Neuroscience and Neurobiology Commons^™

Brain Stimulation Reward Is Integrated By A Network Of Electrically-Coupled Gaba Neurons, Matthew Brian Lassen

Theses and Dissertations

Although it is well-established that animals will self-stimulate electric current to various diverse brain structures, the neural substrate of brain stimulation reward (BSR) has eluded identification since its discovery more than a half-century ago. We show that GABA neurons in the midbrain, hypothalamus and thalamus express connexin-36 (Cx36) gap junctions and couple electrically with dopamine application or by stimulation of the internal capsule (IC), which also supports self-stimulation. The threshold for responding for self-stimulation of the IC is the threshold for coupling between these GABA neurons, the degree of responding for IC ICSS is proportional to the magnitude of electrical …

Prior Experience As A Stimulus Category Confound: An Example Using Facial Expressions Of Emotion, Leah H. Somerville, Paul J. Whalen

Dartmouth Scholarship

Facial expressions of emotion represent a stimulus set widely used to assess a broad range of psychological processes. However, a consideration of systematic differences between expression categories, other than differences relating to characteristics of the expressions themselves, has remained largely unaddressed. By collecting experience rankings in a large sample of undergraduates, we observed that the amount of reported experience individuals have had with different facial expressions of emotion systematically differed between all expression categories. These findings shed light on the potential for identifying confounds inherent to comparing some stimulus categories and, in this case, may aid in the interpretation of …

Interval Timer Control Of Puberty In Photoinhibited Siberian Hamsters, Ho Park Jin, Alexander S. Kauffman, Matthew J. Paul, Matthew P. Butler, Annaliese K. Beery, Ruth M. Costantini, Irving Zucker

Neuroscience: Faculty Publications

Puberty, which is markedly delayed in male Siberian hamsters (Phodopus sungorus) born into short day lengths, is controlled by an interval timer regulated by the duration of nocturnal melatonin secretion. Properties of the interval timer were assessed by perturbing normal patterns of melatonin secretion in males gestated and maintained thereafter in 1 of 2 short day lengths, 10 h light/day (10L) or 12L. Melatonin secretion of short-day hamsters was suppressed by constant light treatment or modified by daily injection of propranolol to mimic nocturnal melatonin durations typical of long-day hamsters. Constant light treatment during weeks 3 to 5 induced early …

In Situ Muscle Power Differs Without Varying In Vitro Mechanical Properties In Two Insect Leg Muscles Innervated By The Same Motor Neuron, Anna N. Ahn, Kenneth Meijer, Robert J. Full

All HMC Faculty Publications and Research

The mechanical behavior of muscle during locomotion is often predicted by its anatomy, kinematics, activation pattern and contractile properties. The neuromuscular design of the cockroach leg provides a model system to examine these assumptions, because a single motor neuron innervates two extensor muscles operating at a single joint. Comparisons of the in situ measurements under in vivo running conditions of muscle 178 to a previously examined muscle (179) demonstrate that the same inputs (e.g. neural signal and kinematics) can result in different mechanical outputs. The same neural signal and kinematics, as determined during running, can result in different mechanical functions, …

Neuroprotective And Disease-Modifying Effects Of The Ketogenic Diet, Maciej Gasior, Michael A. Rogawski, Adam L. Hartman

Michael A. Rogawski

The ketogenic diet has been in clinical use for over 80 years, primarily for the symptomatic treatment of epilepsy. A recent clinical study has raised the possibility that exposure to the ketogenic diet may confer long-lasting therapeutic benefits for patients with epilepsy. Moreover, there is evidence from uncontrolled clinical trials and studies in animal models that the ketogenic diet can provide symptomatic and disease-modifying activity in a broad range of neurodegenerative disorders including Alzheimer’s disease and Parkinson’s disease, and may also be protective in traumatic brain injury and stroke. These observations are supported by studies in animal models and isolated …

The Effects Of Category Overlap On Information-Integration And Rule-Based Category Learning, Shawn W. Ell, Gregory F. Ashby

Psychology Faculty Scholarship

Three experiments investigate whether the amount of category overlap constrains the decision strategies used in category learning, and whether such constraints depend on the type of category structures used. Experiments 1 and 2 used a category learning task requiring perceptual integration of information from multiple dimensions (information-integration task) and Experiment 3 used a task requiring the application of an explicit strategy (rule-based task). In the information-integration task, participants used perceptual-integration strategies at moderate levels of category overlap, but explicit strategies at extreme levels of overlap – even when such strategies were sub-optimal. In contrast, in the rule-based task, participants used …

