Abstracts Day 2
Cracking neuronal circuits that drive survival behaviors using novel optical methods
Dr. Yeka Aponte (NIH/NIDA)
In my laboratory, we are studying the roles of genetically-identified hypothalamic neurons and their projections in driving the rewarding and addictive nature of food intake. Our ultimate goal is to understand how this behavior, which is essential for survival, is disrupted in eating disorders. obesity is a global epidemic and a major cause of death. Evidence for the addictive properties of food has been growing progressively throughout the last decade. Beginning with early lesion and electrical stimulation studies, the hypothalamus has long been considered essential in regulating feeding. Furthermore, it has been hypothesized that the hypothalamus may regulate food reward through its connections to brain regions associated with reward and goal-directed behaviors, such as the nucleus accumbens (NAc) and the ventral tegmental area (VTA). However, in these experiments, it is not clear which cell types and relevant projections are important for regulating feeding behaviors. Moreover, methods to measure the activity of specific cell types to provide quantitative relationships between neuronal activity and behavior did not exist until recent years. To address these questions, we are manipulating and measuring the activity of genetically-defined neuron types in awake, behaving mice using a combination of optogenetics, chemogenetics, electrophysiology, two-photon fluorescence endomicroscopy, and behavioral assays.
Cellular localization of three inflammatory proteins (COX-1, -2, and TSPO) in drug resistant epilepsy
Ms. Lora Deuitch Weidner, KI-NIH Student (Neuro/NIMH)
Cyclooxygenases (COX-1 and COX-2) and translocator protein (TSPO) are markers of inflammation. In animal models of neuroinflammation, these three proteins have been reported in different cell types, however an investigation of their cellular distribution in drug-resistant epilepsy (DRE) has not been performed. Therefore, we determined the cellular distribution of COX-1, COX-2, and TSPO in the brains of patients with DRE. Understanding which cells express COX-1, COX-2, and TSPO will help to elucidate their function.
We obtained tissue samples from 33 patients with epilepsy. Using multi-labeling immunofluorescence and in-situ techniques, we measured COX-1, COX-2, and TSPO expression within neurons, microglia, and astrocytes.
Immunofluorecent labeling showed COX-1 is expressed in microglia, while COX-2 is expressed in both microglia and neurons. TSPO is expressed in microglia, neurons, and astrocytes. In-situ labeling showed for all three proteins a higher expression in microglia than in astrocytes.
We found in surgical brain tissue samples from people with DRE that COX-1 is mainly expressed in microglia, COX-2 is expressed in both microglia and neurons, and TSPO is expressed in microglia, astrocytes, and neurons. Understanding the cellular distribution of these three inflammatory proteins will help researchers understand the function of these proteins during inflammation.
From SingIe synapses to clinical studies. Therapeutic developments from optogenetics
Dr. Antonello Bonci (NIH/NIDA)
The mesolimbic and mesocortical systems play a central role in a wide variety of physiological behaviors essential for survival. Motivation, learning and reward, all depend on a well balanced activity in these systems. On the other hand, many neurological and psychiatric conditions such as substance use disorders, schizophrenia, OCD, stem when pathologies within these systems occur.
The main goal of my talk will be to give a broad overview of the lines of research that are being pursued in my Laboratory at the moment. First, I will discuss the role of long-term plasticity at excitatory synapses in the limbic system in modulating the development and expression of reward, aversion, and cocaine-dependent behaviors. Second, I will discuss our recent findings on midbrain non-neuronal populations such as microglia and astrocytes.
Finally, I will discuss the promising results from our optogenetic-based clinical studies using repetitive Transcranial Magnetic Stimulation (rTMS), which appears to be a very promising therapy against cocaine use disorders. My hope is that this brief presentation will pave the way for building scientific collaborations with Scientists working at Karolinska.
Savants, non-savants and the formation of lasting memories
Dr. Lars Olson (KI/Neuro)
It has been said that unless we understand the mindboggling abilities of prodigious savants, we do not understand the mechanisms leading to the formation of lasting memories in the rest of us. What we seem to know is that structural synaptic plasticity is needed to consolidate memories and to recover from CNS injury, and that pathological plasticity underlies conditions such as addiction and PTSD. The yin and yang of plasticity are the nerve growth stimulating systems, epitomized by BDNF, and the nerve growth inhibiting systems, particularly Nogo-type signaling, involving some 20 known ligands, receptors, co-receptors and modulators. We found that Nogo receptor 1 (NgR1) mRNA is always down-regulated by increased neural activity, suggesting a mechanism to temporarily increase plasticity as needed to consolidate new memories. Indeed, NgR1 is also down-regulated in rodent ECT models, and transgenic mice that cannot down-regulate NgR1 remember for a day but not a month, unless the NgR1 transgene is turned off during the first week after a memory forming event. In contrast, mice lacking NgR1 maintains childhood-like plasticity into adulthood. Recently, we showed that NgR1 overexpression reduces the density of dendritic spines and dendrite complexity, and also alters the response to cocaine. NgR1 serves as a negative regulator of structural synaptic plasticity and dendritic complexity in a brain region-specific manner.
