Max Planck Florida Corporation

THE DEVELOPMENT OF DIRECTION SELECTIVITY IN VISUAL CORTEX

NEURONAL INTRACELLULAR SIGNALING UNDERLYING SYNAPTIC, CIRCUIT AND BEHAVIORAL PLASTICITY

MECHANISMS OF RAS SIGNALING IN SINGLE SYNAPSES

OPTIMIZATION OF GENETICALLY ENCODED VOLTAGE AND NEUROTRANSMITTER INDICATORS FOR MULTIWAVELENGTH IN VIVO ANALYSIS OF BRAIN CIRCUITS - THE BRAIN IS REMARKABLY DYNAMIC, ADAPTIVE, AND FLEXIBLE IN RESPONSE TO ENVIRONMENTAL CHANGES. THESE CAPACITIES ARE ENABLED BY DIVERSE CELL TYPES WHICH COMMUNICATE WITH AN ARRAY OF CHEMICAL NEUROTRANSMITTERS (NTS) OR NEUROMODULATORS (NMS) AND RECEPTORS. NEUROCHEMICAL INPUTS HAVE A WIDE-RANGING AND DRAMATIC INFLUENCE ON NEURONAL ACTIVITY AND CIRCUIT DYNAMICS. TO UNDERSTAND THE LOGIC BY WHICH MULTIPLE CONVERGENT INPUTS SHAPE NEURONAL ACTIVITY, IT IS ESSENTIAL TO RECORD THE TIMING AND LOCATION OF NT AND NM RELEASE AND THE DYNAMIC CHANGES IN MEMBRANE VOLTAGE THAT RESULT. OUR TEAM HAS DEVELOPED GENETICALLY ENCODED INDICATORS, AS WELL AS HIGH-SPEED AND RESOLUTION MICROSCOPY, TO ALLOW SIMULTANEOUS OPTICAL MEASUREMENT OF VARIOUS NT/NM RELEASE AND DIFFUSION AND POST-SYNAPTIC ACTIVITY IN VIVO WITH CELL-TYPE AND CIRCUIT SPECIFICITY. BROAD APPLICATIONS OF THESE TECHNOLOGIES HAVE STARTED TO REVEAL HOW NEUROMODULATORS COLLECTIVELY MANIPULATE BRAIN-WIDE STATES. DESPITE THESE SUCCESSES, SIGNIFICANT HEADROOM EXISTS TO OPTIMIZE THESE INDICATORS TO ENABLE SENSITIVE IMAGING IN SMALL STRUCTURES, HIGHER THROUGHPUT, AND MEASUREMENTS IN SPARSELY-INNERVATED BRAIN AREAS. MOREOVER, EXISTING NT AND VOLTAGE INDICATORS ARE NEARLY ALL GREEN IN COLOR, AND OPTIMIZATION OF OTHER COLORS IS NEEDED TO ENABLE MULTIPLEXING, ALONG WITH HARDWARE TO PERFORM SUCH RECORDINGS AND ALGORITHMS TO PROCESS THEM. FINALLY, THESE NEW TOOLS MUST BE RIGOROUSLY AND SYSTEMATICALLY BENCHMARKED IN VIVO TO ALLOW THE LARGE COMMUNITY OF USERS TO BETTER DESIGN AND INTERPRET MEASUREMENTS IN BEHAVIORAL EXPERIMENTS. WITH AVAILABLE TECHNOLOGY, WE HAVE YET TO ADDRESS THE DIVERSITY OF CHEMICAL NEUROTRANSMISSION AT SCALES CRUCIAL TO UNDERSTANDING BRAIN CIRCUIT FUNCTION. THEREFORE THE OVERARCHING GOAL OF THIS UM1 PROPOSAL IS TO ESTABLISH A MULTIDISCIPLINARY, MULTI-INVESTIGATOR, AND MULTI-INSTITUTION PROGRAM FOCUSING ON DEVELOPING TOOLS FOR MEASURING MOLECULAR INPUTS TO NEURONS AND RESULTING ACTIVITY, INCLUDING: ENGINEERING OPTIMIZED AND MULTI-COLOR FP-BASED INDICATORS FOR NT/NM AND VOLTAGE (AIM 1); DETAILED CHARACTERIZATION AND BENCHMARKING OF INDICATORS IN VIVO (AIM 2); DISSEMINATING VETTED, BEST-OF-CLASS REAGENTS AND RELATED TESTING DATA (AIM 3). OUR EFFORT WILL PROVIDE THE FOUNDATION FOR UNRAVELING THE LOGIC OF INPUT-OUTPUT TRANSFORMATION IN DEFINED CELL TYPES IN VIVO, WHICH UNDERLIE INFORMATION PROCESSING, BRAIN STATES, CIRCUIT PLASTICITY, AND (ULTIMATELY) BEHAVIOR.

DECIPHERING BIOCHEMICAL NETWORKS IN SINGLE DENDRITIC SPINES

FUNCTIONAL ORGANIZATION OF VISUAL CORTEX

MULTIPLEX INTERROGATION OF NEUROMODULATORY SIGNALING IN BEHAVING ANIMALS WITH ENHANCED DEPTH AND RESOLUTION - PROJECT SUMMARY THE DYNAMIC ADAPTABILITY OF THE MAMMALIAN BRAIN TO ENVIRONMENTAL CHANGES IS REMARKABLE, AS IT IS THE COMPLEXITY OF THE NETWORKS OF NEURONS UNDERLYING THE OPERATIONS THAT ALLOW FOR SUCH ADAPTATIONS. ALTHOUGH WE HAVE SOME UNDERSTANDING OF THE ANATOMICAL AND FUNCTIONAL BASIS OF THIS, WE ARE STILL LACKING A DETAILED PICTURE OF HOW THE MODULATION OF NEURONAL ACTIVITY WORKS. WHAT IS THE TIMING AND LOCATIONS OF THESE NEUROMODULATOR RELEASE AND RELATIONSHIP WITH EXCITATORY/INHIBITORY CIRCUITS? HOW DOES THE NEUROMODULATORS CIRCUITRY ACCOMPLISH THE REGULATION OF FIRING AND SYNAPTIC PROPERTIES OF TARGETED NEURONS? FILLING THESE GAPS IN KNOWLEDGE WOULD ADVANCE OUR UNDERSTANDING OF ALL ASPECTS OF NEUROMODULATOR BIOLOGY AND ALLOW DISCOVERY OF NEW THERAPEUTIC STRATEGIES. TO HELP CLOSE THIS GAP, WE HAVE USED CREATIVE APPROACHES TO THE DEVELOPMENT OF GENETICALLY ENCODED TO DIRECTLY REPORT BEHAVIORALLY TRIGGERED AND MODULATED NEUROMODULATOR RELEASE INCLUDING SEROTONIN (5-HT), DOPAMINE (DA) AND NOREPINEPHRINE (NE). WE HAVE DISSEMINATED THESE INDICATORS TO THE NEUROSCIENCE COMMUNITY AND SPURRED MAJOR DISCOVERIES OF NOVEL MECHANISMS REGULATING NEUROMODULATOR RELEASE UNDERLYING MOTIVATION AND ADDICTION. BUILD ON THIS INITIAL SUCCESS, WE PROPOSE TO FURTHER EXPAND THE EFFECTIVENESS OF THIS TOOLBOX OF NM SENSORS TO ENABLE IMAGING SPARSE RELEASE AT DEPTH AND SUBCELLULAR RESOLUTION. OUR SPECIFIC GOALS ARE TO (1) IMPROVE THE SENSITIVITY OF OUR CURRENT SENSORS TO ENABLE ROBUST IMAGING OF SPARSE NEUROMODULATOR RELEASE, PUSH THEIR SPATIAL RESOLUTION TO THE SUBCELLULAR LEVEL AND INCREASE LINEARITY OF RESPONSE AT LOWER CONCENTRATIONS; (2) EXPAND THEIR SPECTRAL RANGE TO RED/FAR-RED TO ENHANCE IMAGING DEPTH, SNR AND IN VIVO MULTIPLEX MEASUREMENT AND MANIPULATION OF MULTIPLE CIRCUIT COMPONENTS USING TWO OR THREE DISTINCT COLORS, AND (3) CHARACTERIZE THE POSSIBLE INTERFERENCE OF CURRENT SENSORS WITH ENDOGENOUS SIGNALING AND SYSTEMATICALLY VALIDATE EMERGING SENSORS WITH A WIDE-RANGING MICROSCOPY APPROACHES IN VIVO. OUR STRATEGY RELIES ON A DYNAMIC COLLABORATION BETWEEN THE SENSOR DESIGN TEAM AND END USERS TO OBTAIN CONTINUOUS FEEDBACK TO IMPLEMENT EFFICIENT IMPROVEMENTS TO THE SENSORS. IT IS OUR GOAL TO RAPIDLY DISSEMINATE A WIDE RANGE OF WELL-CHARACTERIZED, HIGHLY SENSITIVE INDICATORS FOR THE NEUROSCIENCE COMMUNITY TO BE EMPLOYED TO STUDY BEHAVING MICE, FISH, FLIES AND WORMS, TO ENRICH OUR KNOWLEDGE ON THE FUNCTIONAL ROLES OF NEUROMODULATORS IN THE BRAIN CIRCUITRY.