Classification Of Neuronal Nicotinic Acetylcholine Receptors In Rat Ca1 Hippocampal Interneuron Subpopulations Defined By Calcium-Binding Protein Mrna Expression, Richard M. Burgon

Theses and Dissertations

In this study, the single-cell relative quantitative mRNA expression of three Calcium-binding proteins (CaBPs; calbindin, calretinin, parvalbumin) and eight nicotinic acetylcholine receptor (nAChR) subunits (alpha2-alpha5, alpha7, beta2-beta4) from interneurons from the stratum radiatum or stratum oriens within the CA1 region of rat hippocampi was analyzed using quantitative real time RT-PCR. Eighty-seven percent of the interneurons examined expressed CaBP mRNA. Parvalbumin mRNA was detected in 64%, while calbindin and calretinin expression was detected in 26% and 40% of interneurons, respectively. CaBP expression was not exclusive; the average number of CaBP mRNA detected per interneuron of the 47 interneurons examined for CaBP …

Using Literature And Innovative Assessments To Ignite Interest And Cultivate Critical Thinking Skills In An Undergraduate Neuroscience Course, Eileen Lynd-Balta

Biology Faculty/Staff Publications

Science education reform initiatives emphasize 1) the value of concepts over facts; 2) the benefits of open-ended, inquiry-based problem-solving rather than protocols leading to a single correct answer; and 3) the importance of a multidisciplinary approach to teaching that is not confined by departmental boundaries. Neuroscientists should be at the forefront of this movement by the very nature of the discipline we study. Neuroscience is a relatively new field that integrates diverse subjects (anatomy, physiology, pharmacology, molecular biology, computer science, and psychology) and experimental advances are constantly changing and expanding our understanding of brain function. How can we convey this …

Exposure Of Nervous System Cells To Polychlorinated Biphenyls (Pcbs), Results In Alterations Of Neurotrophic Factor Expression, Gordon H. Gurley

Dissertations

Toxic insult by PCBs results in learning and memory deficits in humans. Alterations in expression of neurotrophic factors (NF) and/or their receptors have been linked to changes in learning and memory. How PCBs affect cognition is not known. We suggest that PCBs affect cognition by altering NF expression.

We exposed cultured C6 rat glioblastoma cells (an astrocyte cell-line) to medium containing PCB (Aroclor 1254 (10ppm)). Control cells were treated with dimethyl sulfoxide (DMSO) or regular medium. Enzyme-linked immunosorbent assays (ELISA) were used to determine glial cell-line derived neurotrophic factor(GDNF) and nerve growth factor (NGF) concentrations in all samples. We also …

Dissociation Of Automatic And Strategic Lexical-Semantics: Functional Magnetic Resonance Imaging Evidence For Differing Roles Of Multiple Frontotemporal Regions, Brian T. Gold, David A. Balota, Sara J. Jones, David K. Powell, Charles D. Smith, Anders H. Andersen

Neuroscience Faculty Publications

Behavioral research has demonstrated three major components of the lexical-semantic processing system: automatic activation of semantic representations, strategic retrieval of semantic representations, and inhibition of competitors. However, these component processes are inherently conflated in explicit lexical-semantic decision tasks typically used in functional magnetic resonance imaging (fMRI) research. Here, we combine the logic of behavioral priming studies and the neurophysiological phenomenon of fMRI priming to dissociate the neural bases of automatic and strategic lexical-semantic processes across a series of three studies. A single lexical decision task was used in all studies, with stimulus onset asynchrony or linguistic relationship between prime and …

Diverse Mechanisms Of Antiepileptic Drugs In The Development Pipeline, Michael A. Rogawski

Michael A. Rogawski

There is a remarkable array of new chemical entities in the current antiepileptic drug (AED) development pipeline. In some cases, the compounds were synthesized in an attempt improve upon the activity of marketed AEDs. In other cases, the discovery of antiepileptic potential was largely serendipitous. Entry into the pipeline begins with the demonstration of activity in one or more animal screening models. Results from testing in a panel of such models provide a basis to differentiate agents and may offer clues as to the mechanism. Target activity may then be defined through cell-based studies, often years after the initial identification …

Medial Prefrontal Activity Differentiates Self From Close Others, Todd F. Heatherton, Carrie L. Wyland, C. Neil Macrae, Kathryn E. Demos, Bryan T. Denny, William M. Kelley

Dartmouth Scholarship

No abstract provided.

