Connectomic reconstruction predicts the functional organization of visual inputs to the navigation center of the Drosophila brain.

Many animals, including humans, navigate their surroundings by visual input, yet we understand little about how visual information is transformed and integrated by the navigation system. In Drosophila melanogaster, compass neurons in the donut-shaped ellipsoid body of the central complex generate a sense of direction by integrating visual input from ring neurons, a part of the anterior visual pathway (AVP). Here, we densely reconstruct all neurons in the AVP using FlyWire, an AI-assisted tool for analyzing electron-microscopy data. The AVP comprises four neuropils, sequentially linked by three major classes of neurons: MeTu neurons, which connect the medulla in the optic lobe to the small unit of anterior optic tubercle (AOTUsu) in the central brain; TuBu neurons, which connect the anterior optic tubercle to the bulb neuropil; and ring neurons, which connect the bulb to the ellipsoid body. Based on neuronal morphologies, connectivity between different neural classes, and the locations of synapses, we identified non-overlapping channels originating from four types of MeTu neurons, which we further divided into ten subtypes based on the presynaptic connections in medulla and postsynaptic connections in AOTUsu. To gain an objective measure of the natural variation within the pathway, we quantified the differences between anterior visual pathways from both hemispheres and between two electron-microscopy datasets. Furthermore, we infer potential visual features and the visual area from which any given ring neuron receives input by combining the connectivity of the entire AVP, the MeTu neurons' dendritic fields, and presynaptic connectivity in the optic lobes. These results provide a strong foundation for understanding how distinct visual features are extracted and transformed across multiple processing stages to provide critical information for computing the fly's sense of direction.

An unusual complication of cocaine toxicity.

A 25-year man presented to the Accident and Emergency Department complaining of dizziness and shortness of breath after taking 70 grams of cocaine over 10 hours. He said a friend had noticed that his skin had turned dark blue. On examination the patient was severely centrally and peripherally cyanosed. His pulse oximeter oxygen saturations were 88% on air. An arterial blood gas showed a methaemoglobin level of 45.6%. The patient was diagnosed with cocaine-induced methaemoglobinaemia and given methyl thioninium chloride (methylene blue). He made an uneventful recovery.

Exploring potential mechanisms in alarm treatment for primary nocturnal enuresis.

OBJECTIVE: In the treatment of childhood nocturnal enuresis the enuresis alarm has consistently proved effective. However, the various proposals advanced to explain its therapeutic mechanism generally lack empirical support. In this clinical trial we investigated the hypothesis that the alarm promotes reduced nocturnal urine production through increased urine concentration (enabling the child to sleep through the night). MATERIAL AND METHODS: Measurements of urinary vasopressin and osmolality were made pre- and post-alarm treatment in a group (n=12) of outpatient children (aged 7-12 years) with severe (more than four times a week) nocturnal enuresis. RESULTS: Of the study group, 75% achieved the success criteria, with 89% predominantly sleeping through the night on dry nights, confirming that arousability is unlikely to be the principal mode of action. All those becoming dry showed an increase in urine concentration post-treatment. For half this was associated with an increase in post-treatment vasopressin whilst for the rest, although increases in osmolality were observed, there was no associated increase in vasopressin. CONCLUSIONS: Although based on a small sample this study offers an insight into possible therapeutic mechanisms of an enuresis alarm. It suggests that most children who become dry sleep through the night and that increased nocturnal urine concentration (and thus reduced urine volume) is likely to be the means whereby this is achieved. Furthermore, the study suggests two possible mechanisms whereby nocturnal urine concentration is achieved: either increased production of vasopressin or enhanced water transport across the urothelium.