I'M ALLEN KRETZKI. WELCOME TO THE ROBERT WHITNEY NEWCOMB MEMORIAL LECTURE. THIS IS A LECTURE THAT WE DO EVERY YEAR, THANKS TO THE GENEROSITY OF NEWCOMB MEMORIAL FUND. IT WAS ESTABLISHED IN COLLABORATION WITH THE FOUNDATION FOR NIH TO DO TWO THINGS, FUND HIGH SCHOOL STUDENTS TO WORK AT THE NIH, SUSAN RAY HAS BEEN ORGANIZING THAT PROGRAM FOR A LONG TIME NOW, QUITE A NUMBER OF STUDENTS HAVE COME THROUGH THE PROGRAM. THEY ARE ALL LISTED IN THE BOOK. AND TO HAVE THE ANNUAL LECTURE, AND ALSO IN THE BOOK WE'LL SHOW THE LIST OF PREVIOUS NEWCOMB SPEAKERS. I THINK WE'VE DONE A GREAT JOB PICKING OUTSTANDING SPEAKERS AND WE WELCOME TODAY'S SPEAKER AS WELL, HERWIG BAIER, WHO WILL BE INTRODUCED IN A FEW SECONDS. THE EMPHASIS ON SUPPORTING HIGH SCHOOL STUDENTS IN THE LAB COMES FROM ROBERT NEWCOMB'S FIRST EXPERIENCE IN THE LAB, WHERE HE WORKED WITH CLAUDE CLAY HERE AT THE NIH. CLAUDE CLAY JUST RECENTLY DIED, ACTUALLY, THERE WAS A NICE SYMPOSIUM TO HONOR HER, A FABULOUS BIOCHEMIST AND SET ROBERT OFF TO AN EXCITING CAREER IN SCIENCE. HE GOT HIS DOCTORATE FIRST BACHELORS AT UNIVERSITY OF COLORADO, DOCTORATE AT UNIVERSITY OF HAWAII WHERE HE GOT INTERESTED IN NEUROPEPTIDES, POSTDOCTORAL AT STANFORD WITH ROBERT SHELLER, INTEREST IN NEUROPEPTIDES. DURING HIS CAREER HE ALSO DISCOVERED A NUMBER OF NEUROTOXINS, WHICH INFLUENCED ION CHANNEL FUNCTIONS, SOMETHING A NUMBER OF PEOPLE AT NINDS REMAIN EXTREMELY INTERESTED IN. HE WAS ALSO FUNDED BY THE NIH FOR QUITE A NUMBER OF YEARS, SO A LONG AND DEEP CONNECTION TO THE NIH. SO WE THANK THE NEWCOMB FAMILY FOR THIS TRUST AND WE WELCOME THEM. AGAIN, EVERY YEAR WE SEE THEM. IT'S FABULOUS. AND WE WELCOME YOU ALL TO THE LECTURE TODAY. I'LL TURN IT OVER TO DR. BURGESS TO INTRODUCE TODAY'S SPEAKER. >> IT IS MY VERY GREAT PLEASURE TO WELCOME DR. HERWIG BAIER AS TODAY'S SPEAKER. DR. BAIER IS MANAGING DIRECTOR OF MACK PLANCK INSTITUTE FOR NEUROBIOLOGY IN GERMANY AND WON MANY DISTINGUISHED AWARDS, OTTO HAHN MEDAL, SLOAN FELLOWSHIP CLINGENSTEIN. I MET HERWIG 12 YEARS AGO A GREEN POSTDOC, I WOULD GO EVERY YEAR TO THE BIG MEETING IN MADISON, WISCONSIN, AND SIT THROUGH DAYS AND DAYS OF PEOPLE TALKING ABOUT GASTRALTION AND GUT MORPHOAGAIN SIS UNTIL THE LAST SEMINAR, BEHAVIOR, ALWAYS A TREMENDOUS RELIEF WHEN SOMEONE FROM HERWIG'S LAB WOULD TALK ABOUT STRUCTURE AND FUNCTION OF THE NERVOUS SYSTEM. THIS WAS EXCITING BECAUSE ACTUALLY THE ZEBRAFISH WAS A ADOPTED AS A MODEL IN THE '60s BY GEORGE DRIESINGER TO UNDERSTAND THE FUNDAMENTAL DEVELOPMENT, BUT FOR MANY YEARS THE EMPHASIS WAS VERY MUCH ON THE DEVELOPMENT AND ONLY RECENTLY HAS BEEN A TRANSITION TO UNDERSTANDING FUNCTION AS WELL. THIS TRANSITION HAS BEEN LED PRIMARILY BY PEOPLE LIKE HERWIG. SO DR. BAIER RECEIVED HIS Ph.D. AT THE MAX PLANCK INSTITUTES, DID SOME BEAUTIFUL WORK WITH FRIEDRICHBONHOFER. IN 1997 JOINED THE BIG SCREEN, GENETIC MUTATION IN ZEBRAFISH AND DID EXTRAORDINARY WORK, COMPLEX I THINK, INJECTING MINUTE QUANTITIES OF DIFFERENT COLORED DYES INTO THE NASAL AND TEMPORAL RETINA TO SEE HOW PROJECTION WAS PERTURBED, SETTING THE STAGE FOR UNDERSTANDING NOT JUST DEVELOPMENT OF THE VISUAL SYSTEM BUT ALSO FUNCTION OF THE VISUAL SYSTEM AS WELL IN YEARS AFTER THAT. SO IN 1998 HE JOINED THE FACULTY AT UCSF WHERE HE ROSE TO THE RANK OF FULL PROFESSOR, THERE HE BRIDGED THIS GAP FROM DEVELOPMENT TO FUNCTION. SO INITIALLY HE WAS LOOKING AT THE EFFECTS OF MUTATIONS ON DEVELOPMENT, BUT THEN IN SOME REALLY IMPORTANT WORK STARTED DEVELOPING THE TOOLBOX OF ENABLE MODERN CIRCUIT NEUROSCIENCE TO BE CARRIED OUT IN ZEBRAFISH. IN 2007 PUBLISHED A SCREEN FOR CELLS IN THE BRAIN, THIS BROKE THE FIELD OPEN BECAUSE IT GAVE US GENETIC ACCESS TO DIFFERENT GROUPS OF NEURONS. THAT WORK HAS BEEN INCREDIBLY IMPORTANT AND I THINK THE REAGENTS FROM THAT PAPER ARE USED BY ALMOST EVERY ZEBRAFISH NEUROSCIENCE LAB AROUND THE WORLD TODAY. IN 2011 HE WAS RECRUITED AS THE DIRECTOR OF THE MAX PLANCK SOCIETY AND ESTABLISHED A LAB AND PUSHED THE TECHNICAL BOUNDARIES FURTHER, BRINGING TOGETHER TOGETHER BIOLOGIESISTS AND ENGINEERS, I HAD THE OPPORTUNITY TO TOUR HIS LAB LAST YEAR AND WAS LOOKING AT THIS EXTRAORDINARY MICROSCOPE. AS I WAS SORT OF UNDERSTANDING THE THINGS IT COULD DO, THE THIRD LAW ESPOUSED BY ARTHUR C. CLARK CAME TO MIND, THAT ANY SUFFICIENTLY ADVANCED TECHNOLOGY IS INDISTINGUISHABLE FROM MAGIC. THAT'S ALL I COULD REALLY THINK OF LOOKING AT THIS MICROSCOPE. LESS WELL KNOWN BUT PERTINENT SO I'LL LEAVING WITH THE SECOND KNOWN LAW, THE ONLY WAY TO DISCOVER LIMITS OF THE POSSIBLE IS TO VENTURE A LITTLE WAY PAST THEM INTO THE IMPOSSIBLE. WITH THAT I'D LIKE TO WELCOME DR. BAIER AND WE'RE ALL VERY MUCH LOOKING FORWARD TO HIS TALK. [APPLAUSE] >> WOW, THAT'S A VERY KIND INTRODUCTION. I'M VERY GRATEFUL FOR THE INVITATION. AND IT'S A GREAT HONOR TO BE -- TO GIVE THIS NEWCOMB MEMORIAL LECTURE, PARTICULARLY PLEASED DR. NEWCOMB AND HIS FAMILY ARE HERE ALSO, AND THE ENTOURAGE, SO WONDERFUL. THANK YOU VERY MUCH. SO YEAH, WE'VE BEEN INTERESTED IN BEHAVIOR AND NEURAL CIRCUITRY THAT UNDERLIES BEHAVIOR FOR A VERY LONG TIME. AS HARRY MENTIONED, SEVERAL REVOLUTIONS IN THE TECHNOLOGY