The Edmond and Lily Safra Center for Brain Sciences at the Hebrew University of Jerusalem Invites you to the symposium:
Advances in Brain Sciences
2024
Glimpses of the future
November 11-12, 2024
Room 2004, Goodman building, Safra Campus
Seminar Invited Speakers:
Monday, Nov 11
09:00-10:00- Hagar Lavian
TUM
Unveiling the Zebrafish Head Direction Network
Animals can use different strategies to navigate. They may guide their movements by relying on external cues in their environment or by using an internal cognitive map of the space around them. In many species, the head direction of the animal is represented by head direction neurons and is influenced by both motor and visual information. Here, we used calcium imaging and electron microscopy reconstructions to discover, for the first time in a vertebrate, a topographically organized head direction network in the larval zebrafish hindbrain. This network consists of GABAergic neurons that arborize in the interpeduncular nucleus (IPN), where their connectivity pattern supports the implementation of a ring attractor network. We further used light sheet and two-photon calcium imaging to investigate how navigationally relevant visual inputs, directional whole field motion and landmark position, are integrated in this network. We detected visually responsive neurons in the anterior hindbrain (aHB) and IPN, in which the head direction is integrated. We further show that the representation in the IPN of both these stimuli is topographically arranged in a way that aligns itself with the representation of the heading signal in this region. Using neuronal ablations, we show that the landmark responses, but not the whole field motion responses, require intact habenula input to the IPN. Overall our findings suggest the IPN as a site for integration of the heading signal from the aHB with visual information, shedding light on how different types of navigational signals are processed in the vertebrate brain.
10:00-11:00- Shirley Mark
Oxford
Flexible and abstract neural representations of structural knowledge
Relations between task elements often follow hidden underlying structural forms such as periodicities or hierarchies, whose inferences fosters performance. However, transferring structural knowledge to novel environments requires flexible representations that are generalizable over particularities of the current environment, such as its stimuli and size. In this talk, I will demonstrate through two behavioral experiments, that humans can indeed exploit such abstract structural knowledge to enhance their performance. Drawing inspiration from established neural representations in the hippocampal formation during spatial navigation, I will propose an algorithm that exploits flexible representations of abstract structural knowledge, infers the correct representation to recall and exploits it, when engaging in novel tasks. Lastly, I will describe fMRI results that suggest that such abstract representation exists in the Entorhinal Cortex, shedding light on the neural substrates involved in this cognitive process.
11:00-12:00 – João Marques
Champalimaud
How can larval zebrafish help us understand the neural basis of internal states and memories?
A central question of neuroscience is to understand the neural basis of behavior. This question is particularly enigmatic for behaviors that involve cognition, as is the case for foraging, that is modulated by internal brain states, or for tasks that rely on working memory, the ability to keep and manipulate information in mind for short periods of time. For long it was thought that these abilities were exclusive to mammals, not existing in simpler animals. In this seminar, I will challenge this idea by presenting my work studying two sophisticated behaviors that larval zebrafish have. My goal is to show that these animals, that have no cortex, and a tiny brain with only 100.000 neurons, have unexpected sophisticated cognitive abilities.
I will start by showing that larval zebrafish, while foraging for live prey, spontaneously alternate between two persistent internal states. In the exploitation state, the animal generates small localized trajectories that promote hunting. In the exploration state, the animal generates long-ranging trajectories that enhance spatial dispersion. Using tracking microscopy to monitor whole-brain neuronal activity in freely moving larvae, I discovered a dorsal raphe subpopulation which encodes the exploitation state and neurons in the habenula that trigger state transitions. This work revealed an important hidden variable that shapes the temporal structure of motivation and decision-making, showing that larval foraging is much more sophisticated than previously thought.
