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Abstract: Experience impacts learning and perception. Familiarity with stimuli that later become the conditioned stimulus (CS) in a learning paradigm, for instance, reduces the strength of that learning—a fact well documented in studies of conditioned taste aversion (CTA; De la Casa & Lubow, 1995; Lubow, 1973; Lubow & Moore, 1959). Recently, we have demonstrated that even experience with “incidental” (i.e., non-CS) stimuli influences CTA learning: Long Evans rats pre-exposed to salty and/or sour tastes later learn unusually strong aversions to novel sucrose (Flores et al., 2016), and exhibit enhanced sucrose-responsiveness after learning in gustatory cortex (GC; Flores et al., 2018). These findings suggest that incidental taste exposure (TE) may change spiking responses that have been shown to underlie the processing of tastes in GC. Here, we test this hypothesis, evaluating whether GC neuron spiking responses change across 3 days of taste exposure. Our results demonstrate that the discriminability of GC ensemble taste responses increases with this familiarization. Analysis of single-neuron responses recorded across multiple sessions reveals that taste exposure not only enriches identity and palatability information in taste-evoked activity but also enhances the discriminability of even novel tastes. These findings demonstrate that “mere” familiarization with incidental episodes of tasting changes the neural spiking responses of taste processing and provides specific insight into how such TE may impact later learning. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 20 Jan 2022 00:00:00 GMT
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Abstract: Restraint stress indicated induction of morphology, biochemistry, and behavioral impairments. Several investigations have reported that curcumin has a protective effect against stress disturbance. The present study is designed to investigate the effects of curcumin on learning and memory, activity, biochemical, morphology changes, and apoptosis in the hippocampus and prefrontal cortex of restraint stress rats. For chronic restraint stress, the rats were kept in the restrainers for 2.5 h per day for 21 consecutive days. The animals received the gavage of curcumin every other day for 21 days. After stress, the animals were subjected to behavioral tests. In restraint stress rats, locomotor activity and step-through latency were decreased using open field and shuttle box, respectively. Then, the rats were sacrificed to assess their serum and brains. A reduction was seen in the serum malonedialdehyde levels and number of neurons in the hippocampus and prefrontal cortex. The significantly decreased serum total antioxidant capacity levels and increased apoptotic cells were observed in the hippocampus and prefrontal cortex. Finally, curcumin inhibited and reversed the changes of stress induced in the prefrontal cortex and hippocampus of the rats. These findings provided evidence for the protective effect of curcumin therapy on biochemical, morphology, and behavioral changes induced by restraint stress. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 13 Jan 2022 00:00:00 GMT
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Abstract: Goal-directed behavior and habit are parallel and, at times, competing processes. The relative balance of flexible, goal-directed responding as compared to inflexible habitual responding is highly dependent on experience (e.g., training history in a task) and conditions under which the behavior was formed. Reinforcer devaluation tasks have been used widely across species to study the neurobiology of goal-directed behavior. In rodents, under some conditions, extended training in reinforcer devaluation tasks transforms goal-directed responses into habits, rendering the animals insensitive to devaluation. In nonhuman primates, no studies have previously evaluated the impact of extended training. Here we trained four macaques in a variant of the standard reinforcer devaluation task (Málková et al., 1997), in which we presented objects with either a standard number of exposures (i.e., up to 55) or with a high number of exposures (i.e., up to 454). We tested for goal-directed behavior at three time points during the course of this extended training with different combinations of high- and low-repetition objects and stratified results based on whether the preferred or nonpreferred reinforcer was devalued. We found robust devaluation effects across all three cycles of training; however, the magnitude of the effect was modulated by reinforcer preference and by the relative training history of the objects. These data argue against habit formation after overtraining in the reinforcer devaluation task in macaques, a finding that is consistent with reports in humans and with tasks in rodents that employ multiple stimuli, reinforcers, and instrumental actions. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 13 Jan 2022 00:00:00 GMT
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Abstract: Generalization is an adaptive process that allows animals to deal with threatening circumstances similar to prior experiences. Systems consolidation is a time-dependent process in which memory loses it precision concomitantly with reorganizational changes in the brain structures that support memory retrieval. In this, memory becomes progressively independent from the hippocampus and more reliant on cortical structures. Generalization, however, may take place much faster in adult animals depending on the presence of sex hormones. Notwithstanding its relevance, there are few studies on sex differences in memory modulation. Here, a contextual fear discrimination task was used to investigate the onset of memory generalization and hippocampus-independence in adolescent male and female rats (P42–49). Subjects were tested 2, 7, 14, 21, or 28 days after training, with females showing memory generalization from day 21 on, whereas males surprisingly unable to discriminate contexts at any time. Ovariectomized (OVX) females, however, displayed an early onset of generalization. Consistently, pretest pharmacological blocking of dorsal hippocampus was able to impair memory retrieval in females, but not in males, which indicate that precise memory is dependent on the hippocampus. To our notice, this is the first report of a memory systems consolidation process—expressed in its two dimensions, neuroanatomical and qualitative—in adolescent female rats, and one that can also be accelerated by the reduction of sex hormones through ovariectomy. It is also unprecedented that despite adolescent male rats being able to remember fear learning, they did not discriminate contexts with any precision. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 13 Jan 2022 00:00:00 GMT
