Biology Commons^™

Swimming Rhythm Generation In The Caudal Hindbrain Of The Lamprey, James T. Buchanan

Biological Sciences Faculty Research and Publications

The spinal cord has been well established as the site of generation of the locomotor rhythm in vertebrates, but studies have suggested that the caudal hindbrain in larval fish and amphibians can also generate locomotor rhythms. Here, we investigated whether the caudal hindbrain of the adult lamprey (Petromyzon marinus and Ichthyomyzon unicuspis) has the ability to generate the swimming rhythm. The hindbrain-spinal cord transition zone of the lamprey contains a bilateral column of somatic motoneurons that project via the spino-occipital (S-O) nerves to several muscles of the head. In the brainstem-spinal cord-muscle preparation, these muscles were found to …

Electrical And Biomechanical Properties Of Rat Ventricular Myocytes: Effect Of Exercise-Training & Beta-Adrenergic Regulation, Xinrui Wang

Dissertations (1934 -)

Heart disease is one of the leading causes of morbidity and mortality in the western world, and programs of exercise-training have been shown to ameliorate cardiovascular risk factors and protect against heart diseases. The cellular/molecular mechanisms of regular exercise induced adaptations in the heart remains incomplete. To address this, female and male Sprague-Dawley rats were randomly assigned to exercise trained (TRN) or sedentary (SED) groups. After 6-8 weeks training, ventricular myocytes were isolated and studied.Exercise-training prolonged the action potential duration (APD) in myocytes isolated from apex and base regions at low stimulation rate (1Hz), while shortening the APD at high …

Dynamic Sex Chromosomes In Old World Chameleons (Squamata: Chamaeleonidae), Stuart V. Nielsen, J. L. Banks, R. E. Diaz Jr., P. A. Trainor, Tony Gamble

Biological Sciences Faculty Research and Publications

Much of our current state of knowledge concerning sex chromosome evolution is based on a handful of ‘exceptional’ taxa with heteromorphic sex chromosomes. However, classifying the sex chromosome systems of additional species lacking easily identifiable, heteromorphic sex chromosomes is indispensable if we wish to fully understand the genesis, degeneration and turnover of vertebrate sex chromosomes. Squamate reptiles (lizards and snakes) are a potential model clade for studying sex chromosome evolution as they exhibit a suite of sex‐determining modes yet most species lack heteromorphic sex chromosomes. Only three (of 203) chameleon species have identified sex chromosome systems (all with female heterogamety, …

Dynamics Of E. Coli Single Stranded Dna Binding (Ssb) Protein-Dna Complexes, Edwin Antony, Timothy M. Lohman

Biological Sciences Faculty Research and Publications

Single stranded DNA binding proteins (SSB) are essential to the cell as they stabilize transiently open single stranded DNA (ssDNA) intermediates, recruit appropriate DNA metabolism proteins, and coordinate fundamental processes such as replication, repair and recombination. Escherichia coli single stranded DNA binding protein (EcSSB) has long served as the prototype for the study of SSB function. The structure, functions, and DNA binding properties of EcSSB are well established: The protein is a stable homotetramer with each subunit possessing an N-terminal DNA binding core, a C-terminal protein-protein interaction tail, and an intervening intrinsically disordered linker (IDL). EcSSB …

Functional Traits Of Tropical Trees And Lianas Explain Spatial Structure Across Multiple Scales, Adam Thomas Clark, Nattei Detto, Helene C. Muller-Laudau, Stefan A. Schnitzer, S. Joseph Wright, Richard Condit, Stephen P. Hubbell

Biological Sciences Faculty Research and Publications

1. Dispersal and density dependence are major determinants of spatial structure, population dynamics and coexistence for tropical forest plants. However, because these two processes can jointly influence spatial structure at similar scales, analysing spatial patterns to separate and quantify them is often difficult.
2. Species functional traits can be useful indicators of dispersal and density dependence. However, few methods exist for linking functional traits to quantitative estimates of these processes that can be compared across multiple species.
3. We analysed static spatial patterns of woody plant populations in the 50 ha Forest Dynamics Plot on Barro Colorado Island, Panama with methods that distinguished …

