Local Immediate versus Long-Range Delayed Changes in Functional Connectivity Following rTMS on the Visual Attention...

Area of Science:

• Neuroscience
• Cognitive Science

Background:

• The interhemispheric competition hypothesis posits that selective attention relies on mutual inhibition between parietal cortex connections.
• Inhibitory repetitive transcranial magnetic stimulation (rTMS) over parietal cortex induces interhemispheric imbalance, with effects potentially delayed up to 30 minutes.

Purpose of the Study:

• To investigate the temporal dynamics of inhibitory rTMS effects on the cortical network integrity supporting sustained visual attention.

Main Methods:

• Healthy participants received 15 minutes of 1 Hz offline inhibitory rTMS (or sham) over the left parietal cortex.
• Functional connectivity (FC) was measured using fMRI during a bilateral visual tracking task, focusing on the intraparietal sulcus (IPS), frontal eye fields (FEF), and human MT+ (hMT+).

Main Results:

• FC between the left IPS and other attention network regions significantly decreased immediately post-rTMS, recovering within 30 minutes.
• Delayed increases in FC were observed between the left and right FEF (~36 min) and other unstimulated regions (~48 min).

Conclusions:

• Inhibitory rTMS induces large-scale, dynamic changes in cortical organization, impacting attention networks.
• The immediate disruption and subsequent compensatory increases in FC support the role of interhemispheric balance in sustained visual attention.
• Findings inform models of network reorganization and highlight potential compensatory mechanisms relevant to stroke recovery.