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Abstract: Although the interrupting effect of chronic pain on voluntary-directed attention is well-documented, research on the impact of chronic pain on involuntary-directed attention remains incomplete. This study aimed to investigate the influence of chronic pain on involuntary as well as voluntary allocation of attention as, respectively, indexed by the P3a and P3b components in the event-related potential derived from the electroencephalogram. Both involuntary and voluntary captures of attention were compared between 33 patients with chronic pain and 33 healthy controls using an auditory three-stimulus oddball task (with standard, target, and unexpected distractor tones). The results revealed a reduced P3a amplitude as well as a reduced P3b amplitude in patients with chronic pain compared to healthy controls, indicating a detrimental effect of chronic pain on involuntary and voluntary attention, respectively. This study extends the picture of the impairing effects of chronic pain on attentional allocation to a current task and attentional allocation to information outside the focus of attention. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 23 Dec 2021 00:00:00 GMT
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Abstract: The parahippocampal cortex (PHC) in the primate brain is implicated in the medial temporal lobe (MTL) memory network for spatial and episodic memory, but the precise function of this region remains unclear. Importantly, the rodent postrhinal cortex (POR) provides a structural and connectional homolog to the primate PHC. This homology permits the use of the powerful tools available in rodent models to better understand the function of the PHC in the human and nonhuman primate brains. Although many articles have compared and dissociated the function of the rodent POR from other areas in the MTL implicated in learning, memory, and memory-guided behavior, there are no in-depth reviews, particularly covering the last two decades of research. Nor has there been a review of the literature on the potential role of the POR in attention. Here, we review the anatomical and functional connectivity of the POR in rats, examine the evidence for proposed behavioral functions of this region, and suggest a model that accounts for the array of observations. We propose that the rodent POR binds nonspatial information and spatial information to represent the current local physical environment or context, including the geometry of the space and the spatial layout of objects and features in the environment. The POR also automatically monitors the environment for changes and updates representations when changes occur. These representations of context are available to be used by multiple brain regions, including prefrontal, posterior cortical, and hippocampal areas, for context-guided behavior, associative learning, and episodic memory. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 16 Dec 2021 00:00:00 GMT
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Abstract: Attention Deficit Hyperactivity Disorder (ADHD) is a highly prevalent and disabling disorder that frequently persists into adulthood. Many patients are considered nonresponders to typical pharmacological treatments due to insufficient symptoms’ reduction or the inability to tolerate the side effects of these medications. Agmatine is an endogenous neuromodulator with emotional- and cognitive-enhancing properties that arises as a promising agent to manage several Central Nervous System disorders. Here, we investigated the effects of chronic treatment with agmatine on behavioral impairments exhibited by adult Spontaneously Hypertensive Rats (SHR), an animal model for the study of ADHD. Adult male Wistar and SHR (3–4 months old) received intraperitoneal (i.p.) treatment with saline (NaCl 0.9%) or agmatine (30 mg/kg/day) during 20 consecutive days and were evaluated in a battery of behavioral tasks. Agmatine treatment improved olfactory and recognition memory impairments of SHR evaluated in the olfactory discrimination, object recognition, and social recognition memory tasks. In addition, agmatine administration improved the cognitive flexibility in the water maze test. Agmatine did not alter SHR’s locomotor activity and hedonic-like behaviors observed in the open-field and splash tests, respectively. No changes were observed in SHR’s systolic blood pressure following agmatine treatment. This study provides the first evidence that agmatine improves olfactory and cognitive impairments observed in an animal model of ADHD. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Thu, 16 Dec 2021 00:00:00 GMT
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Abstract: Our emotional response to people is discordant with their emotional experience in competitive situations; this phenomenon is termed “counterempathy.” Using event-related potentials, this study investigated the neural underpinnings of the effect of forgiveness on counterempathy. Twenty-seven female university students participated in a two phase-interpersonal competitive game with two other players whose smiles and frowns indicated the participant’s losing and winning, respectively. In the “passive” phase, participants were passively punished with a high- or low-intensity noise chosen by the opponent each time they lost a trial (i.e., the opponent smiles). During the break, participants received a negative or friendly message from each opponent. Participants were more likely to forgive the opponent who had sent a friendly message. In the “active” phase, participants could punish both opponents when they won a trial (i.e., the opponent frowns). Behavioral data showed that participants’ empathic responses were inconsistent with the opponents’ expressions, and that forgiveness could weaken this effect. The electrophysiological data revealed that both very early emotional sharing (reflected in the N170) and late elaborative cognitive evaluation stage (reflected in the P300) of counterempathy were affected by forgiveness, whereas the early automatic cognitive evaluation stage (reflected in the feedback-related negativity [FRN]) was not. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Mon, 22 Nov 2021 00:00:00 GMT
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Abstract: Age-related impairments in cognitive function occur in multiple animal species including humans and nonhuman primates. Humans and rhesus monkeys exhibit a similar pattern of cognitive decline beginning in middle age, particularly within the domain of executive function. The prefrontal cortex is the brain region most closely associated with mediating executive function. Previous studies in rhesus monkeys have demonstrated that normal aging leads to an increase in myelin degradation in the prefrontal regions that correlates with cognitive decline. This myelin deterioration is thought to result, at least in part, from the age-related emergence of chronic low levels of inflammation. One therapeutic that may arrest the deleterious effects of neuroinflammation is curcumin (CUR), the primary component of the spice turmeric. CUR has been shown to be a potent anti-inflammatory and antioxidant and improves performance on tasks for working memory and motor function. In the present study, middle-aged monkeys (12–21 years old) were given daily dietary supplementation of 500 mg of curcumin or vehicle over a period of 3–4 years. Here, we present data from a series of both object and spatial reversal tasks. Compared to vehicle, the CUR group showed enhanced performance on object, but not spatial reversal learning. These findings suggest that curcumin may improve specific aspects of executive function. (PsycInfo Database Record (c) 2022 APA, all rights reserved) PubDate: Mon, 15 Nov 2021 00:00:00 GMT
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