Tree Species Vary Widely In Their Tolerance For Liana Infestation: A Case Study Of Differential Host Response To Generalist Parasites, Marco D. Visser, Stefan A. Schnitzer, Helene C. Muller-Laudau, Eelke Jongejans, Hans De Kroon, Liza S. Comita, Stephen P. Hubbell, S. Joseph Wright

Biological Sciences Faculty Research and Publications

1. Lianas are structural parasites of trees and reduce individual host tree growth, survival and fecundity. Thus, liana infestation is expected to affect tree population growth rates, with potentially different effects in different species depending on the frequency of liana infestation and the impact of liana infestation on population growth rates. Previous studies have documented the myriad negative effects of lianas on trees and variation in liana infestation among tree species; however, no study has quantified the impact of liana infestation on individual tree species population growth rates. Lianas are increasing in abundance in multiple Neotropical sites, which may have profound …

Lianas Reduce Community-Level Canopy Tree Reproduction In A Panamanian Forest, Maria M. Garcia Leon, Laura Martinez Izquierdo, Filipe Niery Arantes Mello, Jennifer S. Powers, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

1. Lianas are a key component of tropical forests, where they compete intensely with trees, reducing tree recruitment, growth and survival. One of the most important potential outcomes of liana competition is the reduction of tree reproduction; however, no previous study has experimentally determined the effects of lianas on tree reproduction beyond a single tree species.
2. We used a large‐scale liana removal experiment to quantify the effect of lianas on community‐level canopy and understorey tree and palm reproduction. In 2011, we removed lianas from eight 6,400‐m² plots (eight plots served as controls) and surveyed understorey tree reproduction in 2012, canopy …

Does Soil Moisture Availability Explain Liana Seedling Distribution Across A Tropical Rainfall Gradient?, Eric Manzane-Pinzon, Guillermo Goldstein, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Liana density tends to increase with decreasing rainfall and increasing seasonality. However, the pattern of liana distribution may be due to differences in soil water retention capacity, not rainfall and seasonality per se. We tested the effect of rainfall and soil substrate with respect to the distribution of liana seedlings in six sites across a rainfall gradient from the wet Atlantic to the dry Pacific in central Panama. Soils were either limestone, with low water-holding capacity, or laterite, with higher water-holding capacity. We sampled liana seedlings at each site using three 1 × 100 m transect. We found that …

Pleiotropic And Novel Phenotypes In The Drosophila Gut Caused By Mutation Of Drop-Dead, Sean Conway, Christine Lynn Sansone, Anika Benske, Kaitlin Kentala, Johan Billen, Jozef Vanden Broeck, Edward M. Blumenthal

Biological Sciences Faculty Research and Publications

Normal gut function is vital for animal survival, and deviations from such function can contribute to malnutrition, inflammation, increased susceptibility to pathogens, diabetes, neurodegenerative diseases, and cancer. In the fruit fly Drosophila melanogaster, mutation of the gene drop-dead (drd) results in defective gut function, as measured by enlargement of the crop and reduced food movement through the gut, and drd mutation also causes the unrelated phenotypes of neurodegeneration, early adult lethality and female sterility. In the current work, adult drd mutant flies are also shown to lack the peritrophic matrix (PM), an extracellular barrier that lines the lumen of the …

Cryptic Diversity In The Neotropical Gecko Genus Phyllopezus Peters, 1878 (Reptilia: Squamata: Phyllodactylidae): A New Species From Paraguay, Pier Cacciali, Sebastian Lotzkat, Tony Gamble, Gunther Köhler

Biological Sciences Faculty Research and Publications

The gecko genus Phyllopezus is distributed mainly along South America’s “Dry Diagonal” (Caatinga, Cerrado, and Chaco). The genus has been the subject of recent taxonomic analyses and includes four described species and seven candidate species referred to here as Phyllopezus pollicaris sensu lato. In Paraguay, Phyllopezus is known from the Chaco and Cerrado where it is abundant, and also from a small isolated population from a rocky hill formation named “Cordillera de Los Altos” (Los Altos mountain range). Here we analyzed genetic samples from across its range, including new samples from Paraguay, using DNA barcoding analysis of the mitochondrial 16S …

Allosteric Regulation Alters Carrier Domain Translocation In Pyruvate Carboxylase, Yumeng Liu, Melissa M. Budelier, Katelyn Stine, Martin St. Maurice

