How does the brain generate and maintain a persistent high-aggression state? While
pathological, persistent aggression is a common symptom in many diverse mental health disorders
including schizophrenia, bipolar disorder, post-traumatic stress disorder, autism, Rett syndrome, and
traumatic brain injury, we lack a fundamental understanding of the neural mechanisms underlying
persistent social states. Many models of aggression posit that this dysregulation occurs through the
failure of “top-down” inhibitory control of subcortical circuits for aggression, through the circuit and
synaptic basis for these models remain unclear. Here, we propose that pathological aggression may
hijack circuit mechanisms used to generate persistent aggressive states in adaptive contexts. In
particular, the experience of aggression has long been known to facilitate the emergence of a persistent
high-aggression state, enabling animals to defend territory and status across long periods of time.
Examining how experience “updates” neural circuits in the healthy brain to facilitate future aggression
provides a unique window on how these circuits become dysregulated under pathological conditions.
What are the neural mechanisms underlying experience-dependent updating? To explore this,
we will look longitudinally at the changing relationship between neural activity in the ventromedial
hypothalamus, ventrolateral area (VMHvl), an aggression output area with a well-described role in
aggression in both sexes, and its “upstream” inhibitory inputs. In this proposal, we will test the novel
hypothesis that aggression experience stabilizes a persistent aggressive state through a circuit
“rerouting” mechanism rather than changes in the activity of inhibitory control loci.
Using a variety of methods for supervised and unsupervised behavioral analysis, virally
mediated anatomical tracing, synaptic physiology, optogenetics and cellular resolution high-density
recordings, we will look longitudinally at how experience alters the fundamental properties of this circuit
to implement behavioral change. First, we will map the putative identity of circuit nodes with the
architectural capacity to reroute inhibition and characterize the changes in synaptic strength of this
circuit across experience. Next, we will specifically examine the relationship between the activity of the
regulatory input and the circuit-level output across experience. Lastly, we will perform high-density
population recordings to elucidate the changes in the underlying computations being performed by the
circuit to stabilize a high aggression state. Together, these data will provide a comprehensive
integrated framework for understanding how experience generates a persistent behavioral state, and
will pave the way for novel activity-dependent tools that may be able to detect neural signatures of
experience and behavioral persistence in patient populations at risk for aggression dysregulation.