Systems Neuroscience

ABSTRACT: The lateral habenula (LHb) impacts motivated behavior through dense direct and indirect projections to midbrain dopaminergic and serotonergic neurons. Some LHb neurons project directly to midbrain dopaminergic or serotonergic neurons; others project indirectly through one of multiple types of midbrain GABAergic neurons. Similar to dopaminergic neurons, the LHb encodes reward prediction error (RPE) - the discrepancy between expected and actual value – a powerful computation that guides learning from environmental feedback.

PROJECT SUMMARY When Confucius said, “Tell me who are your friends, and I’ll tell you who you are,” he was noticing that how we behave and communicate is shaped by who we choose to hang out with every day. We constantly mimic the mannerisms and behaviors of friends and loved ones. Yet the neural basis of how we imitate, and more importantly who we choose to emulate and why, is largely unknown. Parrots provide a powerful yet untapped model system for social learning.

Project summary Although single neurons occasionally project to a single downstream target, it is more often the case that their axons collateralize and project to multiple distinct anatomical areas. This feature of neuroanatomy has been appreciated for over 100 years and is theorized to be critical to coordinating brain-wide states. Despite this, collateral projections have largely been overlooked in contemporary neuroscience.

Summary Genetic technologies have revolutionized the way scientists can dissect out brain circuitry by inserting G protein-coupled receptors that enable selective modulation of neurons in target structures. Amongst them, a promising tool,DREADDS (designer receptors exclusively activated by designer drugs) is used to modulate neural activity pharmacologically in targeted brain regions. Unfortunately, DREADDS also require invasive methods to deliver the genes that express the receptor.

Summary Strategic behaviors often take account of uncertainty. For example, if we are presented with two conflicting pieces of information, we give less weight to the more uncertain source of information – i.e., the source of information that leads to lower accuracy overall. Notably, even insects behave as if they make strategic use of their own uncertainty. Importantly, the neural correlates of uncertainty are essentially unknown. In this collaborative project, we will use modeling and neural imaging to identify the neural correlates of uncertainty.

Project Summary / Abstract Systems neuroscience has viewed the brainstem noradrenergic nucleus, Locus Coeruleus (LC), as the source of a global arousal signal, which modulates cognitive functions by altering operations throughout the entire central nervous system. This is achieved, presumably, by this small collection of only ~1,600 neurons in rodents spiking synchronously.

ABSTRACT A critical step towards understanding how neural circuits drive behavior is the ability to record the activity of all neurons in an organism while it interacts with its environment in an unconstrained manner. A promising vertebrate model system in this regard is the zebrafish larva, which performs complex visually-driven behaviors such as hunting from an early age, and due to its transparency allows large-scale neural imaging at single- neuron resolution.

Although neuroscience has provided a great deal of information about how neurons work, the fundamental question of how neurons function together in a network to produce cognition has been difficult to address. Our group has been at the forefront of developing methods that allow large scale monitoring of identified neurons, monitoring of voltage signals by optical means and elucidation of subcellular events in dendrites, all of which can now be done in awake behaving animals.

Project Summary Working memory, the ability to temporarily hold multiple pieces of information in mind for manipulation, is central to virtually all cognitive abilities. Recent technical advances have opened an unprecedented opportunity to comprehensively dissect the neural circuit mechanisms of this ability across multiple brain areas. The task to be studied is a common form of decision-making that is based on the gradual accumulation of sensory evidence and thus relies on working memory.

Understanding the mechanisms that the nervous system uses to control movement is critical for understanding brain and behavior, and one of the fundamental questions in neuroscience. The control of movement emerges from the activity of different motor control centers, that converge onto output systems, mostly located in the spinal cord. While the spinal circuits that underlie different aspects of motor control have been relatively well characterized, the way by which these circuits are coordinated by supraspinal motor control centers remains elusive.