Neuroscience and Neurobiology Commons^™

Evidence Accumulator Or Decision Threshold - Which Cortical Mechanism Are We Observing?, Patrick Simen

Faculty & Staff Scholarship

Most psychological models of perceptual decision making are of the accumulation-to- threshold variety. The neural basis of accumulation in parietal and prefrontal cortex is therefore a topic of great interest in neuroscience. In contrast, threshold mechanisms have received less attention, and their neural basis has usually been sought in subcortical structures. Here I analyze a model of a decision threshold that can be implemented in the same cortical areas as evidence accumulators, and whose behavior bears on two open questions in decision neuroscience: (1) When ramping activity is observed in a brain region during decision making, does it reflect evidence …

Brainstorm: Head Injuries And The Nfl, Part 2: A History Of Terms – Cte And Concussion, John J. Medina Ph.D.

Brainstorm

The history of research into the relationship between head injuries and contact sports starts not with football, but with boxing.

Focal Adhesion Kinase Modulates Cdc42 Activity Downstream Of Positive And Negative Axon Guidance Cues, Jonathan P. Myers, Estuardo Robles, Allison Ducharme-Smith, Timothy M. Gomez

Neuroscience: Faculty Publications

There is biochemical, imaging and functional evidence that Rho GTPase signaling is a crucial regulator of actin-based structures such as lamellipodia and filopodia. However, although Rho GTPases are believed to serve similar functions in growth cones, the spatiotemporal dynamics of Rho GTPase signaling has not been examined in living growth cones in response to known axon guidance cues. Here we provide the first measurements of Cdc42 activity in living growth cones acutely stimulated with both growth-promoting and growthinhibiting axon-guidance cues. Interestingly, we find that both permissive and repulsive factors can work by modulating Cdc42 activity, but in opposite directions. We …

The Putative Cannabinoid Receptor Gpr55 Modulates Synaptic Plasticity In The Hippocampus, Corinne Marie Badgley

Theses and Dissertations

Endocannabinoids (eCBs) are small molecules that are capable of modulating synaptic plasticity of both excitatory and inhibitory synapses in the brain. While eCBs bind to transient receptor potential vanilloid 1 (TRPV1) and cannabinoid receptor 1 (CB1) in the central nervous system, we recently identified a form of non-CB1, non-TRPV1 mediated long term depression activated by the eCB anandamide at CA1 hippocampal stratum radiatum interneurons. GPR55, an orphan G-protein receptor, has been identified in the hippocampus and is capable of activation by eCBs, making it a good candidate for mediating this non-CB1, non-TRPV1 form of synaptic plasticity. Here we performed whole-cell …

Endogenous Dynorphin Protects Against Neurotoxin-Elicited Nigrostriatal Dopaminergic Neuron Damage And Motor Deficits In Mice, Qingshan Wang, Eun-Joo Shin, Xuan-Khanh Thi Nguyen, Quan Li, Jae-Hyung Bach, Guoying Bing, Won-Ki Kim, Hyoung-Chun Kim, Jau-Shyong Hong

Neuroscience Faculty Publications

BACKGROUND: The striato-nigral projecting pathway contains the highest concentrations of dynorphin in the brain. The functional role of this opioid peptide in the regulation of mesencephalic dopaminergic (DAergic) neurons is not clear. We reported previously that exogenous dynorphin exerts potent neuroprotective effects against inflammation-induced dopaminergic neurodegeneration in vitro. The present study was performed to investigate whether endogenous dynorphin has neuroprotective roles in vivo.

