The off-line effect of affective touch on multisensory integration and tactile perceptual accuracy during the somatic signal detection task

Affective touch refers to the emotional and motivational facets of tactile sensation and has been linked to the activation of a specialised system of mechanosensory afferents (the CT system), that respond optimally to slow caress-like touch. Affective touch has been shown to play an important role in the building of the bodily self: the multisensory integrated global awareness of one’s own body. Here we investigated the effects of affective touch on subsequent tactile awareness and multisensory integration using the Somatic Signal Detection Task (SSDT). During the SSDT, participants were required to detect near-threshold tactile stimulation on their cheek, in the presence/absence of a concomitant light. Participants repeated the SSDT twice, before and after receiving a touch manipulation. Participants were divided into two groups: one received affective touch (CT optimal; n = 32), and the second received non-affective touch (non-CT optimal; n = 34). Levels of arousal (skin conductance levels, SCLs) and mood changes after the touch manipulation were also measured. Affective touch led to an increase in tactile accuracy, as indicated by less false reports of touch and a trend towards higher tactile sensitivity during the subsequent SSDT. Conversely, non-affective touch was found to induce a partial decrease in the correct detection of touch possibly due to a desensitization of skin mechanoreceptors. Both affective and non-affective touch induced a more positive mood and higher SCLs in participants. The increase in SCLs was greater after affective touch. We conclude that receiving affective touch enhances the sense of bodily self therefore increasing perceptual accuracy and awareness. Higher SCLs are suggested to be a possible mediator linking affective touch to a greater tactile accuracy. Clinical implications are discussed.

In your eyes: vision of the body alters touch perception in women with eating disorder symptoms

We investigated the effects of non-informative vision of the body on exteroceptive multisensory integration and touch perception in participants presenting with different levels of eating disorder (ED) symptoms. The study employed a sample of women reporting low (low ED; n = 31) vs high (high ED; n = 34) levels of subclinical ED symptoms who undertook the Somatic Signal Detection task (SSDT). During the SSDT, participants are required to detect near-threshold tactile stimulation at their fingertip with and without a simultaneous light flash next to the stimulated fingertip. Previous research has found that participants have a tendency to erroneously report touch sensations in the absence of the stimulation, and especially when the light flash is presented. In this study, participants completed the SSDT under two conditions: while their hand was visible (non-informative vision), and while their hand was hidden from sight (no vision). Non-informative vision of the hand was found to have a different effect on SSDT performances according to participants’ levels of ED symptoms. High ED participants were better able to correctly detect the touch during the SSDT when their hand was visible. Conversely, for low ED participants, vision of the body was linked to a greater effect of the light in inducing false reports of touch. We suggest that in those with high ED symptoms, vision of the body may exacerbate a predisposition to focusing on external rather than internal bodily information.

A case of hypereosinophilic syndrome with STAT5b N642H mutation

ABSTRACT Hypereosinophilia is defined as persistent eosinophilia (>1.5 × 109/L). Hypereosinophilic syndrome (HES) is a term used to describe a group of disorders characterized by sustained hypereosinophilia associated with end-organ damage. Based on underlying molecular mechanism of eosinophilia, there are different subtypes of HES. Diagnosis of HES subtype can be challenging, especially in the absence of overt lymphoid/myeloid neoplasms or discernable secondary causes. Long-term outpatient follow-up with periodic complete blood count and repeated bone marrow biopsy may be needed to monitor disease activity. Somatic signal transducer and activation transcription 5b (STAT5b) N642H mutation was recently found to be associated with myeloid neoplasms with eosinophilia. We report a case of HES who presented with pulmonary embolism and acute eosinophilic pneumonia, found to have recurrent STAT5b N642H mutation by next-generation sequencing, suggesting possible underlying myeloid neoplasm.

Transcranial alternating current stimulation at 10 Hz modulates response bias in the Somatic Signal Detection Task

BackgroundOngoing, pre-stimulus oscillatory activity in the 8-13 Hz alpha range has been shown to correlate with both true and false reports of peri-threshold somatosensory stimuli. However, to directly test the role of such oscillatory activity in behaviour, it is necessary to manipulate it. Transcranial alternating current stimulation (tACS) offers a method of directly manipulating oscillatory brain activity using a sinusoidal current passed to the scalp.ObjectiveWe tested whether alpha tACS would change somatosensory sensitivity or response bias in a signal detection task in order to test whether alpha oscillations have a causal role in behaviour.MethodsActive 10 Hz tACS or sham stimulation was applied using electrodes placed bilaterally at positions CP3 and CP4 of the 10-20 electrode placement system. Participants performed the Somatic Signal Detection Task (SSDT), in which they must detect brief somatosensory targets delivered at their detection threshold. These targets are sometimes accompanied by a light flash, which could also occur alone.ResultsActive tACS did not modulate sensitivity to targets but did modulate response criterion. Specifically, we found that active stimulation generally increased touch reporting rates, but particularly increased responding on light trials. Stimulation did not interact with the presence of touch, and thus increased both hits and false alarms.ConclusionstACS stimulation increased reports of touch in a manner consistent with our observational reports, changing response bias, and consistent with a role for alpha activity in somatosensory detection.