FRONT NOW ENABLING US TO PEEK INTO THE BRAIN AND WATCH AN ANIMAL THINK, MAKE DECISIONS, WEIGH OPTIONS, AND THEN EXECUTE A BEHAVIORAL PROGRAM. SO TODAY I'M NOT GOING TO TALK ABOUT TECHNOLOGY VERY MUCH. IT WILL BE WOVEN IN HERE AND THERE AND THE EFFICIENT ARTIST WILL RECOGNIZE CERTAIN TECHNIQUES. BUT I'M NOT GOING TO EMPHASIZE THOSE ASPECTS. I REALLY WANT TO TALK ABOUT BIOLOGY AND WHAT WE'VE LEARNED ABOUT HOW THE VISUAL SYSTEM AND VISUAL MOTOR SYSTEM OF THE LARVAL ZEBRAFISH ARE PROCESSING INFORMATION AND CONVERTING INITIAL INTO DIRECTED BEHAVIOR. AND I HOPE I CAN CONVINCE YOU THAT NOW THE ZEBRAFISH IS BECOMING OR HAS BECOME A PREMIER MODEL SYSTEM TO INVESTIGATE THESE QUESTIONS. SO, THE BIG QUESTION THAT WE'RE ASKING IS THAT OF THE NEURAL BASIS OF INNATE BEHAVIOR. HOW IS SENSORY INPUT TRANSFORMED INTO MOTOR OUTPUT? AS I WILL SHOW YOU, BOTH VISUAL INPUTS OR SENSORY AND MOTOR OUTPUTS ARE ORCHESTRATED AND MOTIVATED, NOT SURPRISING OF COURSE, THAT TELLS US OUR OBSERVATIONS OF OUR OWN BEHAVIOR TELL US THIS MUST BE TRUE. BUT SO FAR IN THE AVAILABLE ANIMAL SYSTEMS, THIS COMPLEXITY HAS REALLY NOT BEEN TAKEN INTO ACCOUNT AND APPRECIATED FOR LACK OF TOOLS. SO I'LL SHOW YOU THIS BBC NATURE MOVIE OF TWO ANIMALS INTERACTING, HERE'S A DRAGON FLY THAT SITS ON A TWIG SEEING SOMETHING WE CAN'T SEE YET. THAT'S A PREDATOR. SO HE'S TAKING OFF, AND THE FROG IS DARTING AT IT TRYING TO CATCH IT. IN THIS CASE THE FROG LOST. THE DRAGON FLY GOT AWAY. BUT OF COURSE ANCESTORS WERE SUCCESSFUL CATCHING INSECTS INCLUDING DRAGON FLIES, THIS IS WHY HE'S AROUND. THE DRAGON FLY HAS BEEN SUCCESSFUL, MANY ANIMALS CAN ESCAPE FROM APPROACHING PREDATOR USING VISUAL INFORMATION, SEEING A LOOMING EXPANDING OBJECT IN THEIR PHOTORECEPTORS AND CONVERT INTO A COMMAND IN THIS CASE THAT MEANS GET AWAY AS QUICKLY AS POSSIBLE. SO HERE IS THE MOVIE AGAIN. SO THE FROG IS TRYING TO CATCH PREY, AND THE DRAGON FLY IS ESCAPING A PREDATOR. SO I WILL TALK ABOUT BOTH OF THESE TASKS IN MY TALK. MOSTLY FOCUSING ON PREY CAPTURE AND HUNTING BY LARVAL ZEBRAFISH. I HAVE FIVE CHAPTERS. WE'LL SEE HOW FAR I CAN GO THROUGH THEM. MANY DATA I WILL PRESENT TODAY ARE UNPUBLISHED, ALWAYS GREAT FUN TO ME SO BEAR WITH ME. I WILL POINT YOU TO THE LITERATURE AT THE BOTTOM OF THE SLIDE SHOULD SOME OF THIS BE PUBLISHED. SO I WILL TALK ABOUT THE BEHAVIOR THAT WE'RE INVESTIGATING, PREY CAPTURE, AND I WILL SHOW YOU HOW WE CAN ANALYZE THIS AND DISSECT IT INTO KINEMATIC PARAMETERS. THEN I WILL TELL YOU ABOUT THE SENSORY SURFACE, ABOUT THE RETINAL CELLS AND PRE-TECTAL AND TECTAL CELLS THAT RESPOND TO PREY, HOW THEY ARE ARRANGED IN ORGANIZATIONAL PRINCIPLES WE'VE DISCOVERED. THEN WE'LL TALK ABOUT THE MOTOR OUTPUT, SO STARTING WITH THE TECTUM, WHICH RECEIVES ALL THIS INFORMATION, WE'LL ASK HOW DOES THE TECTUM CONVERT THE SENSORY INFORMATION INTO A MOTOR COMMAND. THIS WILL BE THE SUBJECT HERE IN THIS FOURTH CHAPTER WHERE WE'LL LOOK IN GREATER DETAIL AT THE CELL TYPES OF THE TECTUM AND WHICH ONES ARE INVOLVED IN APPROACH AND ESCAPE COMMANDS. THEN FINALLY IF I FIND THE TIME, I WILL TELL YOU ABOUT A RECENT STUDY IN WHICH WE STUDIED NEURAL MODULATION OF THE APPROACH VERSUS ESCAPE DECISION, TO SHOW YOU THE SYSTEM IS NOT ENTIRELY HOT WIRED, ALTHOUGH HOT WIRING PLAYS AN IMPORTANT ROLE, CAN BE MODULATED INTO THE FLEXIBLE BY THE NEEDS OF THE ANIMAL. OKAY. THIS IS A MOVIE OF THE LARVAL ZEBRAFISH HERE. HERE IS ONE OF HIS FAVORITE PREY ITEMS, A PARAMECIUM, ACTUALLY THERE'S QUITE A FEW OF THEM. WE'RE FILMING THIS LARVAL ZEBRAFISH BOTH FROM THE TOP AND FROM THE SIDE. HERE IS THE UNWITTING VICTIM OF THIS FIERCE PREDATOR, THEY APPROACH AND SUCK IT INTO THEIR MOUTHS. THEY ARE INCREDIBLY EFFICIENT. THIS MOVIE IS SLOWED DOWN SUBSTANTIALLY. THEY CAN CLEAN OUT A PETRI DISH WITH 100 PARAMECIA IN HALF AN HOUR OR SO. THEY ARE VERY GOOD AT THIS. AND THIS BEHAVIOR IS ALREADY POSING -- LETTING US POSE COGNITIVE INTERESTING NEUROSCIENCE QUESTIONS. SO HOW COME THE FISH CAN FOCUS ON ONE PREY OBJECT WITH ALL OTHER PREY OBJECTS SWIMMING IN THE DISH? IN WORK I DON'T SHOW TODAY WE'RE INVESTIGATING THIS ISSUE OF BOTTOM-UP TARGET SELECTION. SO THIS IS THE FINAL FRAME OF THIS MOVIE, THE LAST MOMENT IN THE LIFE OF A PARAMECIUM, AND WE CAN SEE ALREADY THAT THE FISH IS DOING INTERESTING MOVEMENTS WITH HIS BODY, SO, AGAIN, THIS IS SEQUENCE HERE. HERE THE FISH CAUGHT A PARAMECIUM, HE'S GOING TO CATCH ANOTHER ONE. I BELIEVE THIS ONE HERE. WE CAN NOW IN THE LAB, THIS IS WORK DONE BY A VERY TALENTED GRADUATE STUDENT, DUNCAN MANZ, WE CAN USE MACHINE VISION TO UNDERSTAND IN DETAIL HOW THE BODY POSTURE, THE TAIL, THE EYES AND THE JAW ARE COORDINATED TO LET THIS LARVA ZEBRAFISH CATCH A PARAMECIUM. YOU SEE HERE THE TRACERS, WE'RE LOOKING AT JAW, TRAIL, SWIMMING MOVEMENTS AND THE EYES AND WE CAN NOW START TO PARSE THIS AND SEGMENT THIS SEQUENCE OF BEHAVIORS INTO MEANINGFUL CAPTURE STRIKES, WE CAN LET OUR COMPUTER DETECT THE DIFFERENT SWIM BOARDS AND THEN RELATE THESE MUSCLE GROUPS THAT DRIVE THESE DIFFERENT PARTS OF THE BODY, AND SEE HOW THEY ARE COORDINATED. OKAY. SO PRINCIPAL COMPONENT ANALYSIS, JUST LOOKING AT THE TAIL IN THIS