ABSTRACT. It is widely argued that personalized instruction based on individual differences in learning styles or genetic predispositions could improve learning outcomes. However, this proposition has resisted clear demonstration in human studies, where it is difficult to control experience and quantify outcomes. Here, we take advantage of the tractable nature of vocal learning in songbirds (Lonchura striata domestica) to test the idea that matching instruction to individual genetic predispositions can enhance learning. We use both cross-fostering and computerized instruction with synthetic songs to demonstrate that matching the tutor song to individual predispositions can improve learning across genetic backgrounds. Moreover, we find that optimizing instruction in this fashion can equalize learning differences across individuals that might otherwise be construed as fixed and genetically determined. Our results demonstrate potent, synergistic interactions between experience and genetics in shaping song, and indicate the likely importance of such interactions for other complex learned behaviors.

David G. Mets1 and Michael S. Brainard1,2 1 Center for Integrative Neuroscience, University of California, San Francisco, CA 94158; Howard Hughes Medical Institute, University of California, San Francisco, CA 94158. 2Departments of Physiology and Psychiatry, University of California, San Francisco, CA 94158.

ABSTRACT. Addiction vulnerability is highly heritable and addiction behaviors differ between sexes. Addiction studies in non-human animals should account for these known biological sources of variation, yet addiction phenotypes in mice are often studied in a single sex and strain. Here, we test how the behavioral and neural transcriptional response to cocaine depends on both genetic diversity and sex among genetically diverse mice. Comparing the eight founder strains of the Diversity Outbred population, we found robust differences in cocaine intravenous self-administration – especially among wild-derived strains. Using RNA sequencing of striatum from the eight founder strains of the Diversity Outbred, we assessed the main effects of repeated cocaine versus saline injection, genetic background, sex, and all interaction effects on global gene expression. Most effects were genetic – transcriptional profile is more highly heritable than in the BXD – but few genes were differentially expressed through a main effect of cocaine. Instead, cocaine-related molecular phenotypes manifested as interactions with sex and genetic background, and the strongest cocaine exposure effects were attributable to cocaine’s interaction with both sex and genetic background. A number of genes were upregulated after cocaine exposure in a sex and strain specific manner including the immediate early gene Arc and the cytoskeletal adapter to PI3K signaling Myo16. Altogether, these results demonstrate the context specificity of cocaine response mechanisms while reiterating the necessity of incorporating genetic diversity and sex differences when studying the biological basis of addiction. The variation in neurobehavioral response to cocaine suggests potential mechanisms of differential vulnerability to addiction.

Michael C. Saul1, Price E. Dickson1, Vivek M. Philip1, Leona H. Gagnon1, Tyler Roy1, Troy Wilcox1, Michael Leonardo1, Ashley Olsen1, Center for Systems Neurogenetics of Addiction1,2,3,4, Elissa J. Chesler1. Funding Support: NIDA P50 DA039841, NIDA R01 DA037927. 1The Jackson Laboratory, Bar Harbor, ME; 2UNC Chapel Hill, Chapel Hill, NC; 3SUNY Binghamton, Binghamton, NY; 4Pittsburgh University, Pittsburgh, PA

ABSTRACT. Danila Cuomo1, Megan Nitcher1 and David Threadgill1

Most human diseases result from a complex interplay of genetic, epigenetic and environmental factors, and current scientific approaches do not adequately capture these complex interactions. Understanding such gene-by-environment interactions will enable a more accurate toxicant risk assessment and public health protection. Traditional epidemiological approaches are limited in exploring factors contributing to differential susceptibility. To overcome this limitation, new genetically-diverse mouse resources such as the Collaborative Cross and Diversity Outcross have been developed to better model the genetic diversity found in human populations. Childhood exposure to lead, a potent neurotoxin for which there is no safe blood level, can impact intelligence and behavior. To specifically address the influence of genetic background on neurotoxicity from lead exposure, we are utilizing a recombinant inbred intercross mouse population which allows controlled exposures within a population setting to identify genetic polymorphisms that drive either susceptibility or resistance to lead neurotoxicity. To this end, F1 males and females derived from crosses of Collaborative Cross inbred lines receive early-life exposure to lead through lactation and then through drinking water to mimic human exposure. Preliminary results reveal significant variation in blood lead levels between strains exposed to the same dose. We are also assessing long-term effects of lead exposure on behavior and cognition in adult mice with early-life exposure. Differences between strains could provide us the key in understanding mechanisms by which genetics and toxic exposure contribute to neurological phenotype and provide new tools for exposure detection, risk assessment, and interventions to reduce lasting effects of early-life lead exposure.

