DLPFC Stimulation Suppresses High-Frequency Neural Activity in the Human sgACC

Area of Science:

• Neuroscience
• Psychiatry
• Brain Stimulation

Background:

• Transcranial magnetic stimulation (TMS) is a non-invasive brain stimulation technique used to treat depression.
• The dorsolateral prefrontal cortex (DLPFC) is a common target for TMS, hypothesized to work by inhibiting the subgenual anterior cingulate cortex (sgACC).
• Understanding the precise neural mechanisms, particularly in deep brain regions like the sgACC, remains challenging.

Purpose of the Study:

• To investigate how TMS applied to the DLPFC influences neural activity in the sgACC.
• To elucidate the neural mechanisms underlying the antidepressant effects of TMS.

Main Methods:

• Recruited two neurosurgical patients with indwelling electrodes.
• Delivered TMS pulses to the DLPFC while simultaneously recording local field potentials from the sgACC.
• Performed spectral analysis to examine changes in neural activity.

Main Results:

• TMS stimulation of the DLPFC led to a decrease in high-frequency activity (HFA; 70-180 Hz) in the sgACC.
• This HFA decrease was more pronounced in the sgACC compared to other recorded regions.
• TMS-evoked HFA power showed an anticorrelation between DLPFC and sgACC, while low-frequency phase locking was enhanced.

Conclusions:

• Findings suggest that TMS to the DLPFC effectively suppresses neural firing in the sgACC.
• This suppression of sgACC activity may represent a key mechanism for the mood-regulating effects of TMS in depression treatment.