In an innovative new publication from the Anderson lab at Caltech, ‘An approximate line attractor in the hypothalamus encodes an aggressive state,’ Nair et al. use the Inscopix miniscope to investigate the population dynamics of the ventromedial hypothalamus (VMHvl) during aggressive behavior.
This brain region was previously shown to cause attack behavior when optogenetically stimulated, although, in apparent contradiction, very few neurons from the region exhibited time-locked activity with aggressive episodes. To address this seeming inconsistency, Nair et al. showed computational prowess by analyzing previously recorded in vivo calcium imaging data from over 300 neurons in this deep brain region of the hypothalamus during aggressive, social behaviors using the nVista system from three previous studies in the Anderson lab (Remedios et al., (2017) Nature; Karigo et al., (2021) Nature; Yang et al., (2022) Nature).
They demonstrated that in a manner more often reported for higher-order cortical and hippocampal regions, the VMHvl encodes the phases of attack through a specific type of population activity pattern–an ‘approximate line attractor.’ Using dimensionality reduction strategies, they were able to differentiate specific behaviors like sniffing, from attack or dominance mounting behaviors using only the recorded neural activity. To emphasize the novelty of this finding, they further showed that a neighboring hypothalamic region, the medial preoptic nucleus (MPOA), exhibits entirely different action-specific coding for related social behaviors.
Thus, the activity of the VMHvl subverts expectations by representing attack behavior as an emergent property of the neuronal population, rather than through action-specific cell populations. We congratulate Nair et al. on changing our conceptions of neural representations in the hypothalamus, and look forward to other cool, miniscope research findings!
Dr. Peter Schuette, is a Field Scientific Consultant for the US, West Coast region and a Neuroscience PhD with expertise in neuromodulation and memory from Dr. Nanthia Suthana’s lab at UCLA. As a post-doctoral fellow, under the joint mentorship of Drs. Avishek Adhikari and Jonathan Kao at UCLA, Peter extensively researched threat-induced behaviors using computational and systems neuroscience approaches. We are thrilled to have Peter contribute to the successes of the Inscopix miniscope community!