1 Department of Molecular and Cellular Medicine, College of Medicine, Texas A&M University, College Station, TX 77843, USA

ABSTRACT. Exposure to environment toxicants including pesticides, particulate matter from engine exhaust and other forms of smoke take a toll on human health. Depending on the toxicant however, not all individuals are equally susceptible to the deleterious effects. In assessing relative risk across individuals, genetic constitutions come in play. For example, it has been shown that risk for developing Parkinson’s disease following exposure to paraquat, an herbicide, is markedly affected by one’s genotype for the Glutathione S-transferase enzyme. More robust research on toxicogenetics requires an appropriate animal model. In this presentation, the author will present his work on genetic variability in neurological response to paraquat, MPTP and an organophosphorus compound, diisopropylflurophosphate in the BXD family of recombinant inbred mouse strains.

Byron C. Jones, University of Tennessee Health Science Center, Memphis TN Supported in part by USPHS grant ES 022614 and DoD grant W81XWH-17-1-0472.

ABSTRACT. AR Dunn1, AR Ouellette1, SM Neuner1,2, J-G Zhang1, V Philip1, KMS O’Connell1, CC Kaczorowski1 Alzheimer's disease (AD) is complex, with both genetic and environmental factors regulating disease progression. Identification of gene-by-environment interactions that modulate AD pathogenesis will be critical to understanding disease mechanisms and developing novel and personalized treatments; however, gene-by-environment interactions in AD have been largely under-explored. We recently developed a panel of genetically diverse mice carrying familial AD mutations (AD-BXDs; Neuner, 2018) that are ideally suited to investigate translationally-relevant GxE interactions. Here, we used AD-BXDs to determine how genetics and diet interact to modify AD-related pathogenesis. We fed a chronic high-fat diet (HFD; 45% fat) to 10 strains of AD-BXDs and nontransgenic littermates (Ntg-BXDs) and monitored metabolic and cognitive function. Finally, we analyzed gene expression in the hippocampus and hypothalamus using RNAseq. Gene-by-diet interactions accounted for a substantial proportion of variance in metabolic and cognitive phenotypes across the population, and the contribution of gene-by-diet interactions on these phenotypes differed depending on genotype. Metabolic function correlated more closely with cognitive function in AD-BXDs compared to Ntg-BXDs. These results suggest that diet and genetic background interact to mediate vulnerability to AD pathogenesis, and that metabolic factors (e.g., weight, glucose metabolism) contribute to cognitive decline differentially in normal aging versus AD. Ongoing analyses will determine how transcriptomic changes within the hippocampus and hypothalamus regulate effects on cognitive and metabolic phenotypes in chow- and HFD-fed mice. Identifying genetic modifiers of environmental contributors to AD will be critical to improvements in personalized therapeutics and precision medicine to delay, prevent or treat the disease.

1The Jackson Laboratory, Bar Harbor, Maine, 04609 USA 2Neuroscience Institute, University of Tennessee Health Science Center, Memphis, Tennessee 38163 USA

