Behavioral Neuroscience

Methylphenidate differentially affects the social ultrasonic vocalizations of wild-type and prodromal Parkinsonian rats.
Prodromal signs of Parkinson’s disease (PD), including vocal communication deficits, are poorly understood and do not respond adequately to current pharmacologic treatments. Norepinephrine dysfunction is involved early in PD; thus, drug therapies targeting norepinephrine may be useful as a treatment of prodromal signs. This study used a validated, translational rodent model of prodromal PD, the male Pink1−/− rat, which exhibits ultrasonic vocalization (USV) deficits as early as 2 months of age. The purpose of this preclinical study was to investigate a dose-dependent (2.5, 5.0, 7.5, 10 mg/kg) response of methylphenidate on USV parameters with the hypothesis that methylphenidate would increase vocalization output. Because methylphenidate is a psychostimulant with known adverse side effects, we also hypothesized that potential side effects including anxietylike behavior and spontaneous activity would be increased in a dose-dependent manner. To accomplish this, wild-type (WT) and Pink1−/− rats were administered a dose of a vehicle (saline) and a methylphenidate dose in a randomized within-subjects design and then assessed for USVs, anxiety behavior (open field), and limb motor (cylinder) activity. The results suggest that methylphenidate does not alter USV emissions in Pink1−/− rats; however, methylphenidate increased the total number of vocalizations and duration of frequency-modulated calls in WT rats. Methylphenidate dose dependently influenced spontaneous movements in both WT and Pink1−/− rats, as expected, while methylphenidate increased anxiety in Pink1−/− rats and not WT rats. This study demonstrates a difference in response to a psychostimulant between Pink1−/− rats and WT rats. (PsycInfo Database Record (c) 2025 APA, all rights reserved)
Progesterone treatment is not necessary for sexual experience-enhanced paced mating behavior in estradiol benzoate-primed female rats.
Sexual behavior in female rats varies depending on sexual history and the combination of ovarian hormones administered to induce receptivity. Experiment 1 tested whether paced mating behavior differed in sexually experienced rats when receptivity was induced with sequential estradiol benzoate (EB) and progesterone (P) or EB-Alone. Rats gained paced mating experience under EB/P (10 μg EB 48 hr + 1 mg P 4–6 hr before mating) and then were primed with EB-Alone (2 μg EB for 6 days). Rats primed with EB-Alone were fully receptive but returned to the male more slowly, spent less time with the male, had longer interintromission intervals, showed fewer proceptive behaviors and more rejection behaviors, and had significantly longer test durations compared to when rats were primed with EB/P. Experiment 2 tested whether sexual experience-induced changes to paced mating behavior occur under both EB/P and EB-Alone hormone priming regimens. Rats received EB/P or EB-Alone prior to four paced mating tests. With sexual experience under either hormone regimen, rats showed shorter contact-return latencies to intromission, shorter interintromission intervals, and more proceptive behaviors. However, relative to EB/P-primed rats, EB-Alone-primed rats exited the male compartment more frequently after mounts and intromissions, spent less time with the male, had longer interintromission intervals, displayed fewer proceptive behaviors and more rejection behaviors, and had longer test durations, indicating lower sexual motivation. Collectively, these data illustrate that experience-enhanced paced mating behavior occurs with either EB/P or EB-Alone priming, but progesterone further facilitates mating behavior. (PsycInfo Database Record (c) 2025 APA, all rights reserved)
Acute early life stress alters threat processing in adult rats.
Individuals diagnosed with stress-related psychiatric disorders in adulthood are likely to have experienced early life stress, suggesting that early adversity is an important vulnerability factor in the subsequent development of trauma- and anxiety-related psychiatric illness. It is important to develop animal models of psychiatric dysfunction to determine evident vulnerability considerations, potential biomarkers, and novel treatment avenues to improve the human condition. In our model of acute early life stress (aELS), 15 footshocks are delivered in a single session on postnatal day 17. The following experiments investigated the persistent impacts of our aELS procedure on stress-enhanced fear learning, anxiety-related behaviors, maintenance of fear, and resistance to extinction in adult male and female rats. The findings from these experiments demonstrate that our aELS procedure yields enhanced fear learning and increased anxiety. This enhanced fear is maintained over time, yet it extinguishes normally. Taken together, these results demonstrate that exposure to 15 footshocks during a single session early in life (postnatal day 17) recapitulates a number of important features of trauma- and anxiety-related disorder symptomatology, but not others. Future studies are needed to determine the persistent physiological phenotypes resulting from aELS and the neurobiological mechanisms that mediate these long-term changes. (PsycInfo Database Record (c) 2025 APA, all rights reserved)
Dopamine-mediated behavioral alterations following exposure to a social video in socially isolated mice during the developmental period.
Video exposure is known to affect brain function, yet its impact on neurodevelopmental processes remains unclear. This study aimed to investigate whether exposure to a video depicting social behavior induces behavioral and neurological changes in socially isolated mice. On Postnatal Day (PND) 21, male mice were separated from their dams and randomly assigned to three groups: socially grouped mice; socially isolated mice (ISO), where mice were housed without any social stimulation; and social video-exposed mice (SVE), where mice were exposed to a social video played on a tablet from PND21 to PND56 under socially isolated conditions. On PND56, all animals underwent behavioral tests. Compared to the socially grouped mice and ISO group, the SVE group showed an attenuated response to amphetamine treatment. In the social cognition test, the ISO group exhibited decreased affiliative behavior and increased offensive and defensive behavior. However, the SVE group showed a partial improvement in social cognition, including increased affiliative behaviors and decreased defensive behaviors, although no changes in offensive behaviors were observed. Furthermore, the SVE group exhibited elevated levels of tyrosine hydroxylase and dopamine transporter in key social cognition regions—namely the prefrontal cortex, retrosplenial cortex, and hippocampus. This neurochemical shift implies that socially isolated mice can acquire social behaviors through exposure to video-based social interactions. These effects may be related to the compensatory response of the dopamine system, which is implicated in various psychiatric disorders. (PsycInfo Database Record (c) 2025 APA, all rights reserved)
Organization of spontaneous spatial behaviors under dark conditions is unaffected in adult male and female long–Evans rats after moderate prenatal alcohol exposure.
Prenatal alcohol exposure can produce disruptions in a wide range of cognitive functions, but it is especially detrimental to spatial navigation. In open environments, rodents organize their spatial behaviors around centralized locations, termed home bases, from which they make circuitous and slow locomotor trips (progressions) into the rest of the environment. Open-field behaviors are organized even under darkened test conditions, suggesting a role for self-motion cues (vestibular, motor, etc.). The impact of moderate prenatal alcohol exposure (mPAE) on the organization of spontaneous open-field behaviors under darkened conditions has not been investigated. Here we tested adult female and male rats with mPAE or saccharin control exposure in a circular open field for 30 min in a testing room that was made completely dark. While general locomotion, as measured by reductions in travel distance and increased stop duration, decreased across the test session, the organization of these behaviors, as measured by stop duration, home base establishment, home base stability, progression accuracy, and scaling of peak speeds with progression length, did not differ between mPAE and saccharin control rats. Together, the findings strongly suggest that spontaneous movement organization in relation to self-motion cues remains intact in adult mPAE rats. (PsycInfo Database Record (c) 2025 APA, all rights reserved)

Behavioral Neuroscience - Vol 139, Iss 1