NMDA Receptor Inhibition on Rodent Optimal Decision-Making in the Diminishing Returns Task

There has been growing interest in using N-methyl-D-aspartate (NMDA) receptor antagonists as treatments for mood disorders, but there is still much to learn about their cognitive effects. Research shows NMDA receptors can affect decision-making, and the antagonist MK-801 has had varying effects in rodents. Specifically, some have reported impairments in working memory while foraging behaviors remained intact, while others have demonstrated changes in choice behavior related to delay or risk in behavior tasks. We investigated the role of NMDA receptors in the specific paradigm of optimal decision-making to further confirm MK-801’s effects and to explore whether inhibiting NMDA receptors alters optimal decision-making processes. To accomplish this, we used the Diminishing Returns task, in which rats were placed in a chamber containing two levers that returned rewards after delays. One lever had a fixed delay (FD) returning a reward after 10 s. The other lever had a progressive delay (PD) that increased by 1 s after each press. The task included two conditions allowing rats to change the delay schedule: no-reset and reset. In both conditions, there was an optimal response rate that returned the most rewards at the least amount of delay. A total of 24 male and female Sprague-Dawley rats were injected with doses of MK-801 (0.06 mg/kg, 0.1 mg/kg, 0.2 mg/kg) and saline as the control before testing in the task. We hypothesized MK-801 would diminish the ability to make optimal decisions. In the no-reset condition, rats on the 0.2 mg/kg dose made significantly more choices for the PD lever compared to the other treatments (56.9% ± 4.8%). In the reset condition, females made significantly more PD lever presses than males after receiving saline (females: 93.8% ± 1.1%, males: 88.7% ± 1.8%). Also, males and females on the 0.2 mg/kg dose made more optimal sequences of choices (females: 3.38 ± 0.87, males: 6.48 ± 1.67). These results reveal complex effects of sex and NMDA receptors on optimal foraging behaviors and overall task responsiveness. Therefore, the findings suggest inhibiting NMDA receptors may not detrimentally affect the cognitive mechanisms involved in optimal decision-making as it is measured in this task

Relationship between sex and MK801\u27s effects in rats.

In this study, we are investigating the effects of MK-801 on male and female Sprague Dawley rats. According to D’Souza et al. (2001), females have a stronger reaction to MK-801 than males. Correspondingly, the current study measures the varied effects of MK-801 on rat models using an optimal decision-making task. The rats are injected with doses of MK-801. Then, they choose between a Fixed-Delay (FD) (ten-second intervals) and a Progressive-Delay (PD) lever (one second progressive increase) to receive rewards. We are currently in the process of obtaining results analyzing the relationship between sex and MK-801’s effects

Effects of NMDA inhibition of rodent decision-making and reward-seeking behavior

In this study, we are investigating the relationship between NMDA receptor antagonists and decision-making. Rats choose between a Fixed-Delay (FD) lever that dispensed a sugar pellet in ten-second intervals and a Progressive-Delay (PD) lever that dispensed a sugar pellet at progressively increasing time intervals of one second. After training on the optimal decision-making task, rats were injected with MK-801 in a randomized sequence of doses of 0.06 mL/g, 0.1 mL/ 0.2mL/g with saline as the control. Analysis of behaviors in relation to optimal choices is ongoing in relation to the varying doses of MK-801

Effects of Lavender Oil on Predator Odor Induced Anxiety in Rats

The purpose of the present study was to explore the effects of a potential treatment for anxiety because there is a need for treatments that are easily obtainable and inexpensive. The study tested the anxiolytic effects of lavender oil on rats experiencing severe anxiety induced by predator odor. The study used eight female rats. Four control rats were exposed to diffused water, while four experimental rats were exposed to diffused lavender oil. The rats\u27 anxiety was induced using bobcat urine and was observed behaviorally in the open-field test. The anxiety responses were measured as rearing, defecating, climbing walls, freezing, grooming and spending time near walls. Administering lavender oil did not significantly reduce anxious behavior, unlike the conclusions from previous research. Further research should explore the potential for using essential oils as treatments

Analyzing drug-affected optimal performance of rats using generalized linear mixed models

NMDA receptor antagonists are increasingly being researched for treating mood disorders, but there is much to learn about their cognitive effects. MK-801 has had varying effects on rodent decision-making. In this study, Sprague Dawley rats were injected with doses of MK-801 and saline before completing a task where lever presses returned fixed or progressively delayed rewards. Rats obtained more rewards by making optimal decisions considering the accumulated delays. By measuring optimal performance, we are further investigating the role of NMDA receptors in decision-making. Results of drug effects and optimal performance are currently being analyzed using generalized linear mixed models

Drosophila muller f elements maintain a distinct set of genomic properties over 40 million years of evolution.

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25-50%) than euchromatic reference regions (3-11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11-27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4-3.6 vs. 8.4-8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu

\u3ci\u3eDrosophila\u3c/i\u3e Muller F Elements Maintain a Distinct Set of Genomic Properties Over 40 Million Years of Evolution

The Muller F element (4.2 Mb, ~80 protein-coding genes) is an unusual autosome of Drosophila melanogaster; it is mostly heterochromatic with a low recombination rate. To investigate how these properties impact the evolution of repeats and genes, we manually improved the sequence and annotated the genes on the D. erecta, D. mojavensis, and D. grimshawi F elements and euchromatic domains from the Muller D element. We find that F elements have greater transposon density (25–50%) than euchromatic reference regions (3–11%). Among the F elements, D. grimshawi has the lowest transposon density (particularly DINE-1: 2% vs. 11–27%). F element genes have larger coding spans, more coding exons, larger introns, and lower codon bias. Comparison of the Effective Number of Codons with the Codon Adaptation Index shows that, in contrast to the other species, codon bias in D. grimshawi F element genes can be attributed primarily to selection instead of mutational biases, suggesting that density and types of transposons affect the degree of local heterochromatin formation. F element genes have lower estimated DNA melting temperatures than D element genes, potentially facilitating transcription through heterochromatin. Most F element genes (~90%) have remained on that element, but the F element has smaller syntenic blocks than genome averages (3.4–3.6 vs. 8.4–8.8 genes per block), indicating greater rates of inversion despite lower rates of recombination. Overall, the F element has maintained characteristics that are distinct from other autosomes in the Drosophila lineage, illuminating the constraints imposed by a heterochromatic milieu