Biology subjects

Harpaz-Rotem, I.

Publications and source records attributed to Harpaz-Rotem, I..

3 recordsLinked to original sources

bioRxiv2025

Beta bursts mediate amygdala gating of hippocampal emotional encoding

The amygdala and hippocampus are key structures in emotional processing, yet the transient neural dynamics coordinating their interaction remain poorly understood. We simultaneously recorded single-neuron activity and local field potentials from these regions in epilepsy patients performing an emotional image-rating task. Neurons in both areas exhibited firing rate changes predictive of subjective emotional valence. While conventional spectral analysis revealed no valence-specific patterns, beta bursts (13-30 Hz)--transient, high-power events-were uniquely modified by task features. In both regions, beta bursts were associated with increased gamma amplitude and enhanced phase coherence, with beta-gamma phase-amplitude coupling capturing emotion-related dynamics. Critically, amygdala beta bursts were associated with strong suppression of hippocampal firing, coinciding with interneuron activation, during negative valence/highest arousal processing, whereas hippocampal bursts showed no reciprocal influence. These findings suggest that beta bursts may represent a temporally precise neural correlate of emotional appraisal and a candidate mechanism for targeted neuromodulation in mood disorders.

neuroscience↗

bioRxiv2022

Neural patterns differentiate traumatic from sad autobiographical memories in PTSD

For people with post-traumatic stress disorder (PTSD), recalling traumatic memories often displays as intrusions that differ profoundly from processing of regular negative memories. These mnemonic features fueled theories speculating a qualitative divergence in cognitive state linked with traumatic memories. Yet to date, little empirical evidence supports this view. Here, we examined neural activity of PTSD patients who were listening to narratives depicting their own memories. An inter-subject representational similarity analysis of cross-subject semantic content and neural patterns revealed a differentiation in hippocampal representation by narrative type: Semantically similar sad autobiographical memories elicited similar neural representations across participants. By contrast, within the same individuals, semantically thematically similar trauma memories were not represented similarly. Furthermore, we were able to decode memory type from hippocampal multivoxel patterns. Finally, individual symptom severity modulated semantic representation of the traumatic narratives in the posterior cingulate cortex. Taken together, these findings suggest that traumatic memories are a qualitatively divergent cognitive entity.

neuroscience↗

bioRxiv2020

A Shift from Value- to Saliency- Neural Encoding of Subjective Value in Combat Veterans with PTSD during Decision Making under Uncertainty

Military personnel engaged in combat are vulnerable to Posttraumatic Stress Disorder (PTSD), following traumatic experiences in the battlefield. Prior research has mostly employed fear-related paradigms to unravel neural underpinnings of fear dysregulation in individuals with PTSD. The ability to acquire and update fear responses depends critically on the individuals ability to cope with uncertainty, yet the role of individual uncertainty attitudes in the development of trauma-related psychopathology has hardly been examined. Here, we investigated the association between PTSD-related alterations and the subjective valuation of uncertain outcomes during decision-making. We used a monetary gambling paradigm inspired by behavioral economics in conjunction with fMRI and explored neural markers of both vulnerability and resilience to PTSD in a group of combat veterans. Behaviorally, PTSD symptom severity was associated with increased aversion to uncertainty. Neurally, activity in the ventromedial prefrontal cortex (vmPFC) during valuation of uncertain options was associated with PTSD symptoms, an effect which was specifically driven by numbing symptoms. Moreover, the neural encoding of the subjective value of those uncertain options was markedly different in the brains of veterans diagnosed with PTSD, compared to veterans who experienced trauma but did not develop PTSD. Most notably, veterans with PTSD exhibited enhanced representations of the saliency of rewards and punishments in the neural valuation system, especially in ventral striatum, compared with trauma-exposed controls. Our results point to a link between the function of the valuation system under uncertainty and the development and maintenance of PTSD symptoms, and stress the significance of studying reward processes in PTSD.

neuroscience↗