METHODS: 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and methamphetamine (MA), two commonly used neurotoxins in rodent models of Parkinson's disease, were administered to wild-type (Dyn⁺/⁺) and prodynorphin-deficient mice (Dyn⁻/⁻). We examined dopaminergic neurotoxicity by using an automated video tracking system, HPLC, …

Amygdala Responses To Averted Vs Direct Gaze Fear Vary As A Function Of Presentation Speed, Reginald B. Adams, Robert G. Franklin Jr, Kestutis Kveraga, Nalini Ambady, Robert E. Kleck, Paul J. Whalen, Nouchine Hadjikhani, Anthony J. Nelson

Dartmouth Scholarship

We examined whether amygdala responses to rapidly presented fear expressions are preferentially tuned to averted vs direct gaze fear and conversely whether responses to more sustained presentations are preferentially tuned to direct vs averted gaze fear. We conducted three functional magnetic resonance imaging (fMRI) studies to test these predictions including: Study 1: a block design employing sustained presentations (1 s) of averted vs direct gaze fear expressions taken from the Pictures of Facial Affect; Study 2: a block design employing rapid presentations (300 ms) of these same stimuli and Study 3: a direct replication of these studies in the context …

Brainstorm: Head Injuries And The National Football League, Part 1: An Introduction, John J. Medina Ph.D.

Brainstorm

This is all about head injuries and the National Football League. I have some mixed feelings writing about this subject mostly because — big surprise — it is not a pretty story.

Connexin-32 And Connexin-43 Immunoreactivity In Rodent Taste Buds, Amanda E. Bond

Electronic Theses and Dissertations

Studies indicate that ATP is one of the primary neurotransmitters in taste transduction. ATP release occurs from taste cells via specific hemichannels such as pannexin/connexin hemichannels (Huang et al., 2007; Romanov et al., 2007). We hypothesize that Type II (receptor) and possibly Type III (presynaptic) cells release ATP at sites containing pannexin/connexin hemichannels. In this study, we examine the presence of connexin–32–LIR (Like Immunoreactivity) and connexin–43–LIR in rodent taste buds through immunocytochemical analysis and DAB (Di–amino–benzidine) immunoelectron microscopy. We observed that connexin–32–LIR co–localizes with P2X2–LIR in nerve fibers and in a small subset of NCAM–LIR cells. Connexin–32–LIR does not co–localize …

Impact Of Tdcs On Performance And Learning Of Target Detection: Interaction With Stimulus Characteristics And Experimental Design, Brian A. Coffman, M. C. Trumbo, R. A. Flores, Christopher M. Garcia, A. J. Van Der Merwe, Eric M. Wassermann, Michael Patrick Weisend, Vincent P. Clark

Wright State Research Institute Publications

We have previously found that transcranial direct current stimulation (tDCS) over right inferior frontal cortex (RIFC) enhances performance during learning of a difficult visual target detection task (Clark et al., 2012). In order to examine the cognitive mechanisms of tDCS that lead to enhanced performance, here we analyzed its differential effects on responses to stimuli that varied by repetition and target presence, differences related to expectancy by comparing performance in single- and double-blind task designs, and individual differences in skin stimulation and mood. Participants were trained for 1 h to detect target objects hidden in a complex virtual environment, while …

Enhancement And Suppression Of Ultradian And Circadian Rhythms Across The Female Hamster Reproductive Cycle, Brian J. Prendergast, Annaliese K. Beery, Matthew J. Paul, Irving Zucker

Neuroscience: Faculty Publications

The impact of ovarian hormones on hamster ultradian rhythms (URs) is unknown. We concurrently monitored URs and circadian rhythms (CRs) of home cage locomotor activity during the estrous cycle, pregnancy, and lactation of Syrian hamsters. URs with a mean period of 4–5 h were evident during the dark phase in more than 90% of females on days 1 and 2 of the estrous cycle but were significantly less prevalent on cycle days 3 and 4. The period of the UR did not vary as a function of estrous cycle stage, but at all stages, the UR period was longer in …

Dynamic Gene Expression In The Human Cerebral Cortex Distinguishes Children From Adults, Kirstin N. Sterner, Amy Weckle, Harry T. Chugani, Adi L. Tarca, Chet C. Sherwood, Patrick R. Hof, Christopher W. Kuzawa, Amy M. Boddy, Asad Abbas, Ryan L. Raaum, Lucie Grégoire, Leonard Lipovich, Lawrence I. Grossman, Monica Uddin, Morris Goodman, Derek E. Wildman

Publications and Research

In comparison with other primate species, humans have an extended juvenile period during which the brain is more plastic. In the current study we sought to examine gene expression in the cerebral cortex during development in the context of this adaptive plasticity. We introduce an approach designed to discriminate genes with variable as opposed to uniform patterns of gene expression and found that greater inter-individual variance is observed among children than among adults. For the 337 transcripts that show this pattern, we found a significant overrepresentation of genes annotated to the immune system process (pFDR>0). Moreover, genes known to …

Effect Of Nicotine On Body Composition, Laura O'Dell

Selected Works Temporary Series

No abstract provided.

