Dissociable implicit sequence learning mechanisms revealed by continuous theta-burst stimulation.
This study aimed to investigate the role of M1 in learning simple (“first-order conditional”) and more complex (“second-order conditional”) sequences. It was hypothesized that continuous theta burst stimulation (cTBS) over M1 would result in poorer learning of the simple sequence only. Forty-eight healthy adults received cTBS to either M1 or the parietal lobe or received sham cTBS before immediately completing 2 visuomotor sequence learning tasks. The tasks only differed in relation to the structure (i.e., simple vs. complex) of the sequence. The group who received cTBS over M1 demonstrated significantly poorer lea...
Source: Behavioral Neuroscience - March 14, 2019 Category: Neuroscience Source Type: research
Brief isolation during infancy enhances the formation of long-term memories in infant rodents.
In this study, infant (i.e., Postnatal Day 17) rats were placed in a context and shocked. Infants familiarized to an open field arena for 30 min the day before exhibited enhanced retention when tested 1 day later (Experiments 1 and 2). While brief exploration of an open field soon before learning (i.e., the behavioral tagging procedure) resulted in better memory when rats were tested 1, but not 3, days later, familiarized rats had enhanced long-term memory (LTM) at both intervals (Experiment 3). Furthermore, familiarization, but not brief open field exposure, enhanced LTM for a nonhippocampal task (Experiment 4), suggestin...
Source: Behavioral Neuroscience - March 4, 2019 Category: Neuroscience Source Type: research
Photoperiod regulates hypothalamic miR-155 gene expression in female, but not male, Siberian hamsters (Phodopus sungorus).
In this study, we tested the hypothesis that photoperiod regulates miR-155 gene expression in Siberian hamsters and whether there were sex differences in this photoperiod regulation. miR-155 gene expression levels were measured in hypothalamus, hippocampus, and spleen of male and female Siberian hamsters reared in short days (SDs) or long days (LDs). As expected, SD-reared hamsters had significantly reduced body mass, lightened pelage color, and lower reproductive organ size than LD-reared hamsters. Notably, SDs increased hypothalamic miR-155 gene expression in females but not in males. No differences were observed in hipp...
Source: Behavioral Neuroscience - February 11, 2019 Category: Neuroscience Source Type: research
The effects of clavulanic acid and amoxicillin on cue-primed reinstatement of cocaine seeking.
Research using the cocaine self-administration and reinstatement animal model of relapse finds that the beta-lactam antibiotic, ceftriaxone, attenuates cocaine-primed reinstatement of cocaine seeking and upregulates two proteins that regulate glutamate release and reuptake (xCT and GLT-1, respectively) in the nucleus accumbens core (NAc). We tested three compounds with beta-lactam rings for their ability to attenuate cue-primed reinstatement and increase GLT-1 and xCT expression in the NAc and prefrontal cortex (PFC). Rats self-administered intravenous cocaine for 1 hr/day for 7 days then 6 hrs/day for 10 days. Cue-primed ...
Source: Behavioral Neuroscience - February 4, 2019 Category: Neuroscience Source Type: research
Reduction of BDNF results in GABAergic neuroplasticity dysfunction and contributes to late-life anxiety disorder.
The GABAergic neuroplasticity dysfunction (GND) has been proposed as a distinct pathology for late-life anxiety disorder (LLAD). Brain-derived neurotrophic factor (BDNF) is a critical signaling molecule that regulates the GABAergic neuroplasticity. This research was designed to explore our hypothesis that the reduction of BDNF along with aging could induce GND, which might contribute to LLAD, and application of exogenous BDNF might reverse LLAD by restoring the GABAergic neuroplasticity. We focused on the hippocampus because it is the neural core of mood regulation and can be affected by aging. Compared to young mice, BDNF...
Source: Behavioral Neuroscience - February 4, 2019 Category: Neuroscience Source Type: research
Naloxone disrupts the development of a conditioned ejaculatory preference based on a somatosensory cue in male rats.
This study confirms that opioid transmission is necessary for the establishment of a somatosensory CEP. (PsycINFO Database Record (c) 2019 APA, all rights reserved) (Source: Behavioral Neuroscience)
Source: Behavioral Neuroscience - February 4, 2019 Category: Neuroscience Source Type: research
Conditioned partner preference in male and female rats for a somatosensory cue.
This study demonstrates that a somatosensory cue previously used to establish sexual arousal as a contextual cue on rats can be used as a discrete, partner-based cue to establish a CPC for a particular partner wearing the jacket and that stronger conditioning occurs when the jacket is explicitly paired with the sexual reward state. (PsycINFO Database Record (c) 2019 APA, all rights reserved) (Source: Behavioral Neuroscience)
Source: Behavioral Neuroscience - February 4, 2019 Category: Neuroscience Source Type: research
Local geometric properties do not support reorientation in hippocampus-engaged homing pigeons.
In this study, pigeons were trained to find a food reward hidden in 2 opposite corners in a rectangular arena. The animals were then tested in a kite-shaped environment similar to Pearce, Good, Jones, and McGregor (2004). We found that pigeons, unlike rats, were not able to identify the correct corner in the kite arena even though elements clearly preserved the correct long wall-short wall geometric configuration and the local aspect of the trained goal. This behavioral study was followed by a c-Fos, IEG analysis of brain activation that contrasted pigeons exposed to the trained, familiar rectangular environment with pigeo...
