Resources
Authors & Affiliations
Krista Wahlstrom, Justin Campbell, Martina Hollearn, Markus Adamek, James Swift, Lou Blanpain, Tao Xie, Peter Brunner, Stephan Hamann, Amir Arain, Lawrence Eisenman, Joseph Manns, Jon Willie, Cory Inman
Abstract
Studies suggest the basolateral amygdala (BLA) modulates memory-consolidation processes via interactions with downstream brain regions like the hippocampus. Furthermore, direct electrical stimulation of the BLA in humans enhances declarative memory, and this memory enhancement is marked by oscillatory interactions between the BLA and hippocampus. However, the BLA disproportionately projects to the anterior hippocampus compared to the posterior hippocampus, regions that process non-spatial information about objects and spatial information about scenes, respectively. Nevertheless, the premise that the BLA prioritizes some kinds of memories over others has not been directly tested in humans. In the current study we tested whether brief electrical stimulation of the BLA could differentially enhance declarative memory for specific images of objects and scenes. Epilepsy patients undergoing seizure monitoring via intracranial depth electrodes viewed a series of images of neutral objects and scenes, half of which were immediately followed by brief, low-amplitude electrical stimulation of the BLA. Amygdala stimulation enhanced memory for object images but not scene images when patients were given a recognition-memory test the next day. We also leveraged direct electrical stimulation of the BLA to interrogate the effective connectivity between the amygdala and hippocampus. Using Single Pulse Evoked Potentials (SPEP) we determined how the amygdala interacts with the hippocampus to favor memory for objects compared to scenes. Overall, our results suggest that the BLA initiates memory prioritization processes by differentially engaging the anterior vs. posterior hippocampus, providing fundamental insight into how BLA projections to hippocampal regions contribute to the neural dynamics of memory prioritization.