Beyond body maps: Information content of specific body parts is distributed across the somatosensory homunculus.

The homunculus in primary somatosensory cortex (S1) is famous for its body part selectivity, but this dominant feature may eclipse other representational features, e.g., information content, also relevant for S1 organization. Using multivariate fMRI analysis, we ask whether body part information content can be identified in S1 beyond its primary region. Throughout S1, we identify significant representational dissimilarities between body parts but also subparts in distant non-primary regions (e.g., between the hand and the lips in the foot region and between different face parts in the foot region). Two movements performed by one body part (e.g., the hand) could also be dissociated well beyond its primary region (e.g., in the foot and face regions), even within Brodmann area 3b. Our results demonstrate that information content is more distributed across S1 than selectivity maps suggest. This finding reveals underlying information contents in S1 that could be harnessed for rehabilitation and brain-machine interfaces.

Robotic hand augmentation drives changes in neural body representation.

Humans have long been fascinated by the opportunities afforded through augmentation. This vision not only depends on technological innovations but also critically relies on our brain's ability to learn, adapt, and interface with augmentation devices. Here, we investigated whether successful motor augmentation with an extra robotic thumb can be achieved and what its implications are on the neural representation and function of the biological hand. Able-bodied participants were trained to use an extra robotic thumb (called the Third Thumb) over 5 days, including both lab-based and unstructured daily use. We challenged participants to complete normally bimanual tasks using only the augmented hand and examined their ability to develop hand-robot interactions. Participants were tested on a variety of behavioral and brain imaging tests, designed to interrogate the augmented hand's representation before and after the training. Training improved Third Thumb motor control, dexterity, and hand-robot coordination, even when cognitive load was increased or when vision was occluded. It also resulted in increased sense of embodiment over the Third Thumb. Consequently, augmentation influenced key aspects of hand representation and motor control. Third Thumb usage weakened natural kinematic synergies of the biological hand. Furthermore, brain decoding revealed a mild collapse of the augmented hand's motor representation after training, even while the Third Thumb was not worn. Together, our findings demonstrate that motor augmentation can be readily achieved, with potential for flexible use, reduced cognitive reliance, and increased sense of embodiment. Yet, augmentation may incur changes to the biological hand representation. Such neurocognitive consequences are crucial for successful implementation of future augmentation technologies.

Right-wing politicians prefer the emotional left.

Physiological research suggests that social attitudes, such as political beliefs, may be partly hard-wired in the brain. Conservatives have heightened sensitivity for detecting emotional faces and use emotion more effectively when campaigning. As the left face displays emotion more prominently, we examined 1538 official photographs of conservative and liberal politicians from Australia, Canada, the United Kingdom and the United States for an asymmetry in posing. Across nations, conservatives were more likely than liberals to display the left cheek. In contrast, liberals were more likely to face forward than were conservatives. Emotion is important in political campaigning and as portraits influence voting decisions, conservative politicians may intuitively display the left face to convey emotion to voters.

Overdose in young people using heroin: associations with mental health, prescription drug use and personal circumstances.

OBJECTIVE: To identify patterns of mental health, prescription drug use and personal circumstances associated with heroin overdose in young people. DESIGN: Linkage of data on use of Pharmaceutical Benefits Scheme (PBS) prescription drugs with data from a self-report questionnaire. SETTING: Inner metropolitan Melbourne, Australia. SUBJECTS: 163 young people, 15-30 years, using heroin. MAIN OUTCOME MEASURES: Personal circumstances, mental health (as measured by various scales), and PBS-listed prescription drug use. RESULTS: Young people using heroin reported high rates of feelings of hopelessness, depression, antisocial behaviour, self-harm and diagnosed mental illness. A prior history of overdose was associated with previous mental illness, which in turn was associated with being female, having poor social support, being dissatisfied with relationships, and living alone or in temporary accommodation. While feelings of hopelessness and antisocial behaviour were strongly associated with overdose history, the number of PBS prescription drugs used had a very strong relationship with overdose, particularly benzodiazepines, other opioids, tricyclic antidepressants and tranquillisers. CONCLUSIONS: Further research to explore causal relationships between prescription drugs and heroin overdose is warranted. Improved data linkage to PBS records for general practitioners may facilitate safer prescribing practices.