CASE OF LOTS OF BOUTS IN 2D, LET US ISOLATE FIVE DIFFERENT MOTOR PRIMITIVES, WHICH WITH THE APPROACH SWIMS, SCOOT SWIMS LARGER AMPLITUDE, TURNS IN BOTH DIRECTIONS, LARGE TURNS, SMALL TURNS, ALSO A VERY SPECIALIZED KIND OF TURN CALLED A J TURN IN WHICH ONLY THE TIP OF THE TAIL IS BENDING, AND BECAUSE OF THE SHAPE OF THE FISH THESE KINDS OF TURNS HAVE BEEN CALLED J-TURNS. ALL OF THESE ARE STRUNG TOGETHER IN A SEQUENCE. WE CAN NOW SEQUENCE THE BEHAVIOR AND BASICALLY ISOLATE FIVE SYLLABLES IN THIS BEHAVIORAL LANGUAGE. HUNTING AND CATCHER STRIKES ARE CHARACTERIZED BY STEREOTYPED SCALE JAW AND EYE MOVEMENTS. WE CAN HAVE A COMPUTER MAKE DECISIONS ABOUT THEM, SO WE CAN SEQUENCE HOURS OF VIDEO. WE DON'T DO THIS, HAVE TO DO THIS BY HAND. WE FIND ONLY FIVE MOTOR PRIMITIVES, SO FIVE SYLLABLES. AND THESE MOTOR PRIMITIVES ARE FLEXIBLY STRUNG TOGETHER AND DUNCAN IS TRYING TO UNDERSTAND SYNTAX OF THIS LANGUAGE, ASKING WHICH MOTOR PRIMITIVE CAN FOLLOW ANOTHER MOTOR PRIMITIVE, WHAT IS THE SUPERSTRUCTURE OF THE SEQUENCES. SO NEXT TIME I CAN TELL YOU ABOUT THAT. SO NOW I'VE HOPEFULLY CONVINCED YOU THE BEHAVIOR IS COMPLEX. NOW, LET'S DO SOME PSYCHOPHYSICS AND ASK WHAT IS A PREY ITEM TO A FISH? WHAT CONSTITUTES A PREY ITEM? AND WHAT ARE THE NEURAL CORRELATES OF RECOGNIZING, DETECTING AND PURSUING PREY? FOR THIS WORK JULIE IN THE LAB DEVELOPED A PARADIGM, PLACED A FISH MOUNTED IN THE DISH, MOUNTED, YOU CAN SEE THE FLAB OF AGOROS IN WHICH THE ANIMAL IS EMBEDDED, CAN SHOW ON A SCREEN, A PRESIDENT CLINTON YEAH TIRE CELL PHONE SCREEN OR EVEN SMALLER, OR IT CAN BE A PROJECTION, SHE CAN NOW DISPLAY STIMULI TO THE FISH IN THIS CASE A SMALL MOVEMENT IN FRONT OF THE FISH, THE FISH RESPONDS WITH A TYPICAL MOVEMENT OF THE TAIL THAT CHARACTERIZES PREY CAPTURE. NOW WHEN SHE SWITCHES THE CONTRAST AND SHOWS A BLACK DOT LOOMING, EXPANDING IN SPACE, THE FISH SHOWS AN ENTIRELY DIFFERENT BEHAVIOR WHICH THE COMPUTER HAS NO TROUBLE DISTINGUISHING FROM THE PREY CAPTURE MOVEMENTS. THOSE ARE THE LARGE AMPLITUDE C-BENDS THAT CHARACTERIZE ESCAPE STARTING RESPONSES. SO PREY IS AN OBJECT OF A PARTICULAR SIZE, THE PREY CAPTURE SCORE AS A FUNCTION OF THE SIZE OF THE DOT. ANYTHING BETWEEN 1 AND 5 OR 8 DEGREES HERE IS ACCEPTED AS PREY. AND THEN PREY CAPTURE IS MUCH LESS PROBABLE IN RESPONSE TO LARGER. IT ALSO HAS TO MOVE AT A CERTAIN SPEED SO THERE'S A CERTAIN WINDOW WITH WHICH THE FISH ACCEPTS AS PRAYER INFORMATION. IN YOU MAY THE STIMULUS TOO BIG OR TOO FAST YOUR MACHINE SYSTEM CANNOT DETECT PREY CAPTURE MOVEMENTS ANYMORE. THIS IS REMINISCENT OF THE LITERATURE IN AMPHIBIANS AT M.I.T. IN THE '60s AND 70s THAT LOOK AT THE RESPONSES OF TOADS AND OTHER AMPHIBIANS, TO DIFFERENT STIMULI, SHOWING SIMILAR SIZE DEPENDENCE OF APPROACH OR ORIENTATION, SHOWN HERE, AND WHEN YOU MAKE THE STIMULUS TOO BIG THE TOAD TURNS AWAY AND ESCAPES. SO WHAT'S HAPPENING IN THE BRAIN AND WHERE IN THE BRAIN IS PREY INFORMATION ENCODED? SO FOR THIS WE LOOKED AT THE PROJECTIONS OF RETINAL GANGLION CELLS INTO THE BRAIN. AND IN THE LAB IT WAS MAPPED OUT USING SINGLE AXON TRACING AND GENETIC LINES, CABLES THAT RUN FROM THE HIGH INTO THE CONTRALATERAL BRAIN AND HE NAMED FOLLOWING A NOMENCLATURE INTRODUCED BY STEVE EASTER 20 YEARS AGO, NAMED THE FIELDS AND NUMBERED THEM ACCORDING TO POSITION ALONG THE OPTIC TRACK. THE BIG THING UP HERE IS OPTIC TECTUM WHICH RECEIVES 95% OF ALL THE RETINAL GANGLION CELLS. SO ABOUT HALF OF THOSE CELLS THOUGH MAKE COLLATERALS IN THE ARBORIZATION FIELDS AS I WILL SHOW YOU IN A SECOND. THESE ARE NINE ARBORIZATION FIELDS PLUS THE TECTUM. IN THE TECTUM WE FIND A LAYERED ORGANIZATION SO EACH RETINAL GANGLION CEREALS DEPICT IN THE THE BRAINBOW LABELING CHOOSES AT THE BEGINNING OF INNERVATION ONE OF NINE LAYERS IN THE TECTUM AND FORMS A FLAT ARBOR IN JUST ONE OF THESE LAYERS. AND WE CAN NOW LOOK AT MANY SINGLE RETINAL GANGLION CELLS DONE USING A MOSAIC SPARSE GENERIC LABELING METHOD LOOKING AT GANGLION CELL TYPES IN THE ZEBRAFISH AND THERE IS 14 TYPES, THIS IS PROBABLY AN UNDERESTIMATE AND THERE ARE MORE TYPES BUT THEN BECOMES AN ISSUE OF LUMPING OR SPLITTING DIFFERENT CATEGORIES. THESE ARE THE CANONICAL TYPES. AND THEY VERY MUCH ARE SIMILAR AND ARE SIMILAR TO RETINAL GANGLION CELL ARBORIZATION OR STRATIFICATION IN OTHER ANIMALS. ESTUARDO HAS INFORMATION ABOUT THE AXONAL PROJECTIONS IN THE RETINAL GANGLION CELLS, LOOKED AT 500 AND FOUND 20 PATHWAYS FROM THE EYE INTO THE BRAIN, THESE ARE THE AXON PROJECTION PATTERNS OF THE CELLS I'VE SHOWN YOU BEFORE. HE FINDS PROJECTION CLASSES, DIFFERENT PROJECTION CLASSES, THAT ARE CONSISTING OF DIFFERENT COMBINATIONS OF THESE ARBORIZATION FIELDS AND LAYERS OF THE TECTUM. SO, THIS IS A SCHEMATIC DEPICTION OF THE PROJECTOME, EACH LINE CORRESPONDS TO ONE PROJECTION PATTERN THAT I'VE JUST SHOWN YOU. AND INDICATED HERE ARE THE ORIGINAL RECIPIENT TARGETS, SO THERE ARE SOME VERY SIMPLE PROJECTION PATTERNS, FOR INSTANCE THICK LINES HERE ARE RETINAL GANGLION CELL EXONS THAT DO NOT BRANCH AND GO INTO ONE OF THE LAYERS OF THE TECTUM. OTHERS ARE MORE COMPLICATED, THIS ONE MAKING COLLATERAL AND GOING INTO THE SUPERFICIAL LAYER IN THE