Closed-loop brain stimulation augments fear extinction in male rats

Dysregulated fear reactions can result from maladaptive processing of trauma-related memories. In post-traumatic stress disorder (PTSD) and other psychiatric disorders, dysfunctional extinction learning prevents discretization of trauma-related memory engrams and generalizes fear responses. Although PTSD may be viewed as a memory-based disorder, no approved treatments target pathological fear memory processing. Hippocampal sharp wave-ripples (SWRs) and concurrent neocortical oscillations are scaffolds to consolidate contextual memory, but their role during fear processing remains poorly understood. Here, we show that closed-loop, SWR triggered neuromodulation of the medial forebrain bundle (MFB) can enhance fear extinction consolidation in male rats. The modified fear memories became resistant to induced recall (i.e., 'renewal' and 'reinstatement') and did not reemerge spontaneously. These effects were mediated by D2 receptor signaling-induced synaptic remodeling in the basolateral amygdala. Our results demonstrate that SWR-triggered closed-loop stimulation of the MFB reward system enhances extinction of fearful memories and reducing fear expression across different contexts and preventing excessive and persistent fear responses. These findings highlight the potential of neuromodulation to augment extinction learning and provide a new avenue to develop treatments for anxiety disorders.

Premorbid screening of healthy students may carry latent liability for schizophrenia or bipolar affective disorder with neurocognitive and neurophenomenological methods

Introduction

This study was carried out to map psychosis spectrum disorder risk factors.

Objectives

Our goal was to find what kind of instrumental methods may help to detect latent liabilities for schizophrenia and bipolar affective disorder

Methods

Using online questionnaires n=710 students were screened. Groups were formed based on the inclusion criteria: N = 25 people prone to mood swings, N = 30 people prone to odd experiences and delusive thinking, and a normal control group with N = 30 people. Personality, temperament, self-experiences, affectivity scales, and cognitive screening were conducted in addition to actigraphy coupled with a mobile application for detecting subjective experiences (EMA). Furthermore, instrumental examination of self-agency, testing time interval discrimination and (re)production, eye-tracking, EEG-microstates, and laboratory testing of inflammatory, immunologic and cardio-metabolic measures of allostatic load were applied.

Results

Self-experience disorders: both risk groups showed significantly higher scores than the control group (CG). Self-agency: based on incorrectly attributed responses, the positive schizotypy risk factor (PSF) group differed from the CG (p = 0.003). Antisaccade study: the PSF group showed a difference from the CG (p = 0.002). Actigraphy: based on the distributions of diurnal cumulative activities, it distinguished those with a cyclothymic risk factor (CTF) from the CG (67% probability in the k-means clustering procedure).

Conclusions

Healthy students with a latent liability for schizotypy or bipolarity could be distinguished by some targeted laboratory methods. Susceptibility for bipolarity was indicated by actigraphic analyzes, and the risk for schizotypal development was indicated by deficiencies in the self-agency experience and by anti-saccadic eye movement disorders.

Disclosure

No significant relationships.