A NOVEL APPROACH TO CRACK NEURONAL MECHANISMS THAT SHAPE COMPUTATIONS IN THE BRAIN - PROJECT SUMMARY LIVING IN THIS EVER-CHANGING ENVIRONMENT, WE CONTINUALLY ADAPT AND LEARN NEW BEHAVIORS. THE COMPUTATION MECHANISMS IN OUR BRAIN MUST BE HIGHLY PLASTIC TO SUPPORT SUCH FLEXIBILITY. PROBLEMS WITH THIS ADAPTIVE PROCESS, ON THE OTHER HAND, RESULT IN INFLEXIBLE AND MALADAPTIVE BEHAVIORS, THE MAIN SYMPTOMS OF ATTENTION-DEFICIT / HYPERACTIVITY DISORDER (ADHD), OBSESSIVE-COMPULSIVE DISORDER (OCD), AND OTHER BRAIN DISORDERS. THE GOAL OF THIS PROPOSAL IS TO ESTABLISH AN EXPERIMENTAL METHOD TO APPROACH WHAT NEURONAL SUBSTRATES AND MECHANISMS SUPPORT OUR FLEXIBLE BEHAVIOR. NEURONAL COMPUTATIONS ARE MEDIATED BY COORDINATED ACTIVITY PATTERNS ACROSS NEURONS, REFERRED TO AS NEURONAL DYNAMICS. WHEN WE LEARN/ADAPT BEHAVIOR, UNDERLYING NEURONAL DYNAMICS CHANGE. THIS RECONFIGURATION OF NEURONAL DYNAMICS IS CONSTRAINED BY SYNAPTIC INTERACTIONS AMONG NEURONS. THUS, CHANGES IN SYNAPTIC INTERACTIONS, OR SYNAPTIC PLASTICITY, LIKELY MEDIATE THE SHAPING OF NEURONAL DYNAMICS AND BEHAVIOR. THEREFORE, NEURONAL DYNAMICS AND SYNAPTIC PLASTICITY ARE TWO PILLARS OF BRAIN FUNCTIONS THAT COOPERATE TO FLEXIBLY ADAPT BEHAVIORS. YET, DYNAMICS AND PLASTICITY HAVE RARELY BEEN STUDIED TOGETHER DUE TO THE LACK OF APPROPRIATE BEHAVIORAL PARADIGMS AND EXPERIMENTAL METHODS TO EXAMINE THEM. TO BRIDGE THIS GAP, I HAVE ESTABLISHED A NOVEL BEHAVIORAL PARADIGM ALONG WITH A PROPOSAL FOR A MOLECULAR SCREENING METHOD TO IDENTIFY THE BRAIN AREAS WHERE SYNAPTIC PLASTICITY IS RESPONSIBLE FOR ADAPTING ACTIONS. ELECTROPHYSIOLOGICAL RECORDINGS AT SUCH BRAIN AREAS COMBINED WITH MANIPULATION OF PLASTICITY WILL ALLOW US TO CRACK A CAUSAL RELATIONSHIP BETWEEN PLASTICITY AND NEURONAL DYNAMICS: WE WILL IDENTIFY WHAT KINDS OF CHANGES IN NEURONAL DYNAMICS ARE INDUCED BY SYNAPTIC PLASTICITY AND HOW THOSE CHANGES RESULT IN IMPROVED BEHAVIOR. BY COMBINING MOLECULAR, SYSTEMS, AND THEORETICAL NEUROSCIENCE METHODS, OUR EXPERIMENTAL APPROACH WILL LINK PLASTICITY, DYNAMICS, AND BEHAVIOR TO EXPLAIN THE ALGORITHMIC BASIS OF FLEXIBLE COMPUTATIONS IN THE BRAIN. IDENTIFYING NEURAL SUBSTRATES CONTROLLING FLEXIBLE BEHAVIORS PROVIDES A FOUNDATION FOR EXAMINING HOW DYSFUNCTIONS OF SUCH SUBSTRATES RESULT IN MALADAPTIVE BEHAVIORS OBSERVED IN VARIOUS BRAIN DISORDERS. OUR NOVEL APPROACH TO COMBINE ELECTROPHYSIOLOGY WITH MANIPULATIONS OF PLASTICITY HAS THE POTENTIAL TO BECOME A NEW STANDARD IN NEUROSCIENCE; AND, LINKING NEURONAL DYNAMICS AND PLASTICITY MAY INSPIRE NOVEL METHODS IN MACHINE LEARNING AND ARTIFICIAL INTELLIGENCE. THUS, OUR FINDINGS AND UNCONVENTIONAL APPROACH WILL HAVE A BROAD IMPACT IN NEUROSCIENCE AND BEYOND.