TECTUM, AND OTHERS ARE COMPLICATED, SOME EXONS CONNECT MORE DEEPLY WITH THE ARBORIZATION FIELDS. SO HOW CAN WE MAP VISUAL FEATURES INTO THIS -- ONTO THESE VISUAL PATHWAYS AND HOW CAN WE UNDERSTAND THE PRINCIPLES, COMPUTATIONS CARRIED OUT IN THE SYSTEM THAT RESULT IN DIFFERENT BEHAVIOR? WE'VE ONLY SEEN THE TIP OF THE ICEBERG BUT I'LL SHOW WHAT YOU ADVANCES WE'VE MADE. FOR PREY CAPTURE, JULIE USED THE HEAD FIXED PREPARATION, WHOLE BRAIN CALCIUM IMAGING USING A RETINAL GCaMP EXPRESSER LINE TO IMAGE FROM THESE RETINAL GANGLIA CELL TERMINALS AT DIFFERENT PLANES ALONG THE OPTIC TRACK AND FOUND AMONG ALL THE AF, ONLY AF7 SHOWED APPRECIABLE RESPONSE TO PREY INFORMATION. THERE'S VERY STRONG RESPONSE IN THE OPTIC TECTUM. SO HERE'S AN EXAMPLE. SO THIS IS A FISH THAT HAS BEEN HEP SIXED, AND WE'RE DANGLING LIVE PARAMECIUM, YOU CAN SEE INCREASED ACTIVITY, VERY LITTLE AF8 AND 9, SOME IN THE OPTIC TECTUM. YOU CAN MAKE OUT A TRAVELING WAVE IN THE AF7, VERY WELL EXPLAINED BY A RETINAL TOPIC ORGANIZATION OF RETINAL GANGLIA CELLS INTO THE NUCLEUS, NEUROPILLARS MAY BE 10 OR 15, AND THIS IS RESPONSE TO ARTIFICIAL STIMULUS, A DOT ON A SCREEN. SO, WHEN WE NOW MEASURE THE TUNING FUNCTION IN BOTH AF7 AND THE AF THAT IS IN THE SAME OPTICAL PLANE AND VARY THE STIMULUS SIZE FROM 1 DEGREE TO 14 DEGREES THERE'S A TUNING CURVE FOR THE CALCIUM RESPONSES MATCHING THE BEHAVIORAL TUNING USING PSYCHOPHYSICS BEFORE, SO THERE'S A NICE MATCH HERE. AF9 IS MORE INTERESTED IN LARGER STIMULI, DOES NOT RESPOND TO THE SMALL PREY-LIKE STIMULI, AND DOES NOT SHOW ANY MATCH TO THE BEHAVIORAL TUNING FUNCTION. AND SIMILAR MATCHES SEEN HERE FOR THE SPEED OF THE STIMULUS. SO AN ABLATION USING PULSED LASER REVEALS THAT AF7 IS NECESSARY FOR THE FULL BLOWN PREY DETECTION, SO AF7 WAS ABLATED, PREY CAPTURE SCORE DROPPED. IN ABLATION OF AF9, A MUCH LARGER AREA, BY THE WAY, DOES NOT AFFECT PREY CAPTURE OF THE ANIMALS. AND VICE VERSA, ABLATION OF AF9 REDUCES OPTO MOTOR RESPONSE BUT NOT PREY CAPTURE, DOUBLE ASSOCIATION OF BEHAVIOR AND ANATOMICAL PATHWAY. THE PICTURE EMERGING IS PARTICULAR RETINAL GANGLIA CELLS THAT CARRY INFORMATION ABOUT PREY INTO THE BRAIN, CONVERT INTO AF7, FROM THE PROJECTOME WE KNEW THE SAME RETINAL GANGLIA CELLS CONTINUE TO INNERVATE THE MOST SUPERFICIAL LAYER OF THE OPTIC TECTUM. SO THE TYPES THAT PROJECT TO AF7 ARE BISTRATIFIED. WE NOW HAVE SOME INFORMATION ABOUT THIS DIFFUSED TYPE NOW FROM A GENETIC MARKER THAT WE'VE ISOLATED, AND THIS IS IN FACT VERY SENSITIVE TO THE SIZE OF THE OBJECT, AND IT'S SIZE TUNING MATCHES THE BEHAVIOR. WE'RE BEGINNING TO ASSIGN BEHAVIORAL FUNCTION TO RETINAL CELL TYPE. WE LACK GENETIC MARKER THAT LETS US DO THE CORRESPONDING EXPERIMENTS, BUT IT WOULD BE VERY NICE IF THAT WAS THE SPEED-DETECTING SYSTEM. COMBINATIONS OF FEATURES, TOGETHER, LEND IDENTITY AND PREY IDENTITY TO OBJECTS IN THE OUTSIDE WORLD. SO THIS IS THE SYSTEM THAT I WAS TALKING ABOUT, RETINAL GANGLION CELLS HERE, THE SECOND LINE FROM THE TOP MAKING COLLATERALS IN AF7 AND PROJECTING TO S-O, SIMILAR EXPERIMENTS USING BEHAVIORAL ASSAYS FOUND DEEP LAYERS HERE IN THE DEEPER LAYERS, MIDDLE LAYERS IN THE TECTUM, RESPOND SPECIFICALLY TO LOOMING INFORMATION. EVEN MORE DEEPLY DIMMING RESPONSES , THEN THERE IS A SYSTEM HERE NOT AS WELL DEFINED FOR PHOTOTACTIC RESPONSES TO THE ONSET OF LIFE, CONNECTING VISUAL SYSTEM TO NUCLEI REQUIRED FOR PHOTOTAXIS, AND THERE'S A BODY OF WORK INCLUDING AF5 AND HERE THIS SFGS-1 LAYER SHOWN BY MARTIN MEYER'S GROUP AND JOHAN'S GROUP A FEW YEARS BACK. SO, I'D LIKE TO TALK NOW ABOUT THE MOTOR MAP AND INTRODUCE SOME OPTOGENETICS. A SIMPLE EXPERIMENT I DIDN'T THINK WOULD WORK, WORKED VERY NICE. HE USES A TECTUM-SPECIFIC LINE FOR CHANNEL RHODOPSIN IN MAYBE TECTUM NEURONS, AND POINTS AT DIFFERENT NEURONS, WHAT BEHAVIORS CAN ELICIT BY STIMULATING DIFFERENT LOCATION IN THE TECTUM, RUNS AN ALGORITHM ON BEHAVIORAL OUTCOMES AND CAN CLUSTER THEM HERE, ALL THE PURPLE ONES ARE ESCAPE RESPONSES, TAIL BEATS STRONGLY IN THE DIRECTION THAT'S CONTRALATERAL TO THE STIMULATION SITE. SO CONTRALATERAL TO TECTUM THAT WAS STIMULATED. AND THEN HERE, IN THIS CORNER, THERE IS A CLUSTER OF RESPONSES WHICH HAVE A MUCH SMALLER BOUT ANGLE HERE IN THIS TWO DIMENSIONAL SPACE, ORIENTATION TERMS WHERE THE TAIL MOVES A FEW DEGREES EITHER TO THE LEFT OR TO THE RIGHT. LET'S LOOK AT THIS POPULATION OF RESPONSES NOW. SO WHAT THOMAS DISCOVERED, THIS IS A VERY NICE CONFIRMATION OF THE METHOD, IS THAT DEPENDING ON WHERE ALONG THE ANTERIOR POSTERIOR AXIS HE PLACED THE FIBER THERE WAS A GRADIENT OR MAPPING OF THE RESPONSES, WITH THE BOUT ANGLES BEING LARGER IF HE STIMULATED THE POSTERIOR PART OF THE TECTUM, AND QUITE SMALL OR ZERO WHEN STIMULATING ANTERIOR PART OF THE TECTUM, CONSISTENT WITH THE ORIGINAL TOPIC ORGANIZATION OF THE VISUAL SYSTEM. SO OBJECTS THAT ARE IN FRONT OF THE ANIMAL WOULD BE REPRESENTED IN THE ANTERIOR TECTUM. SO IF THE ANIMAL IS INTERESTED IN CATCHING THOSE PARAMECIA IN FRONT, THE TAIL SHOULD NOT MOVE MUCH, SYMMETRICALLY AND PROPEL THE FISH FORWARD. WHEN THE PREY IS IN THE BACK, THE ANIMAL SHOULD MAKE A TURN. SO THIS IS A VERY NICE CONFIRMATION