Stimulus Intensity Control and the Cortical Evoked Response

Abstract

Cortical evoked potentials to light flashes of 4 intensities and performances on a kinesthetic figural after-effects perceptual task (KFA) were obtained from normal and nonparanoid schizophrenic subjects. In previous studies it had been shown that individual differences in perception of stimulus intensity could be inferred from KFA performance. In this study, it was hypothesized that individuals whose KFA scores indicated a tendency to reduce the perceived intensity of strong stimulation would show a comparable response tendency on a cortical evoked response procedure. Significant correlations were found between evoked response latency and amplitude measures and KFA values in both normal and psychiatric groups. Sex differences in evoked response parameters were also found, males showing a steeper intensity-response function than females. Further, sex was found to be an important moderator variable of the relationship between evoked response measures and KFA values. These findings were interpreted in terms of a theoretical construct regarding a stimulus intensity control mechanism in the central nervous system. 1 N the associate author's recent paper on the schizophrenias, 10 a formulation was presented regarding a stimulus intensity control mechanism in the central nervous system. The purpose of this study is to demonstrate a neurophysiological basis for the formulation and to extend its application to sensory behavior studies of nonpsychiatric individuals. Based originally and in large part upon the work of Petrie and her colleagues, 9 -10 -u the stimulus intensity control hypothesis was aimed at reconciling two apparently contradictory kinds of findings in the literature on schizophre-

High Intensity Dependence of Auditory Evoked Dipole Source Activity Indicates Decreased Serotonergic Activity in Abstinent Ecstasy (MDMA) Users

“…Evidence from both older and more recent work suggests a relationship between high intensity dependence of sensory evoked potentials and such distinct personality traits as high sensation seeking, novelty seeking, extraversion, impulsivity, and psychopathy (Barrat et al 1987;Carrillo-de-la-Pena 1992;Hegerl and Juckel 1993;Hegerl et al 1989Hegerl et al , 1995aHegerl et al , 1995bJuckel et al 1995;Lukas 1987;Raine 1989;Raine and Venables 1990;Stenberg et al 1988;Zuckerman 1990;Zuckerman et al 1988). Within the augmenting/reducing concept first proposed by Buchsbaum and Silverman (1968) a high intensity dependence (augmenting) of sensory evoked activity is viewed as reflecting a central mechanism regulating neuronal sensitivity and providing the organism with an optimal level of sensory stimulation. Moreover, a relationship between high intensity dependence of sensory evoked potentials and the development of drug or alcohol abuse is also discussed in the older literature (Zuckerman 1972).…”

“…For this purpose, we recorded auditory evoked potentials (AEP) and used the method of dipole source analysis. An old debate exists on the dependence of the amplitude of sensory evoked potentials on stimulus intensity (Buchsbaum and Silverman 1968;review in: Carillo-dela-Pena 1992;Von Knorring and Perris 1981;Von Knorring 1982;Zuckerman et al 1974Zuckerman et al , 1988. In more recent years, extensive work suggested that a high intensity dependence is associated with a low functioning of serotonergic neurotransmission (Hegerl and Juckel 1993;Hegerl et al 1994Hegerl et al , 1996Von Knorring 1982;Von Knorring and Perris 1981).…”

Intensity dependence of auditory P2 in monozygotic twins discordant for Vietnam combat: Associations with posttraumatic stress disorder

“…Interestingly, the pattern of increased P2 amplitude intensity slopes observed in the present sample of combat veterans with PTSD is strikingly similar to that reported in our previous study of female Vietnam nurse veterans with PTSD [11] (Figures 1 and 2). Additionally, the repeated measures ANOVA for P2 amplitude revealed a significant main effect for stimulus (F (3,129) = 53.0, p < 0.001) and a significant diagnosis × stimulus interaction (F (3,129) = 3.8, p = 0.04) but no main effect for diagnosis (F (1,43) = 1.3, p = 0.26). Follow-up t-test comparisons indicated that the groups did not significantly differ in P2 amplitude to the 74 dB (t (43) = 0.0 p = 0.99), 84 dB (t (43) = -1.0, p = 0.37), 94 dB (t (43) = -1.2, p = 0.24), or 104 dB (t (43) = -1.6, p = 0.11) tone.…”

“…Because PTSD is characterized by heightened nervous system sensitivity, Paige and colleagues proposed that veterans with PTSD would show a reduction in the amplitude of the P2 component at higher tone-intensity levels, producing a shallow amplitude intensity slope [1]. Termed "reducing" by early investigators [3], this ERP response pattern of decreased intensity dependence is believed to reflect a protectively tuned sensory system that protects the organism from sensory overload via a central gating mechanism. In contrast, the opposite pattern of increasing amplitudes in response to increasing stimulus intensities (i.e., "augmenting" or increased intensity dependence) has been linked to a cortex tuned to seek out increases in stimulus intensity.…”

Altered processing of sensory stimuli in patients with migraine

“…When stimuli are delivered at increasing intensity, the evoked cortical responses increase in certain individu als, but decrease in others. 98 This so called augmentingreducing response has been widely studied, mainly in the context of auditory stimuli. The intensity depend ence of AEPs (IDAP) is expressed by the amplitudestimulus intensity slope of the cortical N1-P2 wave, where N1 is the greatest negative component 60-150 ms post stimulus and P1 is the greatest positivity from 120-200 ms. Interestingly, IDAP correlates inversely with central serotonergic transmission, as evaluated indirectly by biochemical and pharmacological methods.…”