Touching cognition: a doctoral journey through somatosensory system in mouse models of disease
Mr. Konrad Juczewski, KI-NIH Student (Neuro/NIAAA)
Together with other senses, thoughts and experience, touch shapes our cognition. Disturbances to the development of the somatosensory system have serious consequences for social behavior and may lead to neurodevelopmental disorders. In our study, we used three mouse models of disease: DISC1-cc transgenic mouse (DISC1 is a molecule implicated in psychiatric disorders); Fmr1 KO and BC1 KO mice (molecules crucial in fragile X syndrome (FXS)). In DISC1-cc mice we activated truncated protein DISC1-cc for a controlled period of time during critical developmental period. We found that this transient disruption of DISC1 signaling produced neurons that lack plasticity in adulthood that may be associated with cognitive deficits and the delayed onset of psychiatric symptoms in late adolescence. In FXS-related projects, we focused on analyzing somatosensory processing defects that lead to hypersensitivity to touch in FXS patients. We showed neuronal mechanisms that appear to underlie an altered behavior in these mouse models. In all projects, using the whisker system as a model system we have obtained insight into potential disease mechanism causing human brain disorders. Extending our study to other brain areas and sensory modalities with specific focus on plasticity of cortico-striatal projections and their role in sensory integration will be a great beginning of the future collaborations.
Circuits regulating motivated behaviors
Dr. Konstantinos Meletis (KI/Neuro)
Lateral habenula receives a number of different inputs from a number of brain regions, which most likely play important but also discrete roles in regulating specific aspects of motivated behavior. The molecular identity and functional specification of discrete inputs in regulating motivated behaviors remains to be determined. We have focused on defining the anatomical and molecular identity of neuronal population through monosynaptic rabies tracing and single neuron RNA sequencing, to generate a whole-brain map of neurons that regulate lateral habenula function. We have found molecularly distinct pallidal and hypothalamic neurons with projections to lateral habenula, allowing us to apply in vivo optogenetics and GCaMP6-based imaging of neural activity in order to define their role in avoidance behavior and during classical conditioning. In summary, we have been able to determine the function of discrete neuron types during behavior that through regulation of lateral habenula can regulate specific aspects of reward and punishment representation and learning.
Health disparities in pain: From pain experience to pain assessment
Mr. Troy Dildine, KI-NIH Student (CNS/NIMH)
Health Disparities (HDs) are negative health outcomes that affect disadvantaged populations. These negative health outcomes are present among many diseases and symptoms, including the number one reason individuals seek medical treatment, pain. HDs in pain include both 1) pain experience: increased pain and pain ratings in disadvantaged patients and 2) pain assessment: doctors under-treat and under-assess pain in disadvantaged patients. We present current literature on disparities in pain, compare the literature to our current experimental pain outcomes for race and sex, and hypothesize potential mechanisms to study to better understand these biased outcomes.
Assays To Lead The Way: Collaborative Discovery at the NCATS Chemical Genomics Center
High-throughput screening (HTS) has been widely implemented in drug discovery and has become one of the major sources of therapeutic small molecule leads. Success in screening has been driven by progress in automation technology and assay development, at biochemical, cellular and model organism-based levels. HTS also relies on collaboration between inter-disciplinary teams with expertise in fields including engineering, biology, informatics, and chemistry. The NCATS HTS facilities engage in collaborations with extramural partners from academia government and biotech/pharma. This seminar will describe the NCATS collaborative process and opportunities for CSHL scientists to work with NCATS, with an emphasis on oncology programs, and highlight research related to screening development and discovery at the NIH. It will describe the processes involved in biological target identification, assay development and HTS, and subsequent medicinal chemistry support towards development of chemical probes that arise from screening.
