Gaby Maimon, Ph.D.
Investigator, Howard Hughes Medical Institute
Humans and animals have the remarkable capacity to remember spatial locations, time intervals, event probabilities, and other contextually relevant variables. The Maimon lab aims to understand how brains form quantitatively precise memories of such variables and how these memories guide behavior. The group’s long term goal is to inform the nature of cognition and abstract thought—from molecular contributors, through neural circuits, to behavior.
Psychologists turn to notions such as working memory, event prediction, stimulus valuation, and internal spatial maps to help explain human and animal behavior. However, the intellectual frameworks for thinking about these cognitive concepts, as well as our understanding of their neural implementation, remain in their infancy.
Work in the Maimon lab is inspired by the fact that insects, despite having tiny brains, appear capable of performing specific cognitive operations extremely well. For example, desert ants know if they are 30 or 90 meters away from their nest and honeybees communicate, with their waggle dance, if a flower patch is 30 or 90 degrees to the left of the sun. By seeking comprehensive descriptions of how insect brains perform such quantitatively precise internal calculations, the lab aims to discover general principles of cognition across animals.
The group studies the genetically tractable fruit fly, Drosophila melanogaster, and the lab has pioneered one of the main approaches it uses: monitoring neural activity in flies performing flight or walking behaviors in virtual reality, while glued to a tiny platform.
In recent work, the Maimon lab discovered a neuronal circuit that allows insects to build and update an internal, compass-like sense of orientation. This circuit operates even in complete darkness, wherein flies must mathematically integrate their angular velocity over time—i.e., tally how fast they are rotating left or right at each moment—so as to update their sense of angular heading. The central features of this biological circuit are nearly identical to those proposed in classic computer models on how mammalian brains build a sense of heading. This fly work thus begins to suggest what might happen in the human brain as we get our bearing after exiting a subway station, or when an Alzheimer’s patient is confused about where they are in space.
Ongoing experiments are focused on how fly brains calculate and use a diverse set of quantitative variables. For example, the group is studying how navigating flies remember specific angles or 2D locations in spatial environments and then use these memories to guide where to walk. The lab is also examining how flies rank the suitability of a given location for egg-laying relative to other nearby locations, and how flies predict the likelihood of salient events occurring in the immediate future.
As the neurons and neural networks mediating the abovementioned calculations become clear, the lab is increasingly studying sub-cellular mechanisms that contribute to their implementation. Thus, the group seeks to describe across multiple levels of biological organization—from molecules, to circuits, to behavior—how brains internally compute the values of variables, store those values in memory, and, ultimately, use those memories to compel goal-directed actions. Because psychologists and neuroscientists lack a deep understanding of how such operations are implemented in any brain, this work in flies should help to springboard the development of a similarly rich understanding of cognition in larger nervous systems.