OF THE ORIGINAL TOPIC ORGANIZATION, AND SHOWS THE MOTOR MAP FOLLOWS THESE SO YOU MAY HAVE NOTICED OR I'M GOING TO POINT OUT TO YOU THAT SOME OF THESE TERMS ARE -- TURNS ARE IN THE OPPOSITE DIRECTION. PRESENT A PREY ITEM ON THE RIGHT, RECORD TO THE LEFT, THE FISH MAKES A MOVEMENT FOUGHT LEFT, WHICH IF EVERYTHING WERE CONSTANT WOULD LEAD TO ORIENTATION AWAY FROM THE PREY ITEM. AND THIS IS IN FACT WHAT YOU WOULD PREDICT FOR A SYSTEM THAT CAN MOVE ITS EYES. SO, IN THIS CASE -- SO HERE THE EYE IS TILTED TO THE LEFT, AND WE ARE NOW CONSIDERING AN OBJECT THAT IS IN THIS PART OF THE VISUAL FIELD RIGHT IN FRONT OF THE ANIMAL, THE ANIMAL SHOULD MAKE A TAIL MOVEMENT IN THE DIRECTION OF THE BLUE ARROW WHICH WOULD PUT IT ON A COURSE TO THE LEFT. WHEN THE EYE IS MOVED TEMPORALLY, SORRY, NASALLY, INCLINED NASALLY, STIMULATION OF THE SAME PART OF THE VISUAL FIELD, SAME GROUP OF RETINAL GANGLION CELLS, SHOULD RESULT IN A TAIL MOVEMENT TO THE LEFT IN œBECAUSE ASSUMING TRAJECTORY OF PREY ANIMAL SUCH AS THIS THE ANIMAL WOULD WANT TO MAKE A RIGHT TURN. THOMAS COULD DEMONSTRATE DEPENDING ON POSITION OF THE EYE, IN THIS CASE THE EYE IS TILTED TO THE LEFT, SO IN THE TEMPORAL DIRECTION, HERE IS TO THE NASAL, DEPENDING ON THE POSITION OF THE EYE THE STIMULATION OF THE SAME IDENTICAL LOCATION IN THE TECTUM COULD LEAD TO TURNS OF THE TAIL TO THE LEFT OR TO THE RIGHT. SO, CLEARLY, THERE IS NOT A FIXED MOTOR COMMAND THAT THE TECTUM IS SENDING TO THE HIND BRAIN PRE-MOTOR CIRCUITS WHICH WILL ALWAYS LEAD TO THE SAME BEHAVIOR, BUT THE SYSTEM HAS A WAY OF INTEGRATING THE POSITION OF THE EYE AND MAKE ADJUSTMENTS DEPENDING ON WHERE THE EYE GAZE IS DIRECTED. SO I THINK THIS IS A VERY COOL RESULT, AND WE -- LED US TO THINK HARD ABOUT THIS PROBLEM. WE HAVEN'T LOCALIZED WHERE THE INTEGRATION IS HAPPENING. WE DON'T THINK IT'S HAPPENING IN THE TECTUM BUT IT'S PROBABLY HAPPENING DOWNSTREAM IN THE HIND BRAIN, THIS IS JUST A QUANTIFICATION OF THIS PHENOMENON. THOMAS MAPPED OUT USING SINGLE CELL TRACINGS SIMILAR TO RETINAL GANGLION CELLS, MAPPED OUT TECTAL PROJECTOME WITH HUNDREDS OF NEURONS, SUPERIMPOSED THEM IN STANDARD REFERENCE BRAIN. THIS IS ONE OF THE PICTURES HE GENERATED. HE COULD DIVIDE SINGLE PROJECTION NEURONS INTO CLASSES HERE AND DREW THEM ALL IN DIFFERENT COLORS, AND WHAT WE THINK AS A HYPOTHESIS NOW, THERE'S SOME EVIDENCE FROM HIND BRAIN IMAGE AING THAT DIFFERENT WIRES COMING OUT OF DIFFERENT CABLES, OUT OF THE TECTUM, CAN DRIVE DIFFERENT LOCOMOTOR RESPONSE INCLUDING ORIENTATION TERMS TO LEFT AND RIGHT AND ESCAPES. MY STUDENT THOMAS INSISTS I TELL YOU THIS IS A HYPOTHESIS, I THINK IT'S VERY NICE FOR THE STUDENT TO BE VERY CAUTIOUS ABOUT THESE CLAIMS, SO WE'RE STILL WORKING ON THIS ISSUE WHICH INVOLVES DOING OPTOGENETIC STIMULATION OF TECTUM AND BEHAVIORAL RECORDING, AT THE SAME TIME VOLUMETRIC WHOLE BRAIN IMAGING OF RESPONSE IN THE HIND BRAIN, DAUNTING BUT THOMAS IS MAKING PROGRESS, A HYPOTHETICAL FRAMEWORK INTO WHICH WE'RE PLACING THE DATA AND TESTING. NOW LET'S LOOK AT THE TECTUM. I TOLD YOU WHAT WE KNOW ABOUT SENSORY INPUTS, ABOUT HYPOTHESES AND SOME FACTS, ABOUT THE MOTOR OUTPUTS. WHAT'S HAPPENING IN BETWEEN IN THE TECTUM? SO WE DECIDED TO DO A CELLULAR ANALYSIS OF THE CIRCUITRY OF THE TECTUM. WE STARTED WITH IMAGING. THIS IS VOLUMETRIC, USING ARRAY OF VISUAL SIMPLE STIMULI, CHANGING LUMENS SLOWLY OR FAST. THEN USING DIFFERENT PREY-LIKE STIMULI, SO SMALL-SIZE DOT THAT WE MOVED HERE, ON THE SCREEN, DIFFERENT PARTS OF THE VISUAL FIELD, SO THIS IS SORT OF A VERY COARSE RECEPTOR FIELD MAPPING. AND THEN WE ALSO USED LUMING STIMULI IN OUR BATTERY OF STIMULI. EACH FISH WAS LABELED WITH GCaMP, LOCALIZING GCaMP, WE RAN REGRESSORS, ON THE POPULATION OF NEURONS AND DIVIDED INTO CLASSES DEPENDING ON RESPONSE PROFILE. THIS IS THE FIRST PASS ANALYSIS. EACH LINE CORRESPONDS TO ONE NEURON THAT WE'VE IMAGED AND BRIGHT COLORS INDICATE STRONG RESPONSE AND DARK COLORS CORRESPOND TO SUPPRESSION OF RESPONSES. HERE IS HIERARCHICAL CLASSING WITH BAR CODES WE'RE GENERATING. WHAT WE FIND IS WE FIND POPULATION OF NEURONS THAT ARE VERY HIGHLY SPECIALIZED, FOR INSTANCE HERE TECTAL NEURONS THAT RESPOND PREFERENTIALLY TO DARKENING OF THE SCREENING, DO NOT CARE ABOUT LUMING ALTHOUGH THAT CONTAINS A DARKENING, THEY CAN DISTINGUISH AGAINST THE SCREEN TURNING SLOWLY DARK AND A DISC TURNING THE SCREEN DARK WITH TEMPORAL KINETICS AND THERE'S SPECIAL LUMEN CELLS, HIGHLY SPECIALIZED, AND PREY CAPTURE CELLS, HERE FOR INSTANCE THE LAST CATEGORY THAT'S QUITE A FEW CELLS THAT RESPOND TO SMALL MOVING OBJECT, DO NOT RESPOND APPRECIABLY TO ANY OF THE OTHER STIMULI. THIS IS VERY INTERESTING FROM A SYSTEMS NEUROSCIENCE PERSPECTIVE THERE ARE ALMOST LABELED LINES IN THE TECTUM WITH SPECIALIZED SUBCIRCUITS CONCERNED WITH ASPECTS OF VISUAL ENVIRONMENT, THOSE COULD BE -- THOSE CELLS COULD BE THE SUBSTRATE FOR INITIATING APPROPRIATE MOTOR COMMANDS. SO, DOMINICK ACTUALLY HAD MADE SURE THAT YOU COULD NOW GO FROM THESE PHYSIOLOGICAL RESPONSE TYPES WHICH ARE CORRELATIONS WITH THE STIMULI, ALL THE WAY TO CELL TYPE CLASSIFICATIONS. OKAY? FOR THAT HE BUILT INTO HIS TRANSGENIC