Currents contributing to decision making in neurons B31/B32 of Aplysia

Biophysical properties of neurons contributing to the ability of an animal to decide whether or not to respond were examined. B31/B32, two pairs of bilaterally symmetrical Aplysia neurons, are major participants in deciding to initiate a buccal motor program, the neural correlate of a consummatory feeding response. B31/B32 respond to an adequate stimulus after a delay, during which time additional stimuli influence the decision to respond. B31/B32 then respond with a ramp depolarization followed by a sustained soma depolarization and axon spiking that is the expression of a commitment to respond to food. Four currents contributing to decision making in B31/B32 were characterized, and their functional effects were determined, in current- and voltage-clamp experiments and with simulations. Inward currents arising from slow muscarinic transmission were characterized. These currents contribute to the B31/B32 depolarization. Their slow activation kinetics contribute to the delay preceding B31/B32 activity. After the delay, inward currents affect B31/B32 in the context of two endogenous inactivating outward currents: a delayed rectifier K⁺ current (I_K-V) and an A-type K⁺ current (I_K-A), as well as a high-threshold noninactivating outward current (I_maintained). Hodgkin-Huxley kinetic analyses were performed on the outward currents. Simulations using equations from these analyses showed that I_K-V and I_K-A slow the ramp depolarization preceding the sustained depolarization. The three outward currents contribute to braking the B31/B32 depolarization and keeping the sustained depolarization at a constant voltage. The currents identified are sufficient to explain the properties of B31/B32 that play a role in generating the decision to feed.     

Reversal of Hartmann’s procedure: still a complicated operation

Hartmann’s procedure, colonic resection with an end colostomy and rectal closure, is used in a variety of surgical emergencies. It is a common surgical procedure that is often practiced in patients with colonic obstruction and colonic perforation, resolving the acute clinical situation in the majority of cases. Reversal of Hartmann’s procedure with restoration of bowel continuity occurs in a significantly low percentage of patients. There are several reasons contributing to the fact that many patients remain with a permanent colostomy following Hartmann’s procedure. These include factors related to the patients’ clinical status but also to the significant difficulty and morbidity related to the surgical reversal of Hartmann’s procedure. The aim of this study was to review the factors related to the fairly low percentage of patients undergoing Hartmann’s reversal as well as surgical techniques that could help surgeons restore intestinal continuity following Hartmann’s procedure and deal with the postoperative outcomes.     

Up the Ladder of Concern: Youth and Young Adult Cannabis Use

This paper aims to review patterns of cannabis (i.e., marijuana and hashish) use among high-risk Israeli youth and young adults based on research conducted by the Ben-Gurion University, Regional Alcohol and Drug Abuse Research Center. A total of 1074 Israeli youth (67.0% male, 33.0% female) were studied from 2004 to 2016. The youth and young adults included those placed in residential programs for learning and/or behavior problems (youth villages) and were school dropouts referred to a 90-day treatment facility for drug abuse. Country of origin, determined by mother’s birthplace, revealed 42.4% of the youth was of Israeli origin and 57.6% from other countries—mostly the former Soviet Union and Ethiopia. About “village” youth, no gender or religious status (secular/non-secular) differences were found for lifetime and last month cannabis use. Immigrant origin youth, than those with Israeli status, reported more lifetime and last month use as well as cannabis availability. Youth from families with low socio-economics status reported a higher rate of last month cannabis use than those with better economic conditions. Among school dropouts, no gender or religious status differences were found for lifetime and last month cannabis use and availability. For all study youth, binary logistic regression results indicated six factors significantly predicted last month cannabis use: male gender, age, last month binge drinking, illicit drug selling, reduced relations with friends, and cannabis availability. In terms of policy and service provision, high-risk youth (e.g., those in residential programs, whether for learning and/or behavior problems) should be priority for drug prevention efforts.     

Diagnosis of retinal arterial macroaneurysm presenting as subhyaloid hemorrhage by indocyanine green videoangiography

A 66-year-old hypertensive woman complained of sudden loss of vision in her left eye. The clinical examination disclosed a subhyaloid hemorrhage obscuring the fovea. Fluorescein angiography showed a hyperfluorescent spot under the hemorrhage, but details were obscured. Indocyanine green videoangiography revealed a retinal arterial macroaneurysm as the cause of bleeding. Indocyanine green videoangiography appears to be useful in the diagnosis of retinal arterial macroaneurysm obscured by preretinal hemorrhage.