MR diffusion tensor imaging detects rapid microstructural changes in amygdala and hippocampus following fear...

Area of Science:

• Neuroscience
• Neuroimaging
• Brain Plasticity

Background:

• Fear conditioning (FC) involves cellular and molecular plasticity in amygdala and hippocampal circuits.
• Altered fear circuit dynamics are linked to anxiety disorders, including posttraumatic stress disorder (PTSD).
• In vivo evidence of early fear circuit changes following FC is currently unknown.

Purpose of the Study:

• To investigate if in vivo diffusion tensor imaging (DTI) can detect rapid microstructural changes after fear conditioning (FC).
• To establish an experimental mouse model for studying PTSD-related brain alterations.
• To compare DTI measurements before and after FC in mice.

Main Methods:

• Utilized a repeated measures design with in vivo DTI.
• Measured DTI parameters in mice (n=18) before, 1 hour after, and 1 day after FC.
• Employed voxel-wise repeated measures analysis to assess changes in fractional anisotropy (FA).

Main Results:

• Fractional anisotropy (FA) showed significant changes in the amygdala and hippocampus post-FC.
• FA increased then decreased in the amygdala, and decreased then increased in the hippocampus.
• DTI revealed distinct, rapid in vivo microstructural responses in fear circuits following FC.

Conclusions:

• DTI is sensitive to rapid, in vivo microstructural changes in brain regions mediating FC.
• FC elicits distinct and rapid in vivo responses in the amygdala and hippocampus.
• DTI indices show potential as a translational tool for early PTSD risk detection.