Behavioral Neuroscience

Stages of estrous mediate the stress-induced impairment of associative learning in the female rat

by Martin Paczynski

Shors, T.J., Lewczyk, C., Paczynski, M., Mathew, P.R. and Pickett, J.(1998) NeuroReport 9, 419–423

Exposure to a stressful event facilitates classical eyeblink conditioning in male rats and impairs conditioning in... more Exposure to a stressful event facilitates classical eyeblink conditioning in male rats and impairs conditioning in females. The contribution of stages of estrous to the stress-induced impairment of eyeblink conditioning was evaluated. Females in proestrus, estrus and diestrus were either exposed to an acute stressor of intermittent tailshocks or swim stress and compared to unstressed females in the three stages. Females in proestrus, when estrogen levels are high, acquired the conditioned response at a facilitated rate relative to females in other stages. However, exposure to a stressor of either intermittent tailshocks or inescapable swim stress severely impaired acquisition in females during proestrus. These results suggest that the enhancing effect of estrogen on procedural memory formation is disrupted by previous exposure to a stressful event.

Acute Stress Persistently Enhances Estrogen Levels in the Female Rat

by Martin Paczynski

Shors, T.J., Pickett, J., Wood, G. and Paczynski, M. (1999) Stress. 3(2), 163-171

Here we tested whether exposure to either tailshock or swim stress alters ovarian hormone levels, estrogen and... more Here we tested whether exposure to either tailshock or swim stress alters ovarian hormone levels, estrogen and progesterone, in females and whether the effects are persistent. Adrenal hormone levels were also measured in males and females. Estradiol levels were elevated in unstressed females during proestrus relative to females in other stages of estrous, and exposure to the stressors enhanced estradiol beyond basal levels. For females stressed during diestrus 2, estradiol levels were elevated immediately after stressor cessation and up to 24 hrs. Exposure to tailshock, but not swim-stress, transiently enhanced progesterone in females stressed during the stage of proestrus and estrus. Glucocorticoid levels were elevated in response to both stressors and were supraelevated in females under both basal and stress conditions relative to males, particularly in blood from females exposed to acute swim stress. These results indicate that exposure to a relatively acute stressful event immediately and persistently enhances serum estradiol and are discussed in the context of reports that exposure to the same stressors immediately and persistently impairs associative learning in the female rat.

"Behavioural manifestations of third ventricular colloid cysts"

by Robert Winer

Journal of Neurology, Neurosurgery, and Psychiatry 1985;48:847

This case calls to attention behavioral manifestations associated with colloid cyst of the third ventricle without... more This case calls to attention behavioral manifestations associated with colloid cyst of the third ventricle without hydrocephalus.
In general, it is the impression of my neurosurgical colleagues in the United States that in the absence of hydrocephalus, removal of a colloid cyst is not mandatory.

It is my hope that reports of cases such as this will raise the awareness of behavioral manifestations in colloid cysts of third ventricle without hydrocephalus.

Neural Correlates of Unpredictability in Behavioral Patterns of Wild-type and R6/2 Mice

by S. Lee Hong

Knowing beans: Human mirror mechanisms revealed through motor adaptation

by Michael Toma

Novel aminopropiophenones as potential antidepressants

by Nicholas Cozzi

Time determines the neural circuit underlying associative fear learning

by Nicolas Guyon

Altered Neural and Behavioral Dynamics in Huntington's Disease: An Entropy Conservation Approach

by S. Lee Hong

Background

Huntington's disease (HD) is an inherited condition that results in neurodegeneration of the... more Background

Huntington's disease (HD) is an inherited condition that results in neurodegeneration of the striatum, the forebrain structure that processes cortical information for behavioral output. In the R6/2 transgenic mouse model of HD, striatal neurons exhibit aberrant firing patterns that are coupled with reduced flexibility in the motor system. The aim of this study was to test the patterns of unpredictability in brain and behavior in wild-type (WT) and R6/2 mice.

Methodology/Principal Findings

Striatal local field potentials (LFP) were recorded from 18 WT and 17 R6/2 mice (aged 8–11 weeks) while the mice were exploring a plus-shaped maze. We targeted LFP activity for up to 2 s before and 2 s after each choice-point entry. Approximate Entropy (ApEn) was calculated for LFPs and Shannon Entropy was used to measure the probability of arm choice, as well as the likelihood of making consecutive 90-degree turns in the maze. We found that although the total number of choice-point crossings and entropy of arm-choice probability was similar in both groups, R6/2 mice had more predictable behavioral responses (i.e., were less likely to make 90-degree turns and perform them in alternation with running straight down the same arm), while exhibiting more unpredictable striatal activity, as indicated by higher ApEn values. In both WT and R6/2 mice, however, behavioral unpredictability was negatively correlated with LFP ApEn.

Conclusions/Significance

HD results in a perseverative exploration of the environment, occurring in concert with more unpredictable brain activity. Our results support the entropy conservation hypothesis in which unpredictable behavioral patterns are coupled with more predictable brain activation patterns, suggesting that this may be a fundamental process unaffected by HD.

Examining absolute and relative pitch as automatic processes via auditory-visual Stroop test

by Miren Edelstein

Published in the Fall 2011 edition of the Yale Review of Undergraduate Research in Psychology

Poster presented at the California Cognitive Science Conference (2011), Berkeley Psychology Undergraduate Research Conference (2011) and Society for Neuroscience Meeting (2011)

Attention alters visual plasticity during exposure-based learning

by Diego Gutnisky

Gutnisky DA, Hansen BJ, Iliescu BF, Dragoi V. Current Biology 2009 Apr 14;19(7):555-60. Epub 2009 Mar 5.

