Behavioral Neurobiology Commons^™

The Sonic Hedgehog Effector Smoothened Modulates Cholinergic Interneuron Activity, Physiology, And Striatum-Dependent Behaviors, Santiago Uribe-Cano

Dissertations, Theses, and Capstone Projects

The striatum is a central node in action selection and associative learning, integrating cortical, thalamic, and neuromodulatory input. Among its principal modulators, dopamine (DA) and acetylcholine (ACh) are known for their temporally coordinated yet mechanistically distinct influences on striatal output. However, the upstream signals that regulate their dynamic interplay, particularly within cholinergic interneurons (CINs)—the primary source of striatal ACh—remain incompletely characterized. This dissertation investigates the role of Smoothened (Smo), a G protein-coupled receptor (GPCR) effector of Sonic Hedgehog (Shh) signaling, in modulating ACh signaling dynamics in the striatum.

Building on evidence that midbrain DA neurons co-release Shh and that CINs …

Automatic Analysis Of The Frequency, Vigor, And Complexity Of Spontaneous Locomotion Bouts Of Mice With Loss And Gain Of Function Of The G Protein-Coupled Receptor Smoothened In Cholinergic Neurons, Aleksandra Feshchenko

Dissertations, Theses, and Capstone Projects

Locomotion, a fundamental behavior, is classically assessed using simple metrics of velocity and total distance moved in an open field. This behavior however offers rich data about the organization and breadth of actions an animal can take while only facing limitations due to the bio-mechanical constraints of the organism. Importantly, these actions are not biased towards a particular task-solution space imposed by many behavioral paradigms. Here, to analyze motor complexity in freely ambulating mice, we developed a method for the automatic and unbiased identification of locomotor bouts which we call Bout Finder (BF). This analysis utilizes Open Feld data to …

Dendritic Spine Density And Morphology In The Dorsolateral Striatum Following A High Fat Diet, Tikva Nabatian

Dissertations, Theses, and Capstone Projects

Obesity rates have been dramatically rising in recent years and in 2017-2018 more than 42% of adults in the United States were obese. Obesity is associated with numerous health problems, including cardiovascular disease, stroke, insulin resistance, and type II diabetes. The prevalence of highly palatable and calorically dense foods high in fats and sugars is a significant factor in the increase in obesity rates. Many suggest that palatable food affects the brain in ways similar to drugs of abuse, reinforcing the consumption of highly palatable foods in the same way drugs reinforce drug use. While numerous weight loss programs and …

Dietary Regulation Of Silent Synapses In The Dorsolateral Striatum, Allison M. Meyers

Dissertations, Theses, and Capstone Projects

Obesity and drugs of abuse share overlapping neural circuits and behaviors. Cravings for drugs of abuse increase during abstinence, a phenomenon known as incubation. In obesity, increased craving is observed in individuals during dieting. Diets often fail, with return to- or increase above- original weight. The extent to which this reflects an incubation phenomenon has not been carefully examined. One mechanism underlying incubation is the reemergence of a developmental mechanism called silent synapses. Silent synapses are 'temporary' synapses that are important for remodeling brain circuits. They are prevalent during early development but largely disappear by adulthood. Drugs of abuse increase …

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 …

Basal Ganglia Involvement In The Playfulness Of Juvenile Rats, Stephen M. Siviy

Psychology Faculty Publications

Play is an important part of normal childhood development and can be readily studied in the laboratory rat in the form of rough‐and‐tumble play. Given the robust nature of rough‐and‐tumble play, it has often been assumed that the basal ganglia would have a prominent role in modulating this behavior. Recent work using c‐fos expression as a metabolic marker for neural activity combined with temporary inactivation of relevant corticostriatal regions and pharmacological manipulations of opioid, cannabinoid, and dopamine systems has led to a better understanding of how basal ganglia circuitry may be involved in modulating social play in the juvenile rat. …

Possible Breakdown Of Dopamine Receptor Synergism In A Mouse Model Of Huntington's Disease, Samantha F. Kennedy

LSU New Orleans Theses and Dissertations

The model of basal ganglia function proposed by Albin, Young and Penney (1989) describes two anatomically independent motor pathways, the direct and indirect. However, under normal conditions striatal dopamine (DA) is required for the expression of motor behavior, and DAergic control of the two pathways (via D1 and D2 receptors, respectively) is dependent on co-activation. We tested for a possible breakdown of D1/D2 synergism using transgenic R6/1 mice bearing the human huntingtin allele (Htt). Motor stereotypy, observed prior to the onset of HD-related symptoms, was rated on a 5-point scale following activation of: A) D1 receptors alone, B) D2 receptors …

Behavioral And Neuroanatomical Outcomes Of Early And Late Preterm Hypoxic-Ischemic Injury And The Neuroprotective Effects Of Whole-Body Hypothermia: An Animal Model, Haley C. Garbus

University Scholar Projects

The overarching aims of this research were: first, to characterize the anatomical and behavioral effects of preterm hypoxic-ischemic (HI) injury in rodent models; and second, to explore the method of passively induced whole-body hypothermia as a neuroprotective intervention following HI. Clinical research of preterm injured infants has shown a large range of behavioral deficits, including delays in language learning, spatial and non-spatial memory, visual attention, and motor coordination. The current studies focused on these behavioral abnormalities, using HI rodent models. Specifically, we explored a model for early preterm HI (HI induced on postnatal day (P) 3 in rats), and compared …

Investigating Habits: Strategies,Technologies And Models, Kyle S. Smith, Ann M. Graybiel

Dartmouth Scholarship

Understanding habits at a biological level requires a combination of behavioral observations and measures of ongoing neural activity. Theoretical frameworks as well as definitions of habitual behaviors emerging from classic behavioral research have been enriched by new approaches taking account of the identification of brain regions and circuits related to habitual behavior. Together, this combination of experimental and theoretical work has provided key insights into how brain circuits underlying action-learning and action-selection are organized, and how a balance between behavioral flexibility and fixity is achieved. New methods to monitor and manipulate neural activity in real time are allowing us to …

Diet-Induced Obesity: Dopaminergic And Behavioral Mechanisms As Outcomes And Predictors, Vidya Narayanaswami

Theses and Dissertations--Pharmacy

Obesity and drug abuse share common neural circuitries including the mesocoticolimbic and striatal dopamine reward system. In the current study, a rat model of diet-induced obesity (DIO) was used to determine striatal dopamine function, impulsivity and motivation as neurobehavioral outcomes and predictors of obesity. For the outcome study, rats were randomly assigned a high-fat (HF) or a low-fat (LF) diet for 8 wk. Following the 8-wk HF-diet exposure, rats were segregated into obesity-prone and obesity-resistant groups based on maximum and minimum body weight gain, respectively, and neurobehavioral outcomes were evaluated. For the predictor study, neurobehavioral antecedents were evaluated prior to …