A Reevaluation of the Question: Is the Pubertal Resurgence in Pulsatile GnRH Release in the Male Rhesus Monkey (Macaca mulatta) Associated With a Gonad-Independent Augmentation of GH Secretion?

A somatic signal has been posited to trigger the pubertal resurgence in pulsatile GnRH secretion that initiates puberty in highly evolved primates. That GH might provide such a signal emerged in 2000 as a result of a study reporting that circulating nocturnal GH concentrations in castrated juvenile male monkeys increased in a 3-week period immediately preceding the pubertal resurgence of LH secretion. The present study was conducted to reexamine this intriguing relationship, again in an agonadal model. Four castrated juvenile male monkeys were implanted with indwelling jugular catheters, housed in remote sampling cages, and subjected to 24 hours of sequential blood sampling (every 30 min) every 2 weeks from 19.5 to 22 months of age. Twenty-four-hour profiles of circulating GH concentrations were analyzed using the pulse detection algorithm, PULSAR, and developmental changes in pulsatile GH release with respect to the initiation of the pubertal rise of LH secretion (week 0; observed between 22.5 and 32 mo of age) were examined for significance by a repeated-measures ANOVA. Changes in the parameters of pulsatile GH secretion, including mean 24-hour GH concentration and GH pulse frequency and pulse amplitude for 3 (n = 4) and 6 (n = 3) months before week 0 were unremarkable and nonsignificant. These findings fail to confirm those of the earlier study and lead us to conclude that the timing of the pubertal resurgence of GnRH release in the male monkey is not dictated by GH. Reasons for the discrepancy between the two studies are unclear.

Somatosensory amplification and illusory tactile sensations

Experimental studies have demonstrated that it is possible to induce convincing bodily distortions in neurologically healthy individuals, through cross-modal manipulations; such as the rubber hand illusion (Botvinick and Cohen, 1998), the parchment skin illusion (Jousmaki and Hari, 1998) and the Somatic Signal Detection Task (SSDT; Lloydet al., 2008). It has been shown previously with the SSDT that when a tactile stimulus is presented with a simultaneous light flash, individuals show both increased sensitivity to the tactile stimulus, and the tendency to report feeling the stimulus even when one was not presented; a tendency which varies greatly between individuals but remains constant over time within an individual (McKenzieet al., 2010). Further studies into tactile stimulus discrimination using the Somatic Signal Discrimination Task (SSDiT) have also shown that a concurrent light led to a significant improvement in people’s ability to discriminate ‘weak’ tactile stimuli from ‘strong’ ones, as well as a bias towards reporting any tactile stimulus as ‘strong’ (Poliakoffet al., in preparation), indicating that the light may influence both early and later stages of processing. The current study investigated whether the tendency to report higher numbers of false alarms when carrying out the SSDT is correlated with the tendency to experience higher numbers of cross-modal ‘enhancements’ of weak tactile signals (leading to classifications of ‘weak’ stimuli as strong, and ‘strong’ stimuli as ‘stronger’). Results will be discussed.

Somatic mutations activating STAT3 in human inflammatory hepatocellular adenomas

Inflammatory hepatocellular adenomas (IHCAs) are benign liver tumors. 60% of these tumors have IL-6 signal transducer (IL6ST; gp130) mutations that activate interleukin 6 (IL-6) signaling. Here, we report that 12% of IHCA subsets lacking IL6ST mutations harbor somatic signal transducer and activator of transcription 3 (STAT3) mutations (6/49). Most of these mutations are amino acid substitutions in the SH2 domain that directs STAT3 dimerization. In contrast to wild-type STAT3, IHCA STAT3 mutants constitutively activated the IL-6 signaling pathway independent of ligand in hepatocellular cells. Indeed, the IHCA STAT3 Y640 mutant homodimerized independent of IL-6 and was hypersensitive to IL-6 stimulation. This was associated with phosphorylation of tyrosine 705, a residue required for IL-6–induced STAT3 activation. Silencing or inhibiting the tyrosine kinases JAK1 or Src, which phosphorylate STAT3, impaired constitutive activity of IHCA STAT3 mutants in hepatocellular cells. Thus, we identified for the first time somatic STAT3 mutations in human tumors, revealing a new mechanism of recurrent STAT3 activation and underscoring the role of the IL-6–STAT3 pathway in benign hepatocellular tumorigenesis.