Homotopic reciprocal functional connectivity between anterior human insulae

Area of Science:

• Neuroscience
• Human Brain Imaging
• Functional Connectivity

Background:

• The insula plays a vital role in various cognitive and emotional processes.
• Understanding inter-insular connectivity is crucial for mapping brain networks.
• Previous research has not fully elucidated the direct functional links between the right and left insulae.

Purpose of the Study:

• To investigate the functional connectivity between the right and left insulae in the human brain.
• To determine the nature and latency of evoked responses between contralateral insular structures.

Main Methods:

• Utilized stereotactically placed depth electrodes in both insulae of a single patient undergoing epilepsy surgery evaluation.
• Applied bipolar 1 Hz electrical stimulation to the posterior short gyri of the anterior insula.
• Recorded evoked responses in contralateral insular structures.

Main Results:

• Electrical stimulation of one insula evoked responses in the contralateral insula.
• Evoked responses exhibited a short latency of 8-24 milliseconds.
• Demonstrated bi-directional homotopic and heterotopic functional connectivity between the right and left anterior insulae.

Conclusions:

• Established the first evidence of direct, bi-directional functional connectivity between the right and left anterior insulae.
• The short latency suggests mono- or oligo-synaptic connections, likely involving the corpus callosum.
• This finding advances our understanding of interhemispheric brain communication via the insular cortex.