Biological Psychology Commons^™

Circuits Underlying Serotonin Mediated Sex Differences In Fear Learning, Rebecca Ravenelle

Dissertations, Theses, and Capstone Projects

Post-traumatic stress disorder (PTSD) is a trauma-related disorder characterized by intense fearful memory formation. Women are twice as likely as men to develop PTSD, indicating there may be sex differences in the underlying neural circuits. Given that serotonin (5-HT) dysfunction is implicated in PTSD, and 5-HT modulates fear learning, we investigated whether there are sex differences in the modulation of fear learning by 5-HT. We administered the selective serotonin reuptake inhibitor (SSRI) citalopram (20mg/kg or 10m/kg, i.p.) once to male and female mice prior to auditory fear conditioning and tested the effects on fear memory the next day. We found …

Neurodevelopmental Mechanisms Of Adverse Trauma Outcomes In Emerging Adulthood, Olena Kleshchova

Dissertations, Theses, and Capstone Projects

Background: Exposure to traumatic stress and adversity during the formative years of development can have adverse effects on mental health, neuroendocrine stress system function, and the brain, that persist into adulthood. One candidate mechanism that might confer vulnerability to enduring adverse outcomes of early life trauma is disruption of normal brain maturation. As the brain matures, functional interactions among brain regions change until the functional brain architecture (i.e., the functional connectome) reaches a mature state in adulthood. Given that different neural circuits have distinct developmental trajectories and sensitive periods, traumatic stress at a given point in development might have …

Experience-Dependent Changes In Nucleus Accumbens Activity Predict Cued Approach Learning: Contribution Of Nmda Receptors, Mercedes Vega Villar

Dissertations, Theses, and Capstone Projects

Animals learn associations between environmental cues and the natural rewards they predict (e.g., food, water, sex). As a result, reward-predictive cues come to trigger vigorous reward-seeking responses. Many neurons in the nucleus accumbens (NAc) become excited upon presentation of an already-learned reward-predictive cue. These NAc responses encode the motivational value of the cue and are necessary for the expression of the subsequent approach behavior. However, the precise temporal relationship between the emergence of cue-evoked excitations in the NAc and the acquisition of cued approach behavior remains unknown. In Experiment 1, NAc activity was recorded as rats learned to approach a …

Emotion Processing Deficits In Psychopathy: Does Cueing To Relevant Facial Features Increase Cognitive And Emotional Empathy?, Shawn E. Fagan

Dissertations, Theses, and Capstone Projects

Psychopathy is a multifaceted disorder characterized by a lack of cognitive and emotional empathy. The traditional model of psychopathy divides the disorder into two factors: Factor 1 consists of the interpersonal and affective traits of psychopathy while Factor 2 measures antisocial behaviors and lifestyle choices. The attention-to-the-eyes hypothesis argues that psychopathic individuals have impaired emotion recognition (specifically for fear) due to deficits in orienting attention to salient facial features like the eyes. Psychopathic individuals also display blunted autonomic responding to emotional stimuli, though whether this is due to attention-orienting deficits remains to be clarified. The present project investigated whether empathy-related …

Murine Genetic Variance In Sugar And Fat-Conditioned Flavor Preferences: Roles Of Dopamine, Opioid And Nmda Receptors And Nutritive Sensing, Tamar T. Kraft

Dissertations, Theses, and Capstone Projects

As obesity and diabetes have emerged as a severe public health crisis, understanding the mechanisms underlying the consumption of sugars and fats has become a topic of vigorous study. From a biological standpoint, genetic dispositions, neurochemical and hormonal influences, and predetermined orosensory and postingestive signals that modulate the hunger and satiety process may govern physiological aspects of the obesity puzzle. In addition to an innate appetite and attraction for simple carbohydrates and fats, learning plays an important role in modulating preferences for sugar- and fat-rich foods in rodents, including inbred mouse strains. Marked genetic variance has been observed among murine …

The Role Of The Direct And Indirect Basal Ganglia Pathways In The Learning, Performance, And Goal-Directed Control Of Action Sequences, Eric Garr

Dissertations, Theses, and Capstone Projects

Animals engage in intricately woven action sequences that are constructed from trial-and-error learning, but the mechanisms by which the brain links together individual actions which are later recalled as fluid chains of behavior are not fully understood. The aim of this dissertation is to investigate the learning and goal-directed control of action sequences in rats. Experiment 1 addresses a question that comes out of a reinforcement learning model of action sequencing: how does the extent of training change how the performance of an action sequence is impacted by reward devaluation. The data show that action sequences remain goal-directed overall regardless …