Source: Behavioral Neuroscience - January 21, 2019 Category: Neuroscience Source Type: research
Pair-housing rats does not protect from behavioral consequences of an acute traumatic experience.
Posttraumatic stress disorder (PTSD) is an extremely debilitating disease with a broad array of associated symptoms, making the disorder difficult to diagnose and treat. In humans, patients seem to benefit from group therapy or other means of promoting social behavior. To test these effects on our rodent model of PTSD, adult, male rats were housed in either single or pair conditions prior to and during an acute stressor to induce PTSD-like behaviors in these rats. Subsequently, rats were assessed for PTSD-like symptoms to determine the effect of social housing on stress-induced phenotypes. Posttrauma phenotypes, including ...
Source: Behavioral Neuroscience - January 10, 2019 Category: Neuroscience Source Type: research
Psychosocial stress reactivity is associated with decreased whole-brain network efficiency and increased amygdala centrality.
Cognitive and emotional functions are supported by the coordinated activity of a distributed network of brain regions. This coordinated activity may be disrupted by psychosocial stress, resulting in the dysfunction of cognitive and emotional processes. Graph theory is a mathematical approach to assess coordinated brain activity that can estimate the efficiency of information flow and determine the centrality of brain regions within a larger distributed neural network. However, limited research has applied graph-theory techniques to the study of stress. Advancing our understanding of the impact stress has on global brain ne...
Source: Behavioral Neuroscience - October 25, 2018 Category: Neuroscience Source Type: research
Neonatal hippocampal lesions facilitate biconditional contextual discrimination learning in monkeys.
This study examined whether selective neonatal hippocampal lesions in monkeys (Macaca mulatta), which left the surrounding cortical areas (parahippocampal cortex) intact, affect contextual learning and memory compared with controls. Monkeys were tested with an automated touch-screen apparatus so that stimuli and contextual cues could be manipulated independently of one another. The data suggest that animals with neonatal hippocampal lesions have sparing of function with regard to contextual learning and memory when (a) contextual information is irrelevant or (b) relevant for good discrimination performance, and (c) when tr...
Source: Behavioral Neuroscience - October 25, 2018 Category: Neuroscience Source Type: research
Analysis of learning deficits in aged rats on the W-track continuous spatial alternation task.
Young and aged animals were tested on a spatial alternation task that consisted of two interleaved components: (1) an “outbound” or alternation component (working memory) and (2) an “inbound” component, requiring the animal to remember to return to a central location in space (spatial memory). In the present study, aged rats made more outbound errors throughout testing, resulting in significantly more days to reach learning criterion, as compared to young rats. Furthermore, while all animals were able to learn the hippocampus-dependent inbound component of the task, most aged animals remained just above chance on t...
Source: Behavioral Neuroscience - October 22, 2018 Category: Neuroscience Source Type: research
Impairment of the context preexposure facilitation effect in juvenile rats by neonatal alcohol exposure is associated with decreased Egr-1 mRNA expression in the prefrontal cortex.
The context preexposure facilitation effect (CPFE) is a variant of contextual fear conditioning in which learning about the context (preexposure) and associating the context with a shock (training) occur on separate occasions. The CPFE is sensitive to a range of neonatal alcohol doses (Murawski & Stanton, 2011). The current study examined the impact of neonatal alcohol on Egr-1 mRNA expression in the infralimbic (IL) and prelimbic (PL) subregions of the mPFC, the CA1 of dorsal hippocampus (dHPC), and the lateral nucleus of the amygdala (LA), following the preexposure and training phases of the CPFE. Rat pups were exposed t...
Source: Behavioral Neuroscience - October 22, 2018 Category: Neuroscience Source Type: research
Experience, memory, and the places they meet.
Studies of learning and memory have made significant advances in characterizing the mechanisms of single memories, formed when surprising and unpredictable events trigger synaptic modifications in response to tightly timed coincidental cues. Yet outside the laboratory setting, few natural experiences are wholly unique, and much of our behavior is shaped progressively through the interactions of perceived experiences, recently formed memories and distant acquired knowledge. Despite the necessity of these memory dynamics, relatively little is known about how previously established associations are accessed, updated, and appl...
Source: Behavioral Neuroscience - October 15, 2018 Category: Neuroscience Source Type: research
Anterior thalamic nuclei, but not retrosplenial cortex, lesions abolish latent inhibition in rats.
The present study examined the effects of excitotoxic lesions in 2 closely related structures, the anterior thalamic nuclei and the retrosplenial cortex, on latent inhibition. Latent inhibition occurs when nonreinforced preexposure to a stimulus retards the subsequent acquisition of conditioned responding to that stimulus. Latent inhibition was assessed in a within-subject procedure with auditory stimuli and food reinforcement. As expected, sham-operated animals were slower to acquire conditioned responding to a stimulus that had previously been experienced without consequence, relative to a non-preexposed stimulus. This l...
Source: Behavioral Neuroscience - October 15, 2018 Category: Neuroscience Source Type: research