ABSTRACT. Evolutionarily ancient neuromodulatory systems play an important role in mood and behavior. Variation in these systems is thought to contribute to inter- and intra-species behavioral diversity and differences in susceptibility to mental illness in humans. In order to elucidate the contribution of genetic variation in neuromodulatory genes to behavioral diversity, I have focused on two candidate genes: the vasopressin V1a receptor, which plays a major role in social behavior, and the serotonin 1a receptor, which modulates anxiety and stress-related behaviors. Variation in repetitive elements in the promoter of the V1a receptor gene have been associated with both individual and species level differences in receptor expression and social behavior in voles. I demonstrated that these variants directly contribute to differences in gene expression and behavior by creating transgenic mice carrying different versions of this repetitive element. The highly mutable nature of repetitive DNA elements may thus represent an evolutionary mechanism for generating sociobehavioral diversity. Within the serotonin 1a receptor system, a single nucleotide polymorphism (SNP; rs6295) in the gene promoter has been linked to differences both in depression risk and anti-depressant responsiveness in humans. Using a combination of epidemiological and post-mortem approaches in humans, I found that rs6295 has region-specific and developmental impacts on gene expression and is associated with increased risk for psychiatric hospitalization. I then created multiple humanized lines to model rs6295, which demonstrated the importance of epistatic interactions and genomic location in SNP penetrance and highlighted the challenges associated with modeling non-coding human genetic variation in mice.

Zoe R. Donaldson Department of Molecular, Cellular, and Developmental Biology and Department of Psychology & Neuroscience, University of Colorado Boulder, Boulder, Colorado, USA

Current Funding Support: Whitehall Foundation, Dana Foundation, NSF IOS-1827790, NIH DP2OD026143, R00 MH102352

ABSTRACT. Stressful events in early life might lead to stress resilience or vulnerability, depending on an adjustable stress-response set-point, which can be altered during postnatal sensory development and involves epigenetic regulation of corticotropin-releasing hormone (CRH). During the critical developmental period (CDP) of thermal-control establishment in 3-day-old chicks, heat stress was found to affect both body temperature and expression of CRH in the hypothalamic paraventricular nucleus (PVN). Both increased during heat challenge in chicks that were trained to be vulnerable to heat, whereas they decreased in chicks that were trained to be resilient. Accordingly, DNA CpG methylation (5mC) and hydroxymethylation (5hmC) at the CRH intron, which we found to serve as a repressor element, displayed low 5mc% alongside high 5hmc% in resilient chicks, and high 5mc% with low 5hmc% in vulnerable ones. RE1-silencing transcription factor (REST), which has a binding site on this intron, bound abundantly during acute heat stress and was nearly absent during moderate stress, restricting repression by the repressor element, and thus activating CRH gene transcription. Furthermore, REST assembled into a protein complex with TET3, which bound directly to the CRH gene. Finally, the adjacent histone recruited the histone acetylation enzyme GCN5 to this complex, which increased H3K27 acetylation during harsh, but not moderate heat conditioning. We conclude that an epigenetic mechanism involving both post-translational histone modification and DNA methylation in a regulatory segment of CRH is involved in determining a resilient or vulnerable response to stress later in life.

N Meiri 1, T Cramer 1,2, T Rosenberg 1,2, T Kisliouk 1

1Institute of Animal Science, ARO, The Volcani Center, Bet Dagan, Israel, 2The Robert H. Smith Faculty of Agriculture, Food and Environment, the Hebrew University of Jerusalem, Rehovot, Israel, Funding Support: Israel Science Foundation grant no. 1646/15

ABSTRACT. We have previously shown that the mediodorsal thalamic nucleus (MD) is critically involved in modulation of fear memory. Now we have identified the neural circuits upstream and downstream of this MD function, and showed that this circuit underlies the psychotherapy for long lasting attenuation of fear memory. A psychotherapeutic regimen utilizing alternating bilateral sensory stimulation (ABS), also called eye movement desensitization and reprocessing (EMDR), has been used to treat posttraumatic stress disorders (PTSD). However, the neural basis underlying the long-lasting effect of this treatment, has not been identified. Here, we found a novel neuronal pathway mediating the persistent fear attenuation driven by the superior colliculus (SC) activity. We successfully induced a long-lasting fear reduction in fear-conditioned mice by pairing visual ABS with conditioned tone stimuli during fear extinction. Among the visual stimulation protocols tested, the ABS-pairing provided the strongest fear-reducing effect and yielded sustained increases in the activities of the SC and the MD. Optogenetic manipulations revealed that the SC-MD circuit was necessary and sufficient to prevent the return of fear. The ABS suppressed fear-encoding cells and stabilized inhibitory neurotransmission in the basolateral amygdala (BLA) through an MD-BLA feedforward inhibitory circuit. Taken together, these results revealed the SC-MD-BLA circuit underlying an effective strategy for sustainably attenuating traumatic memories in PTSD patients.

