Neuronal population representation of human emotional memory

Poster Session D - Monday, April 15, 2024, 8:00 – 10:00 am EDT, Sheraton Hall ABC

Dustin Fetterhoff¹ (dr.dustin.fetterhoff@gmail.com), Robin Hellerstedt¹, Manuela Costa¹, Johannes Sarnthein², Bryan Strange^1,3; ¹Universidad Politécnica de Madrid, ²University Hospital Zurich, ³Reina Sofia Centre for Alzheimer’s Research

Understanding how emotional processing modulates learning and memory is crucial for the treatment of neuropsychiatric disorders that lead to memory dysfunction and emotional dysregulation. We investigated how the human medial temporal lobe (MTL) supports emotional memory in both single neurons and neuronal populations during encoding and recognition of an emotional memory task in patients with medically intractable epilepsy. Our findings reveal distinct representations for both remembered compared to forgotten, and emotional compared to neutral scenes in neuronal populations located in the amygdala, hippocampus, and entorhinal cortex. Using principal component analysis (PCA) and its demixed counterpart (dPCA), we demonstrate that a distributed network of human MTL neurons exhibiting mixed selectivity on a single-unit level collectively processes emotion and memory, with a small percentage of individual neurons responding conjointly to emotion and memory despite an interaction in the recorded population. We found that neurons exhibit the highest firing rates during emotional, subsequently remembered trials, a possible mechanism for emotional memory enhancement. Additionally, we found that misses and correct rejections were similarly represented, suggesting that the neuronal populations respond to subjective, rather than veridical, judgments of novelty. Finally, we examined the relationship between neuronal spiking and both scalp EEG and intracranial LFPs. These results expand our understanding of the neural mechanisms underlying emotional memory by focusing on the activity of individual neurons rather than signals measured at more macroscopic levels, like electrical intracranial local field potentials (LFPs) and hemodynamic responses measured with functional magnetic resonance imaging (fMRI).

Topic Area: LONG-TERM MEMORY: Episodic