Past events

The effect of the detailed connectivity of a neural circuit on its function and the resulting behavior of the organism, is a key question in many neural systems Here, I study the circuit for nociception in C elegans which is composed of the same neurons in the two sexes, that are wired differently I set out to elucidate how the topological design of a compact neuronal circuit affects its behavioral output, how genetic sex affects the connectivity and dynamics of a circuit, and how specific circuit components orchestrate together to establish the behavioral sexual dimorphism I used behavioral assays, optogenetics calcium and glutamate imaging, measurement of protein expression, artificial connectivity, molecular and genetic tools, and show that the nociceptive sensory neurons respond similarly in the two sexes, yet the animals display sexually dimorphic behaviors to the same aversive stimuli To uncover the role of the downstream network topology in shaping behavior, I measured the neuronal activity of a key interneuron, and found dimorphic responses to the stimulus as well as dimorphic intrinsic basal interneuron activity I then showed that neuron specific genetic sex plays a role in shaping connectivity and circuit dynamics, and proceed to an artificial subtle synaptic rewiring which flips behavior between sexes Interestingly, when presented with aversive cues, rewired males were compromised in finding mating partners, suggesting that network topologies that enable efficient avoidance of noxious cues have a reproductive " My results present a deconstruction of the design of a neural circuit that controls sexual behavior, and how to reprogram it

Working memory (WM), the process through which information is transiently maintained and manipulated over a brief period of time, is essential for most cognitive functions. However, the mechanisms underlying the generation and stability of WM neuronal representations at the population level remain elusive. To uncover these mechanisms, we trained head-fixed mice to perform  an olfactory working memory task and used optogenetics to delineate circuits causal for behavioral performance. We used mesoscopic and light bead  two photon imaging to record from up to 35,000 secondary motor cortical neurons simulataneously across multiple days and show differential stabilization of different task parameters with learning and practice of the task. We find that cortical working memory representations causal for task performance are highly volatile but only stabilize after multiple days of practice well after task learning. We hypothesize that representational drift soon after learning may allow for higher levels of flexibility for new task rules.  I will also review some of the new open-source tools developed for large-scale imaging of neural activity patterns in freely behaving animals.

The ability to approach or avoid conspecifics is essential for survival in many species, and the nature of the social interaction often determines it. Positive or rewarding interactions with conspecifics lead individuals to approach them, while aversive or threatening interactions lead individuals to avoid them. The rewarding or aversive nature of these interactions is defined as social valence. I will discuss the neuronal circuits and mechanisms underlying social valance encoding.  

Perceivers experience the world around them as organized, with sensory impressions clearly separated into entities. What makes a perceptual object, and what framework relates it to its composing features? A key insight is that under natural conditions, feature and object information is acquired actively, via sensor movements. Motor and sensory variables affect one another reciprocally, forming a closed-loop system. I therefore hypothesize that percepts signifying an object emerge when the motor-sensory loop’s dynamics converge towards a stable attractor. Using snout and whisker tracking data from freely-moving behaving rats, I outline such an attractor for object detection. I demonstrate that whisker-object contact elicits robust signals on a motor-sensory phase-plane, comprised of the derivatives of whisker base-angle and base-curvature. Over consecutive contact epochs, trajectories on the phase-plane converge to a specific area. The area is characterized by a basin of attraction during contact, more so than in free-air whisking. Differences in head-movement behavior are associated with proximity to the attractor, suggesting that the animal makes use of this proposed coding-scheme. Finally, to build upon these insights, I present a novel paradigm for the study of volitional perceptual exploration, in both rewarded and unrewarded contexts. It supports high-resolution study of motor-sensory development starting at birth, throughout task-learning and until mastery. Taken together, these results highlight a novel framework for the study of the perception of features and objects as motor-sensory attractors.