Behavioral neuroscience最新文献

Studies of instrumental responding often include the delivery of a cue that is coincident with the delivery of the reinforcer. One purpose of this is for the cue to be removed during extinction and then presented later to assess whether responding returns (cue-induced reinstatement). In two experiments, we examined the effects of having a cue associated with reinforcement present or absent during extinction. In Experiment 1, the cue was associated with fixed ratio responding for intravenous cocaine or food pellets in one context (Context A), followed by extinction in another context (Context B), where responding produced the cue in one group but did not produce the cue in the other group. Afterward, contextual renewal was assessed with and without the cue in Context A. During extinction, a cue previously associated with cocaine reinforcement caused an increase in responding initially (an extinction burst) and throughout 16 2-hr extinction sessions, as well as weakened contextual renewal when animals were tested with the cue in Context A. In contrast, there were few detectable effects of the cue on extinction and contextual renewal when food pellets were the reinforcer. In Experiment 2, effects of a cue during extinction of progressive ratio responding were revealed with food pellets when animals showed weakened responding on the initial trials of postextinction reacquisition sessions. These experiments demonstrate that the presence of a cue associated with reinforcement during extinction may prolong responding in the short term while creating a more persistent form of extinction that resists relapse. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Hormonal contraceptives (HCs) containing synthetic ovarian hormones are commonly used among reproductive aged women; HCs alter the physiological state of the user by interfering with endogenous hormone concentrations and their actions on the reproductive tract. As ovarian hormones modulate the incidence of substance abuse disorders in women, this experiment explores how modulating female rat ovarian hormonal states with an HC containing the synthetic progestin levonorgestrel influences measures of drug preference and responsivity. First, rats underwent food-light Pavlovian conditioning to measure conditioned orienting, a known predictor of amphetamine (AMP) place preference. Then, rats were conditioned and tested for AMP place preference with either an HC implant or during estrous cycle stages associated with opposing ovarian hormone levels, that is, proestrus (P) or metestrus/diestrus (M/D), while recording ultrasonic vocalizations (USVs) as an index of he donic drug responsivity. Because of dopamine's (DA's) role in reward learning and memory, DA cell number and activity were examined using tyrosine hydroxylase and FOS immunohistochemistry after a final AMP challenge. Conditioned orienting did not differ between cycling and HC-implanted rats. HC rats emitted fewer USVs in response to AMP, showed marginally less AMP place preference, and had lower DA cell activity in the substantia nigra after AMP compared to P rats. M/D rats showed a similar behavioral profile and neural response as HC rats. This experiment suggests ovarian hormones affect drug preference and responsivity, while providing novel insight into how hormone-altering contraceptives may reduce these measures. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Surprising violations of outcome expectancies have long been known to enhance the associability of Pavlovian cues; that is, the rate at which the cue enters into further associations. The adaptive value of such enhancements resides in promoting new learning in the face of uncertainty. However, it is unclear whether associability enhancements reflect increased associative plasticity within a particular behavior system, or whether they can facilitate learning between a cue and any arbitrary outcome, as suggested by attentional models of conditioning. Here, we show evidence consistent with the latter hypothesis. Violating the outcome expectancies generated by a cue in an appetitive setting (feeding behavior system) facilitated subsequent learning about the cue in an aversive setting (defense behavior system). In addition to shedding light on the nature of associability enhancements, our findings offer the neuroscientist a behavioral tool to dissociate their neural substrates from those of other, behavior system- or valence-specific changes. Moreover, our results present an opportunity to utilize associability enhancements to the advantage of counterconditioning procedures in therapeutic contexts. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The present study investigated immediate versus delayed effects of estrogen replacement in ovariectomized (OVX) rats on hyperphagia elicited by gamma-aminobutyric acid (GABA)-A-agonist (muscimol) infusions into the nucleus accumbens shell (AcbSh). First, because intra-AcbSh muscimol-induced feeding has never been explored in OVX rats, a dose-effect curve was generated and compared to sham-operated males, the current point of reference in the literature. Muscimol (5, 10, 25, and 50 ng) increased food intake in both sexes, and both sexes reached the same asymptotic level of intake. Nevertheless, slopes of the linearized dose-effect functions for males and OVX females differed significantly, with females starting at a lower baseline and exhibiting a steeper slope. Next, the behavioral profiles of a behaviorally active, but nonmaximal intra-AcbSh muscimol dose (25 ng), were examined in a separate group of OVX females at two time-points: immediately after injecting 17β-estradiol 3-benzoate (EB) subcutaneously (5 μg), and 24 hr post-EB. Delayed, but not immediate, EB pretreatment suppressed, but did not eliminate, muscimol-driven food intake. However, EB did not change nonfood-directed behaviors such as locomotion or rearing. These results demonstrate that feeding mediated by intra-AcbSh GABA-A receptors is delimited by delayed, but not rapid, effects of estradiol. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Individuals who use cocaine exhibit maladaptive decision-making, overweighting rewards, and underweighting potential risks. We previously showed that chronic cocaine self-administration in young adult male rats causes long-lasting increases in risk taking. The present study expanded upon these findings to determine whether effects of cocaine on risk taking depend on the route of cocaine administration and extend to females. To address the former question, rats in Experiment 1 were trained on the Risky Decision-making Task (RDT), received passively administered cocaine, and were retested in the RDT. Surprisingly, passive cocaine had no effect on risk taking. Experiment 2 determined whether cocaine self-administration increases risk taking in females in a manner comparable to males. Males and females were trained in the RDT, underwent cocaine self-administration, and were retested in the RDT. Unexpectedly, cocaine self-administration had no effect on risk taking in either sex. Because Experiments 1 and 2 involved cocaine exposure at a considerably older age than in previous work, Experiments 3 and 4 determined if cocaine effects on risk taking depend on the age of exposure. Rats began cocaine self-administration at postnatal (PN) day 77 (Experiment 3) or passive cocaine injections starting on PN day 63 (Experiment 4) and were tested in the RDT 3 weeks after cocaine cessation. In these experiments, cocaine increased risk taking in both sexes. These results reveal a limited time window during young adulthood of vulnerability to the effects of chronic cocaine on risk taking. (PsycInfo Database Record (c) 2022 APA, all rights reserved).