GENERATION MECHANISMS OF MEMORY-RELATED INTERNAL SEQUENCES IN THE HOPPOCAMPAL CA1 REGION - PROJECT SUMMARY/ABSTRACT EPISODIC MEMORY IS THE MEMORY THAT ALLOWS US TO MENTALLY RE-EXPERIENCE SPECIFIC EPISODES FROM OUR PERSONAL PAST. DURING MEMORY ENCODING, THE CONTINUOUS STREAM OF EXPERIENCE IS SEGMENTED INTO INDIVIDUAL EPISODES, WHERE EACH EPISODE ENCODES A SEQUENCE OF EVENTS ORDERED IN TIME. YET, HOW NEURAL CIRCUITS PERFORM COMPUTATIONS TO SEGMENT EXPERIENCE AND ENCODE SEQUENTIALLY OCCURRING EVENTS REMAINS UNKNOWN. REVEALING THE CIRCUIT-LEVEL MECHANISMS BEHIND THESE COMPUTATIONS IS ESSENTIAL FOR UNDERSTANDING EPISODIC MEMORY IN BOTH HEALTH AND DISEASE. IN THE HIPPOCAMPUS, A BRAIN AREA ESSENTIAL FOR EPISODIC MEMORY, NEURONS ARE SEQUENTIALLY ACTIVATED AS AN ANIMAL TRAVELS THROUGH AN ENVIRONMENT. THE SEQUENTIAL FIRING OF THESE SO-CALLED PLACE CELLS REPEATS EACH TIME THE ANIMAL REVISITS THE SAME PATH, AS IF THE ANIMAL’S PREVIOUS EXPERIENCE OF TRAVERSING THE PATH IS RECOLLECTED. HOWEVER, RICH SENSORY CUES ARE PRESENT IN EVERY ENVIRONMENT, MAKING IT DIFFICULT TO ASSESS HOW MUCH OF THE SPIKING ACTIVITY IN THE PLACE CELL SEQUENCE IS INDEPENDENT OF DIRECT SENSORY INPUTS. REVERSIBLY TOGGLE SENSORY INPUTS ON AND OFF DURING LOCOMOTION HAS MADE IT POSSIBLE TO ISOLATE THE SEQUENTIAL ACTIVITY PRODUCED BY THE INTERNAL COMPUTATION (INTERNALLY GENERATED SEQUENCES (IGSS)) FROM THAT DRIVEN BY SENSORY INPUTS. THESE IGSS THAT OCCURRED DURING LOCOMOTION COINCIDE WITH THE PERFORMANCE OF MEMORY TASKS, SUGGESTING THAT THEY ARE MEMORY-RELATED SEQUENTIAL ACTIVITY PATTERNS. INTERESTINGLY, IGSS REOCCUR IN EACH TRIAL OF A MEMORY TASK AND SOMETIMES APPEAR FOLLOWING SPONTANEOUS LOCOMOTION ONSET, IMPLYING THAT HIPPOCAMPUS CAN IDENTIFY BEHAVIOR- LEVEL BOUNDARIES AND ENCODE SPECIFIC SEGMENTS OF EXPERIENCE. REVEALING THE NEURAL CIRCUITS THAT UNDERLIE THE EXPRESSION OF IGSS WITHIN A SEGMENT OF EXPERIENCE SUCH AS A SINGLE BEHAVIOR TRIAL WILL PROVIDE NEW INSIGHT INTO HOW CONTINUOUS EXPERIENCE IS SEGMENTED AND SELECTIVELY ENCODED. THE OBJECTIVE OF THIS STUDY IS TO ELUCIDATE THE CIRCUIT-LEVEL MECHANISMS THAT EVOKE IGSS, AND TEST THE HYPOTHESIS THAT DISTINCT TYPES OF INTERNEURONS IN HIPPOCAMPAL CA1 COORDINATELY MODULATE THE STATE OF THE PYRAMIDAL NEURON POPULATION THUS GATING IGS EXPRESSION. ACCOMPLISHED IN THREE AIMS, WE WILL EMPLOY A MULTIDISCIPLINARY APPROACH ENCOMPASSING THE USE OF IN VIVO FUNCTIONAL RECORDINGS, CELL-TYPE SPECIFIC CHEMOGENETIC AND OPTOGENETIC PERTURBATIONS, AND BEHAVIORAL ANALYSIS TO IDENTIFY THE BEHAVIORAL CONDITIONS REQUIRED FOR IGSS TO OCCUR, AND DETERMINE HOW TWO DISTINCT TYPES OF INTERNEURONS COORDINATE TO SIGNAL THE START OF INTEGRATION AND CONTROL THE WINDOW OF INTEGRATION, THUS GATING THE OCCURRENCE OF IGS. COMPLETION OF THESE AIMS WILL CONTRIBUTE TO NOVEL INSIGHTS INTO HOW NEURAL CIRCUITS OPERATE TO SEGMENT EXPERIENCE AND ENCODE EPISODIC MEMORY, AND WHAT CAN GO WRONG UNDER PATHOLOGICAL CONDITIONS SUCH AS DEMENTIA AND ALZHEIMER’S DISEASE WHERE IMPAIRED EPISODIC MEMORY PROFOUNDLY IMPACTS THE PATIENTS’ QUALITY OF LIFE.

LONG-TERM PLASTICITY EXPRESSED IN LAYER 2/3 CORTICAL MICROCIRCUITS

ACTION POTENTIAL SIGNALING IN AXONS OF CNS INTERNEURONS

IMAGING SIGNAL TRANSDUCTION IN SINGLE DENDRITIC SPINES

IDENTIFYING MITOCHONDRIAL MECHANISMS DRIVING LEARNING AND MEMORY - PROJECT SUMMARY THE OVERALL GOAL IS TO UNDERSTAND THE ENERGY SUPPLY MECHANISMS OF LEARNING AND MEMORY. THE HUMAN BRAIN IS A METABOLICALLY VULNERABLE ORGAN, WHERE EVEN AN ACUTE INTERRUPTION IN ENERGY SUPPLY LEADS TO IMMEDIATE COGNITIVE IMPAIRMENT. THIS ENERGY CONSUMPTION IS PRIMARILY AT NEURONAL SYNAPSES, WHICH REQUIRE ENERGY FOR DIVERSE PROCESSES SUCH AS MAINTAINING ION GRADIENTS, MAKING NEW PROTEINS, AND TRANSPORTING MOLECULES. BECAUSE MOST SYNAPSES ARE PLACED FAR FROM THEIR NEURONAL CELL BODY, MERE ATP DIFFUSION IS INSUFFICIENT TO COPE WITH THE IMMEDIATE (MINUTES) AND SUSTAINED (HOURS) ENERGY DEMANDS OF LOCAL BIOLOGICAL PROCESSES – A LOCAL ENERGY SOURCE IS NECESSARY. CONSISTENT WITH THIS NOTION, MY LAB RECENTLY SHOWED THAT MITOCHONDRIA ARE LOCALLY STABILIZED IN DENDRITES. LOCAL IMPAIRMENT OF STABLE MITOCHONDRIA AFFECTS THE ABILITY OF NEARBY SPINES TO UNDERGO SYNAPTIC PLASTICITY, THE CELLULAR BASIS OF LEARNING AND MEMORY (RANGARAJU ET AL., CELL 2019, BAPAT ET AL., BIORXIV 2023). THEREFORE, SPATIALLY STABLE MITOCHONDRIA ARE ESSENTIAL TO FULFILLING THE CONSTANT LOCAL ENERGY DEMANDS OF SYNAPTIC PLASTICITY FORMATION AND MAINTENANCE. IN LIGHT OF OUR RECENT UNPUBLISHED DATA, WE HYPOTHESIZE THAT MITOCHONDRIA SYNTHESIZE ATP ON-DEMAND DURING SYNAPTIC PLASTICITY, AND THE TEMPORAL AND SPATIAL COORDINATION OF MITOCHONDRIAL ENERGY PRODUCTION NEAR SYNAPSES DICTATES SYNAPTIC PLASTICITY IN TIME AND SPACE. SO FAR, THE KNOWN MECHANISMS OF MITOCHONDRIAL ENERGY PRODUCTION ARE PRIMARILY BASED ON INFORMATION AVERAGED ACROSS ALL SUBCELLULAR COMPARTMENTS, BUT HOW PLASTICITY STIMULI REGULATE SUBCELLULAR ENERGY SUPPLY NEAR SYNAPSES IS UNKNOWN. WE AT THE RANGARAJU LAB WILL DISCOVER NOVEL REGULATORS THAT DICTATE THE FLEXIBILITY OF LOCAL MITOCHONDRIAL ENERGY PRODUCTION IN TEMPORAL (MINUTES TO HOURS) AND SPATIAL (MS OF DENDRITE) SCALES RELEVANT FOR SYNAPTIC PLASTICITY FORMATION AND MAINTENANCE. TO TACKLE THIS CHALLENGE, WE COMBINE RECENT INNOVATIONS IN SUBCELLULAR PROTEOMICS AND CRISPR-BASED SCREENING IN PRIMARY NEURONAL CULTURES. IN ADDITION, WE HAVE DEVELOPED STATE-OF-THE-ART METHODS TO MEASURE ATP SYNTHESIS AND CALCIUM HANDLING IN INDIVIDUAL SPINES AND MITOCHONDRIA AT HIGH SPATIAL AND TEMPORAL RESOLUTION TO CHARACTERIZE SUBCELLULAR (DENDRITES, SPINES) REGULATION OF MITOCHONDRIAL ENERGY PRODUCTION AT DIFFERENT STAGES OF SYNAPTIC PLASTICITY. LASTLY, WE WILL CHARACTERIZE OUR NEWLY IDENTIFIED MECHANISMS IN VIVO IN BEHAVIORAL ASSAYS DURING VARIOUS FORMS OF LEARNING AND MEMORY (SPATIAL, MOTOR, SHORT- AND LONG-TERM). OVERALL, WE WILL SYSTEMATICALLY INVESTIGATE THE SYNAPTIC ENERGY LOGISTICS THAT ALLOW THE BRAIN TO PROCESS AND STORE INFORMATION. AS MITOCHONDRIAL DYSFUNCTION IS OFTEN LINKED TO MEMORY AND COGNITIVE IMPAIRMENT, FILLING THE KNOWLEDGE GAP BETWEEN MITOCHONDRIAL MECHANISMS AND COGNITIVE BEHAVIORS WILL PROVIDE NEW SOLUTIONS TO LEARNING AND MEMORY DISORDERS.