FISH NOT ONLY NUCLEAR LOCALIZE THE GCaMP BUT PHOTOACTIVATABLE GMP, IN TERMS OF PHYSIOLOGIC RESPONSE, PREY-SELECTED NEURON AND POINT A LASER AT THIS NEURON TO PHOTOACTIVATE WITH GFP AND LABEL OUTLINE DYE BY DIFFUSION OF GFP THROUGH CYTOPLASM AND RECORDED MORPHOLOGY OF NEURONS AND COLLECTED HUNDREDS OF THESE CELLS. SO THIS METHOD WE CALL FUGIMA, FUNCTION GUIDED MORPHOLOGIC ANALYSIS. THESE ARE A FEW TIMES. IT'S INTERESTING WE HAVE NOW A GOOD OVERVIEW OF TECTAL NEURON TYPES FALLING INTO A FEW CLASSES, THERE'S MONO STRATIFIED CELLS, BISTRATIFIED CELLS, TRISTRATIFIED AND TETRASTRATIFIED CELLS AND NON-STRATIFIED OR DIFFUSE TIMES. THAT'S ALL THE TECTUM WORKS WITH, FIVE MAJOR CLASSES. SO FUGIMA IDENTIFICATION AND REGISTRATION CAN LEAD TO A PICTURE SUCH AS THIS, SO THE LUMING AND PREY SENSITIVE ARE PLOTTED HERE INTO REFERENCE TECTUM. ONE THING WE CAN TAKE FROM THE PICTURE, CELLS ARE INTERMINGLED IN THE TECTUM, DOESN'T SEEM TO BE A RETINAL TOPIC ORGANIZATION. WHICH MAKES SENSE OF COURSE BECAUSE PREY CAN BE ANYWHERE IN YOUR VISUAL FIELD, RIGHT? YOU WANT CELLS LOOKING AT EACH SUBFIELD OF YOUR VISUAL ENVIRONMENT TO POTENTIALLY DETECT PREY. THE SAME TRUE FOR LUMING, PREY CAN APPROACH FROM ANY DIRECTION, YOU WANT CELLS DISTRICTED OVER THE TECTAL SURFACE OR TECTAL SPACE. SO, INSURED IN ORDER TO GET A HANDLE DOMINICK DEVISED A BARCODING SCHEME WHERE HE LOOKED AT THESE INDIVIDUAL MORPHOLOGIES AND ASSIGNED STRATIFICATIONS TO INDIVIDUAL LAYERS, OF THE TECTUM. SO THIS IS -- THESE ARE THE REGISTERED TECTUM, THESE ARE THE DIFFERENT LAYERS THAT HE DISTINGUISHES, AND THEN HE -- THESE ARE FOUR EXAMPLES, NUMBER ONE IS A MONOSTRATIFIED. THIS ONE HAS A VERY BRIGHT SIGNAL HERE IN SFGS 5, 6. NUMBER TWO IS BISTRATIFIED, NUMBER THREE IS TRISTRATIFIED, ET CETERA. HE CLASSIFIED EACH NEURON HE FINDS IN THE TECTUM ACCORDING TO THE BAR CODE SCHEME. AND HE THEN GROUPS THEM INTOP PREY-SENSITIVE AND LUMING-SENSITIVE TO UNDERSTAND IF THERE ARE DISTINGUISHING FEATURES. INTERESTINGLY, ALL OF THESE DIFFERENT CLASSES OF CELLS ARE FOUND IN BOTH CATEGORIES. SO BOTH LUMING AND PREY SYSTEMS USE MONO, BI, TRI STRATIFIED CELLS. WE CANNOT JUDGE BY MORPHOLOGY. YOU SEE THERE'S A TENDENCY OF PREY CELLS TO ARBORIZE IN THE SUPERFICIAL LAYERS OF THE TECTUM AND THE LUMING CELLS ARE MORE IN THE MIDDLE. I THINK THIS IS SHOWN ON THE -- YEAH, QUANTIFIED HERE, SO THIS EMPHASIZES OR SHOWS GRAPHICALLY THE POINT I MADE BEFORE, THAT YOU FIND MAYBE WITH THE EXCEPTION OF TETRA STRATIFIED TYPE WE DO NOT FIND THAT PARTICULAR SENSORY PROCESSING TIED TO PARTICULAR CLASSES OF CELLS. BUT WE DO SEE DIFFERENCES IN THE STRATIFICATION PATTERNS. PREY SENSITIVE CELLS ARE GREATLY OVERREPRESENTED. THE LUMING CELLS MORE IN THE DEEPER LAYER OF THE TECTUM, THE VERY DEEP ONES. THIS ROUGHLY, NOT PERFECTLY, BUT ROUGHLY CORRESPONDS TO THE TWO INPUT PATHWAYS THAT I'VE SHOWN YOU BEFORE, WITH PREY INFORMATION ENTERING THE TECTUM AT THE SURFACE AND LUMING IN THE MIDDLE. OF COURSE, YOU DO NOT EXPECT TO BE THERE, FOR THERE TO BE A PERFECT MATCH OF THE TWO SYSTEMS BECAUSE FIRST OF ALL, YOU HAVE PROCESSING GOING ON, SO YOU WANT FROM THE SURFACE WHERE YOU RECEIVE PREY INPUTS, YOU WANT TO PROCESS THIS IN THE DEEPER LAYERS. YOU WANT TO COMPARE RESPONSES ALSO WITH OTHER SYSTEMS. ALSO, IN THIS ANALYSIS, AS I'M SURE VERY OBSERVANT PEOPLE IN THE AUDIENCE MAY HAVE PICKED UP ON, WE CANNOT DISTINGUISH BETWEEN AXONS AND DENDRITES. SO SIGNALS, A CELL MAY RECEIVE INFORMATION AT THE SURFACE OF THE TECTUM BUT THEN SEND AN AXON INTO THE DEEPER LAYERS, WE NO NOT BE ABLE TO TELL BY MORPHOLOGY WHEREIN PUT AND OUTPUT IS OF THAT CELL. OKAY. THIS IS ALL WE KNOW. I'M NOW GOING TO COME TO THE VERY LAST CHAPTER. THIS IS THE REVENGE OF THE TOAD. IT HAS MADE THE LEAP INTO THE 21ST CENTURY NOW. [LAUGHTER] BUT IT IS NOT PERFECT IN DISTINGUISHING PREY FROM MAYBE A NEUTRAL OBJECT, SUCH AS A FINGER. AND THIS LEADS ME TO THE VERY LAST CHAPTER OF MY SEMINAR. HARRY DO I HAVE TIME? I HAVE NOT -- IT WILL TAKE MAYBE FIVE MINUTES, TEN MINUTES. OKAY. I WANT TO KEEP SOME TIME FOR QUESTIONS. SO I TOLD YOU ABOUT STEREOTYPED HARDWIRED INPUTS INTO THE TECTUM. I TOLD YOU ABOUT TECTAL NEURONS THAT WERE SPECIALIZED IN PROCESSING COMBINATIONS OF FEATURES WHICH ASSIGN SOME VALENTS TO VISUAL OBJECTS. THEY SEEM TO BE QUITE HARDWIRED. HOWEVER, THE SYSTEM IS NOT. IT IS FLEXIBLE. I WANT TO SHOW YOU AN EXAMPLE OF FLEXIBILITY IN THE NEXT COUPLE OF SLIDES. NOW, THIS IS THE MAGIC WORD AT THE MOMENT, FASHIONABLE, INTERNAL STATE. I MEAN BY THAT, HUNGER. SO JUST THINK A MOMENT ABOUT HOW HUNGER SHOULD AFFECT THE CIRCUITRY OF THE TECTUM, MAYBE IT DOESN'T. MAYBE THE TECTUM IS JUST A COLLECTOR OF SENSORY INFORMATION, CONVERTS SENSORY INFORMATION INTO MOTOR COMMANDS AND HUNGER IMPINGES ON THE SYSTEM MAYBE DOWNSTREAM, OR IN WAYS THAT ARE NOT VISIBLE TO OUR ANALYSES. HOWEVER, IT TURNS OUT AS I WILL SHOW YOU THAT NEUROMODULATORY SYSTEMS THAT ARE RELATED TO HUNGER IMPINGE ON THE TECTUM. SO THEY CHANGE THE WAY THESE ZEBRAFISH SEES ITS ENVIRONMENT WHICH IS REALLY COOL. SO THE F-A IS -- LOOKS A BIT MORE -- IS A BIT MORE QUANTITATIVE THAN THIS QUALITATIVE PICTURE. FOR