Seeking drugs or seeking help? Escalating "doctor shopping" by young heroin users before fatal overdose.

OBJECTIVE: To identify prescription drug-seeking behaviour patterns among young people who subsequently died of heroin-related overdose. DESIGN: Linkage of Medicare and Pharmaceutical Benefits Scheme and Coroner's Court records from Victoria. SUBJECTS: Two hundred and two 15-24-year-olds who died of heroin-related overdose between 6 January 1994 and 6 October 1999. MAIN OUTCOME MEASURES: Patterns of use of medical services and prescription drugs listed on the Pharmaceutical Benefits Scheme in the years before death, and use of all drugs just before death. RESULTS: Polydrug use was reported in 90% of toxicology reports, and prescription drugs were present in 80% of subjects. Subjects accessed medical services six times more frequently than the general population aged 14-24 years, and more than half of all prescribed drugs were those prone to misuse, such as benzodiazepines and opioid analgesics. A pattern of increasing drug-seeking behaviour in the years before death was identified, with doctor-visitation rates, number of different doctors seen and rates of prescriptions peaking in the year before death. CONCLUSIONS: An apparent increase in "doctor shopping" in the years before heroin-related death may reflect the increasing misuse of prescription drugs, but also an increasing need for help. Identification of a pattern of escalating doctor shopping could be an opportunity for intervention, and potentially, reduction in mortality.

Association of benzodiazepine injection with the prescription of temazepam capsules.

Temazepam capsules have become a popular choice for benzodiazepine injection by injecting drug users, and serious vascular and tissue damage leading to ulcers and gangrene can result. We compared the self-reported benzodiazepine injecting behaviour of 91 heroin users with their Pharmaceutical Benefits Schedule (PBS) records for the preceding 5 years. We found that individuals prescribed PBS temazepam capsules were more likely to report injecting benzodiazepines than individuals who had either not been prescribed PBS temazepam capsules or had been prescribed PBS temazepam tablets. These results provide empirical support for the argument to limit the prescription and supply of temazepam capsules in Australia.

The effect of left and right poses on the expression of facial emotion.

Research, using composite facial photographs has demonstrated that left-left composites are more emotionally expressive than are right-right composites. The present study investigated whether hemifacial asymmetries in expression are apparent in photographs, that feature one side of the face more than the other. Photographs were taken of the models who turned their heads: (a) 15 degrees to the left, (b) 15 degrees to the right or (c) faced directly towards the camera. It was predicted that left hemiface and midline photographs would be judged as more emotionally expressive than right hemiface photographs, where the left hemiface is less prominent. Three hundred and eighty-four participants viewed photographs of the three posing conditions, and rated each photograph along an emotional expressivity scale. Midline and left hemiface portraits were rated as more emotionally expressive than were right hemiface portraits. To investigate whether this effect was caused by observer's aesthetic/perceptual biases, mirror-reversed versions of the three posing conditions were included. Left hemiface and midline portraits were rated as more emotionally expressive, irrespective of whether they were mirror-reversed. It was concluded that head turns of just 15 degrees can bring about significant changes in the perceived emotionality. The relevance of these findings to painted portraits, which feature the left hemiface more than the right, is discussed.

Which cheek to turn? The effect of gender and emotional expressivity on posing behavior.

Nicholls et al. (1999, Proc. Royal Soc. B, 266, 1517-1522) demonstrated that models turn their left or right cheeks when expressing or concealing emotion, respectively. This study examined whether emotionally expressive individuals are more likely to turn their left cheek when posing for a photograph than less emotionally expressive individuals. One hundred twenty-four normal participants completed an Emotional Expressivity Scale (EES) and posed for a photograph. Females had a higher EES than males and there was a trend for left cheek posers to have a higher EES than right cheek posers. Females were more likely to turn their left cheek than were males. Results support our argument that emotionally expressive individuals turn their left cheek when posing. The higher incidence of leftward poses in females than males may reflect the higher EES for females. These results support the proposition that the leftward bias in painted portraits is related to a desire to capture the emotive qualities of the left side of the face.