Nachum Ulanovsky Lab – Neural Codes for Natural Behaviors

Research Philosophy and Questions

Our lab investigates the neural basis of natural behaviors. We aim to uncover general principles of mammalian brain function, by capitalizing on the unique behaviors of bats – a novel animal model that we pioneered.  Our general approach is to utilize some of the advantages that bats afford – their outstanding navigation, 3D flight, fast movement, their temporally-discrete sensory system (sonar) and excellent vision, and their high sociality – in order to ask general questions in Systems Neuroscience, Behavioral Neuroscience, and Neuroethology; particularly questions that are difficult to address in rodents.  We focus on two types of behaviors: (1) Spatial behaviors: navigation, and spatial learning & memory; and (2) Social behaviors: including social memory. We focus mostly on the hippocampal formation and prefrontal cortex, and we ask: What are the neural codes that underlie complex natural behaviors such as navigation and sociality?  To pursue these questions, we develop world-unique Neurotechnologies – in particular, we develop tiny wireless-electrophysiology devices (neural loggers), weighing only a few grams, which enable recording > 100 neurons simultaneously from the bat's brain during natural behaviors, including flight, navigation, and social interactions with multiple individuals. These loggers include also many on-board behavioral sensors – ultrasonic microphone, motion sensor, altimeter, and GPS – allowing asking unique experimental questions in freely behaving, unrestrained animals. Our study species, Egyptian fruit bats, are easy to work with, and are excellent navigators and highly-social mammals – making them a great model organism for behavioral neuroscience, learning & memory, and social neuroscience. They are also large bats, weighing ~150-180 gr – allowing them to fly freely while carrying our neural-loggers.  This allows us to conduct experiments in world-unique experimental setups: a 700-meter long tunnel, 60x35-meter large flight maze, 3D flight-rooms, social rooms for recording in socially-ineracting animal groups, and we even perform electrophysiological recordings outdoors on a remote oceanic island.  Our long-term vision is to develop a "Natural Neuroscience" approach for studying the neural basis of behavior – tapping into the animal's natural behaviors in complex, large-scale, naturalistic settings – while not compromising on rigorous experimental control. We firmly believe that pursuing such an approach will lead to novel and surprising insights about the Brain.

Recent Discoveries

• We discovered that in flight, 3D hippocampal place cells have nearly spherical 3D place fields. 
• Recordings in the bat presubiculum revealed 3D head-direction cells, which could serve as a 3D compass; and surprisingly, this compass followed a toroidal coordinate system – providing an interesting biological solution to the discontinuity and non-commutativity problems associated with a standard spherical coordinate system. 
• Recordings in entorhinal cortex of flying bats reveled 3D grid cells that exhibited fixed local distances between firing-fields, but no global hexagonal lattice – arguing against many of the prevailing theories on the function of grid cells, which rely on lattice-like periodicity. 
• We discovered a new population of neurons in the hippocampus that are tuned to the egocentric direction and distance to navigational goals - a vectorial representation of spatial goals, which could provide a neural mechanism for goal-directed navigation. 
• In two studies (one and two) we showed nonoscillatory phase-coding in bat place-cells and grid-cells, without any theta oscillations – suggesting that phase-coding, but not oscillations, is conserved across species. 
• Behavioral studies included the discovery of a surprising optimization principle in the sonar system of Egyptian fruit bats; and outdoor research where we tracked bat navigation in the wild, using tiny GPS dataloggers – which provided evidence for a 'cognitive map' on a 100-km scale in bats. 
• We constructed a huge behavioral setup – a 200-meter long tunnel – and found that in bats flying in a very large environment, hippocampal CA1 neurons exhibit a surprising neural code for space – a multifield multiscale code – where the fields of the same neuron differed up to 20-fold in size; theoretical analysis showed that this multiscale code reduced dramatically the decoding-errors.
• When studying the neural basis of social behaviors, we discovered a population of hippocampal neurons that represent the spatial position of a conspecific bat, in allocentric coordinates ; these "social place-cells" may underlie social-spatial cognition in bats and other mammals.
• In pairs of bats flying in the long tunnel, hippocampal neurons exhibited extreme dynamism of the neural code – rapidly switching between coding position when flying alone, to jointly coding position x distance when encountering another bat.
• For more information, see our Publications page.

Positions Available

We are looking for outstanding, highly motivated students who are interested in behavioral neuroscience and systems neuroscience.  Students in the lab come from a variety of academic backgrounds, including Neuroscience, Biology, Psychology, Physics, Mathematics, and Engineering.  We love these diverse perspectives !   We often combine experimental and theoretical / computational approaches to investigate key questions in systems and behavioral neuroscience.

Interview in Nature

World-Unique Experimental Setups & Tools