Biological Sciences Faculty Research and Publications

Pyruvate carboxylase (PC) catalyzes the ATP-dependent carboxylation of pyruvate to oxaloacetate. The reaction occurs in two separate catalytic domains, coupled by the long-range translocation of a biotinylated carrier domain (BCCP). Here, we use a series of hybrid PC enzymes to examine multiple BCCP translocation pathways in PC. These studies reveal that the BCCP domain of PC adopts a wide range of translocation pathways during catalysis. Furthermore, the allosteric activator, acetyl CoA, promotes one specific intermolecular carrier domain translocation pathway. These results provide a basis for the ordered thermodynamic state and the enhanced carboxyl group transfer efficiency in the presence of …

Infanticide In Chimpanzees: Taphonomic Case Studies From Gombe, Claire A. Kirchhoff, Michael L. Wison, Deus C. Mjungu, Jane Raphael, Shadrack Kamenya, D. Anthony Collins

Biological Sciences Faculty Research and Publications

Objectives

We present a study of skeletal damage to four chimpanzee (Pan troglodytes) infanticide victims from Gombe National Park, Tanzania. Skeletal analysis may provide insight into the adaptive significance of infanticide by examining whether nutritional benefits sufficiently explain infanticidal behavior. The nutritional hypothesis would be supported if bone survivorship rates and skeletal damage patterns are comparable to those of monkey prey. If not, other explanations, such as the resource competition hypothesis, should be considered.

Methods

Taphonomic assessment of two chimpanzee infants included description of breakage and surface modification, data on MNE, %MNE, and bone survivorship. Two additional infants …

Mrpl35, A Mitospecific Component Of Mitoribosomes, Plays A Key Role In Cytochrome C Oxidase Assembly, Jodie M. Box, Jasvinder Kaur, Rosemary A. Stuart

Biological Sciences Faculty Research and Publications

Mitoribosomes perform the synthesis of the core components of the oxidative phosphorylation (OXPHOS) system encoded by the mitochondrial genome. We provide evidence that MrpL35 (mL38), a mitospecific component of the yeast mitoribosomal central protuberance, assembles into a subcomplex with MrpL7 (uL5), Mrp7 (bL27), and MrpL36 (bL31) and mitospecific proteins MrpL17 (mL46) and MrpL28 (mL40). We isolated respiratory defective mrpL35 mutant yeast strains, which do not display an overall inhibition in mitochondrial protein synthesis but rather have a problem in cytochrome coxidase complex (COX) assembly. Our findings indicate that MrpL35, with its partner Mrp7, play a key role in coordinating …

General And Specific Promotion Of Flagellar Assembly By A Flagellar Nucleoside Diphosphate Kinase, Xiaoyan Zhu, Emiliya Poghosyan, Radhika Gopal, Yi Liu, Kristine S. Ciruelas, Yousif Maizy, Dennis R. Diener, Stephen M. King, Takashi Ishikawa, Pinfen Yang

Biological Sciences Faculty Research and Publications

Nucleoside diphosphate kinases (NDKs) play a central role in diverse cellular processes using the canonical NDK activity or alternative mechanisms that remain poorly defined. Our study of dimeric NDK5 in a flagellar motility control complex, the radial spoke (RS), has revealed new modalities. The flagella in Chlamydomonas ndk5 mutant were paralyzed, albeit only deficient in three RS subunits. RS morphology appeared severely changed in averaged cryo-electron tomograms, suggesting that NDK5 is crucial for the intact spokehead formation as well as RS structural stability. Intriguingly, ndk5’s flagella were also short, resembling those of an allelic spoke-less mutant. All ndk5’s phenotypes were …

Klf9 And Jnk3 Interact To Suppress Axon Regeneration In The Adult Cns, Akintomide Apara, Joana Galvao, Yan Wang, Murray G. Blackmore, Allison Trillo, Keiichiro Iwao, Dale P. Brown Jr., Kimberly A. Fernandes, Abigail Huang, Tu Nguyen, Masoumeh Ashouri, Ziong Zhang, Peter S. Shaw, Noelia J. Kunzevitzky, Darcie L. Moore, Richard T. Libby, Jeffrey L. Goldberg

