Data from: Network-level changes in the brain underlie fear memory strength

The strength of a fear memory significantly influences whether it drives
adaptive or maladaptive behavior in the future. Yet, how mild and strong
fear memories differ in underlying biology is not well understood. We
hypothesized that this distinction may not be exclusively the result of
changes within specific brain regions, but rather the outcome of
collective changes in connectivity across multiple regions within the
neural network. To test this, rats were fear conditioned in protocols of
varying intensities to generate mild or strong memories. Neuronal
activation driven by recall was measured using cfos immunohistochemistry
in 12 brain regions implicated in fear learning and memory. The
interregional coordinated brain activity was computed and graph-based
functional networks were generated to compare how mild and strong fear
memories differ at the systems level. Our results show that mild fear
recall is supported by a well-connected brain network with small-world
properties in which the amygdala is well-positioned to be modulated by
other regions. In contrast, this connectivity is disrupted in strong fear
memories and the amygdala is isolated from other regions. These findings
indicate that the neural systems underlying mild and strong fear memories
differ, with implications for understanding and treating disorders of fear
dysregulation.