LARGE SCALE DEVELOPMENT OF SENSORS FOR IMAGING SMALL GTPASE SIGNALS IN SYNAPSES

IDENTIFYING NEURONS FOR INTEROCEPTION USING SIMULTANEOUS PROFILING OF ACTIVITY- AND PROJECTION- SPECIFIC POPULATIONS - PROJECT SUMMARY INTEROCEPTION, THE PROCESS BY WHICH THE BODY SENSES ITS OWN INTERNAL STATE, IS CRITICAL TO MAINTAINING HOMEOSTASIS THROUGH THE DETECTION OF PHYSIOLOGICAL CHANGES THAT ENABLE THE BODY TO ADJUST TO CHANGING DEMANDS. DYSFUNCTION IN INTEROCEPTION MAY LEAD TO ERRONEOUS PREDICTION ERRORS CONCERNING THESE BODILY NEEDS AND IS INCREASINGLY CONSIDERED TO UNDERLIE A NUMBER OF MALADAPTIVE BEHAVIORS AND PSYCHIATRIC DISORDERS, INCLUDING ADDICTION AND EATING DISORDERS. DESPITE THIS, LITTLE PROGRESS HAS BEEN MADE IN IDENTIFYING THE UNDERLYING NEURAL CIRCUIT MECHANISMS OF INTEROCEPTION BECAUSE NON-VERBAL SUBJECTS (E.G. ANIMAL MODELS) CANNOT SELF-REPORT INTERNAL STATES. HERE, WE PROPOSE A NOVEL CONCEPTUAL BEHAVIORAL FRAMEWORK FOR STUDYING INTEROCEPTION IN ANIMAL MODELS IN ORDER TO IDENTIFY NEURONAL ENSEMBLES THAT ENCODE INTEROCEPTION. MOREOVER, HUMAN IMAGING STUDIES HAVE INFORMED US THAT INTEROCEPTION RELIES CRITICALLY ON AN UNDERSTUDIED AREA OF THE BRAIN, THE INSULAR CORTEX, BUT THE FUNCTIONS AND CORRESPONDING PROJECTIONS FROM THE INSULAR CORTEX SUBREGIONS (ANTERIOR TO POSTERIOR) HAVE NOT BEEN WELL-STUDIED. METHODS THAT CAN SIMULTANEOUSLY DELIVER PRECISE INFORMATION CONCERNING BEHAVIOR AND PROJECTIONS IN A HIGH-THROUGHPUT WAY ARE THEREFORE REQUIRED. MOLECULAR PROFILING TECHNIQUES HAVE BEEN INCREASINGLY USEFUL FOR IDENTIFYING CELL TYPES THAT MIGHT SERVES AS THE LINK BETWEEN GENES TO CIRCUITS, BUT CURRENT TECHNIQUES HAVE LIMITATIONS, NAMELY THE MODALITY BY WHICH THE PROFILING OCCURS. WE THEREFORE ALSO PROPOSE A NEW TRANSCRIPTOMIC MOLECULAR PROFILING TECHNIQUE, CALLED SNAP-TRAP (SIMULTANEOUS NEURONAL ACTIVITY AND PROJECTION – TRANSLATING RIBOSOME AFFINITY PURIFICATION), THAT ENABLES COINCIDENT PROFILING OF BOTH ACTIVITY-DEPENDENT AND PROJECTION-SPECIFIC NEURONAL MARKERS. WE WILL VALIDATE THIS TECHNIQUE USING A WELL-DEFINED NEURAL CIRCUIT WITH KNOWN MOLECULAR MARKERS AND BEHAVIORAL CONSEQUENCES. WE WILL THEN APPLY THE METHODOLOGY TO THE INSULAR CORTEX AND ITS ROLE IN INTEROCEPTION. THIS TECHNIQUE WILL ALSO ENABLE US TO MAKE COMPARISONS OF NEXT-GENERATION RNA-SEQUENCING TO SINGLE- CELL RNA SEQUENCING FOR THE PURPOSE OF IDENTIFYING USEFUL MARKERS FOR BEHAVIORAL VALIDATION. LASTLY, WE WILL MAP OUR FINDINGS BACK ONTO TISSUE SECTIONS TO ACHIEVE SPATIAL TRANSCRIPTOMIC INFORMATION. THROUGH THESE EXPERIMENTS WE HOPE TO ACHIEVE A COMPREHENSIVE TRANSCRIPTOMIC MAP OF THE INSULAR CORTEX THAT CAN BE PRECISELY DELINEATED ACCORDING TO PARTICULAR BEHAVIORS AND PROJECTIONS, AND CAN BE USED AS A BASIS FOR UNDERSTANDING HOW DYSFUNCTION IN INTEROCEPTION LEADS TO MALADAPTIVE BEHAVIORS. THE SNAP- TRAP TECHNIQUE MAY THEN BE USED BY THE BROADER NEUROSCIENCE COMMUNITY IN OTHER BRAIN REGIONS AND BEHAVIORAL TASKS TO GAIN INSIGHTS INTO THE NEURAL UNDERPINNINGS OF COMPLEX BEHAVIORS AND THEIR ASSOCIATED PSYCHIATRIC DISORDERS.

OPTOGENETIC SIGNALING INHIBITORS FOR STUDYING BRAIN PLASTICITY

CRCNS: ROLE OF MACHRS ON CA 1 PYRAMIDAL NEURONS IN MEMORY FORMATION AND STABILITY - THE FORMATION AND RETENTION OF MEMORIES OF OUR DAILY EXPERIENCES DEPEND ON A BRAIN REGION CALLED THE HIPPOCAMPUS. AMONG THE EXTENSIVE NEUROMODULATORY INPUTS THE HIPPOCAMPUS RECEIVES, CHOLINERGIC INPUTS FROM THE BASAL FOREBRAIN ARE CRUCIAL FOR LEARNING AND MEMORY. THESE SAME INPUTS ELICIT REDUCED NEURONAL RESPONSE WITH AGING, AND DEGENERATE IN PATIENTS SUFFERING FROM ALZHEIMER'S DISEASE. DESPITE ITS CRITICAL ROLE IN MEMORY FORMATION AND STABILITY, HOW CHOLINERGIC MODULATION MEDIATES MEMORY FUNCTIONS THROUGH INDIVIDUAL CIRCUIT ELEMENTS IN THE HIPPOCAMPUS REMAINS LARGELY UNKNOWN. IN CA 1, THE MAJOR OUTPUT OF THE HIPPOCAMPUS, ACETYLCHOLINE RECEPTORS ARE EXPRESSED IN MULTIPLE CELL TYPES AND CELLULAR COMPARTMENTS. UNTIL NOW, IT HAS BEEN DIFFICULT TO DETERMINE THE CONTRIBUTION OF INDIVIDUAL ELEMENTS TO THE OVERALL NETWORK EFFECTS OF ACETYLCHOLINE. IN THIS PROJECT, WE WILL STUDY THE ROLE OF MUSCARINIC CHOLINERGIC RECEPTORS LOCATED ON THE PYRAMIDAL NEURONS OF THE CA1 REGION IN THE FORMATION AND LONG-TERM STABILITY OF INTERNALLY GENERATED SEQUENCES (IGS), THE SEQUENCES GENERATED DURING LOCOMOTION WHILE SENSORY CUES ARE HELD CONSTANT AND AS ANIMALS PERFORM MEMORY TASKS. WE WILL USE IGS AS A REPRESENTATIVE OF MEMORY-RELATED ACTIVITY PATTERNS TO REVEAL HOW CHOLINERGIC ACTIVITY MODULATES THE FORMATION OF AND THE LONG TIMESCALE DRIFT IN THE HIPPOCAMPAL CODE AND IN TURN REFINES THE BEHAVIOR BY ACTIVATING CELL-TYPE-SPECIFIC ACETYLCHOLINE RECEPTORS. OUR EXPERIMENTAL APPROACH IS TO MANIPULATE THE STRENGTH AND LOCUS OF CHOLINERGIC MODULATION IN CA1 WHILE IMAGING LARGE NUMBERS OF NEURONS IN AWAKE HEAD-FIXED MICE ENGAGED IN A HIPPOCAMPUS-DEPENDENT MEMORY TASK. SPECIFICALLY, WE WILL SELECTIVELY MODULATE THE CA1 PYRAMIDAL NEURONS WITH CELL-TYPE SPECIFIC NEUROPHARMACOLOGICAL TOOLS. INTEGRATING COMPUTATIONAL MODELING WITH FINDINGS FROM EXPERIMENTS, WE WILL ELUCIDATE POSSIBLE PLASTICITY AND NETWORK MECHANISMS RESPONSIBLE FOR THE OBSERVED NEURONAL DYNAMICS. BY COMBINING EXPERIMENTAL AND COMPUTATIONAL APPROACHES TO ELUCIDATE THE CHOLINERGIC CONTROL OF PLASTICITY OVER MEMORY FORMATION AND STABILITY ACROSS THE CELLULAR, CIRCUIT, AND BEHAVIORAL LEVELS, WE WILL CONTRIBUTE NOVEL INSIGHTS INTO THE EFFECTS OF A DISRUPTION IN CHOLINERGIC SIGNALING. OUR RESULTS MAY INDICATE WHICH PHYSIOLOGICAL PARAMETERS COULD BE ALTERED TO COMPENSATE FOR THE LOSS OF CHOLINERGIC SIGNALS, AND LEAD TO THE DEVELOPMENT OF NEW TREATMENT OPTIONS FOR MEMORY DISORDERS.