Biological Sciences Faculty Research and Publications

Neurons in the adult mammalian CNS decrease in intrinsic axon growth capacity during development in concert with changes in Krüppel-like transcription factors (KLFs). KLFs regulate axon growth in CNS neurons including retinal ganglion cells (RGCs). Here, we found that knock-down of KLF9, an axon growth suppressor that is normally upregulated 250-fold in RGC development, promotes long-distance optic nerve regeneration in adult rats of both sexes. We identified a novel binding partner, MAPK10/JNK3 kinase, and found that JNK3 (c-Jun N-terminal kinase 3) is critical for KLF9's axon-growth-suppressive activity. Interfering with a JNK3-binding domain or mutating two newly discovered serine phosphorylation acceptor …

Reversible Plasticity Of Detrusor Smooth Muscle: Evidence For A Key Role Of “Slipping” Actomyosin Cross-Bridges In The Control Of Urinary Bladder Compliance, Thomas J. Eddinger

Biological Sciences Faculty Research and Publications

No abstract provided.

Effects Of Lightning On Trees: A Predictive Model Based On In Situ Electrical Resistivity, Evan M. Gora, Phillip M. Bitzer, Jeffrey C. Burchfield, Stefan A. Schnitzer, Stephen P. Yanoviak

Biological Sciences Faculty Research and Publications

The effects of lightning on trees range from catastrophic death to the absence of observable damage. Such differences may be predictable among tree species, and more generally among plant life history strategies and growth forms. We used field‐collected electrical resistivity data in temperate and tropical forests to model how the distribution of power from a lightning discharge varies with tree size and identity, and with the presence of lianas. Estimated heating density (heat generated per volume of tree tissue) and maximum power (maximum rate of heating) from a standardized lightning discharge differed 300% among tree species. Tree size and morphology …

Monitoring Replication Protein A (Rpa) Dynamics In Homologous Recombination Through Site-Specific Incorporation Of Non-Canonical Amino Acids, Nilisha Pokhrel, Sofia Origanti, Eric Parker Davenport, Disha M. Gandhi, Kyle Kaniecki, Ryan A. Mehl, Eric C. Greene, Chris Dockendorff, Edwin Antony

Biological Sciences Faculty Research and Publications

An essential coordinator of all DNA metabolic processes is Replication Protein A (RPA). RPA orchestrates these processes by binding to single-stranded DNA (ssDNA) and interacting with several other DNA binding proteins. Determining the real-time kinetics of single players such as RPA in the presence of multiple DNA processors to better understand the associated mechanistic events is technically challenging. To overcome this hurdle, we utilized non-canonical amino acids and bio-orthogonal chemistry to site-specifically incorporate a chemical fluorophore onto a single subunit of heterotrimeric RPA. Upon binding to ssDNA, this fluorescent RPA (RPAf) generates a quantifiable change in fluorescence, thus serving as …

Trees As Islands: Canopy Ant Species Richness Increases With The Size Of Liana-Free Trees In A Neotropical Forest, Benjamin J. Adams, Stefan A. Schnitzer, Stephen P. Yanoviak

Biological Sciences Faculty Research and Publications

The physical characteristics of habitats shape local community structure; a classic example is the positive relationship between the size of insular habitats and species richness. Despite the high density and proximity of tree crowns in forests, trees are insular habitats for some taxa. Specifically, crown isolation (i.e. crown shyness) prevents the movement of small cursorial animals among trees. Here, we tested the hypothesis that the species richness of ants (S_a) in individual, isolated trees embedded within tropical forest canopies increases with tree size. We predicted that this pattern disappears when trees are connected by lianas (woody vines) or …

A Leptin-Regulated Circuit Controls Glucose Mobilization During Noxious Stimuli, Jonathan N. Flak, Deanna M. Arble, Warren Pan, Christa Patterson, Thomas Lanigan, Paulette B. Goforth, Jamie Sackner, Maja Joosten, Donald A. Morgan, Margaret B. Allison, John Hayes, Eva Feldman, Randy J. Seeley, David P. Olson, Kamal Rahmouni, Martin G. Myers Jr.