ILLUSTRATION ALLISON BARKA AND A POSTDOC PUSH FISH IN THE RACETRACK CHAMBER AND PUT DOTS ON THE IPAD, SOMETHING THEY CAN CATCH. WHEN WE MAKE BIG DOTS THE FISH ESCAPE. THEY DON'T LIKE THEM. THIS IS A CONFIRMATION OF THE PSYCHOPHYSICS I'VE SHOWN YOU BEFORE ON A QUALITATIVE SCALE. THIS F-A IS NICE, WE CAN DO IT ON LOTS OF FISH AND DO MANIPULATION SUCH AS GENETIC PERTURBATION, ADD DRUGS AND ASK HOW THEY RESPOND. WE CAN MAKE A TUNING CURVE, THIS IS A REMINDER AS WE CHANGE THE SIZE OF THE OBJECTS SOME ARE TOO SMALL, SOME ARE -- THE FISH LIKES TO HUNT, 1 TO 5 DEGREES, AND THEN OTHERS ARE TOO BIG, WHICH THE FISH ESCAPES FROM, AND THEN THIS AMBIGUOUS RANGE BETWEEN 5 AND 10 DEGREES ROUGHLY, AND WHAT I'M GOING TO SHOW YOU IS THAT HUNGER MAKES THE FISH PERCEIVE AMBIGUOUS STIMULUS AS POTENTIAL PREY AND THIS MAKES THEM ESCAPE. WE CAN DISTINGUISH FED FROM STARVED BY LOOKING AT BELLIES, PARAMECIA IN THE GUT, WE CAN SWAP THEM AND THEN MEASURE THE PSYCHOMETRIC TUNING FUNCTION. THIS IS A FUNCTION OF THE SIZE OF THE DOT. WE CAN PLOT SOMETHING LIKE THE VALENCE INDEX, ONE OF THE METRICS IS SHOWN HERE. THE LARGER THE VALUE, THE MORE APPROACHES THE FISH SHOWED TO THE DOTS OF THE PARTICULAR SIZE. FOR STARVED FISH, THEY ACCEPT THESE SMALL OBJECTS AS PREY. AND FED FISH ARE -- IGNORE THEM OR ESCAPE FROM THEM. SO THERE'S A NICE SHIFTING OF THE CURVE BY INTERNAL STATE. SO FILOSA IN THE LAB, WHO SPEARHEADED THIS STUDY, IMAGED, CAN I FIND CELLS THAT RESPOND TO PARTICULAR SIZES? AND HE DID, UNSURPRISINGLY. HERE IS THREE EXAMPLES. HE CALCULATED LIKE THE WEIGHTED MEAN RESPONSE ANGLE, SO IF THERE WERE TWO RESPONSES FOR THIS CELL, 40 DEGREES AND 40 DEGREES, HE JUST ASSUMED THAT THE PREFERRED RESPONSE ANGLE WAS AROUND 35 DEGREES. EACH CELL HAD ONE AVERAGE RESPONSE SIZE. AND THEN NOW HE PLOTTED THAT, AND THIS IS THE CUMULATIVE PROBABILITY FUNCTION, THE FUNCTION OF THIS DISTRIBUTION, AND FOR THE STARVED FISH THE RESPONSES WERE CLEARLY SHIFTED TO THE LEFT. THAT MEANS MORE CELLS IN THESE STARVED ANIMALS TECTA RESPONDED TO THE SMALLER STIMULI. AND THIS WAS THE CONTROL WHERE WE TESTED WHETHER OR NOT THE ODOR THAT CAME WITH THE PARAMECIA HAD AN EFFECT ON TUNING FUNCTIONS TO RULE OUT THERE WERE OTHER NON-VISUAL EFFECTS ON THE TUNING CURVES, AND THEY ARE NOT. OKAY. SO HOW CAN WE MANIPULATE THE SYSTEM? ONE MUTANT THAT WE HAD IN THE LAB THAT PROVIDED A VERY NICE ENTRY POINT WAS AFFECTING THE DEFENSIVE BEHAVIOR GENERALLY OF THESE FISH. THIS IS A MUTATION THAT AFFECTS THE HPA AXIS, IN FISH CALLED THE HPI, YOU CAN IGNORE THIS MOST OF THE TIME. THIS AXIS IS HIGHLY CONSERVED, STARTS WITH HYPOTHALAMUS THAT SECRETES A NEUROPEPTIDE IN A ACTIVATES PITUITARY, INITIATES SECRETION OF ACTH, ACTS ON ADRENAL, RELEASING GLUCOCORTICOIDS. IT PREPARES FOR STRESS RESPONSE. THEY HAVE A VERY IMPORTANT FUNCTION, WHICH IS CENTRAL TO MANY PSYCHIATRIC DISEASES IN FACT. THEY FEED BACK ON THE BRAIN AND INHIBIT THE PRODUCTION OF THESE TWO HORMONES HERE, CRS AND ACTH, BY VIRTUE OF A RECEPTOR, THE GLUCOCORTICOID RECEPTOR THAT BINDS CORTISOL, MIKE RATES MIGRATES AND ACTS AS REPRESSOR. WHEN YOU MEASURE CORTISOL LEVELS, IN ZEBRAFISH, THEY ARE ELEVATED IN FED FISH. THIS MAY BE A BIT COUNTER INCUE ACTIVE, IF YOU USE CORTISOL CORTISOL AS A CRUDE READOUT, WHICH THE FISH HAS, THEN YOU WOULD EXPECT A STARVED FISH WOULD BE STRESSED BUT IT'S THE OTHER WAY AROUND. THE FED FISH ARE THE ONES THAT HAVE A HIGH CORTISOL LEVEL. THE STARVED FISH ARE THE ONES THAT HAVE REDUCED LEVELS OF CORTISOL. SO IT DOES MAKE MORE SENSE WHEN YOU CONSIDER THAT HIGH CORTISOL IS NOT -- CORRELATES WITH ANXIETY, THAT A FED FISH MAY ACTUALLY BE MORE ANXIOUS AND MAY BE LESS BOLD TO PURSUE AMBIGUOUS STIMULI. LOW CORTISOL CORRELATES WITH BOLDNESS, THE HUNGRY FISH SHOULD BE BOLDER AND SHOULD GO AFTER THINGS THAT MAY TURN OUT TO BE DANGEROUS TO THEM. SO IN A MUTANT THAT WE HAD IN THE LAB, THAT CARRIES A LOSS OF FUNCTION OF THE GLUCOCORTICOID RECEPTOR THIS FEEDBACK IS DISRUPTED, SO THESE ANIMALS HAVE A CONSTANTLY CHRONICALLY ELEVATED STRESS AXIS. WE ASKED HOW DO THESE FARE IN THE TECTAL RESPONSES? BEHAVIOR IS CONSISTENT WITH THESE ANIMALS BEING FED. AND ALSO THE SYSTEM, THE MUTANT, THE TUNING FUNCTION OF THE TUNING DISTRIBUTION IN THE TECTUM IS ALSO SHIFTED IN THE SAME DIRECTION AS FOR A STARVED ANIMAL. NOW, WE CAN ALLEVIATE THIS BY ADDING FLUOXETINE. WE CAN ADD A SEROTONIN REUPTAKE INHIBITOR, CURING, TURNING A FED FISH INTO A STARVED FISH, IN TERMS OF ITS RESPONSES IN THE TECTUM AND ALSO ITS BEHAVIOR. OKAY. SO ALLESANDRO WAS INTERESTED IN WHAT HAPPENS TO INDIVIDUAL NEURONS IN THE TECTUM, AS WE MAKE THESE SWITCHES. AND SO THIS INVOLVED IMAGING FROM THE SAME ANIMAL INTO TWO DIFFERENT STATES. IT'S VERY DIFFICULT TO TURN A STARVED FISH INTO A FED FISH, ON THE STAGE OF A TWO PHOTO ONMICROSCOPE. HE USE SEROTONIN AS A PROXY, AS A WAY TO WITHIN A FEW MINUTES TURN A FED FISH INTO A HUNGRY FISH. AND I'M GOING TO FOR THE SAKE OF TIME JUST SHOW YOU THE SUMMARY. HE FOUND THAT WHEN HE TOOK THE FED TECTA OBSERVED SWITCHINGS OF INDIVIDUAL NEURONS, EITHER FROM -- HE OBSERVED SWITCHES IN TUNING OF INDIVIDUAL NEURONS, TWO CASES