NEURAL CIRCUIT MECHANISMS CONTROLLING NON-HOMEOSTATIC FEEDING - PROJECT SUMMARY COMPULSIVE EATING IS A MAJOR CONTRIBUTOR TO THE OBESITY EPIDEMIC IN THE US, AS OVER 35% OF ADULTS ARE NOW CLASSIFIED AS OVERWEIGHT OR OBESE. BEHAVIORAL OUTCOMES SUCH AS COMPULSIVE EATING DERIVE FROM A COMPLEX INTERACTION OF GENETICS, INNATE BEHAVIORS AND LEARNING ABOUT PREVIOUS EXPERIENCES. CUE-FOOD ASSOCIATIONS (E.G. ADVERTISING, EATING IN FRONT OF THE TELEVISION, ETC.) THAT ARE FORMED DURING PERIODS OF HUNGER LEAD TO LONG-LASTING MEMORIES THAT CONTROL NON-HOMEOSTATIC OVERCONSUMPTION. HOWEVER, THE NEURAL CIRCUITRY, AND SPECIFICALLY THE MOLECULAR CELL TYPES, GOVERNING THIS BEHAVIOR ARE NOT WELL DEFINED. USING AN ORIGINAL PARADIGM THAT INDUCED OVERCONSUMPTION IN SATED MICE WITH CONTEXTUAL CUES, I HAVE ESTABLISHED A ROLE OF THE INSULAR CORTEX, AND SPECIFICALLY NOS1 NEURONS WITHIN THE INSULAR CORTEX, AS CRITICAL MEDIATORS OF LEARNED OVERCONSUMPTION. THESE NEURONS DO NOT PLAY A ROLE IN HOMEOSTATIC FEEDING ITSELF AND ARE THEREFORE HYPOTHESIZED TO PROVIDE TOP DOWN CONTROL OF HOMEOSTATIC FEEDING CIRCUITRY TO CONTROL FOOD INTAKE. MOREOVER, A PROJECTION FROM THE INSULAR CORTEX TO THE CENTRAL AMYGDALA IS NECESSARY TO GENERATE THIS OVERCONSUMPTION RESPONSE. UNDER THE PRIMARY MENTORSHIP OF DR. JEFFREY FRIEDMAN AT THE ROCKEFELLER UNIVERSITY AND THE CO-MENTORSHIP OF DR. DENISE CAI AT THE ICAHN SCHOOL OF MEDICINE AT MOUNT SINAI, I WILL CONTINUE TO BUILD ON MY BEHAVIORAL AND MOLECULAR NEUROSCIENCE EXPERTISE WHILE DEVELOPING MY TRAINING IN OPTOGENETICS AND IN VIVO CALCIUM IMAGING. IN THE MENTORED K-PHASE OF THIS GRANT, I WILL ANALYZE THE ROLE OF A MOLECULARLY DEFINED CORTICAL-AMYGDALAR CIRCUIT IN OVERCONSUMPTION USING OPTOGENETICS AND CALCIUM IMAGING TECHNIQUES. I WILL ALSO DETERMINE THE AMYGDALA TARGETS OF INSULAR CORTEX NOS1 NEURONS. IN THE INDEPENDENT PHASE (R00), I WILL UTILIZE RETROGRADE TRACING TECHNIQUES TO EXAMINE THE REGIONS AND MOLECULARLY PROFILE THE CELL TYPES THAT DIRECTLY PROJECT TO THE INSULAR CORTEX NEURONS THAT CONTROL OVERCONSUMPTION, AND TEST CAUSALLY HOW THEY ARE FUNCTIONALLY INVOLVED IN NON-HOMEOSTATIC FEEDING. TOGETHER, THESE DATA WILL ESTABLISH A CELL-TYPE SPECIFIC CIRCUIT THROUGH THE INSULAR CORTEX THAT CONTROLS OVERCONSUMPTION IN RESPONSE TO ENVIRONMENTAL STIMULI. THIS DATA WILL EXPAND THE KNOWLEDGE OF HIGHER-ORDER BRAIN REGIONS INVOLVED IN FEEDING BEHAVIOR AND MAY LEAD TO THE DEVELOPMENT OF NOVEL THERAPEUTIC AVENUES TO CONTROL OVEREATING. AT THE SAME TIME, THE RESEARCH AND TRAINING PLANS PROPOSED IN THIS APPLICATION WILL ENABLE ME TO DEVELOP MY TECHNICAL AND PROFESSIONAL SKILLS IN ORDER TO TRANSITION TO AN INDEPENDENT RESEARCH POSITION. WITH THE SUCCESSFUL COMPLETION OF THIS PROJECT, I WILL HAVE DEVELOPED A PLATFORM FOR A FULLY INDEPENDENT RESEARCH PROGRAM AIMED AT UNDERSTANDING HOW THE BRAIN COORDINATES THE INTERPLAY BETWEEN INNATE AND LEARNED BEHAVIORS THAT DRIVE MALADAPTIVE CHOICES.