Hee-Sup Shin Center for Cognition and Sociality Institute for Basic Science

ABSTRACT. NETO2 is an auxiliary subunit for kainate receptors. We previously demonstrated that Neto2 knockout (KO) mice have increased fear expression and slower extinction in cued fear conditioning. Neto2 is widely expressed in the amygdala, medial prefrontal cortex, and ventral hippocampus, brain regions that form the central fear circuit. To find the cellular mechanisms associated with the fear phenotype, we measured the number of parvalbumin (PV)-expressing interneurons surrounded by perineuronal nets (PNNs), since their amount increases throughout development and they are required for fear memory consolidation. In amygdala the fraction of PV-PNN positive cells within the total PNN population was smaller (p=0.003) and PV staining intensity was lower (p=0.002) in Neto2 KO mice compared to WTs, suggesting an immature state of the Neto2-/- amygdala. In the basolateral amygdala, Neto2 KO mice had higher amplitude and frequency of action-potential independent glutamatergic events (mEPSCs) compared to WT mice, indicating stronger glutamatergic synapses, but there was no differences in spontaneous glutamatergic and GABAergic currents. We also observed a larger density of spines on thin dendrites of Neto2 KO compared to WT mice. After fear acquisition Neto2-/- mice had a higher number of c-Fos positive cells in the amygdala compared to Neto2+/+ mice. In conclusion, our results suggest that NETO2 is important for maturity and excitability of the amygdala, potentially influencing fear expression and extinction during cued fear conditioning in adult mice.

Marie Mennesson1, 2, Ester Orav1,3, Adrien Gigliotta1, 2, Natalia Kulesskaya1, Suvi Saarnio1, Anna Kirjavainen1, Sebnem Kesaf1, 3 , Frederike Winkel3, Maria Llach Pou3, Juzoh Umemori3, Vootele Voikar3, Victoria Risbrough4, Juha Partanen1, Eero Castrén3, Sari Lauri1,3, Iiris Hovatta1,2

1 Molecular and Integrative Biosciences Research Program, University of Helsinki, Finland ; 2 Department of Psychology and Logopedics, Medicum, University of Helsinki, Finland ; 3 Neuroscience Center, University of Helsinki, Finland ; 4 Department of Psychiatry, University of California, San Diego, USA

ABSTRACT. Autism spectrum disorder (ASD) is characterised by a triad of impairments, one of which is impaired social behaviour. Several different gene mutations are implicated in ASD however it is not clear how these result in behavioural impairment. C. elegans provides a tractable system to investigate the impact of genetic variants on cellular function and relate this to neural circuits that co-ordinate behaviour. We have shown that C. elegans adults elicit a social behaviour in response to progeny1. Using this paradigm, we can probe how genetic variants impact the function of neural circuits that underpin social behaviour. Neuroligin is a synaptic adhesion protein which aids synaptic function. Genetic variations in neuroligin have been shown to be highly penetrant in ASD. The C. elegans genome encodes a single neuroligin orthologue, nlg-1. The nlg-1(ok259) allele is a functional null and has been used in this study to investigate the role of neuroligin in co-ordinating progeny dependent social behaviour. We have identified that nlg-1(ok259) adult worms have an impaired social behaviour in response to progeny. To further our investigations, we have used CRISPR/Cas9 to edit the C. elegans genome to contain an arginine to cysteine amino acid substitution identified in individuals with ASD. In this way we hope to provide further insight into how genetic variations in neuroligin impact on the function of neuronal circuits to cause the behavioural impairments diagnosed in ASD.

