Brain Research Bulletin 82 (2010) 65–73 Contents lists available at ScienceDirect Brain Research Bulletin j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / b r a i n r e s b u l l Research report Cardiovascular and respiratory correlates of deep nociceptive stimulation, suggestions for analgesia, pain imagery and cognitive load as a function of hypnotizability Giulia Paoletti a , Maurizio Varanini b , Rita Balocchi b , Carmela Morizzo c , Carlo Palombo c , Enrica L. Santarcangelo d,∗ a Department of Physiology, University of Siena, Italy b Institute of Clinical Physiology, National Council of Research, Pisa, Italy c Department of Internal Medicine, University of Pisa, Italy d Department of Physiological Sciences, University of Pisa, Via San Zeno, 31-56127 Pisa, Italy a r t i c l e i n f o Article history: Received 8 October 2009 Received in revised form 4 March 2010 Accepted 8 March 2010 Available online 12 March 2010 Keywords: Hypnotizability Imagery Suggestions Deep pain Autonomic system a b s t r a c t Hypnotizability is a cognitive trait modulating some physiological responses to cognitive and physical stimulation also in the normal awake state and in the absence of specific suggestions. Aim of the study was the characterization of the cardiovascular correlates of deep pain induced by nociceptive pressor stimulation without (PAIN) and with (AN) suggestions for analgesia, pain imagery/perception (IM) and mental computation (MC) in not hypnotized highly (Highs) and low (Lows) hypnotizable healthy subjects of both genders.The subjective experience of pain intensity, relaxation and task related fatigue were measured through a structured inteview.Heart rate,blood pressure,skin blood flow and respiratory activity were monitored throughout the experimental session. Only Highs perceived lower pain intensity during AN with respect to PAIN and were able to perceive pain during IM. Heart rate decreased during PAIN, increased during MC and did not change during AN and IM in both groups. On the whole, the haemodynamic response consisted of decreased systolic/mean blood pressure and maximum skin blood flow together with increased diastolic blood pressure/minimum skin blood flow in both groups during all conditions. Scarce differences were observed between Highs and Lows (in systolic blood pressure during IM and in respiratory amplitude during PAIN, AN and IM, modulated by gender). The results indicate that in not hypnotized subjects hypnotizability is not associated with relevant differences in the autonomic responses to deep pain, suggestions for analgesia, pain imagery/perception and cognitive load. © 2010 Elsevier Inc. All rights reserved. 1. Introduction Hypnotizability is a multidimensional trait predictive of the ability to respond to hypnotic suggestions [16]. It is classically attributed to peculiar interactions between the anterior cingu- lus and the dorsolateral prefrontal cortex [15,23,34] and can be estimated through standard scales.Hypnotizability may account also for part of the physiological variability in the general pop- ulation because subjects exhibiting high (Highs) or low (Lows) hypnotizability scores show some differences in their physiological responses to cognitive and physical stimulation also in the nor- mal awake state and in the absence of specific suggestions [5,6]. At variance with the sensori-motor domain [6,25,26,38], however, the autonomic responses of not hypnotized healthy Highs and Lows ∗ Corresponding author. Tel.: +39 050 2213465; fax: +39 050 2213527. E-mail address: enricals@dfb.unipi.it (E.L. Santarcangelo). have shown only few differences occurring during moderately aversive cognitive stimulation [40], long-lasting simple relaxation [41] and upright stance [36]. In the response to nociceptive pressor stimulation,heart rate and heart rate variability are similar in highly and low hypnotiz- able healthy females [37].Only the correlations between indexes of heart rate variability obtained in the frequency and time domain suggest different control mechanisms of heart rate variability in the two groups during nociceptive stimulation and, in Highs, between nociceptive stimulation with and without subjectively effective suggestions for analgesia [1]. As the cardiac response is only part of the autonomic reaction possibly occurring during nociceptive stimulation, the main aim of the study was a more detailed characterization of the Highs’ and Lows’ cardiovascular and respiratory responses to deep pain induced by pressor stimulation through the concomitant evalua- tion of heart rate, blood pressure, skin blood flow and respiratory activity. 0361-9230/$ – see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.brainresbull.2010.03.003