Trait-like differences in underlying oscillatory state predict individual differences in the TMS-evoked response.

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Brain Connectivity

Background:

• Combined transcranial magnetic stimulation (TMS) and electroencephalography (EEG) reveal how cognitive states influence brain activity.
• Previous studies showed TMS-evoked responses (TMS-ER) differ between spatial short-term memory (STM) tasks and fixation, indicating cognitive context modulates neural responses.
• Individual variations in TMS-ER shape and sustained patterns of delay-period activity (SPDPA) were observed.

Purpose of the Study:

• To investigate if individual differences in SPDPA predict spectral properties of TMS-ER.
• To determine if these relationships are specific to task-relevant brain regions, such as the prefrontal cortex in STM tasks.

Main Methods:

• Utilized TMS-EEG and source-localization techniques to derive TMS-evoked responses (TMS-ER).
• Analyzed sustained patterns of delay-period activity (SPDPA) and their spectral properties.

Main Results:

• Significant individual differences in SPDPA were found.
• These SPDPA variations predicted individual differences in frequency-dependent TMS-ER parameters, particularly in task-relevant areas like the prefrontal cortex for STM.
• Test-retest reliability confirmed the stability of SPDPA over sessions.

Conclusions:

• Individual differences in SPDPA are linked to trait-like physiological profiles.
• This provides insight into how individual variations in TMS effects relate to stable neural characteristics.
• The findings highlight the role of intrinsic brain dynamics in modulating responses to external stimulation.