How do high- and low-frequency repetitive transcranial magnetic stimulations modulate the temporal cortex

Area of Science:

• Neuroscience
• Neuromodulation
• Auditory Neuroscience

Background:

• Repetitive transcranial magnetic stimulation (rTMS) is increasingly used to modulate brain activity.
• Few studies have investigated rTMS effects on nonmotor cortical excitability, particularly in the temporal lobe.
• Auditory verbal hallucinations are associated with impaired sensory gating, a process potentially measurable by auditory evoked potentials.

Purpose of the Study:

• To investigate the neuromodulatory effects of low- and high-frequency rTMS on cortical excitability in the temporal lobe.
• To assess the impact of temporal rTMS on auditory evoked potential P50 amplitude and P50 ratio.
• To determine if temporal rTMS influences sensory gating.

Main Methods:

• Twenty-four healthy subjects participated in the study.
• Auditory evoked potentials (AEPs) were recorded before and after rTMS.
• Low- and high-frequency rTMS were applied to the temporal lobe, and P50 amplitude and P50 ratio were measured.

Main Results:

• Both low- and high-frequency rTMS resulted in a decrease in P50 amplitude, indicating a modulation of cortical excitability.
• No significant changes were observed in the P50 ratio after either low- or high-frequency rTMS.
• The effects of low- and high-frequency rTMS on P50 amplitude were similar.

Conclusions:

• Temporal rTMS, regardless of frequency, appears to exert a similar neuromodulatory effect on cortical excitability.
• Auditory sensory gating, as measured by the P50 ratio, may not be significantly modulated by rTMS applied to the temporal lobe.