CRCNS: US-GERMAN RES PROP: THE ROLE OF SPONTANEOUS ACTIVITY IN CORTICAL DEVELOPMENT

SENSORY-MOTOR TRANSFORMATIONS IN A NEURAL CIRCUIT FOR OBJECT-DIRECTED WALKING - WALKING TOWARDS A SALIENT OBJECT (PREY, MATE, ETC.) IS A BASIC AND CONSERVED BEHAVIORAL MOTIF SHARED ACROSS MOST TERRESTRIAL ANIMALS, INCLUDING HUMANS. MOBILITY DISORDERS OFTEN IMPACT THIS VITAL FUNCTION OF GOAL-DIRECTED WALKING. DESPITE VARIED EVOLUTIONARY HISTORIES, BOTH VERTEBRATES AND INVERTEBRATES HAVE CONVERGED ON SIMILAR LEG- KINEMATICS STRATEGIES TO DRIVE CHANGES IN WALKING SPEED AND DIRECTION. THEREFORE, A MECHANISTIC UNDERSTANDING OF GOAL-DIRECTED WALKING, IN ANY SPECIES, IS CRITICAL AND WILL HAVE BROAD IMPLICATIONS. CERTAIN DESCENDING OUTPUT PATHWAYS OF THE BRAIN THAT PROJECT TO THE SPINAL-CORD (VERTEBRATES) OR VENTRAL-NERVE- CORD (INVERTEBRATES), HAVE BEEN SHOWN TO CONTROL SPECIFIC ASPECTS OF LEG MOVEMENTS REQUIRED FOR DIRECTED WALKING. HOWEVER, HOW SENSORY INPUTS, LIKE THOSE REPRESENTING A POTENTIAL MATE, ENGAGE APPROPRIATE COMBINATIONS OF DESCENDING PATHWAYS TO MOVE THE ANIMAL AS INTENDED, REMAINS AN OPEN QUESTION. THIS GAP IS DUE TO TWO MAJOR CHALLENGES: 1) DEFINING A CLEARLY RESOLVED SENSORY-MOTOR NEURAL CIRCUIT UNDERLYING OBJECT-DIRECTED WALKING, AND 2) MEASURING AND PERTURBING COMBINATIONS OF DESCENDING PATHWAYS THAT GOVERN THE LEG MOVEMENTS REQUIRED FOR OBJECT-DIRECTED WALKING. WE PROPOSE TO OVERCOME THESE CHALLENGES BY USING THE WELL-ESTABLISHED DROSOPHILA MODEL SYSTEM. IN THE PROPOSED WORK, WE WILL EVALUATE HOW PHYSIOLOGY AND CONNECTIVITY WITHIN A DEFINED AND GENETICALLY ACCESSIBLE, MULTI-LAYERED NEURAL CIRCUIT (THE DNP09 INPUT-OUTPUT CIRCUIT) TRANSFORM OBJECT-TRACKING SENSORY INPUT INTO DIRECTED-WALKING OUTPUT. TO ENABLE THIS, WE DEVELOPED NEW EXPERIMENTAL AND MODELING APPROACHES, THAT PROVIDE HIGH-FIDELITY ACCESS TO THIS NEURAL CIRCUIT AT CELLULAR AND SYNAPTIC RESOLUTION. WE WILL FIRST USE WHOLE-CELL ELECTROPHYSIOLOGICAL RECORDINGS AND BIOPHYSICALLY DETAILED FULL MORPHOLOGY MODELS TO EXAMINE HOW SYNAPTIC LAYOUT OF SPECIFIC VISUAL PATHWAYS RECRUIT THE DNP09 NETWORK DURING OBJECT-DIRECTED TURNING EVENTS. WE WILL THEN USE NOVEL CALIBRATED STIMULATION TECHNIQUES AND CONNECTOME-CONSTRAINED NETWORK MODELS TO CHARACTERIZE HOW DNP09 RECRUITS A POPULATION OF INTERCONNECTED DESCENDING NEURONS THAT ARE POISED TO CONTROL DIRECTED WALKING. THROUGH A COMBINATION OF MODELING AND EXPERIMENTS LEVERAGING TWO-PHOTON HOLOGRAPHY AND HIGH-RESOLUTION KINEMATICS ANALYSIS, WE WILL THEN EXTRACT HOW DESCENDING NEURON POPULATION ACTIVITY STATES ENCODE DIRECTED WALKING MANEUVERS. THE PROPOSED EFFORTS WILL DETERMINE HOW SENSORY-EVOKED NATURALISTIC ACTIVITY PROPAGATES ACROSS A NETWORK OF INTERCONNECTED NEURONS TO DRIVE THE DISTRIBUTED CONTROL OF MOTOR OUTPUTS REQUIRED FOR GENERATING OBJECT-DIRECTED WALKING. THE LONG-TERM OBJECTIVE OF THIS WORK IS TO PROVIDE CROSS-SPECIES TRANSFERABLE MODELS OF HOW COMBINATIONS OF BRAIN OUTPUT PATHWAYS ORCHESTRATE THE DOWNSTREAM MOTOR CIRCUITS FOR EXECUTING APPROPRIATE LOCOMOTOR OUTPUTS, A FUNDAMENTAL PROBLEM IN UNDERSTANDING HOW BRAINS CONTROL BEHAVIORS.

NEW MOLECULAR TOOLS TO CHARACTERIZE CORTICAL CIRCUIT FUNCTION IN NON-MURINE MAMMA

CIRCUIT DYNAMICS UNDERLYING PERCEPTUAL LEARNING IN THE FUNCTIONALLY ORGANIZED VISUAL CORTEX - PROJECT SUMMARY EXPERIENCE SHAPES CORTICAL SENSORY REPRESENTATIONS IN A REMARKABLE MANNER DURING DEVELOPMENT, BUT AFTER MATURATION CAPACITY FOR PLASTICITY BECOMES LIMITED. THE TIGHTLY REGULATED PLASTICITY OF THE MATURE CORTEX ENABLES LEARNING BUT IMPEDES THE BRAIN’S CAPACITY TO REGAIN APPROPRIATE FUNCTION AFTER INJURY, STROKE OR PROLONGED SENSORY LOSS. STUDYING MECHANISMS THAT UNDERLIE PERCEPTUAL LEARNING IN THE ADULT STAGE WILL ADVANCE OUR UNDERSTANDING OF PERCEPTION AND WILL PROVIDE THE FOUNDATION TO DEVELOP NOVEL APPROACHES THAT PROMOTE PLASTICITY IN THE ADULT BRAIN. RECENT STUDIES IN THE TREE SHREW (TUPAIA BELANGERI), A HIGHLY VISUAL MAMMAL THAT SHARES CORTICAL ORGANIZATION FEATURES WITH PRIMATES, SHOW THAT LEARNING A REWARD-BASED ORIENTATION DISCRIMINATION TASK LEADS TO LONG LASTING CHANGES IN EXCITATORY RESPONSES THAT INCREASE DISCRIMINABILITY BETWEEN TASK RELEVANT STIMULI IN THE MATURE PRIMARY VISUAL CORTEX (V1). HOWEVER, WE LACK A CLEAR UNDERSTANDING OF THE UNDERLYING CIRCUIT MECHANISMS THAT ARE RESPONSIBLE FOR THESE CHANGES. I WILL COMBINE MY PREVIOUS EXPERIENCE STUDYING MECHANISMS OF SYNAPTIC PLASTICITY WITH NEW TRAINING FOCUSED ON EXPANDING MY TECHNICAL EXPERTISE IN CUTTING EDGE OPTICAL APPROACHES TO UNCOVER THE MECHANISMS UNDERLYING PERCEPTUAL LEARNING IN THE TREE SHREW. PRELIMINARY DATA SUGGEST THAT A TRANSIENT AND FEATURE SPECIFIC DECREASE IN THE INHIBITORY NETWORK RESPONSE PRECEDES CHANGES IN THE EXCITATORY NEURONAL POPULATION ASSOCIATED WITH ENHANCED PERFORMANCE, SHOWING THAT THE LEARNING PROCESS IN TREE SHREW V1 LAYER 2/3 IS A PRECISE ONE WHERE CIRCUIT ELEMENTS ARE ENGAGED WITH BOTH FEATURE AND TEMPORAL SPECIFICITY. I WILL EMPLOY CHRONIC 2-PHOTON IMAGING IN COMBINATION WITH NOVEL GENETIC ENHANCERS AND PRECISE RNASCOPE TECHNOLOGY TO DETERMINE CHANGES IN THE RESPONSE PROPERTIES OF V1 INHIBITORY NEURAL SUBPOPULATIONS DURING PERCEPTUAL LEARNING (AIM 1). ADDITIONALLY, I WILL DEFINE CHANGES IN THE FUNCTIONAL SYNAPTIC ARCHITECTURE OF EXCITATORY NEURONS THAT UNDERGO LEARNING-RELATED CHANGES (AIM 2) BY APPLYING CALCIUM IMAGING OF DENDRITIC SPINES THROUGH THE LEARNING PROCESS. FINALLY, I WILL ESTABLISH THE SPATIOTEMPORAL RECRUITMENT OF ACETYLCHOLINE RELEASE DURING DISCRIMINATION LEARNING (AIM 3) BY TAKING ADVANTAGE OF A RECENTLY DEVELOPED CHOLINERGIC SENSOR THAT CAN BE IMAGED CHRONICALLY THROUGH LEARNING STAGES. THIS PROJECT CAPITALIZES ON THE FUNCTIONAL ORGANIZATION OF THE TREE SHREW V1 AREA AS A UNIQUE MODEL TO ADDRESS HOW PERCEPTUAL LEARNING IS IMPLEMENTED IN HIGHLY STRUCTURED CORTICAL NETWORKS AKIN TO THOSE FOUND IN THE PRIMATE CORTEX. THE STUDIES WILL TAKE PLACE IN A COLLABORATIVE ENVIRONMENT AT MAX PLANCK FLORIDA INSTITUTE FOR NEUROSCIENCE (MPFI) KNOWN FOR DEVELOPING INNOVATIVE APPROACHES TO ADDRESS FUNDAMENTAL QUESTIONS ABOUT NEURAL CIRCUITS AND HOSTING ONE OF THE FEW TREE SHREW COLONIES IN THE WORLD. COMPLETION OF THESE AIMS AND TRAINING PLAN WILL LEAD TO A COMPREHENSIVE FRAMEWORK DESCRIBING THE PROGRESSION OF LEARNING-RELATED PLASTICITY IN A FUNCTIONALLY STRUCTURED CORTEX UPON WHICH I WILL BUILD AN INDEPENDENT RESEARCH PROGRAM IN THE FUTURE.