Biological Sciences Faculty Research and Publications

Adipocytes secrete the hormone leptin to signal the sufficiency of energy stores. Reductions in circulating leptin concentrations reflect a negative energy balance, which augments sympathetic nervous system (SNS) activation in response to metabolically demanding emergencies. This process ensures adequate glucose mobilization despite low energy stores. We report that leptin receptor–expressing neurons (LepRb neurons) in the periaqueductal gray (PAG), the largest population of LepRb neurons in the brain stem, mediate this process. Application of noxious stimuli, which often signal the need to mobilize glucose to support an appropriate response, activated PAG LepRb neurons, which project to and activate parabrachial nucleus (PBN) …

Ventricular Action Potential Adaptation To Regular Exercise: Role Of Β-Adrenergic And KAtp Channel Function, Xinrui Wang, Robert H. Fitts

Biological Sciences Faculty Research and Publications

Regular exercise training is known to affect the action potential duration (APD) and improve heart function, but involvement of β-adrenergic receptor (β-AR) subtypes and/or the ATP-sensitive K⁺ (K_ATP) channel is unknown. To address this, female and male Sprague-Dawley rats were randomly assigned to voluntary wheel-running or control groups; they were anesthetized after 6–8 wk of training, and myocytes were isolated. Exercise training significantly increased APD of apex and base myocytes at 1 Hz and decreased APD at 10 Hz. Ca²⁺ transient durations reflected the changes in APD, while Ca²⁺ transient amplitudes were unaffected by wheel …

The Discovery Of Xy Sex Chromosomes In A Boa And Python, Tony Gamble, Todd A. Castoe, Stuart V. Nielsen, Jason L. Banks, Daren C. Card, Drew R. Schield, Gordon W. Schuett, Warren Booth

Biological Sciences Faculty Research and Publications

For over 50 years, biologists have accepted that all extant snakes share the same ZW sex chromosomes derived from a common ancestor [1, 2, 3], with different species exhibiting sex chromosomes at varying stages of differentiation. Accordingly, snakes have been a well-studied model for sex chromosome evolution in animals [1, 4]. A review of the literature, however, reveals no compelling support that boas and pythons possess ZW sex chromosomes [2, 5]. Furthermore, phylogenetic patterns of facultative parthenogenesis in snakes and a sex-linked color mutation in the ball python (Python regius) are best explained by boas and pythons possessing …

Blurred Lines Between Competition And Parasitism, Tara E. Stewart, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Accurately describing the ecological relationships between species is more than mere semantics-doing so has profound practical and applied implications, not the least of which is that inaccurate descriptions can lead to fundamentally incorrect predicted outcomes of community composition and functioning. Accurate ecological classifications are particularly important in the context of global change, where species interactions can change rapidly following shifts in species composition. Here, we argue that many common ecological interactions-particularly competition and parasitism-can be easily confused and that we often lack empirical evidence for the full reciprocal interaction among species. To make our case and to propose a theoretical …

The Noncanonical Roles Of Two Primordial Molecules In Flagella, Xiaoyan Zhu

Dissertations (1934 -)

Motile cilia and flagella are ancient organelles that eukaryotic organisms today still rely on to thrive in their natural environment. Not surprisingly, accumulated evidence has shown that the intricate motility machinery, the microtubule-based axoneme, is evolutionarily conserved down to the molecular level. This notion is epitomized by the signature axonemal complex, the radial spoke (RS). The RS is part of a control center conferring the high frequency and tightly regulated movement. Key RS proteins discovered in biflagellate green alga, Chlamydomonas reinhardtii, are also generated by nearly all ciliated organisms, including Homo sapiens. Among them are two subunits from primordial protein …

Assessment Of Five Chilling Tolerance Traits And Gwas Mapping In Rice Using The Usda Mini-Core Collection, Michael Schläppi, Aaron K. Jackson, Georgia C. Eizenga, Aiju Wang, Chengcai Chu, Yao Shi, Naoki Shimoyama, Debbie L. Boykin

Biological Sciences Faculty Research and Publications

Rice (Oryza sativa L.) is often exposed to cool temperatures during spring planting in temperate climates. A better understanding of genetic pathways regulating chilling tolerance will enable breeders to develop varieties with improved tolerance during germination and young seedling stages. To dissect chilling tolerance, five assays were developed; one assay for the germination stage, one assay for the germination and seedling stage, and three for the seedling stage. Based on these assays, five chilling tolerance indices were calculated and assessed using 202 O. sativa accessions from the Rice Mini-Core (RMC) collection. Significant differences between RMC accessions made the five …

