Development of somatosensory perception in children: a longitudinal QST-study.

Cross-sectional studies on somatosensory perception in children demonstrate lower pain thresholds for children compared with adolescents. The aim of the present longitudinal study was to replicate these age-related differences in a longitudinal design. Total 38 children and adolescents aged 6 to 16 years (two girls and two boys within each year) participated in this study. Quantitative sensory testing (QST) according to the protocol of the German research network on neuropathic pain (DFNS) was assessed twice with an interval of 15.8 ± 3.0 months. Bland-Altman analyses describe the short-term reliability of the measurements. Intraindividual sensory development was measured using paired t-test and quantified by effect sizes Cohen's d between the two measurements. QST parameters showed good short-term reliability. Over a period of 1 year, children became less sensitive to painful stimuli, especially to cold pain, pressure pain, and mechanical pain. No systematic developmental changes were observed in response to the other somatosensory stimuli. QST is reliable over short retest intervals. In line with previous results from cross-sectional studies, we find a decrease in pain sensitivity with increasing age but no differences in nonnociceptive somatosensory processing over a period of 1 year in children between 6 and 16 years of age. Taken together, these results highlight the importance of a reference-based interpretation of the individual QST data.

Being with virtual others: Neural correlates of social interaction.

To characterize the neural correlates of being personally involved in social interaction as opposed to being a passive observer of social interaction between others we performed an fMRI study in which participants were gazed at by virtual characters (ME) or observed them looking at someone else (OTHER). In dynamic animations virtual characters then showed socially relevant facial expressions as they would appear in greeting and approach situations (SOC) or arbitrary facial movements (ARB). Differential neural activity associated with ME>OTHER was located in anterior medial prefrontal cortex in contrast to the precuneus for OTHER>ME. Perception of socially relevant facial expressions (SOC>ARB) led to differentially increased neural activity in ventral medial prefrontal cortex. Perception of arbitrary facial movements (ARB>SOC) differentially activated the middle temporal gyrus. The results, thus, show that activation of medial prefrontal cortex underlies both the perception of social communication indicated by facial expressions and the feeling of personal involvement indicated by eye gaze. Our data also demonstrate that distinct regions of medial prefrontal cortex contribute differentially to social cognition: whereas the ventral medial prefrontal cortex is recruited during the analysis of social content as accessible in interactionally relevant mimic gestures, differential activation of a more dorsal part of medial prefrontal cortex subserves the detection of self-relevance and may thus establish an intersubjective context in which communicative signals are evaluated.