Exercise and BDNF reduce Aβ production by enhancing α-secretase processing of APP
Mr. Saket Milind Nigam, KI-NIH Student (Neuro/NIA)
Alzheimer’s disease (AD) is an age-related neurodegenerative disorder characterized by aggregation of toxic forms of amyloid β peptide (Aβ). Treatment strategies have largely been focused on inhibiting the enzymes (β- and γ-secretases) that liberate Aβ from the amyloid precursor protein (APP). While evidence suggests that individuals who exercise regularly are at reduced risk for AD and studies of animal models demonstrate that running can ameliorate brain Aβ pathology and associated cognitive deficits, the underlying mechanisms are unknown. However, considerable evidence suggests that brain-derived neurotrophic factor (BDNF) mediates beneficial effects of exercise on neuroplasticity and cellular stress resistance. Here we describe a mechanism by which BDNF affects APP processing. Using a transgenic mouse model of Alzheimer’s disease and cultured human neural cells, we demonstrate that exercise and BDNF reduces toxic Aβ peptides through a mechanism involving enhanced α-secretase processing of APP. This anti-amyloidogenic APP processing involves subcellular redistribution of α-secretase and an increase in intracellular neuroprotective APP peptides capable of binding and inhibiting BACE1. Moreover, our results suggest that BDNF’s ability to promote neurite outgrowth is primarily exerted through pathways other than APP processing. Taken together, factors influencing BDNF may hold both therapeutic and prophylactic value in the battle against AD.
Identifying Medication Targets for Drug Addiction: Redirecting the Dopamine D3 Receptor Hypothesis
Dr. Amy Newman (NIH/NIDA)
The dopamine D3 receptor (D3R) is a target for the development of medications to treat substance use disorders. D3R-selective compounds with high affinity and varying efficacies have been discovered, providing critical research tools for cell-based studies that have been translated to in vivo models of drug abuse. D3R antagonists and partial agonists have shown especially promising results in rodent models of psychostimulant relapse-like behavior, however, to date, advancement to human studies has been limited. Using the high resolution D3R crystal structure in combination with small molecule SAR, VK4-116, was designed and synthesized. VK4-116 demonstrated high D3R binding affinity (Ki=6 nM) and ~1700-fold selectivity over D2 receptors. In rats trained to self-administer the prescription opiate oxycodone, under an FR1 schedule, VK4-116 attenuated self-administration, inhibited oxycodone seeking during extinction testing and blocked oxycodone-induced reinstatement to drug seeking. VK4-116 also significantly attenuated naloxone-precipitated conditioned place aversion in chronic oxycodone treated rats, but had no effect on oxycodone-induced analgesia. These data suggest that D3R antagonists may be suitable alternatives or adjunctive to opiate-based medications currently used clinically, in treating opiate addiction and that the highly D3R-selective VK4-116 is a new lead molecule for development.
Decoding Neural Control of Animal Behavior Using In Vivo Deep Brain Calcium Imaging
Dr. Da-Ting Lin (NIH/NIDA)
An influential striatal model postulates that neural activities in the striatal direct and indirect pathways promote and inhibit movement, respectively. Normal behavior requires coordinated activity in the direct pathway to facilitate intended locomotion and indirect pathway to inhibit unwanted locomotion. In this striatal model, neuronal population activity is assumed to encode locomotion relevant information. Here, we propose a novel encoding mechanism for the dorsal striatum. We identified spatially compact neural clusters in both the direct and indirect pathways. Detailed characterization revealed similar cluster organization between the direct and indirect pathways, and cluster activities from both pathways were correlated with mouse locomotion velocities. Using machine-learning algorithms, cluster activities could be used to decode locomotion relevant behavioral states and locomotion velocity. We propose that neural clusters in the dorsal striatum encode locomotion relevant information, and that coordinated activities of direct and indirect pathway neural clusters are required for normal striatal controlled behavior.
Evaluation of the Monoamine Stabilizer (-)-OSU6162 as a Potential Novel Treatment for Alcohol Use Disorders
Ms. Ida Fredriksson, KI-NIH Student (CNS/NIDA)
Alcohol use disorder (AUD) represent a major health problem worldwide. One of the main problems in the treatment of AUD is the high rate of relapse. Alcohol Cravings, in combination with decreased cognitive functions including impulse control, often lead to relapse. The dopamine system mediates the rewarding properties of alcohol but is also involved in impulsive behavior. The monoamine stabilizer OSU6162 (OSU) has the ability to stimulate, suppress, or show no effect on DA activity, depending upon the prevailing dopaminergic tone. We hypothesize that OSU might stabilize DA activity in both the acute and abstinence phase of alcohol and modulate the complex dopaminergic transmission regulating impulsive behavior. The aim of this study was to evaluate the potential of OSU as a novel treatment for AUD using several established animal models. The results showed that OSU attenuated voluntary alcohol consumption, operant alcohol self-administration, alcohol withdrawal symptoms, cue-induced reinstatement of alcohol seeking, and increased impulse control in alcohol drinking rats. This highlights OSU’s potential to prevent relapse triggered by alcohol craving, alcohol related cues and or an urge to relieve abstinence symptoms. In addition, OSU might normalize the complex dopaminergic transmission regulating impulsive behavior leading to an enhanced impulse control. This study indicates that OSU may serve as a novel treatment of AUD.
