Cortical processing of tactile stimuli applied in quick succession across the fingertips: temporal evolution of dipole sources revealed by magnetoencephalography

Abstract

We used magnetoencephalography (MEG) to investigate the cortical processing of an innocuous facial tactile stimulus in healthy subjects and in a group of subjects suVering from chronic temporomandibular disorder (TMD). Equivalent current dipoles (ECDs) were extracted for a time period of 1 s following stimulus application, and their location, duration and onset time determined. The counts of ECDs extracted did not diVer signiWcantly between the two groups. In contrast, we found statistically signiWcant diVerences in ECD duration and onset time. SpeciWcally, ECD duration was longer in the TMD group in the precentral gyrus, and ECD onset time was earlier in the parietal operculum. In addition, we found diVerences in the internal organization and clustering of the brain areas involved indicating a less tight association and a less coordinated stimulus information processing in the TMD group. Altogether, these results show that an innocuous facial tactile stimulus is diVerently processed in the brain of TMD subjects, when compared to controls, reXecting altered brain mechanisms due to chronic pain.

Multimodal psychodynamic psychotherapy induces normalization of reward related activity in somatoform disorder

“…Our paradigm was hence apt to be used in the investigation of reward related activity. All of the four regions with diminished neuronal differentiation in acute somatoform patients are involved in the processing of external stimuli and support our initial hypothesis of disturbed reward processing of external stimuli in somatoform patients: The postcentral gyrus (BA 1, 2, 3) is the primary somatosensory cortex (Kurth et al 2000;Karageorgiou et al 2008). The cluster observed in our study probably represents the somatotopic fi eld of the right index fi nger, since this fi nger responded to the target cue in the paradigm and the observed activation is in accordance with the somatotopic representation of the index fi nger as described in previous studies (Nakamura et al 1998;Stippich et al 1999;van Westen et al 2004).…”

TAC-Cell inputs to human hand and lip induce short-term adaptation of the primary somatosensory cortex

“…Air-driven membrane stimulators (Karageorgiou et al, 2008) have been used to stimulate finger tips but the amplitude or rise time of the stimuli was not defined. In addition, they have limited scope and cannot be used to stimulate all body parts.…”

Brain rhythm attractor breakdown in Alzheimer's disease: Functional and pathologic implications

“…Information processing in the brain is not a static linear process, but involves serial, parallel, and feedback pathways that are differentially activated across circadian and ultradian cycles [4–11]. This dynamic process allows, through temporal binding of neuronal activity between areas, the integration and retrieval of multimodal information [12–14], but also allows the formation of memory engrams through strengthening and pruning of synapses [9,15].…”