2

<p>Inhibition in the Human Auditory Cortex</p> - Table

Grand-averaged waveforms for all subjects.

<p>Test responses, except for SI, were suppressed in both Experiment 1 (A) and 2 (B).</p

Correlation of %suppression between experiments.

<p>Plots showing the relationship of %suppression between Experiment 1 (x axis) and Experiment 2 (y axis) for the auditory (A) and somatosensory (B) experiments. The r and p values presented were obtained from all collected data.</p