Rapid effects of tryptamine psychedelics on perceptual distortions and early visual cortical population receptive fields.

N, N-dimethyltryptamine (DMT) is a psychedelic tryptamine acting on 5-HT2A serotonin receptors, which is associated with intense visual hallucinatory phenomena and perceptual changes such as distortions in visual space. The neural underpinnings of these effects remain unknown. We hypothesised that changes in population receptive field (pRF) properties in the primary visual cortex (V1) might underlie visual perceptual experience. We tested this hypothesis using magnetic resonance imaging (MRI) in a within-subject design. We used a technique called pRF mapping, which measures neural population visual response properties and retinotopic maps in early visual areas. We show that in the presence of visual effects, as documented by the Hallucinogen Rating Scale (HRS), the mean pRF sizes in V1 significantly increase in the peripheral visual field for active condition (inhaled DMT) compared to the control. Eye and head movement differences were absent across conditions. This evidence for short-term effects of DMT in pRF may explain perceptual distortions induced by psychedelics such as field blurring, tunnel vision (peripheral vision becoming blurred while central vision remains sharp) and the enlargement of nearby visual space, particularly at the visual locations surrounding the fovea. Our findings are also consistent with a mechanistic framework whereby gain control of ongoing and evoked activity in the visual cortex is controlled by activation of 5-HT2A receptors.

The Effects of Tryptamine Psychedelics in the Brain: A meta-Analysis of Functional and Review of Molecular Imaging Studies.

There is an increasing interest in the neural effects of psychoactive drugs, in particular tryptamine psychedelics, which has been incremented by the proposal that they have potential therapeutic benefits, based on their molecular mimicry of serotonin. It is widely believed that they act mainly through 5HT2A receptors but their effects on neural activation of distinct brain systems are not fully understood. We performed a quantitative meta-analysis of brain imaging studies to investigate the effects of substances within this class (e.g., LSD, Psilocybin, DMT, Ayahuasca) in the brain from a molecular and functional point of view. We investigated the question whether the changes in activation patterns and connectivity map into regions with larger 5HT1A/5HT2A receptor binding, as expected from indolaemine hallucinogens (in spite of the often reported emphasis only on 5HT2AR). We did indeed find that regions with changed connectivity and/or activation patterns match regions with high density of 5HT2A receptors, namely visual BA19, visual fusiform regions in BA37, dorsal anterior and posterior cingulate cortex, medial prefrontal cortex, and regions involved in theory of mind such as the surpramarginal gyrus, and temporal cortex (rich in 5HT1A receptors). However, we also found relevant patterns in other brain regions such as dorsolateral prefrontal cortex. Moreover, many of the above-mentioned regions also have a significant density of both 5HT1A/5HT2A receptors, and available PET studies on the effects of psychedelics on receptor occupancy are still quite scarce, precluding a metanalytic approach. Finally, we found a robust neuromodulatory effect in the right amygdala. In sum, the available evidence points towards strong neuromodulatory effects of tryptamine psychedelics in key brain regions involved in mental imagery, theory of mind and affective regulation, pointing to potential therapeutic applications of this class of substances.

Campanha nacional de doaçäo de próteses: resultados parciais do Serviço de Reabilitaçäo da Santa Casa de Säo Paulo / National camping of prothesis donation: parcial results from Santa Casa of Säo Paulo Rehabilitation Center

Neste estudo os autores apresentam os resultados parciais da Campanha Nacional de Doaçöes de Próteses pelo Sistema Unico de Saúde, no Centro de Reabilitaçäo da Santa Casa de Säo Paulo.Foram incluídos 138 pacientes com 150 amputaçöes, 94 por cento destas de membros inferiores.Nossos resultados säo comparados com os da literatura

Hospitalizaçäo evitável em uma unidade pediátrica do Recife / Avoided hospitalization in a pediatric unit of Recife, Brazil

Oitenta e sete pacientes pediátricos, portadores de afecçöes diversas em que predominavam as infecçöes agudas do trato aéreo ou do digestivo, encaminhados, principalmente por médicos do INAMPS, para internamento no HGP/IMIP, foram examinados por dois pediatras que, sigilosa e independentemente, opinaram sobre a indicaçäo da internaçäo. Em toda a casuística, nos portadores de doença respiratória aguda, e nos portadores de afecçäo do tubo digestivo, foram altos os percentuais de internaçöes consideradas evitáveis. Também foi elevado o percentual de concordância entre os pareceres, indicando ou näo a hospitalizaçäo, segundo os dois pediatras. Os gastos do INAMPS, com a hospitalizaçäo admitida como evitável, foram de 18% do total em toda a casuística e de 40% do total nos afetados por doenças respiratória aguda