Choice Dynamics in Concurrent Ratio Schedules of Reinforcement

Roughly 50 years of research has demonstrated that choice changes as a function of the amount of reinforcement available from two concurrently available schedules of reinforcement, and this function has been labeled the generalized matching law. The matching law, however, historically only accounts for choice between two variable-interval schedules of reinforcement. If the matching law is to be a general perspective for how organisms allocate behavior amongst several alternatives, then it ought to account for behavior when reinforcers depend on work requirements in addition to time requirements. To study these contexts, the present experiments employed concurrent ratio schedules that were programmed nonindependently. As such, responses to one ratio schedule simultaneously incremented the response counter for both schedules. The probability of reinforcement increased on both schedules as responses were allocated to either schedule. In Experiment 1, response allocation of pigeons was assessed when three lengths of changeover delays (0 s, 2.5 s, and 10 s) were in effect. Experiment 2 compared choice in concurrent variable-ratio and fixed-ratio schedules. Experiment 3 controlled the number of reinforcers delivered to two concurrently-available variable-ratio schedules. When concurrent variable-ratio schedules were in effect, the matching law described choice well in all three experiments. Choice on concurrent fixed-ratio schedules was inconsistent across pigeons. The main variable controlling response allocation in all experiments was the distribution of reinforcement. By controlling the number of reinforcers delivered to each schedule, choice can be brought under precise control even when ratio schedules are in effect. These results support extensions of the generalized matching law to contexts in which reinforcers are contingent on response requirements rather than time requirements

Signaling Changes in Reinforcer Ratios Facilitates Adaptive Forgetting in Pigeons

Forgetting is often characterized as maladaptive, but if a cue no longer signals the consequences of a response, then forgetting the previously learned stimulus-response discrimination is adaptive. Pigeons pecked for food in concurrent schedules of reinforcement. The relative frequency of food delivery on each key changed pseudorandomly across sessions with an overnight break in the middle of each session. New sessions began immediately after the last food delivery in the previous session. When the change from one session to the next was not signaled, responses remained under the control of the previous session\u27s ratio of reinforcement. When the session change was signaled by a change in the color of the keylights, control by the ratio from the previous session was diminished. Without interference from past ratios, sensitivity to the ratio of reinforcement was greater in the signaled than the unsignaled condition. This decrease in sensitivity to past ratios marks an example of adaptive forgetting

A treatment evaluator tool to monitor the real-world effectiveness of inhaled aztreonam lysine in cystic fibrosis

Background: Studies are required that evaluate real-world outcomes of inhaled aztreonam lysine in patients with cystic fibrosis (CF). Methods: Our treatment-evaluator tool assessed the effectiveness of inhaled aztreonam in routine practice in 117 CF patients across four time periods (6–12 (P2) and 0–6 months (P1) pre-initiation, and 0–6 (T1) and 6–12 months (T2) post-initiation). Outcomes were: changes in %-predicted forced expiratory volume in 1 s (FEV1), body-mass index (BMI), hospitalisation days and intravenous antibiotic usage. Results: Median FEV1% predicted for each 6-month period was 38.9%, 34.6%, 37.1% and 36.5%; median change was − 2.0% between P2 and P1, increasing to + 0.6% (p < 0.001) between P1 and T1. Annualised hospital bed-days was reduced (p = 0.05) post-initiation, as was intravenous antibiotics days (p = 0.001). BMI increased over 6 months post-initiation (p ≤ 0.001). Conclusions: In patients with CF in routine practice, inhaled aztreonam lysine is associated with improved lung function and weight, and reduced hospitalisation and intravenous antibiotic use

Molecular excitation in the Interstellar Medium: recent advances in collisional, radiative and chemical processes

We review the different excitation processes in the interstellar mediumComment: Accepted in Chem. Re

Erythroid-Specific Expression of β-globin from Sleeping Beauty-Transduced Human Hematopoietic Progenitor Cells

Gene therapy for sickle cell disease will require efficient delivery of a tightly regulated and stably expressed gene product to provide an effective therapy. In this study we utilized the non-viral Sleeping Beauty (SB) transposon system using the SB100X hyperactive transposase to transduce human cord blood CD34+ cells with DsRed and a hybrid IHK–β-globin transgene. IHK transduced cells were successfully differentiated into multiple lineages which all showed transgene integration. The mature erythroid cells had an increased β-globin to γ-globin ratio from 0.66±0.08 to 1.05±0.12 (p = 0.05), indicating expression of β-globin from the integrated SB transgene. IHK–β-globin mRNA was found in non-erythroid cell types, similar to native β-globin mRNA that was also expressed at low levels. Additional studies in the hematopoietic K562 cell line confirmed the ability of cHS4 insulator elements to protect DsRed and IHK–β-globin transgenes from silencing in long-term culture studies. Insulated transgenes had statistically significant improvement in the maintenance of long term expression, while preserving transgene regulation. These results support the use of Sleeping Beauty vectors in carrying an insulated IHK–β-globin transgene for gene therapy of sickle cell disease

