The P300 in pain evoked potentials

Abstract

Pain evoked potentials (EPs) have been used in the last two decades as means of obtaining objective measures of pain, in clinical and experimental setups. The possibility that the pain EP wave contains elements of the endogenous P300 potential rather than being a neurophysiological correlate of pain has been raised by a number of authors, but the issue has not been resolved. In this study, two experiments were performed to study the effect of nonmodality-specific factors on the laser EP: (1) a stimulus attend as opposed to a stimulus-ignore condition and (2) counterbalanced oddball and task P300 stimulus presentations. The latter was to permit full examination of the separate and combined influences of each condition on the EP. Stimuli were given to the radial hand of 10 healthy volunteers using a CO2 laser. The positive component of the laser EP was affected by both manipulations relating to (1) attention (P = 0.0146) and (2) the frequency condition (P = 0.003) in the P300 paradigm. The task condition in the second paradigm did not affect the positive wave on its own, although its effect was visible in interaction with frequency (P = 0.033). In conclusion, although the presence of a somatic component in the laser EP cannot be rules out, we suggest that the laser EP contains a definite non-modality-specific P300 component, and is not a pure neurophysiological correlate of pain intensity.

Painful cutaneous laser stimuli induce event-related oscillatory EEG activities that are different from those induced by nonpainful electrical stimuli

“…The response to the painful cutaneous laser may reflect the salience of the stimulus, defined as "the ability of the stimulus to capture attention" (Mouraux and Iannetti 2009; see also Downar et al 2002Downar et al , 2003Legrain et al 2005;Lorenz and GarciaLarrea 2003;Zaslansky et al 1995). We controlled for the effect of baseline salience of the two stimuli within each participant by matching the salience of the electric stimulus to that of the painful laser stimulus through adjustments in the intensity of the stimuli.…”

Dipole source analyses of laser evoked potentials obtained from subdural grid recordings from primary somatic sensory cortex

“…Source analysis from subdural recordings is a refinement of source analysis techniques from scalp recordings, which improves the accuracy of the localization for scalp and subdural recordings (Zaslansky et al 1995). Our prior study of parasylvian sources was carried out on potentials arising from noci- (Legrain et al 2005Mouraux and Iannetti 2009).…”

A Painful Cutaneous Laser Stimulus Evokes Responses From Single Neurons in the Human Thalamic Principal Somatic Sensory Nucleus Ventral Caudal (Vc)

“…In the same study, the velocity calculated from the subdural LEP P2 is much faster than C-fiber conduction velocities. It is more likely that the latency of the P2 peak is the result of cortical processing of an earlier barrage of nociceptive inputs rather than to C-fiber-related conduction delays (Becker et al 1993;Kanda et al 1996;Miltner et al 1989;Siedenberg and Treede 1996;Towell and Boyd 1993;Zaslansky et al 1995Zaslansky et al , 1996.…”

“…Scalp LEPs are degraded further by muscle and blink artifacts; by temporal and spatial filtering at the level of the scalp, skull, and cerebrospinal fluid (Cooper et al 1965;Gevins et al 1994;Pfurtscheller and Cooper 1975); and by large interelectrode distances (Gevins et al 1994). Scalp studies have reported that directed attention increases the LEP P2 peak but not the LEP N2 peak (Becker et al 1993;Kanda et al 1996;Miltner et al 1989;Siedenberg and Treede 1996;Towell and Boyd 1993;Zaslansky et al 1995Zaslansky et al , 1996.…”