The State of Teaching Philosophy in Behavior Analysis Training Programs.

Professional organizations that oversee the accreditation of graduate training programs in behavior analysis have increased didactic training requirements for programs in various domains across the years. One of the areas in which this has occurred concerns training in philosophy within behavior science. Although content-hour requirements for didactic philosophical training have increased, the contents of this training are not prescribed and are left to the discretion of individual programs. We conducted a survey of verified course sequence programs to assess the current state of training in philosophy in behavior analysis graduate training programs. The results provided a list of common topics and readings in philosophy courses, and indicated an emphasis on radical behaviorism and the works of B. F. Skinner. The list of topics and readings obtained provides a resource for course design, and we suggest that exposing students to a broader range of behavioristic and nonbehavioristic topics and readings may enhance students' orientation to philosophical issues in behavior analysis. Supplementary Information: The online version contains supplementary material available at 10.1007/s40617-023-00889-8.

A preliminary evaluation of habituation and dishabituation of operant responding in mice.

Previous research has suggested that operant response decrements within experimental sessions are due in part to habituation to the repeated presentation of reinforcers. One way to assess the role of habituation in within-session response decrements is to conduct a test for dishabituation, a phenomenon in which a habituated response to a given stimulus recovers following the presentation of some strong or novel stimulus other than the habituated stimulus. Dishabituation of operant responding has been demonstrated on several occasions in the literature, but studies with non-human subjects have thus far been limited to those using rats and pigeons. Two experiments attempting to replicate these findings with mice were conducted. Two groups of mice nose-poked for a sweetened condensed milk/water reinforcer on either a fixed-ratio 4 or variable-interval 15 s schedule of reinforcement. During testing, baseline sessions were then alternated with two test conditions and a control condition. Test conditions included a 5 s auditory stimulus or flashing of the house light presented mid-session. Control conditions were identical to baseline. Dishabituation was not observed for either group in Experiment 1. In Experiment 2, dishabituation was not observed for the fixed-ratio 4 group but was observed for the variable interval 15 s group. Considerations for further study of operant dishabituation in mice are discussed.

Broad Therapeutic Time Window for Driving Motor Recovery After TBI Using Activity-Dependent Stimulation.

BACKGROUND: After an acquired injury to the motor cortex, the ability to generate skilled movements is impaired, leading to long-term motor impairment and disability. While rehabilitative therapy can improve outcomes in some individuals, there are no treatments currently available that are able to fully restore lost function. OBJECTIVE: We previously used activity-dependent stimulation (ADS), initiated immediately after an injury, to drive motor recovery. The objective of this study was to determine if delayed application of ADS would still lead to recovery and if the recovery would persist after treatment was stopped. METHODS: Rats received a controlled cortical impact over primary motor cortex, microelectrode arrays were implanted in ipsilesional premotor and somatosensory areas, and a custom brain-machine interface was attached to perform the ADS. Stimulation was initiated either 1, 2, or 3 weeks after injury and delivered constantly over a 4-week period. An additional group was monitored for 8 weeks after terminating ADS to assess persistence of effect. Results were compared to rats receiving no stimulation. RESULTS: ADS was delayed up to 3 weeks from injury onset and still resulted in significant motor recovery, with maximal recovery occurring in the 1-week delay group. The improvements in motor performance persisted for at least 8 weeks following the end of treatment. CONCLUSIONS: ADS is an effective method to treat motor impairments following acquired brain injury in rats. This study demonstrates the clinical relevance of this technique as it could be initiated in the post-acute period and could be explanted/ceased once recovery has occurred.

Membraneless dialysis--is it possible?

Direct contact between uremic blood and a fluid capable of receiving uremic toxins is possible. Such contact by itself is, however, not beneficial because the selection of molecules that are removed is dependent on diffusion coefficients in blood. This selection is inadequate and would result in the exhaustion of a patient's albumin pool before useful reduction in the urea pool was achieved. Direct contact that is accomplished by sandwiching blood between two layers of a sheathing fluid, followed by diafiltration of the sheathing fluid through conventional membranes and recirculation of the sheathing fluid, is possible. This adaptation of membraneless transport of molecules from blood eliminates almost all contact of blood with solid artificial surfaces and the subsequent diafiltration and recirculation of the sheathing fluid allows precise control of what is removed from the system. Slightly hyperosmotic protein is carried back by the recirculating sheathing fluid. Only solutes and water that pass the diafilter, which operates on a cell-free fluid, are able to leave the system. The system depends strongly on the ability to keep cells out of the sheathing fluid. Preliminary results and earlier reports indicate that this separation is possible and more precise measurements are underway. A quantitative design of a wearable dialyzer based on a circulating sheathing fluid is presented.

MagScrew total artificial heart in vivo performance above 200 beats per minute.

PURPOSE: Downsizing pulsatile devices requires an increase of beat rate if flow capacity is to be maintained. We applied this concept to the preclinical MagScrew total artificial heart (TAH). DESCRIPTION: The device fills passively with a stroke volume of 45 ml and beat rates up to 250 beats per minute (bpm). EVALUATION: Stable hemodynamics were observed during a 30-day bovine implant with a flow of 8.7 +/- 1.2 L/min at beat rates of 204 +/- 18 bpm. Device filling was exceptional up to 250 bpm generating flow of greater than 12 L/min. Beat rate adapted to preload in a way similar to a Frank-Starling response. Left and right atrial pressures were balanced. The aortic pulse pressure was 49-70 mm Hg, which translates to a pulsatility index of 0.49-0.77. Organ functions were preserved and blood damage did not occur. CONCLUSIONS: Increasing the beat rate while downsizing the MagScrew TAH was successful with strong flow generation by passive filling. Pulsatility was maintained at high beat rates. This innovative approach may be used to develop small pulsatile pumps.

In vivo performance and biocompatibility of the MagScrew ventricular assist device.

Currently available ventricular assist devices (VADs) have limitations in long-term durability and blood compatibility. We evaluated a prototype of a pulsatile MagScrew VAD for in vivo hemodynamic performance and biocompatibility. The device is composed of an actuator, blood pump housing, diaphragm, pusher plate, and bioprosthetic valves. Its protein-coated ("biolized") blood-contacting surface inhibits clot formation. Forces between moving parts of the actuator are transmitted magnetically, eliminating a primary source of friction and wear. The pump fills passively and is highly preload sensitive. The device was implanted into three calves for 90, 10, and 57 days, respectively. No anticoagulants were given postoperatively. The device functioned without technical problems during the entire course of each experiment, with mean device flow ranging between 5.4 and 9.0 L/min. Autopsy of the first two calves revealed no sign of embolization and clean blood-contacting surfaces of the devices. The third experiment was complicated by a prosthetic valve endocarditis with infectious embolization, and a few small depositions were found in the pump. In conclusion, the MagScrew VAD has demonstrated a high level of performance and biocompatibility in three calves studied for 10-90 days. Vigorous development is in progress to bring this device to preclinical readiness and thus provide surgeons with the VAD of choice for permanent implantation.