Functional Analysis Of Microrna Pathway Genes In The Somatic Gonad And Germ Cells During Ovulation In C. Elegans, Carmela Rios, David Warren, Benjamin Olson, Allison L. Abbott

Biological Sciences Faculty Research and Publications

MicroRNAs (miRNAs) are post-transcriptional regulators of gene expression that play critical roles in animal development and physiology, though functions for most miRNAs remain unknown. Worms with reduced miRNA biogenesis due to loss of Drosha or Pasha/DGCR8 activity are sterile and fail to ovulate, indicating that miRNAs are required for the process of oocyte maturation and ovulation. Starting with this penetrant sterile phenotype and using new strains created to perform tissue specific RNAi, we characterized the roles of the C. elegans Pasha, pash-1, and two miRNA-specific Argonautes, alg-1 and alg-2, in somatic gonad cells and in germ cells in the regulation …

Mechanisms And Functions Of Spatial Protein Quality Control, Emily M. Sontag, Rahul S. Samant, Judith Frydman

Biological Sciences Faculty Research and Publications

A healthy proteome is essential for cell survival. Protein misfolding is linked to a rapidly expanding list of human diseases, ranging from neurodegenerative diseases to aging and cancer. Many of these diseases are characterized by the accumulation of misfolded proteins in intra- and extracellular inclusions, such as amyloid plaques. The clear link between protein misfolding and disease highlights the need to better understand the elaborate machinery that manages proteome homeostasis, or proteostasis, in the cell. Proteostasis depends on a network of molecular chaperones and clearance pathways involved in the recognition, refolding, and/or clearance of aberrant proteins. Recent studies reveal that …

Skeletal Muscle Pgc-1Β Signaling Is Sufficient To Drive An Endurance Exercise Phenotype And To Counteract Components Of Detraining In Mice, Samuel Lee, Teresa C. Leone, Lisa Rogosa, John Rumsey, Julio Ayala, Paul M. Coen, Robert H. Fitts, Rick B. Vega, Daniel P. Kelly

Biological Sciences Faculty Research and Publications

Peroxisome proliferator-activated receptor-γ coactivator (PGC)-1α and -1β serve as master transcriptional regulators of muscle mitochondrial functional capacity and are capable of enhancing muscle endurance when overexpressed in mice. We sought to determine whether muscle-specific transgenic overexpression of PGC-1β affects the detraining response following endurance training. First, we established and validated a mouse exercise-training-detraining protocol. Second, using multiple physiological and gene expression end points, we found that PGC-1β overexpression in skeletal muscle of sedentary mice fully recapitulated the training response. Lastly, PGC-1β overexpression during the detraining period resulted in partial prevention of the detraining response. Specifically, an increase in the plateau …

Repeated Evolution Of Digital Adhesion In Geckos: A Reply To Harrington And Reeder, Tony Gamble, E. Greenbaum, T. R. Jackman, A. P. Russell, A. M. Bauer

Biological Sciences Faculty Research and Publications

We published a phylogenetic comparative analysis that found geckos had gained and lost adhesive toepads multiple times over their long evolutionary history (Gamble et al., PLoS One, 7, 2012, e39429). This was consistent with decades of morphological studies showing geckos had evolved adhesive toepads on multiple occasions and that the morphology of geckos with ancestrally padless digits can be distinguished from secondarily padless forms. Recently, Harrington & Reeder (J. Evol. Biol., 30, 2017, 313) reanalysed data from Gamble et al. (PLoS One, 7, 2012, e39429) and found little support for the multiple origins hypothesis. Here, we …

Reductions In Mesolimbic Dopamine Signaling And Aversion: Implications For Relapse And Learned Avoidance, Mykel A. Robble

Dissertations (1934 -)

The ability to adjust behavior appropriately following an aversive experience is essential for survival, yet variability in this process contributes to a wide range of disorders, including drug addiction. It is clear that proper approach and avoidance is regulated, in part, by the activity of the mesolimbic dopamine system. While the importance of this system as a critical modulator of reward learning has been extensively characterized, its involvement in directing aversion-related behaviors and learning is still poorly understood. Recent studies have revealed that aversive stimuli and their predictors cause rapid reductions in nucleus accumbens (NAc) dopamine concentrations. Furthermore, a normally …