Previous Spatial Memory Training And Nicotine Administration Alleviates Cognitive Deficits Produced By Medial Frontal Cortex Lesions In Rats., Rachel L. Norris

Electronic Theses and Dissertations

Rats were administered nicotine (0.3 mg/kg) for 11 consecutive days before and after an electrolytic medial frontal cortex lesion. Behavioral testing was arranged so that the rats were tested on the RAM 1 day after drug administration followed by behavioral testing on the MWT 19 days after drug treatment, or tested on the MWT 1 day after drug administration followed by testing on the RAM4 days after drug treatment. Results of MWT testing showed that regardless of the drug/behavioral testing interval, lesioned rats given nicotine demonstrated enhancement relative to saline-treated animals. Results of RAM testing showed that nicotine improved performance …

Activation In Neural Networks Controlling Ingestive Behaviors: What Does It Mean, And How Do We Map And Measure It?, Alan G. Watts, Arshad M. Khan, Graciela Sanchez-Watts, Dawna Salter, Christina M. Neuner

Arshad M. Khan, Ph.D.

No abstract provided.

Focal Putamen Lesions Impair Learning In Rule-Based, But Not Information-Integration Categorization Tasks, Shawn W. Ell, Natalie L. Marchant, Richard B. Ivry

Psychology Faculty Scholarship

Previous research on the role of the basal ganglia in category learning has focused on patients with Parkinson’s and Huntington’s Disease, neurodegenerative diseases frequently accompanied by additional cortical pathology. The goal of the present study was to extend this work to patients with basal ganglia lesions due to stroke, asking if similar changes in performance would be observed in patients with more focal pathology. Patients with basal ganglia lesions centered in the putamen (6 left side, 1 right side) were tested on rule-based and information-integration visual categorization tasks. In rule-based tasks, it is assumed that participants can learn the category …

Prenatal Cocaine Exposure Alters Alpha2 Receptor Expression In Adolescent Rats, Rosemarie M. Booze, David R. Wallace, Janelle M. Silvers, Barbara J. Strupp, Diane M. Snow, Charles F. Mactutus

Neuroscience Faculty Publications

BACKGROUND: Prenatal cocaine exposure produces attentional deficits which to persist through early childhood. Given the role of norepinephrine (NE) in attentional processes, we examined the forebrain NE systems from prenatal cocaine exposed rats. Cocaine was administered during pregnancy via the clinically relevant intravenous route of administration. Specifically, we measured alpha2-adrenergic receptor (alpha2-AR) density in adolescent (35-days-old) rats, using [3H]RX821002 (5 nM).

RESULTS: Sex-specific alterations of alpha2-AR were found in the hippocampus and amygdala of the cocaine-exposed animals, as well as an upregulation of alpha2-AR in parietal cortex.

CONCLUSION: These data suggest that prenatal cocaine exposure results in a persistent alteration …

Cyclooxygenase-2 Mediates Microglial Activation And Secondary Dopaminergic Cell Death In The Mouse Mptp Model Of Parkinson's Disease, Rattanavijit Vijitruth, Mei Liu, Dong-Young Choi, Xuan V. Nguyen, Randy L. Hunter, Guoying Bing

Neuroscience Faculty Publications

BACKGROUND: Accumulating evidence suggests that inflammation plays an important role in the progression of Parkinson's disease (PD). Among many inflammatory factors found in the PD brain, cyclooxygenase (COX), specifically the inducible isoform, COX-2, is believed to be a critical enzyme in the inflammatory response. Induction of COX-2 is also found in an experimental model of PD produced by administration of 1-methy-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP).