EXPERIENCE-DRIVEN DEVELOPMENT OF RELIABLE STIMULUS REPRESENTATIONS IN DYNAMIC CORTICAL NETWORKS - PROJECT SUMMARY/ABSTRACT THE ONSET OF SENSORY EXPERIENCE TRANSFORMS IMMATURE CORTICAL NETWORKS INTO MATURE REPRESENTATIONS THAT SUPPORT RELIABLE DISCRIMINATION OF BEHAVIORALLY RELEVANT STIMULI. CORTICAL RESPONSES ENCODE STIMULI BY THE PROFILE OF ACTIVITY ACROSS A POPULATION OF NEURONS (POPULATION RESPONSE). TO PROVIDE STIMULUS INFORMATION, POPULATION RESPONSES MUST BE DIFFERENT ACROSS STIMULI AND ALSO RELIABLE ACROSS PRESENTATIONS OF THE SAME STIMULUS. NOVEL TECHNIQUES THAT MEASURE ACTIVITY CHRONICALLY ACROSS LARGE NEURONAL POPULATIONS WITH SINGLE-TRIAL RESOLUTION IN DEVELOPING ANIMALS WILL NOW HELP US DEFINE HOW RELIABLE POPULATION RESPONSES MATURE WITH EXPERIENCE. THIS QUESTION IS FUNDAMENTAL AS A RELIABLE TRANSMISSION OF INFORMATION IS CRITICAL FOR PERCEPTION AND COGNITION. THE CANDIDATE’S PREVIOUS WORK SHOWS THAT A DEVELOPMENTAL ALIGNMENT BETWEEN THE STRUCTURE OF FEEDFORWARD INPUTS AND RECURRENT CONNECTIVITY IN SUPERFICIAL LAYERS 2/3 OF THE FERRET PRIMARY VISUAL CORTEX (V1) CONTRIBUTES TO THE EMERGENCE OF A RELIABLE REPRESENTATION OF EDGE ORIENTATION FOLLOWING THE ONSET OF VISUAL EXPERIENCE. DURING THE K99 PERIOD, THE CANDIDATE WILL EXPAND ON THESE INITIAL FINDINGS ADDRESSING TWO KEY QUESTIONS. FIRST, THE CANDIDATE WILL USE NOVEL METHODS HE HAS DESIGNED FOR 3-DIMENSIONAL ELECTRODE ARRAY RECORDINGS IN DEVELOPING FERRETS TO RESOLVE THE SEQUENCE OF CHANGES IN RESPONSE PROPERTIES AND CONNECTIVITY ACROSS LAYERS 2/3 AND LAYER 4, THE MAIN SOURCE OF FEEDFORWARD INPUTS TO LAYERS 2/3, THAT RESULT IN FEEDFORWARD-RECURRENT ALIGNMENT AFTER EXPERIENCE. SECOND, THE CANDIDATE WILL USE CHRONIC TWO-PHOTON IMAGING TO RESOLVE IF THE MATURATION OF INHIBITORY RESPONSES IN LAYERS 2/3 CONTRIBUTES TO INCREASE POPULATION RESPONSE RELIABILITY IN THIS LAYER. TO ACHIEVE THESE GOALS, THE CANDIDATE WILL BE MENTORED BY DR. DAVID FITZPATRICK, A WORLD-RENOWNED AUTHORITY ON VISION DEVELOPMENT AND AN EXPERT IN IMAGING TECHNIQUES. THROUGH COLLABORATIONS WITH DR. TING AT THE ALLEN INSTITUTE AND DR. YASUDA AT THE MAX PLANCK FLORIDA INSTITUTE FOR NEUROSCIENCE (MPFI), THE CANDIDATE WILL DEVELOP NOVEL GENETIC CONSTRUCTS TO DISRUPT ACTIVITY- DEPENDENT PLASTICITY IN SPECIFIC CORTICAL LAYERS OR NEURONAL TYPES IN FERRET V1. AS AN INDEPENDENT INVESTIGATOR, THE CANDIDATE WILL USE THESE TOOLS TO INVESTIGATE HOW SENSORY EXPERIENCE REFINES CORTICAL CIRCUITS TO PRODUCE A MATURE REPRESENTATION AT THE NEURONAL POPULATION LEVEL. AS A FIRST STEP TOWARDS THIS NOVEL SCIENTIFIC DIRECTION, THE CANDIDATE WILL CONSULT WITH DR. INAGAKI AT MPFI TO RESOLVE WHETHER EXPERIENCE-DRIVEN SYNAPTIC PLASTICITY IN LAYER 4 IS NECESSARY FOR THE EMERGENCE OF RELIABLE POPULATION RESPONSES IN LAYERS 2/3. THIS METHODOLOGICAL APPROACH DIFFERENTIATES THE CANDIDATE’S RESEARCH FROM DR. FITZPATRICK’S, WHICH FOCUSES ON SINGLE-CELL SYNAPTIC ARCHITECTURE AND RESPONSE PROPERTIES. TO ACQUIRE THE PROFESSIONAL SKILLS ESSENTIAL FOR A SUCCESSFUL TRANSITION TO INDEPENDENCE, THE CANDIDATE WILL CONSULT WITH DR. NAMBOODIRI, WHO WILL GUIDE THE CANDIDATE’S PLAN FOR TRAINING IN PROFESSIONAL DEVELOPMENT, FOSTERING HIS SUCCESS AS A YOUNG INVESTIGATOR. THROUGHOUT THE PROJECT PERIOD, THE MENTOR, COLLABORATORS, AND CONSULTANTS WILL WORK TOGETHER AS AN ADVISORY COMMITTEE TO GUIDE THE CANDIDATE AS HE IMPROVES HIS RESEARCH, SECURES AN INDEPENDENT RESEARCH POSITION, AND ESTABLISHES A SUCCESSFUL LAB AT HIS NEW INSTITUTION.

INPUT-SPECIFIC IMAGING AND MANIPULATION OF SYNAPTIC PLASTICITY UNDERLYING SOCIAL MEMORY

PRINCIPLES OF PRESYNAPTIC NETWORKS FOR SINGLE LAYER 2/3 NEURONS IN FERRET VISUAL CORTEX

NEURONAL POPULATION CONTRIBUTIONS TO FINE FEATURE DISCRIMINATION LEARNING AND PERFORMANCE IN THE COLUMNAR ARCHITECTURE OF VISUAL CORTEX

