Tolerance to repeated rewarding electrical stimulation of the insular cortex

Somatosensory Thalamic Activity Modulation by Posterior Insular Stimulation: Cues to Clinical Application Based on Comparison of Frequencies in a Cat Model

“…In IS, such criterion is not available and intensity is chosen almost randomly at a level that avoids tissue damage. Moreover, in a study that showed that repetitive IS eventually had its effects decreased, the authors show that increasing the intensity of stimulation could restore these effects (74). Electrodes positions also affect stimulation effects: in MCS cathodal stimulation would preferentially activate fibers parallel to the cortex, whereas anodal stimulation would preferentially activate fibers perpendicular to the cortex (75).…”

“…A recent study in rats evaluating the effect of 60 Hz IS showed that this stimulation could increase pain thresholds and attributed this effect to the local inhibition of the insular cortex (25). In contrast, the effects of IS at 66.6 Hz on the reward system was attributed to an activation of the insula and the reward circuitry (72)(73)(74).…”

Differential rewarding effects of electrical stimulation of the lateral hypothalamus and parabrachial complex: Functional characterization and the relevance of opioid systems and dopamine

“…This conceptual framework, subsequently developed by Koob and Le Moal, focuses on motivational-affective circuits/systems and hypothesizes that transition towards compulsive use and loss of control is accompanied by chronic perturbations of homeostatic systems (allostasis) and by neuroadaptations, leading to behavioural sensitization (Koob and Le Moal, 2000; Koob et al, 2014). Accordingly, the presence in the brainstem of regions such as the LPBe, which process opiate-mediated positive (and/or aversive) affective information (Garcia et al, 2014; Simon et al, 2007, 2008, 2009, 2011, 2013) and where a tolerance effect has been observed (Hurtado and Puerto, 2016; Hurtado et al, 2016), suggests that this region may possibly form part of wider hedonic-affective circuits that may be hierarchically controlled by anterior prosencephalic regions (Berridge and Kringelbach, 2015; Roitman et al, 2004) and whose components require further elucidation.…”