Dexamphetamine influences funneling illusion based on psychometric score

Abstract

Objectives Our team previously showed that like the experience of the rubber hand illusion (RHI) in people with schizophrenia and their offspring¸ dexamphetamine administration to healthy volunteers increases the stimulus binding windows (BWs) in RHI. It is not clear if similar expansions of BWs are present for unimodal illusions. Studies have also shown that subjective or objective effects of amphetamine would be linked to between‐person variations in personality measures. Therefore, we aimed to examine the effect of dexamphetamine (DEX), a dopamine‐releasing stimulant, on illusory perception using unimodal sensory stimuli (Tactile Funneling Illusion [TFI]) across both temporal and spatial variables. We further examined the relationship between changes in psychometric scores and changes in illusion perception induced by dexamphetamine. Methods Healthy subjects (N = 20) participated in a randomized, double‐blind, counter‐balanced, placebo‐controlled, cross‐over study. The effects of dexamphetamine (0.45 mg/kg, PO, q.d.) on funneling and error of spatial localization (EL) were examined using TFI. Psychotomimetic effects were assessed using a battery of psychological measures. Results Dexamphetamine did not significantly increased the funneling illusion (p = 0.88) or EL (p = 0.5), relative to placebo. However, the degree of change in psychometric scores following dexamphetamine positively correlated with changes in funneling (ρ = 0.48, p = 0.03, n = 20), mainly at 0 ms delay condition (ρ = 0.6, p = 0.004, n = 20). Conclusion Unlike multimodal illusions, alteration of BWs does not occur for unimodal illusions after administration of a dopamine‐releasing agent. However, our findings indicate that moderate release of dopamine, through its psychotomimetic effect, indirectly influences unimodal illusion.

The effects of caffeine and d-amphetamine on spatial span task in healthy participants

“…As shown in Fig 4 , wilcoxon signed rank test with continuity correction indicated that there was a significant increase in PLE scores following d-amphetamine (V = 199, p = 0.00048), relative to placebo (presented in our previous report on funneling illusion [ 100 ]). As shown in Table 1 , d-amphetamine significantly increased scores on the BPRS (V = 129, p = 0.001), MIS (V = 107.5, p = 0.039) and PAS (V = 127, p = 0.017), but not on the Launay-Slade (V = 75, p = 0.16) or SAPS (V = 124.5, p = 0.092) Out of the total of 20 participants, d-amphetamine increased schizotypy scores in 16 participants.…”

“…Likewise, there were significant delay effects on SWM for the total scored (F[2.8, 53] = 6.6, p = 0.0006, η 2 = 0.074, after correction with Greenhouse-Geisser epsilon) but not for the maximum obtained (F[3, 57] = 2.1, p = 0.11, η 2 = 0.03).D-amphetamine effect on PLE. As shown in Fig4, wilcoxon signed rank test with continuity correction indicated that there was a significant increase in PLE scores following damphetamine (V = 199, p = 0.00048), relative to placebo (presented in our previous report on funneling illusion[100]). As shown in Table1, d-amphetamine significantly increased scores on the BPRS (V = 129, p = 0.001), MIS (V = 107.5, p = 0.039) and PAS (V = 127, p = 0.017), but not on the Launay-Slade (V = 75, p = 0.16) or SAPS (V = 124.5, p = 0.092) Out of the total of 20 participants, d-amphetamine increased schizotypy scores in 16 participants.PLE and working memory.…”

Dexamphetamine widens temporal and spatial binding windows in healthy participants

“…We recruited 46 participants, more than double the number of participants in previous dexamphetamine studies on BWs. 22,83 Importantly, our previous TFI study involving 20 healthy par ticipants showed that, although dexamphetamine influenced funnelling illusion based on changes in psychometric score, it failed to modify BWs. 83 We manipulated and compared the illusory and psycho logical effects of dexamphetamine at a moderate dose (about 33 mg), which was 2-3 times higher than that used in most previous dexamphetamine challenge studies.…”

“…22,83 Importantly, our previous TFI study involving 20 healthy par ticipants showed that, although dexamphetamine influenced funnelling illusion based on changes in psychometric score, it failed to modify BWs. 83 We manipulated and compared the illusory and psycho logical effects of dexamphetamine at a moderate dose (about 33 mg), which was 2-3 times higher than that used in most previous dexamphetamine challenge studies. We involved participants whose ages and education levels were very close, which provided a homogeneous population and avoided or decreased agerelated cognitive differences.…”