Dietary Curcumin Promotes Resilience To Chronic Social Defeat Stress In A Highly Susceptible Mouse Strain, Antonio V. Aubry

Dissertations, Theses, and Capstone Projects

Chronic exposure to stress is a risk factor for the development of major depression and post traumatic stress disorder in humans and induces depressive- and anxiety-like phenotypes in rodents. However, there are few pharmacological interventions available that effectively treat maladaptive responses to chronic stress in the clinical setting. One therapeutic agent that has recently shown promise in treating psychiatric disorders is curcumin, a yellow-pigmented polyphenol compound found in the turmeric plant. Curcumin has been shown to prevent the development of stressed-induced depressive-like behavior in rodents and reduce symptoms of depression in clinically diagnosed patients. In this dissertation, I investigated whether …

Curcumin Inhibits The Ikk:Nf-Kappa B Pathway In Neural Fear Circuits, Miguel A. Briones

Dissertations, Theses, and Capstone Projects

The study of how the brain acquires fearful memories has attracted considerable experimental attention, due in part to the promise of discovering novel therapeutic approaches for psychiatric disorders that are characterized by unusually strong and persistent traumatic memories. In recent years, extensive research has focused on studying the neural and molecular mechanisms by which fear memories are acquired, stored, and retrieved in the brain. Once acquired, fear memories may be attenuated using one of 2 procedures: 1) fear extinction, which involves repeated presentation of the fear-arousing stimulus in the absence of an aversive consequence, or 2) interference with the reconsolidation …

The Role Of Glutamate Neurotransmission In The Ventral Tegmental Area In The Expression Of Conditioned Approach Learning, Priscila Hachimine-Merli

Dissertations, Theses, and Capstone Projects

Conditioned stimuli (CSs) come to function as CSs by acquiring the capacity to activate the same mesocorticolimbic dopamine (DA) neurons activated by primary rewards, producing conditioned activation of these neurons and their associated motivational states. This model stipulates that CSs activate mesocorticolimbic DA systems through the activation of glutamate receptors on DA neurons in the ventral tegmental area (VTA). We tested the hypothesis that glutamate receptor stimulation in the VTA is necessary for the expression of conditioned approach. Rats were tested in a conditioned approach protocol that consisted of 7 consecutive conditioning sessions (light presentations and food were paired), one …

The Nucleus Accumbens Core Dopamine D1 And Glutamate Ampa/Nmda Receptors Play A Transient Role In The Performance Of Pavlovian Approach Behavior, Veronica Dobrovitsky

Dissertations, Theses, and Capstone Projects

The role of the nucleus accumbens core (NAc core) continues to be redefined with newly acquired data on neurochemical mechanisms mediating the learning and performance of behavior. Previous empirical data showed that dopamine transmission at the D1 receptor (D1R) plays a transient role in the expression of learned Pavlovian approach behavior. Here we show that, prior to overtraining, dopamine activity at D1Rs specifically within the NAc core is critical for the performance of approach behavior elicited by the recently-acquired reward-paired cue. Blockade of D1Rs in the NAc core, but not the dorsomedial striatum or NAc shell, disrupted approach responses during …

Dopamine D1 And D3 Receptor Polypharmacology In Cocaine Reward And Cocaine Seeking, Ewa J. Galaj

Dissertations, Theses, and Capstone Projects

Background: In the search for efficacious pharmacotherapies to treat cocaine addiction much attention has been given to agents targeting D1 or D3 receptors because of the involvement of these receptors in cocaine-related behaviors. D1 and D3 receptor partial agonists and antagonists have been shown to reduce cocaine reward, reinstatement of cocaine seeking and conditioned place preference (CPP) in rodents and non-human primates. However, translation of these encouraging results with selective D1 or D3 receptor agents has been limited due to a number of factors including toxicity, poor pharmacokinetic properties and extrapyramidal and sedative side effects.

Purpose: Given the …

Status Signaling And The Characterization Of A Chirp-Like Signal In The Weakly Electric Fish Steatogenys Elegans, Caitlin E. Field

Dissertations, Theses, and Capstone Projects

Sensory systems are critical to both exploratory and communicatory processes, the study of which is critical to our understanding of how animals perceive and respond to their environments. In weakly electric fishes the electrosensory system is utilized for both of these purposes. One type of communication, status signaling, is widespread across taxa and frequently hormonally modulated. This hormonal modulation keeps the signal honest, wherein the status of the sender and the production of the status signal itself are both hormone dependent. We investigated exploratory and communicatory strategies of the electromotor system in pulse-type gymnotiforms, with a focus on status communication …