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Catatonia Brain Circuits: Limbic System Review

MHD featured image for catatonia, limbic-system brain circuits, and psychomotor shutdown.

A 2026 systematic review argues that catatonia should be read as a limbic-cortical circuit syndrome, with motor shutdown tied to brain systems for threat, salience, motivation, and emotional regulation. Research Highlights 20 studies met criteria: the 2026 review screened 1,792 records, assessed 54 full texts, and included 20 articles: 13 observational studies and 7 case …

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Olfactory MRI Radiomics Link pTau217 to Alzheimer’s Cognition

MHD featured image for olfactory MRI radiomics, pTau217, and Alzheimer's disease cognitive impairment.

A 2026 multi-cohort Alzheimer’s disease study found that MRI radiomics from the hippocampus and amygdala linked plasma pTau217 and smell identification to cognitive impairment — with more added cognitive signal than simple regional volume. The result is useful because it points to a possible bridge between blood biomarkers and brain-circuit damage, but it is still …

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Subcortical Connectivity Differs in Schizophrenia, Bipolar, Depression

MHD featured image for subcortical connectivity patterns across schizophrenia, bipolar disorder, and depression.

A 2026 resting-state fMRI study of 800 adults found intra-thalamic hypoconnectivity across schizophrenia, bipolar disorder, and major depression, but schizophrenia showed far broader subcortical dysconnectivity than bipolar disorder or depression.1 The calibrated read is that these diagnoses may share a thalamic vulnerability while diverging in striatal and limbic circuitry. Research Highlights Shared thalamic deficit: In …

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Naltrexone Reduced Reappraisal Distress in 38-Person Threat fMRI Trial

Photoreal illustration of brain with vmPFC, amygdala, and threat-processing circuitry highlighted under pharmacological challenge.

The endogenous opioid system has been a candidate target for novel anxiety treatments, but a 2026 placebo-controlled crossover fMRI study in 38 healthy volunteers ran opposite the hypothesis: instead of increasing threat-related distress and amygdala reactivity, 50 mg oral naltrexone reduced subjective distress during cognitive reappraisal (p = 0.044, d = 0.57) and shifted ventromedial …

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Emotional Memory fMRI Separates Arousal From Valence

Photoreal illustration of brain with amygdala and prefrontal cortex highlighted, conveying dual-pathway emotional memory mechanism.

A 2026 fMRI study of 1,006 healthy young adults found that emotional pictures were remembered better than neutral pictures, but the brain signal split after arousal was modeled: amygdala and insula effects dropped out, while negative and positive valence kept separate cortical encoding patterns.1 Research Highlights Emotional pictures had the recall advantage: in the full …

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Astrocyte Calcium Signals Shape Amygdala Fear Memory and Extinction in Mice

Photoreal illustration of astrocytes interacting with neurons in the amygdala, conveying glial role in fear circuit dynamics.

A 2026 Nature mouse study found that basolateral amygdala astrocyte Ca2+ signals tracked fear retrieval and extinction, then showed causality: 3 mg/kg CNO manipulations of astrocyte DREADDs pushed early-extinction freezing in opposite directions while both disrupting later extinction retrieval.1 Research Highlights Astrocytes tracked fear state: after 3 tone-shock pairings and 2 days of 25 cue-only …

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Resting Brain Connectivity Predicts Fear Extinction Learning

Photoreal illustration of brain network connections in the fear-extinction circuitry, with imagery linking amygdala and prefrontal regions.

A 2026 multimodal MRI analysis of 509 healthy adults found that fear acquisition, extinction learning, and renewal were not predicted by one generic “fear circuit” score: functional connectivity predicted acquisition, structural connectivity predicted extinction, and effective connectivity was the only renewal signal.1 The extinction result is the clinically interesting piece because exposure therapy depends on …

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