Helena Rawsthorne, Umaymah El Ghiffari Barnett, Evie Goss-Sampson, Fernando Calahorro, James Dillon, Vincent O’Connor, Lindy Holden-Dye

1. Scott, E. et al. An oxytocin-dependent social interaction between larvae and adult C. elegans. Sci Rep 7, 10122 (2017). Biological Sciences, University of Southampton, SO17 1BJ. Funding support: The Gerald Kerkut Charitable Trust

ABSTRACT. Haploinsufficiency due to a hemideletion in the human chromosome 7q11.23 region is associated with the Williams-Beuren Syndrome (WBS), a developmental disorder characterized by stereotypically hypersocial personality and cardiovascular pathologies. Although the WBS leads to hemizygosity of just 28 protein coding genes, which specific gene(s) contributes to the dramatic social phenotype observed in affected individuals remains mostly unknown. Because majority of the protein-coding genes affected by the typical WBS deletion have orthologs in the fly genome, we developed a research program that aims to take advantage of the power of Drosophila in vivo genetics to decipher the molecular, cellular, and developmental processes that might be affected by WBS genes in the nervous system, and how they affect conserved neural substrates that drive animal sociality. By using a neuronal-specific RNAi-dependent gene knockdown screen of WBS-related genes in Drosophila, we demonstrate that reducing the dosage of at least one gene, eIF4H1, an ancillary modulatory subunit of the highly conserved, rate-limiting eIF4F eukaryotic translation initiation complex, leads to abnormal social interactions in Drosophila. Because recent studies have suggested that the translation initiation complex plays a role in neuronal and behavioral plasticity at the developmental and physiological timescales, including pathologies associated with autism and intellectual disabilities, these data suggest that gene dosage of the human eIF4H1 locus may be responsible, at least in part, to some of the observed characteristic social phenotypes expressed by WBS individuals.

Iris Chin1, Cassondra Vernier1, Yehuda Ben-Shahar1

1Department of Biology, Washington University in St. Louis, St. Louis, MO, USA. Funding Support: National Institute of Health (USA), NIEHS R01 ES02599; National Science Foundation (USA), IOS1707221, DBI1707221.

ABSTRACT. When an animal repeatedly encounters a signal coupled with either a punishment or a reward, it eventually learns to expect both to occur together in a process called associative learning. A central goal in neuroscience is to understand how neural circuits integrate conflicting (rewarding and aversive) experiences that need to be behaviourally resolved during learning.

To shed light into this process at the molecular and cellular level, we are dissecting a neural circuit for sexual conditioning in the C. elegans male.

Sexual conditioning is a form of male-specific associative learning by which a rewarding experience with mates overrides an aversive association with starvation, thus switching the males’ behaviour to a stimulus from repulsion to attraction (Sakai et al., 2013). Previously, our lab implicated the Mystery Cells of the male (MCMs) interneurons and the neuropeptide PDF-1 as regulators of the sexually conditioned switch (Sammut et al., 2015).

Here we show a dual role for the neuropeptide PDF-1 in the regulation of both aversive and appetitive learning in C. elegans. By using a Cre-Lox intersectional strategy we find that PDF acts in distinct subsets of neurons to promote reward and to promote aversion. Also the molecular mechanisms underlying aversion and reward seem to be distinct: whereas only PDF-1 is required to signal reward, both PDF-1 and PDF-2 act redundantly to promote aversion. A similar dual role in encoding value has been recently described for dopamine in both mice and flies, suggesting a conserved value-assignment logic in neural circuits across evolution.

Laura Molina-Garcia1, Susana Colinas-Fischer1, Sergio Benavides-Laconcha1, Lucy Lin1 & Arantza Barrios1

1Department of Cell and Developmental Biology. University College London. UK

ABSTRACT. Animals respond to their changing environment through decision-making: selecting one behavioral response from a set of alternatives expected to produce different outcomes. We have developed a simple decision-making paradigm in larval zebrafish using the evolutionarily conserved acoustic startle response. Larvae select between two distinct behaviors to respond to sudden acoustic stimuli: a Short-Latency C- bend (SLC) or a less vigorous Long-Latency C-bend (LLC), which differ in their kinematic, neuronal, and genetic requirements. This sensorimotor choice is dynamically modulated by stimulus quality and history, as well as by serotonergic and dopaminergic neuromodulatory systems, all hallmarks shared with more complex decision-making. Through a forward genetic screen we have identified the vertebrate-specific G-protein coupled extracellular calcium-sensing receptor (CaSR) as a key regulator of this sensorimotor decision-making. We show that acutely modulating CaSR activity bidirectionally tunes the decision-making bias of larvae, and acute Gαi/o and Gαq/11 signaling are critical for this bias. Our genetic screen also revealed that the AP2 Adaptor Protein Complex which regulates CaSR trafficking is also critical for appropriate decision-making bias. Finally, we have identified changes in the activity of key circuit components underlying these decision-making alterations through functional neural imaging of partially restrained and free-swimming larvae to elucidate how serotonergic signaling and CaSR function influence simple decision-making.