Effect Of Nicotine On Body Composition, Laura O'Dell

Departmental Papers (Psych)

No abstract provided.

Age-Related Changes In The Daily Rhythm Of Photoreceptor Functioning And Circuitry In A Melatonin-Proficient Mouse Strain, Kenkichi Baba, Francesca Mazzoni, Sharon Owino, Susana Contreras-Alcantara, Enrica Strettoi, Gianluca Tosini

Neuroscience: Faculty Publications

Retinal melatonin is involved in the modulation of many important retinal functions. Our previous studies have shown that the viability of photoreceptors and ganglion cells is reduced during aging in mice that lack melatonin receptor type 1. This demonstrates that melatonin signaling is important for the survival of retinal neurons. In the present study, we investigate the effects of aging on photoreceptor physiology and retinal organization in CH3-f+/+ mice, a melatonin proficient mouse strain. Our data indicate that the amplitude of the a and b waves of the scotopic and photopic electroretinogram decreases with age. Moreover, the daily rhythm in …

Brainstorm: Brain Development, Part 2: We’Ve Only Just Begun, John J. Medina Ph.D.

Brainstorm

This is the second installment of a two­-part series briefly summarizing salient characteristics of in utero (literally “in the womb”) human brain development. Here, we will concern ourselves with the nature side of the nature/nurture issue of human behavior.

Imaging Prior Information In The Brain, Scott Gorlin, Ming Meng, Jitendra Sharma, Hiroki Sugihara

Dartmouth Scholarship

In making sense of the visual world, the brain's processing is driven by two factors: the physical information provided by the eyes (“bottom-up” data) and the expectancies driven by past experience (“top-down” influences). We use degraded stimuli to tease apart the effects of bottom-up and top-down processes because they are easier to recognize with prior knowledge of undegraded images. Using machine learning algorithms, we quantify the amount of information that brain regions contain about stimuli as the subject learns the coherent images. Our results show that several distinct regions, including high-level visual areas and the retinotopic cortex, contain more information …

Navigating The Diverse Dimensions Of Stereotypes, With Domain Specific Deficits: Processes Of Trait Judgments About Individuals With Disabilities, Christina G. Boardman

Scripps Senior Theses

Stereotype groups are interrelated. For example, in Australia, New Zealand, and the United States, racial minorities are referred to special education at a much higher rate than are majority racial groups (Tse, Lloyd, Petchkovsky, and Manaia, 2005; Harry, Arnaiz, Klingner, Sturges, 2008). The Stereotype Content Model describes stereotype relationships in terms of an interaction between competence and warmth. Warmth is the more consistent dimension. The nature of competence remains elusive (Fiske, Cuddy, and Glick, 2007; Fiske, Cuddy, Glick, and Xu, 2002). Knowledge of relationships between stereotype groups, which themselves may be effects of bias, could factor into observed competence effects. …

Brainstorm: Brain Development, Part 1: Of Mops And Brain Cells And Human Behavior, John J. Medina Ph.D.

Brainstorm

We have been discussing in equal measure the contributions that both natureand nurture make in the creation of human behavior. In this entry and the next, we are going to focus on the nature side of the discussion, summarizing a few features about how the human brain develops in the womb.