Synaptic computation of visual information in the retina
Dr. Jeffrey Diamonds (NIH/NINDS)
Our laboratory seeks to understand how the brain receives, computes, encodes and transmits information. More specifically, we’d like to learn which biophysical and morphological features equip synapses, neurons and networks to perform these tasks. The retina is a great model system for the study of neuronal information processing: We can deliver precisely defined physiological stimuli and record with high fidelity the output of the retina, as well as activity at various points within the network; in addition, retinal circuitry is particularly well understood, enabling us to interpret more directly the impact of synaptic and cellular mechanisms on circuit function; finally, new genetic tools permit us to identify specific neuronal subtypes, record their activity and manipulate their influence on the network. I will present recent experiments in the lab that exploit these advantages to examine how synapses and neurons within the retinal circuit perform specific visual computations.
Cortical representations of motor sequence features
Ms. Diana Müssgens (KI), KI-NIH Student (Neuro/NINDS)
Organizing movements into meaningful sequences is crucial for both everyday-life and expert motor performance. However, the mechanisms through which the brain represents sequential information remain poorly understood.
The aim of this study is to 1) Investigate how different features of motor sequences such as familiarity (trained/ novel) and similarity (similar/ different) are represented in cortical activity patterns and 2) Characterize how these representations change in relation to performance.
Healthy participants (n= 45) were divided into two training and one control group. The training groups explicitly practiced a set of three different key-press sequences for two days and were subsequently tested on both trained and novel sequences during fMRI scanning. The control group performed the same sequences but without prior training. Both the training and novel set of sequences were designed to contain two structurally similar and one different sequence. All sequences were eight elements long and were performed with the right hand in a serial response time like task.
We used multi-voxel pattern analysis to compare cortical activity patterns for all sequences with each other. We found 1) a clear distinction in the representation for trained and untrained sequences 2) greater discriminability for trained sequences 3) that behavioral features (performance speed) are more clearly reflected in neural representations than sequence structure.
Activity-dependent genetic feedback in brain circuits and disorders
Dr. Kuan Hong Wang (NIH/NIMH)
Mental functions involve coordinated activities among specific neuronal ensembles that are embedded in complex brain circuits. Aberrant ensemble dynamics is thought to underlie the pathophysiology of mental disorders. Our long-term goal is to understand how interactions between genes and experiences affect the emergence of neuronal ensembles in order to improve therapeutic strategies for neurodevelopmental psychiatric disorders. Our recent studies have identified a neural activity-regulated gene Arc as a cellular marker to highlight task-specific neuronal ensembles in the frontal cortex and a molecular probe to regulate neuronal firing, ensemble consolidation and cognitive function. Moreover, we have uncovered reciprocal interactions between frontal dopaminergic input and activity-dependent Arc expression during postnatal development, and established cell-targeted adolescent neuromodulation approaches for long-lasting modification of frontal circuit structure and function. We are interested in pursuing collaborations with KI researchers to further our understanding of the logic and mechanisms underlying the emergence and consolidation of neuronal ensembles during postnatal development and learning, determine how these processes are influenced by psychiatric risk factors, and develop neuromodulation strategies with spatiotemporal precision for restoration of normal mental functions.
Breaking the neural code with brain perturbations
Neurons in the ventral stream of visual processing respond selectively to images of complex objects (e.g. faces). The majority of evidence regarding the link between these neural responses and perception of complex objects remains correlational. It is not yet clear how neural spiking in the ventral stream is read out by the rest of the brain to constrain perception and behavior. In this talk I will bring evidence from electrophysiology, drug microinjections and optogenetics to investigate the causal role of ventral stream neural activity in visual perception. I will then move further and provide a theoretical framework on how can we bridge the causal gap between neural activity and perception by brain perturbations.