RA Jain1, MA Wolman2, KC Marsden3, C Szi1, GC Peet1, M Granato4

1Department of Biology, Haverford College, Haverford, PA, USA. 2Department of Integrative Biology, University of Madison, Wisconsin, Madison, WI, USA. 3Department of Biological Sciences, North Carolina State University, Raleigh, NC, USA. 4Department of Cell & Developmental Biology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA. Funding Support: NINDS F32

ABSTRACT. All animals must make fundamental decisions about which environmental stimuli warrant a response by setting thresholds for their behavior. For example, the acoustic startle response is a highly conserved and essential survival behavior that is triggered by intense sounds that are perceived as threatening. Proper regulation of this response requires establishing a threshold to respond appropriately to threats yet ignore innocuous sounds. The importance of maintaining an appropriate startle threshold is underscored by the fact that heightened startle sensitivity is observed in many cases of schizophrenia, anxiety, and autism. In a recent high-throughput, genome-wide screen using larval zebrafish, cytoplasmic Fragile X Mental Retardation Protein (FMRP)-interacting protein 2 (cyfip2) was identified as a key regulator of the acoustic startle threshold, with cyfip2 loss of function causing acoustic startle hypersensitivity. Here we will present new results revealing cellular and molecular mechanisms of cyfip2-dependent startle threshold regulation. Using pharmacological and targeted mutagenesis approaches, we show that cyfip2 controls the startle threshold through its actin-regulatory function. And with a simultaneous neural activity and behavior imaging technique, we show that cyfip2 acts to dampen the activity of a population of hindbrain excitatory interneurons, spiral fiber neurons, to maintain normal sensitivity. Finally, we will show validation of a second hypersensitive mutant as a mis-sense allele of the reelin receptor, vldlr. Together, this work has identified direct links between two key neurodevelopmental genes, their cellular and molecular substrates, and the control of a clinically important behavioral threshold.

All animals must make fundamental decisions about which environmental stimuli warrant a response by setting thresholds for their behavior. For example, the acoustic startle response is a highly conserved and essential survival behavior that is triggered by intense sounds that are perceived as threatening. Proper regulation of this response requires establishing a threshold to respond appropriately to threats yet ignore innocuous sounds. The importance of maintaining an appropriate startle threshold is underscored by the fact that heightened startle sensitivity is observed in many cases of schizophrenia, anxiety, and autism. In a recent high-throughput, genome-wide screen using larval zebrafish, cytoplasmic Fragile X Mental Retardation Protein (FMRP)-interacting protein 2 (cyfip2) was identified as a key regulator of the acoustic startle threshold, with cyfip2 loss of function causing acoustic startle hypersensitivity. Here we will present new results revealing cellular and molecular mechanisms of cyfip2-dependent startle threshold regulation. Using pharmacological and targeted mutagenesis approaches, we show that cyfip2 controls the startle threshold through its actin-regulatory function. And with a simultaneous neural activity and behavior imaging technique, we show that cyfip2 acts to dampen the activity of a population of hindbrain excitatory interneurons, spiral fiber neurons, to maintain normal sensitivity. Finally, we will show validation of a second hypersensitive mutant as a mis-sense allele of the reelin receptor, vldlr. Together, this work has identified direct links between two key neurodevelopmental genes, their cellular and molecular substrates, and the control of a clinically important behavioral threshold.

JC Deslauriers1,2 and KC Marsden1,2,3

1 Department of Biological Sciences, 2 Genetics Graduate Program, 3W.M. Keck Center for Behavioral Biology, North Carolina State University, Raleigh, North Carolina, USA