Iconic Memory Requires Attention, Marjan Persuh, Boris Genzer, Robert D. Melara

Publications and Research

Two experiments investigated whether attention plays a role in iconic memory, employing either a change detection paradigm (Experiment 1) or a partial-report paradigm (Experiment 2). In each experiment, attention was taxed during initial display presentation, focusing the manipulation on consolidation of information into iconic memory, prior to transfer into working memory. Observers were able to maintain high levels of performance (accuracy of change detection or categorization) even when concurrently performing an easy visual search task (low load). However, when the concurrent search was made difficult (high load), observers' performance dropped to almost chance levels, while search accuracy held at single-task …

Increased Modulation By Cognitive Control Region During Fmri Working Memory Task Suggest Inefficiencies In Network Connectivity In Children With Adhd, Ashley Burgess

Honors College Theses

Attention Deficit / Hyperactivity Disorder is a neurodevelopmental disorder common among children and adolescent populations whose symptoms are believed to be caused by deficits in executive functioning processes such as working memory. Using fMRI analyses, differences in the modulatory influence exhibited by the dorsal anterior cingulate cortex (dACC) on cortico-striatal regions implicated in working memory (2-back) (Owen et al 2005) was assessed between children with ADHD (twenty-three participants; mean age 6 yrs: 6.4-14.9 yrs) and healthy controls (twenty-six participants; mean age 10.1yrs: 6.3-14.1 yrs). Modulatory influence is defined as the degree to which one region exerts control on another region …

The Effects Of Rectal Temperature And Hydration Status On Perceptual Ratings In Dehydrating Males, Ethan A. Talbot

Honors Scholar Theses

Athletes push the limits of what the human body can handle every day. When they exercise in the heat, they can attain dangerous levels of internal temperature and dehydration. Since athletes are sometimes not aware when they are experiencing severe hyperthermia or hypohydration, it is of interest to anyone who exercises in the heat to study whether athletes are consciously aware that they are approaching dangerous physiological limits. This study compares the perceptual values of athletes exercising in the heat to the changes in their internal temperature and hydration status, to see if athletes can reliably predict their heat and …

Evidence For Pit-Type (Slc20) And Napi-Ii-Type (Slc34) Transporters In The Rat Choroid Plexus, Hien M. Le

Honors Scholar Theses

: A major function of the brain choroid plexus (CP) is to regulate the exchange of solutes between the blood plasma and the cerebrospinal fluid (CSF) using selective transporters. CSF inorganic phosphate (P_i) concentration is maintained at about one-half that of plasma and is potentially important because of its regulatory, structural, and biochemical functions. Phosphate is critical for ATP and DNA formation, the linked regulation between phosphate and calcium, and as an intracellular buffer. The human body has two major P_i transporter gene families known as SLC34 (NaPi-II) and SLC20 (PiT), which have wide tissue distribution. Although …

Eye Size At Birth In Prosimian Primates: Life History Correlates And Growth Patterns, Joshua R. Cummings, Magdalena N. Muchlinski, E. Christopher Kirk, Susan J. Rehorek, Valerie B. Deleon, Timothy D. Smith

Neuroscience Faculty Publications

BACKGROUND: Primates have large eyes relative to head size, which profoundly influence the ontogenetic emergence of facial form. However, growth of the primate eye is only understood in a narrow taxonomic perspective, with information biased toward anthropoids.

METHODOLOGY/PRINCIPAL FINDINGS: We measured eye and bony orbit size in perinatal prosimian primates (17 strepsirrhine taxa and Tarsius syrichta) to infer the extent of prenatal as compared to postnatal eye growth. In addition, multiple linear regression was used to detect relationships of relative eye and orbit diameter to life history variables. ANOVA was used to determine if eye size differed according to activity …

Effects Of Maternal Low Protein Diet On Expression Of Drug Transporters In The Blood-Brain Barrier Of Adult Offspring, Bonnie L. Hastings

Senior Theses

Adverse uterine environment, manifested as low birth weight (LBW), has been shown to predispose individuals to hypertension, diabetes, and obesity by mechanisms that are just beginning to be understood. One of the mechanisms is the dysregulation of the expression or function of drug transport proteins, such as the organic anion transporter (OAT) family, which are crucial for the transport of various endogenous and exogenous compounds into and out of all organs, especially the brain. Hence, we examined the status of select drug transporters in the blood-brain barrier (BBB), using a LBW rat model. Maternal low protein diet (LPD) during gestation …

Structural Analysis Of The Drosophila Innexin Shakb: Role Of The N-Terminus In Rectifying Electrical Synapses, William Marks

