Increased functional connectivity between motor and arousal brainstem nuclei and sensorimotor cortex in therapy...

Area of Science:

• Neuroscience
• Psychiatry
• Medical Imaging

Background:

• Neural correlates of treatment-resistant depression (TRD) remain incompletely understood.
• Brainstem functional connectivity (FC) in TRD is under-investigated, despite the brainstem's role in depression.
• Key brainstem nuclei involved in motor and arousal functions are implicated in depressive disorders.

Purpose of the Study:

• To investigate brainstem functional connectivity (FC) in patients with treatment-resistant depression (TRD).
• To explore the relationship between brainstem-cortical FC and the severity of depressive and somatic symptoms in TRD.

Main Methods:

• Resting-state functional MRI (fMRI) was performed on 23 TRD patients and 23 healthy controls.
• Seed-based connectivity (SBC) analysis was conducted using 37 brainstem seeds associated with motor and arousal functions.
• Correlations between significant FC alterations and symptom severity were calculated.

Main Results:

• TRD patients exhibited increased FC between brainstem nuclei (dorsal raphe nucleus, locus coeruleus, cuneiform nucleus, periaqueductal gray) and sensorimotor cortical regions (precentral and postcentral gyrus).
• Specific brainstem regions, including the anterior and lateral divisions of the mesencephalic reticular formation, showed distinct patterns of altered FC with frontal and temporal cortical areas.
• Increased FC between the locus coeruleus and the postcentral gyrus was positively correlated with depressive and somatic symptom severity.

Conclusions:

• Treatment-resistant depression is associated with altered functional connectivity between the brainstem and sensorimotor/frontal cortical networks.
• These brainstem-cortical connectivity changes may represent a neural mechanism underlying the severity of depressive and somatic symptoms in TRD.
• Further research into brainstem pathways could offer novel therapeutic targets for TRD.