METHOD: COX-2-deficient mice or C57BL/6 mice were treated with MPTP to investigate the effects of COX-2 deficiency or by using various doses of valdecoxib, a specific COX-2 inhibitor, which induces inhibition of COX-2 on dopaminergic neuronal toxicity and …

Fms-Like Tyrosine Kinase 3 Ligand Recruits Plasmacytoid Dendritic Cells To The Brain, James Curtin, Gwendalyn King, Carlos Barcia, Chunyan Liu, Francois Hubert, Carole Guillonneau, Regis Josien, Ignacio Anegon, Pedro Lowenstein, Maria Castro

Articles

The lack of professional afferent APCs in naive brain parenchyma contributes to the systemic immune ignorance to Ags localized exclusively within the brain. Dendritic cells (DCs) appear within the brain as a consequence of inflammation, but no molecular mechanisms accounting for this influx have been described. In this study we demonstrate that Fms-like tyrosine kinase 3 ligand (Flt3L) recruits plasmacytoid DCs (pDCs; >50-fold; p < 0.001) to the brain parenchyma. These pDCs expressed IFN-alpha, the hallmark cytokine produced by pDCs, indicating recruitment and activation in situ of bona fide pDCs within the brain parenchyma. Flt3L did not increase the numbers of conventional DCs, macrophages, or B, T, NK, NKT, or microglial cells within the brain. Our data demonstrate that Flt3L reconstitutes a crucial afferent component of the immune response, namely, professional APCs within the brain parenchyma, and this could counteract the intrinsic systemic immune ignorance to Ags localized exclusively within the brain.

Effects Of Lesions Of The Bed Nucleus Of The Stria Terminalis, Laterual Hypothalamus, Or Insular Cortex On Conditioned Taste Aversion And Conditioned Odor Aversion, Christopher T. Roman, Nino Nebieridze, Aristides Sastre, Steve Reilly

Scholarship and Professional Work – COPHS

The effects of permanent forebrain lesions on conditioned taste aversions (CTAs) and conditioned odor aversions (COAs) were examined in 3 experiments. In Experiment 1, lesions of the bed nucleus of the stria terminalis had no influence on CTA or COA acquisition. Although lesions of the lateral hypothalamus induced severe hypodipsia in Experiment 2, they did not prevent the acquisition of CTAs or COAs. Finally, in Experiment 3, lesions of the insular cortex retarded CTA acquisition but had no influence on COA acquisition. The implications of these findings are discussed with regard to the forebrain influence on parabrachial nucleus function during …

Neuronal Pentraxins Mediate Synaptic Refinement In The Developing Visual System, Lisa Bjartmar, Andrew Huberman, Erik Ullian, Rene Renterıa, Xiaoqin Liu, Weifeng Xu, Jennifer Prezioso, Michael Susman, David Stellwagen, Caleb Stokes, Richard Cho, Paul Worley, Robert Malenka, Sherry Ball, Neal Peachey, David Copenhagen, Barbara Chapman, Masaru Nakamoto, Ben Barres, Mark Perin

Biology Faculty Publications

Neuronal pentraxins (NPs) define a family of proteins that are homologous to C-reactive and acute-phase proteins in the immune system and have been hypothesized to be involved in activity-dependent synaptic plasticity. To investigate the role of NPs in vivo , we generated mice that lack one, two, or all three NPs. NP1/2 knock-out mice exhibited defects in the segregation of eye-specific retinal ganglion cell (RGC) projections to the dorsal lateral geniculate nucleus, a process that involves activity-dependent synapse formation and elimination. Retinas from mice lacking NP1 and NP2 had cholinergically driven waves of activity that occurred at a frequency similar …

Axon Guidance Autonomy And Tensional Requirement For Synaptic Function: Is Learning A Forced Response?, Scott Siechen

Natural Science Faculty

Individual neurons extend multiple processes whose growth cones exhibit different responses to their environment. In culture, detached growth cones display guidance autonomy, contain mRNA for cytoskeletal and other axonal components, and are capable of synthesizing protein locally. However, the extent to which growth cone's autonomy contributes to its pathfinding function within the complex in vivo environment is unknown. Here, we show that detached axonal growth cones from identified Drosophila motoneurons maintain balanced filopodial activities as they extend, navigate and target postsynaptic partner cells normally. After detachment, the growth cones continue to synthesize the synaptic vesicle protein Synaptotagmin but, upon contacting …

Mental Retardation: A Mri Study Of 146 Brazilian Children, Armando F. Rocha, Cláudia C. Leite, Fábio T. Rocha

Armando F Rocha

We report results of a magnetic ressonance imaging (MRI) study of 146 Brazilian children, whose intelligence quotient scored less than 70. 50% of MRI examinations did not exhibit any signal of structural lesion (N group), whereas a focal thinning at the junction of the body and splenium of the corpus callosum; ventricular asymmetry; periventricular leukomalacia; gliosis and arachnoid cysts were among the most frequent findings in the remaining of subjects (L group). Maternal stress and altered blood pre ss u re were the most frequent findings in the pre-natal history of both N and L children. Familial antecedents of mental …