I will also present ongoing work, about a memory assay I developed for larval zebrafish. This assay consists on a directional cue that the animal has to memorize, a delay period, where the memory is kept, and a decision where to escape elicited by a non-directional sound. Surprisingly, larvae not only keep information in memory, but share many of the key features of mammalian working memory. Similar to primates they store memories up to 10s. Also, larvae reset the memory after decision, suggesting that it is only used if it is useful. Finally, fish combine information from distinct cues, showing they can manipulate information in memory to make better decisions. But, how is this memory stored in the larval brain? To tackle this question, I performed brain-wide calcium imaging in larvae performing the memory assay and found networks of neurons that form the memory, store it, and make decisions. As such, this work paves the way to discover how memory works in a simple larval fish. Still, the underlying principles may be preserved across species providing insights on how more complex brains, such as ours, generate working memory.
Tuesday, Nov 12
09:00-10:00 – Amit Vinograd
Caltech
The Neural Basis of Affective States
How does the brain regulate innate behaviors and emotional states? My research is driven by a vision to decode evolutionarily conserved neural circuits that regulate affective states like aggression and anxiety. In my work, I combine deep-brain 2-photon calcium imaging and holographic optogenetics, with theoretical neuroscience approaches to unravel latent manifolds of neural activity and their dynamics. One such dynamic, line attractors, is hypothesized to encode continuous variables such as eye position, working memory, and internal states. However, direct evidence of neural implementation of a line attractor in mammals has been hindered by the challenge of targeting perturbations to specific neurons within ensembles. In this talk, I will present our recent breakthroughs that demonstrate that integration and persistent activity are intrinsic properties of neurons encoding an aggressive state and highlight functional connectivity within specific neuronal ensembles. This work effectively bridges circuit and manifold levels, providing definitive evidence of intrinsic continuous attractor dynamics in a behaviorally relevant mammalian system.
10:00-11:00- Noam Saadon Grossman
Harvard
Brain-Wide Functional Specialization: From Somatomotor to Higher-Order Cognition
Sensory and motor information processing in the brain is organized in maps. In the somatomotor domain, adjacent cortical regions correspond to adjacent body parts. In this talk, I will present recent findings suggesting a similar specialized organization in brain-wide components that support higher-order cognitive functions, with a focus on the cerebellum. While traditionally associated with somatomotor functions, growing evidence suggests that the majority of the human cerebellum supports cognitive and affective functions. Using functional MRI, we found that specific cerebellar regions respond to domain-flexible cognitive control while juxtaposed regions differentially respond to language, social, and spatial/episodic task demands. Identifying these organizational principles required intensive mapping of the cerebellum within individual brains, rather than standard group-averaging methods, due to the close juxtaposition of specialized regions and individuals’ idiosyncratic anatomy. Similar organization also exists in the cerebral cortex and the caudate consistent with the presence of multiple basal ganglia – cerebellar – cerebral cortical circuits that maintain functional specialization across their entire distributed extents. The similarity between the anatomical organization of somatomotor and cognitive circuits suggests that insights from the somatomotor domain could enhance our understanding of cognition and offer valuable, potentially translational, perspectives on cognitive disorders.
11:00-12:00- Roey Schurr
Harvard
The Computational and Neural Basis of Cognitive Dynamics and Diversity
Humans adapt their behavior across multiple timescales: from rapid adjustments to changing contexts to lifelong tendencies in how they approach tasks. This variability across time and individuals offers a unique opportunity to uncover the mechanisms and fundamental principles that shape human cognition. At the same time, these sources of variability pose a challenge for identifying the cognitive strategies people use and the neural processes that support them. My research combines computational modeling and neuroimaging to uncover the strategies individuals use and reveal how their dynamics are reflected in neural activity and constrained by brain structure.
I will first describe my work on developing improved methods for mapping the human white matter using microstructural signatures from quantitative MRI. Then, I will describe my work on uncovering dynamical changes of cognition over weeks using computational modeling of longitudinal behavioral data. Finally, I will outline my future plans to reveal the principles that govern cognitive dynamics and individual differences by integrating behavioral experiments, computational models, and neuroimaging.