Biology Theses

Gap junction channels mediate direct intercellular communication in all multicellular animals. They are comprised of the connexin family of proteins in vertebrates and the innexin family in prechordates. Connexins and innexins share many functional and structural similarities as orthologous proteins. Both types are capable of forming electrical synapses. Rectifying junctions are specialized electrical synapses found in neural systems that control escape responses. It has been shown that heterotypic gap junction channels mediate asymmetric properties of rectifying junctions. Shaking B N+16 and Shaking B lethal are variants of the ShakB locus in Drosophila and the organization of these innexins into heterotypic …

Role Of Trp Channels In Mediating The Calcium Signaling Response Of Brain Endothelial Cells To Mechanical Stretch, Jonathan Berrout

Dissertations and Theses (Open Access)

Traumatic brain injury (TBI) often results in disruption of the blood brain barrier (BBB), which is an integral component to maintaining the central nervous system homeostasis. Recently cytosolic calcium levels ([Ca²⁺]i), observed to elevate following TBI, have been shown to influence endothelial barrier integrity. However, the mechanism by which TBI-induced calcium signaling alters the endothelial barrier remains unknown. In the present study, an in vitro BBB model was utilized to address this issue. Exposure of cells to biaxial mechanical stretch, in the range expected for TBI, resulted in a rapid cytosolic calcium increase. Modulation of intracellular and extracellular …

Novel Use Of Dual Anti-Inflammatory Therapy To Overcome Drug Resistance And Improve Functional Recovery Following Spinal Cord Injury, Jennifer Dulin

Dissertations and Theses (Open Access)

Over 1.2 million Americans are currently living with a traumatic spinal cord injury (SCI). Despite the need for effective therapies, there are currently no proven effective treatments that can improve recovery of function in SCI patients. Many therapeutic compounds have shown promise in preclinical models of SCI, but all of these have fallen short in clinical trials.

P-glycoprotein (Pgp) is an active transporter expressed on capillary endothelial cell membranes at the blood-spinal cord barrier (BSCB). Pgp limits passive diffusion of blood-borne drugs into the CNS, by actively extruding drugs from the endothelial cell membrane. Pgp can become pathologically up-regulated, thus …

Population Coding In Laminar Cortical Circuits, Bryan J. Hansen

Dissertations and Theses (Open Access)

One of the fundamental questions in neuroscience is to understand how encoding of sensory inputs is distributed across neuronal networks in cerebral cortex to influence sensory processing and behavioral performance. The fact that the structure of neuronal networks is organized according to cortical layers raises the possibility that sensory information could be processed differently in distinct layers. The goal of my thesis research is to understand how laminar circuits encode information in their population activity, how the properties of the population code adapt to changes in visual input, and how population coding influences behavioral performance. To this end, we performed …

A Comparison Of Kinetic Family Drawings By Children With Autism Spectrum Disorder And Typically Developing Siblings, Rachel Daniels

EVMS School of Health Professions Theses & Dissertations

The purpose of this study was to identify the effects of Autism Spectrum Disorder (ASD) on the diagnosed child’s perception of their family. Specifically, the study compared the Kinetic Family Drawings (Burns & Kaufman, 1970) created by children diagnosed with Autism and those created by typically developing children.

Eight participants between the ages of 6 and 12 were recruited, and split into two groups. One group consisted of four children (three boys and one girl) with a mean age of 6.75 and an Autism Spectrum Disorder Diagnosis. The second group consisted of four typically developing children (three girls and one …

Parkinson’S Disease: Molecular Mechanisms And Treatments, Delia Vahey

Senior Honors Theses

Parkinson’s disease is a motor system disorder that is caused primarily by the loss of dopamine-producing brain cells. The most affected brain structure is the pars compacta of the substantia nigra. This area of the brain is essential to the control of voluntary movement, and so its impairment leads to symptoms such as tremors, rigidity, and impaired balance. The neuronal protein alpha-synuclein has been shown to be heavily involved in the pathogenesis of the disease at the cellular level. The currently available treatments for PD mainly target dopamine regulation, and there been no cure developed for the disease at present. …