It is generally believed that attention enhances the processing of sensory information during perception and learning.... more It is generally believed that attention enhances the processing of sensory information during perception and learning. Here we report that, contrary to common belief, attention limits the degree of plasticity induced by repeated exposure to image features. Specifically, daily exposure to oriented stimuli that are not linked to a specific task causes an orientation-specific improvement in perceptual performance along the "exposed" axes. This effect is modulated by attention: human subjects showed a larger improvement in orientation discrimination when attention is directed toward the location where stimuli are presented. However, the capacity to perform discriminations away from the exposed orientation is enhanced when the exposure stimuli are unattended. Importantly, the improvement in orientation discrimination at the unattended location leads to a robust enhancement in the discrimination of complex stimuli, such as natural texture images, with orientation components along the exposed axes, whereas the improvement in orientation discrimination at the attended location exhibits only weak transfer to complex stimuli. These results indicate that sensory adaptation by passive stimulus exposure should be viewed as a form of perceptual learning that is complementary to practice-based learning in that it reduces constraints on generalization.

Fornix transection impairs learning of randomly changing object discriminations.

by Charlie Wilson

Neurotoxic lesions of ventrolateral prefrontal cortex impair object-in-place scene memory.

by Charlie Wilson

Fornix transection impairs visuospatial memory acquisition more than retrieval.

by Charlie Wilson

Addition of fornix transection to frontal-temporal disconnection increases the impairment in object-in-place memory in macaque monkeys.

by Charlie Wilson

Prefrontal-inferotemporal interaction is not always necessary for reversal learning.

by Charlie Wilson

Dissociable contributions of independent structures in retrieval and new learning.

by Charlie Wilson

Functional localization within prefrontal cortex: Missing the forest for the trees?

by Charlie Wilson

Medial temporal and prefrontal function: recent behavioural disconnection studies in the macaque monkey.

by Charlie Wilson

Sex differences in response to stress and expression of depressive-like behaviours in the rat

by Nikolaos Kokras

Dalla C, Pitychoutis PM, Kokras N, Papadopoulou-Daifoti Z.

Curr Top Behav Neurosci. 2011;8:97-118

Women are more susceptible than men to certain stress-related psychiatric disorders, such as depression. Preclinical... more Women are more susceptible than men to certain stress-related psychiatric disorders, such as depression. Preclinical studies aim to understand these sex differences by studying male and female rats in stress models. In this chapter, we review sex differences in behavioural aspects, as well as neurochemical and neurobiological findings derived from acute, repeated and chronic stress models. In particular, we focus on sex differences in depressive-like symptomatology expressed in the forced swim test, the chronic mild stress (CMS) and the learned helplessness models, the Flinders Sensitive Line rats (FSL), which is a genetic model of depression and in the lipopolysaccharide (LPS)-induced sickness behaviour, a putative inflammatory model of depression. Also, sex differences in stress effects on learning and memory parameters are discussed, because cognitive alterations are often seen in sex-differentiated psychiatric disorders. The observed behavioural alterations are often linked with abnormalities in the endophenotype, such as in hormonal, neurochemical, immune and neuroplasticity indices. From these data, it is clear that all stress models have strengths and limitations that need to be recognized in order to use them effectively in the investigation of sex differences in affective disorders.

Citalopram-mediated anxiolysis and differing neurobiological responses in both sexes of a genetic model of depression

by Nikolaos Kokras

Kokras N, Sotiropoulos I, Pitychoutis PM, Almeida OF, Papadopoulou-Daifoti Z.

Neuroscience. 2011 Aug 4

Disorders such as depression and anxiety exhibit strong sex differences in their prevalence and incidence, with women... more Disorders such as depression and anxiety exhibit strong sex differences in their prevalence and incidence, with women also differing from men in their response to antidepressants. Furthermore, receptors for corticotrophin releasing hormone (CRHR1) and arginine vasopressin receptor subtype 1b (AVPR1b) are known to contribute to the regulation of mood and anxiety. In the present study, we compared the anxiety profile and CRHR1 and AVPR1b expression levels in control Sprague–Dawley (SD) rats and rats of the SD-derived Flinders Sensitive Line (FSL), a genetic model of depression. Additionally, given the apparent sex differences in the therapeutic efficacy of antidepressants and because antidepressants are commonly used to treat comorbid anxiety and depressive symptoms, we assessed whether the anxiolytic effects of an antidepressant occur in a sex-dependent manner. Male and female FSL rats were treated with citalopram 10 mg/kg once daily for 14 days and were then tested in the open field and the elevated plus maze paradigms. Upon completion of the behavioural analysis, AVPR1b and CRHR1 expression levels were monitored in the hypothalamus and the prefrontal cortex (PFC) using Western blotting. According to our results, male FSL rats were more anxious than control SD rats, a difference abolished by citalopram treatment. Baseline anxiety levels were similar in female FSL and SD rats, and citalopram further reduced anxiety in female FSL rats. Importantly, whereas citalopram altered AVPR1b expression in the hypothalamus of male FSL rats, its actions on this parameter were restricted to the PFC in female FSL rats. In both sexes of FSL rats, citalopram did not alter CRHR1 expression in either the hypothalamus or PFC. Our results demonstrate that antidepressant treatment reduces anxiety levels in FSL rats of both sexes: the magnitude of treatment effect was related to the starting baseline level of anxiety and the antidepressant elicited sexually differentiated neurobiological responses in specific brain regions.