Interindividual differences in the perception of dental stimulation and related brain activity

Abstract

For identical diagnoses in the trigeminal innervation territory, individual differences have been clinically observed among the symptoms reported, such as dysesthesia and pain. Different subjective perceptions of unpleasantness and pain intensity may have different cortical substrates. The aim of this study was to identify brain areas in which activation depends on the subjective perception (intensity and unpleasantness) of electric dental stimulation. Electrical stimuli of increasing intensity were applied to maxillary canines in 14 healthy volunteers. Ratings for stimulus intensity and unpleasantness perceived across the stimulation session were reported postscan on 11-point numerical scales. The rating values were then included as covariates in the functional magnetic resonance imaging (fMRI) group analysis. Interindividual differences of intensity ratings were reflected in differential activity of the following brain areas: superior parietal lobule, superior temporal gyrus/anterior insula, inferior and middle temporal gyrus, lingual gyrus, anterior cingulate, and caudate nucleus. Differences related to unpleasantness ratings were reflected in the lingual gyrus. In conclusion, differences of perceived intensity between individuals are reflected in the differential activity of a set of brain areas distinct from those regions, reflecting rating differences of unpleasantness.

The neuronal correlates of intranasal trigeminal function—an ALE meta-analysis of human functional brain imaging data

“…Significant ALE values were observed in a network encompassing the brainstem, the thalamus, the anterior cingulate cortex, the insula and adjoining operculum, the superior parietal lobule, the precentral gyrus, and the primary (S I) and secondary (S II) somatosensory cortices, areas known for the processing of intransal nociceptive stimuli (Bensafi et al, 2008; Boyle et al, 2007; Hari et al, 1997; Hummel et al, 2005; 2009b; Huttunen et al, 1986; Iannilli et al, 2007; 2008). Furthermore, published findings indicate that these areas process other painful stimuli applied to either the face (de Leeuw et al, 2005; de Leeuw et al, 2006; Ettlin et al, 2009; Iannilli et al, 2008) or hand (Bornhovd et al, 2002; Kwan et al, 2000; Peyron et al, 2000). In conjunction with these findings, our data suggest that the processing of intranasal CO 2 stimulation does not utilize a unique network but rather accesses the general pain processing network, also known as the pain matrix.…”

Posterior Insular Molecular Changes in Myofascial Pain

“…Four lines of evidence support this possibility. First, trigeminal sensory processing, including experimental dental pain, occurs in a region contiguous with the posterior insula (Becerra et al, 2006;Ettlin et al, 2009), suggesting that persistent pain could affect this region. Second, individuals with TMD manifest increased white matter volume in a region near the left posterior insula (Gerstner et al, 2009).…”

Insula-specific responses induced by dental pain. A proton magnetic resonance spectroscopy study

“…Based on preliminary work on the examination of toothache-related blood oxygen level-dependent (BOLD) responses demonstrating strong perfusion alterations, the current study was designed to observe more in detail whether this crucial pain processing brain area might react also on the neurotransmitter level [22]. Therefore, the specific aims were to answer the questions, are there basal metabolic changes in the insular cortex under acute pain stimulation (in comparison to a non-stimulated control group), and second,is it possible to find a link between the subjectively experienced pain intensity and the corresponding individual quantifiable spectroscopic metabolites.…”