Retrospective evaluation of whole exome and genome mutation calls in 746 cancer samples

Funder: NCI U24CA211006Abstract: The Cancer Genome Atlas (TCGA) and International Cancer Genome Consortium (ICGC) curated consensus somatic mutation calls using whole exome sequencing (WES) and whole genome sequencing (WGS), respectively. Here, as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium, which aggregated whole genome sequencing data from 2,658 cancers across 38 tumour types, we compare WES and WGS side-by-side from 746 TCGA samples, finding that ~80% of mutations overlap in covered exonic regions. We estimate that low variant allele fraction (VAF < 15%) and clonal heterogeneity contribute up to 68% of private WGS mutations and 71% of private WES mutations. We observe that ~30% of private WGS mutations trace to mutations identified by a single variant caller in WES consensus efforts. WGS captures both ~50% more variation in exonic regions and un-observed mutations in loci with variable GC-content. Together, our analysis highlights technological divergences between two reproducible somatic variant detection efforts

Adaptive Learning and Forgetting in an Unconventional Experimental Routine

Learning and forgetting were assessed concurrently in two experiments that involved the same unconventional routine. The schedule of reinforcement changed every session. Sessions were run back-to-back with a 23-hour mid-session break such that in a single visit to the testing chamber, the subject completed the second half of one session and the first half of the next. The beginning of a new session was either signaled or unsignaled. Experiment 1 involved concurrent variable interval-variable interval schedules with four possible reinforcer ratios. Response allocation was sensitive to the richer schedule and was retained through the mid-session break. Experiment 2 involved peak-interval schedules of varying durations. Temporal discrimination was rapidly acquired before and after the mid-session break, but not retained. Signaling the session change decreased control by past contingencies in both experiments, demonstrating that learning and forgetting can be investigated separately. Forgetting is often thought of as the inability to remember, but remembering and forgetting allow behavior to adapt to a changing environment in distinct and separable ways. These results suggest that the temporal structure of information can impact animals’ capacity to forget and remember

Adaptive learning and forgetting in an unconventional experimental routine

Forgetting is often thought of as the inability to remember, but remembering and forgetting allow behavior to adapt to a changing environment in distinct and separable ways. Learning and forgetting were assessed concurrently in two pigeon experiments that involved the same unconventional routine where the schedule of reinforcement changed every session. Sessions were run back-to-back with a 23-h mid-session break such that in a single visit to the testing chamber, a pigeon completed the second half of one session and the first half of the next. The beginning of a new session was either signaled or unsignaled. Experiment 1 involved concurrent variable–interval variable-interval schedules with four possible reinforcer ratios. Response allocation was sensitive to the richer schedule and was retained through the mid-session break. Experiment 2 involved peak interval schedules of varying durations. Temporal discrimination was rapidly acquired before and after the mid-session break, but not retained. Signaling the session change decreased control by past contingencies in both experiments, demonstrating that learning and forgetting can be investigated separately. These results suggest that the temporal structure of training, such as multiple short daily sessions instead of one long session, can meaningfully impact measurement of animals' capacity to forget and remember

Commentary "A Crisis in Comparative Psychology: Where have all the Undergraduates Gone?" Collaborating with Behavior Analysts Could Avert a Crisis in Comparative Psychology

Abramson's crisis is that, due to lack of interest and opportunities, psychology undergraduates are not pursuing advanced study in comparative psychology at a rate sufficient to sustain it as a discipline. However, what Abramson has not considered is that strictly behavioral comparative research happens frequently in psychology departments under the label "behavior analysis." This work is of high quality, frequently relates animal research to human behavior, and is broadly compatible with comparative cognition in spite of conflicting theoretical attitudes. Fostering communication and collaboration between behavior analysts, comparative cognition researchers, and traditional comparative psychologists is another way to avert the crisis of missing undergraduates in comparative psychology, both by tapping a group of undergraduates with established interests in behavior principles and by widening the base of active researchers in comparative psychology who can serve as potential supervisors to the next generation of comparative psychologists