LOCAL CONTROL OF THE ACTION POTENTIAL IN AXONS

THALAMOCORTICAL MECHANISMS IN PRIMARY VISUAL CORTEX

THE DEVELOPMENT OF FUNCTIONALLY COACTIVE MODULAR CORTICAL NETWORKS - PROJECT SUMMARY A KEY FEATURE OF DEVELOPING SENSORY CIRCUITS IS THE SPONTANEOUS CO-ACTIVATION OF NEURONS, WHICH ORGANIZES NETWORKS AND MAPS IN PREPARATION FOR FUTURE SENSORY EXPERIENCES. WHILE MUCH IS KNOWN ABOUT HOW SENSORY EXPERIENCES REFINE THESE EARLY NETWORKS, THERE IS A SIGNIFICANT GAP IN UNDERSTANDING THE EXPERIENCE- INDEPENDENT CELLULAR MECHANISMS THAT DRIVE THE INITIAL ORGANIZATION OF THESE FUNCTIONAL NETWORKS. THIS RESEARCH PROJECT ADDRESSES THE CRITICAL QUESTION OF HOW SENSORY REPRESENTATIONS OF THE EXTERNAL WORLD ARE FORMED DURING EARLY NEURAL DEVELOPMENT. THE MATURE VISUAL CORTEX IN PRIMATES, CARNIVORES, AND TREE SHREWS IS ORGANIZED INTO MODULES OF SIMILARLY RESPONDING NEURONS, PROVIDING A MODEL TO STUDY THE DEVELOPMENT OF FUNCTIONAL NETWORK ORGANIZATION. EVEN BEFORE EYE-OPENING, MODULAR NETWORKS ARE EVIDENT IN SPONTANEOUS ACTIVITY PATTERNS RESEMBLING FUTURE VISUALLY-EVOKED RESPONSES, THOUGH THE ORIGIN AND TIMING OF THESE PATTERNS ARE NOT WELL UNDERSTOOD. USING CHRONIC IMAGING STUDIES IN DEVELOPING TREE SHREWS, AN IMPORTANT MODEL THAT ALLOWS US TO PROBE THE CIRCUIT MECHANISMS RESPONSIBLE FOR INITIAL NETWORK ORGANIZATION, THIS STUDY AIMS TO INVESTIGATE THE PERIOD BEFORE SENSORY EXPERIENCE WHEN SPONTANEOUS ACTIVITY TRANSFORMS FROM UNSTRUCTURED PATTERNS INTO A HIGHLY ORGANIZED MODULAR ARRANGEMENT. THE PROJECT CONSISTS OF THREE AIMS: (1) DETERMINE HOW SPECIFIC SPATIOTEMPORAL PROPERTIES OF SPONTANEOUS ACTIVITY, SUCH AS CORTICAL WAVE DIRECTIONALITY AND FREQUENCY, INSTRUCT THE EMERGENCE AND ARRANGEMENT OF MODULAR NETWORK PATTERNS IN V1. (2) TEST WHETHER DECORRELATED ON AND OFF INPUTS FROM THE RETINA AND THALAMUS UNDERLIE THE FORMATION OF MODULAR NETWORKS AND AXIAL BIASES IN CORTICAL ACTIVITY, USING DEEP MULTIPHOTON IMAGING AND LAMINAR RECORDINGS TO EXAMINE FEEDFORWARD AND RECURRENT CIRCUIT CONTRIBUTIONS. (3) INVESTIGATE WHETHER EARLY ACTIVITY IN V1 INFLUENCES FUNCTIONAL CONNECTIVITY IN DOWNSTREAM CORTICAL AREAS SUCH AS V2, AND HOW THIS ACTIVITY-DEPENDENT COUPLING GUIDES TOPOGRAPHIC ORGANIZATION ACROSS CORTICAL REGIONS. UNDER THE PRIMARY MENTORSHIP OF DR. DAVID FITZPATRICK, A WORLD-RENOWNED AUTHORITY ON VISION DEVELOPMENT AND AN EXPERT IN IMAGING TECHNIQUES, AND A MENTORING TEAM WITH VARIOUS EXPERTISE SPECIFIC TO THE AIMS DEFINED ABOVE, THE CANDIDATE WILL BECOME PROFICIENT IN SEVERAL TECHNIQUES, INCLUDING ADVANCED IMAGING, DEVELOPMENTAL NEUROPHYSIOLOGY, AND COMPUTATIONAL NEUROSCIENCE. THROUGHOUT THE PROJECT PERIOD, THE MENTOR, COLLABORATORS, AND CONSULTANTS WILL WORK TOGETHER TO GUIDE RESEARCH PROGRESS AND ENSURE THE INVESTIGATOR’S SUCCESSFUL TRANSITION TO AN INDEPENDENT RESEARCH POSITION. DURING THE R00 PHASE AND BEYOND, STUDIES WILL EVOLVE TO EXAMINE HOW SPONTANEOUS ACTIVITY COORDINATES INTERAREAL CIRCUIT FORMATION, LAYING THE GROUNDWORK FOR UNDERSTANDING SYSTEMS-LEVEL INTEGRATION DURING SENSORY DEVELOPMENT AND IDENTIFYING MECHANISMS BY WHICH EARLY CORTICAL ACTIVITY SHAPES LARGE-SCALE NETWORK ARCHITECTURE IMPLICATED IN NEURODEVELOPMENTAL DISORDERS.

SPATIOTEMPORAL DYNAMICS OF ISOZYME-SPECIFIC PKC ACTIVITY DURING PLASTICITY

IN VIVO IMAGING OF LOCAL SYNAPTIC NEUROMODULATION BY DOPAMINE

TREE SHREW USERS MEETING - ABSTRACT FOR RESEARCH PURPOSES, THE TREE SHREW SHARES MANY ADVANTAGES WITH THE RODENT (SMALL BODY SIZE, SHORT REPRODUCTIVE CYCLE, LOW MAINTENANCE COST), BUT IS PHYLOGENETICALLY CLOSER TO PRIMATES, EXHIBITING A MORE DEVELOPED VISUAL SYSTEM AND HIGHER COGNITIVE CAPABILITIES. THERE ARE CURRENTLY SEVERAL ACTIVE TREE SHREW BREEDING COLONIES AND 20-30 VISUAL NEUROSCIENCE LABS IN THE U.S. USING TREE SHREWS AS THEIR MODEL ORGANISM, AND THERE IS RAPIDLY GROWING INTEREST FROM NEW USERS. FURTHERMORE, SINCE COMPLETION OF THE TREE SHREW GENOME IN 2013, SEVERAL GROUPS HAVE BEGUN EFFORTS TO PRODUCE GENETIC TOOLS FOR MEASUREMENT AND MANIPULATION OF NEURONS IN THE TREE SHREW. HERE WE PROPOSE THE FIRST TREE SHREW USERS MEETING TO BRING TOGETHER THE COMMUNITY OF ESTABLISHED AND NEW INVESTIGATORS WHO USE TREE SHREWS IN THEIR STUDIES OF NEUROSCIENCE, WITH A FOCUS ON VISUAL NEUROSCIENCE. WE BELIEVE SUCH A MEETING WILL IMPROVE TOOLS AND SKILLS TRANSFER BETWEEN GROUPS AND LEAD TO POTENTIAL COLLABORATIONS, ULTIMATELY LEADING TO NOVEL SCIENTIFIC DISCOVERIES. WE HAVE PLANNED THE MEETING WITH THE FOLLOWING SPECIFIC AIMS: AIM 1) TO PROVIDE A COLLABORATIVE ENVIRONMENT FOR COMMUNICATION AMONG ESTABLISHED AND NEW TREE SHREW RESEARCHERS, AIM 2) TO DISCUSS THE SUPPLY AND DEMAND FOR TREE SHREWS IN THE US, AND AIM 3) TO DISCUSS EXISTING AND FUTURE DEVELOPMENT OF GENETIC TOOLS IN THE TREE SHREW, INCLUDING ONGOING EFFORTS TOWARDS PRODUCING TRANSGENIC ANIMALS. THIS FIRST MEETING REPRESENTS AN ESSENTIAL STEPPING STONE IN ESTABLISHING A COLLABORATIVE SCIENTIFIC COMMUNITY CENTERED ON THIS SPECIES. A WELL-CONNECTED COMMUNITY WILL ALLOW FOR EFFICIENT INFORMATION EXCHANGE AROUND TOPICS INCLUDING SPECIES CHARACTERISTICS, BREEDING AND REARING, AND EXPERIMENTAL TOOLS AND TECHNIQUES. GIVEN THEIR SMALL SIZE AND HIGH COGNITIVE ABILITY, AND AVAILABILITY OF GENETIC TOOLS, WE BELIEVE THE TREE SHREW ANIMAL MODEL WILL CONTINUE TO PLAY AN IMPORTANT, EXPANDING ROLE IN ADDRESSING NEUROSCIENTIFIC QUESTIONS THAT ARE CURRENTLY INTRACTABLE IN FLIES, RODENTS, AND PRIMATES. PARTICULAR TO VISION SCIENCES, THE TREE SHREW WILL SERVE A CRITICAL ROLE IN OUR UNDERSTANDING OF RETINAL DEVELOPMENT AND DISEASE LEADING TO THERAPEUTIC SOLUTIONS FOR MYOPIA AND GLAUCOMA IN ADDITION TO OTHER VISUAL DISORDERS.