EITHER HE TURNED A LARGE TUNED CELL, SO THIS WOULD BE ONE THAT IS IGNORING PREY, INTO ONE THAT WAS NOW TUNED TO SMALL STIMULI, OR ANOTHER POPULATION OF CELLS WAS SILENT THE FIRST IMAGING TIME AROUND AND BECAME ACTIVE IN RESPONSE TO SMALL STIMULI. SO THIS IS IN FACT -- THIS WAS THE LARGEST EFFECT HE SAW. SO WITH SEROTONIN AS A NEUROMODULATOR, WHAT IT'S DOING, AND GENERALLY TRUE FOR THE SWITCH FROM HUNGRY TO FED, AWAKENS CERTAIN CELLS SUCH AS TYPE 2 CELLS FROM A QUIET STATE THAT ARE NOT ACTIVATED BY VISUAL STIMULUS INTO ONE THAT IS NOW RESPONSIVE. AND THIS LEADS TO THIS SHIFT OF THE PROBABILITY DENSITY FUNCTION I'VE SHOWN YOU EARLIER. SO THIS IS JUST IN THE INTEREST OF TIME -- I'M GOING TO SKIP THIS. JUST A DIAGRAM OF HOW WE IMAGINE THESE MODULATORY SYSTEMS ARE INTERACTING WITH VISUAL PATHWAYS. AND I THINK I SAID ALL OF THIS IN WORDS, FEEDING STATE INFLUENCES SELECTION, SIMPLE BEHAVIORAL TASKS, INTERPRETATION IS HUNGRY FISH TAKE GREATER RISKS, STARVATION RESULTS IN INCREASED POPULATION RESPONSES TO EDIBLE ITEMS IN THE TECTUM. HUNGRY FISH ARE BETTER DETECTING PREY. ACTIVATION OF HPA AXIS MIMICS SATIETY, FLUOXETINE, TONE MIMICS HUNGER. WE ABLATED NEURONS AND THE FISH INTO FED FISH EVEN THOUGH THEY HADN'T EATEN ANYTHING WITH A LINE HARRY BURGESS MADE IN HIS LAB. SO THANK YOU, HARRY. OVERALL, I HOPE I CONVINCED YOU NEUROENDOCRINE SIGNALS SHAPE BEHAVIORAL DECISIONS BY CHANGING VISUAL PROCESSING. SO WITH THAT I'D LIKE TO THANK YOU FOR YOUR ATTENTION. I'M HAPPY TO TAKE QUESTIONS. BEFORE I CLOSE, I'D LIKE TO THANK MY LAB, REALLY A BUNCH OF SUPER HEROES, WHO ARE DOING A FANTASTIC WORK AND I'VE MENTIONED THEM IN PASSING, OR ON THE BOTTOM OF THE SLIDE SO I'M NOT GOING TO REPEAT THAT. OKAY. THANK YOU VERY MUCH FOR YOUR ATTENTION. HAPPY TO TAKE QUESTIONS. [APPLAUSE] >> WE PROBABLY HAVE A FEW MINUTES FOR QUESTIONS. >> THE TUNING YOU SHOW FOR SIZE AND SPEED, YOU SHOW IF THEY ARE INDEPENDENT OF EACH OTHER. I WONDER IS THERE AN INTERACTION YOU MIGHT EXPECT IF IT'S DRIVEN BY SELF MOTION, SO LARGE STIMULI MAY BE MORE EFFECTIVE AS SLOW SPEEDS THAN SLOW STIMULI. >> WE TESTED INDEPENDENTLY. WE HAVE NOT TESTED THIS INTERACTION. SO THE SHORT ANSWER IS WE DON'T KNOW. YEAH. SO I'D LIKE TO HEAR YOUR OPINION HOW WE COULD DESIGN A TEST TO -- MAYBE WE HAVE TO PROBE THE ENTIRE SPACE. >> WELL, YOU HAVE TO AT LEAST PROBE WHO CORE SECTIONS, YEAH. TWO CORE SECTIONS, YEAH >> SO YOU'VE GOT YOUR BEHAVIORAL MAPPING IN THE TECTUM FOR LUMING AND PREY. THIS LOOKS A LOT LIKE THESE OLD RETINAL DETECTIONS OF EDGE AND CONTRAST DETECTION. DO YOU THINK THIS IS A REAL WORLD BEHAVIORAL RECAPITULATION OF THESE OLD RETINAL TECTAL MAPPING EXPERIMENTS? DO YOU KNOW WHAT I'M TALKING ABOUT? >> SO THE MAPPING -- ARE YOU REFERRAL TO THE MOTOR MAP? DIFFERENT PARTS OF THE TECTUM? OR ARE YOU REFERRING TO THE DIFFERENT RESPONSES? >> THE LAYERS IN THE TECTUM THAT WERE DETECTING EDGE, EDGES, RESPONSE TO EDGES, RESPONSE TO CONTRAST, FROM RETINAL STIMULATION. >> YEAH, SO WE LOOKED AT SOME OF THESE MORE ARTIFICIAL STIMULI, JUST ISOLATING EDGES. WE HAVEN'T COME VERY FAR. IT REALLY SEEMS -- I SKIPPED OVER ALL THE THINGS THAT DIDN'T WORK. SO WHAT REALLY -- WHERE WE SAW BEAUTIFUL ISOLATED RESPONSES WERE FOR THESE RATHER REALISTIC STIMULI THAT REPRESENTED SOMETHING THAT THE FISH SHOULD BE INTERESTED IN, AND THAT THE FISH BEHAVIOR IS LAID OUT TO RESPOND TO. SO YOU COULD OF COURSE -- THERE'S AN INFINITE NUMBER OF DIMENSIONS IN VISUAL STIMULUS SPACE YOU COULD TEST. WE FIND THE BEST RESPONSES FOR THESE REALISTIC STIMULI, SO WHICH I THINK TELLS US SOMETHING ABOUT HOW THE SYSTEM IS LAID OUT. AND I THINK IS SOMETHING THAT MAYBE THE VISUAL SYSTEM PEOPLE HERE IN THE AUDIENCE CAN APPRECIATE IS THAT IT SEEMS TO PLACE SORT OF -- IT SEEMS TO ALLOW FOR A SEGREGATION OF VISUAL PATHWAYS, VERY EARLY, INTO BEHAVIORAL STREAMS, BEHAVIORAL SUBFUNCTIONALLIZATION. SO THE FISH TECTUM DOES NOT SEEM TO BE AN OBJECTIVE JUDGE OF STIMULUS DIMENSIONS. SO NOT ALL STIMULUS DIMENSIONS ARE TREATED EQUALLY BUT THE INFORMATION THAT ARRIVES AT THE TECTUM IS ALREADY PACKAGE AND COMBINES TO MAKE BEHAVIORAL SENSE TO THE ANIMAL. THAT WAS A LONG-WINDED ANSWER TO SHORT QUESTION. >> YEAH, ONE MORE QUESTION AND THEN WE'LL -- >> SORRY, REAL QUICK. O THE RELATIVE SIZE OF THE DISK YOU MAKES, WHERE WOULD A FEMALE ZEBRAFISH FIT ON THAT, AND THAT HOW WOULD THAT ACTIVATE THOSE NEURONS? >> OKAY. SO AT THE AGE WE TEST THE ANIMALS AT, THEY ARE NOT MALE AND FEMALE FISH. THEY HAVE NOT DECIDED WHO THEY ARE GOING TO BE. SEX DETERMINATION HAPPENS AT A FEW WEEKS OF AGE. THEY ARE NOT INTERESTED IN FINDING MATES ALSO. THEY ARE REALLY BABY FISH. SO THEY ARE PROBABLY WORRIED TO SEE A BIG ADULT ZEBRAFISH BECAUSE ADULT ZEBRAFISH ARE KNOWN TO EAT EVEN THEIR OWN EGGS. BUT LATER ON, OF COURSE, AT THE AGE OF FOUR WEEKS OR FIVE WEEKS THEY BECOME INTERESTED IN POTENTIAL MATES, AND WE HAVE NO IDEA HOW -- WHERE AND HOW THIS IS REPRESENTED IN THE BRAIN. >> WE'RE RUNNING ON THE LATE SIDE. I WOULD LIKE TO THANK HERWIG FOR THIS IMPORTANT LECTURE. [APPLAUSE] EVERYONE IS INVITED TO A RECEPTION JUST OUTSIDE IN THE LOBBY AS WELL. [END OF PROGRAM]