Identifying Placebo Effects With Data From Clinical Trials, Anup Malani

Anup Malani

A medical treatment is said to have placebo effects if patients who are optimistic about the treatment respond better to the treatment. This paper proposes a simple test for placebo effects. Instead of comparing the treatment and control arms of a single trial, one should compare the treatment arms of two trials with different probabilities of assignment to treatment. If there are placebo effects, patients in the higher-probability trial will experience better outcomes simply because they believe that there is a greater chance of receiving treatment. This paper finds evidence of placebo effects in trials of antiulcer and cholesterol-lowering drugs.

Cognitive-Vestibular Interactions: A Review Of Patient Difficulties And Possible Mechanisms, Douglas A. Hanes, Gin Mccollum

Gin McCollum

Cognitive deficits such as poor concentration and short-term memory loss are known by clinicians to occur frequently among patients with vestibular abnormalities. Although direct scientific study of such deficits has been limited, several types of investigations do lend weight to the existence of vestibular-cognitive effects. In this article we review a wide range of studies indicating a vestibular influence on the ability to perform certain cognitive functions. In addition to tests of vestibular patient abilities, these studies include dual-task studies of cognitive and balance functions, studies of vestibular contribution to spatial perception and memory, and works demonstrating a vestibular influence …

Head Tilt-Translation Combinations Distinguished At The Level Of Neurons, Jan E. Holly, Sarah E. Pierce, Gin Mccollum

Gin McCollum

Angular and linear accelerations of the head occur throughout everyday life, whether from external forces such as in a vehicle or from volitional head movements. The relative timing of the angular and linear components of motion differs depending on the movement. The inner ear detects the angular and linear components with its semicircular canals and otolith organs, respectively, and secondary neurons in the vestibular nuclei receive input from these vestibular organs. Many secondary neurons receive both angular and linear input. Linear information alone does not distinguish between translational linear acceleration and angular tilt, with its gravity-induced change in the linear …

From Faculty For Undergraduate Neuroscience: Encouraging Innovation In Undergraduate Neuroscience Education By Supporting Student Research And Faculty Development, Eric Wiertelak, J. C. Hardwick, M. Kerchner, B. Lom, J. J. Ramirez

Eric Wiertelak

No abstract provided.

Broad, Deep And Indirect: The Potential Influence Of Neuroscience In Law, Amanda C. Pustilnik

Faculty Scholarship

No abstract provided.

Sex Differences In The Anatomical And Functional Organization Of The Periaqueductal Gray-Rostral Ventromedial Medullary Pathway In The Rat: A Potential Circuit Mediating The Sexually Dimorphic Actions Of Morphine, Dayna R. Loyd, Anne Z. Murphy Phd

Neuroscience Institute Faculty Publications

Previous studies have demonstrated that morphine, administered systemically or directly into the PAG, produces a significantly greater degree of antinociception in males in comparison to females. As the midbrain periaqueductal gray (PAG) and its descending projections to the rostral ventromedial medulla (RVM) constitute an essential neural circuit for opioid-based analgesia, the present studies were conducted to determine if sex differences in the anatomical organization of the PAG-RVM pathway, and its activation during persistent inflammatory pain, could account for sex-based differences in opioid analgesia. In the rat, retrograde tracing was combined with Fos immunocytochemistry to investigate sexual dimorphism in the organization …

Center For Behavioral Neuroscience: A Prototype Multi-Institutional Collaborative Research Center, Kelly R. Powell, H. Elliott Albers

Neuroscience Institute Faculty Publications

The Center for Behavioral Neuroscience was launched in the fall of 1999 with support from the National Science Foundation, the Georgia Research Alliance, and our eight participating institutions (Georgia State University, Emory University, Georgia Institute of Technology, Morehouse School of Medicine, Clark-Atlanta University, Spelman College, Morehouse College, Morris Brown College). The CBN provides the resources to foster innovative research in behavioral neuroscience, with a specific focus on the neurobiology of social behavior. Center faculty working in collaboratories use diverse model systems from invertebrates to humans to investigate fear, aggression, affiliation, and reproductive behaviors. The addition of new research foci in …

Behavioral And Neurochemical Responses To Cocaine In Periadolescent And Adult Rats, Laura O'Dell

Laura Elena O'Dell

No abstract provided.