Eye Movement Network Originating from Frontal Eye Field: Electric Cortical Stimulation and Diffusion Tensor Imaging

Area of Science:

• Neuroscience
• Neurosurgery
• Epileptology

Background:

• Frontal eye fields (FEFs) play a critical role in visual attention and eye movements.
• Understanding FEF connectivity is essential for neurosurgical interventions.
• Previous studies have not fully elucidated the subcortical pathways of the FEFs.

Purpose of the Study:

• To investigate the subcortical networks originating from the frontal eye fields (FEFs).
• To identify the precise anatomical course of FEF-connected fibers using diffusion tensor imaging (DTI).
• To provide critical anatomical information for preventing surgical complications during deep brain stimulation (DBS).

Main Methods:

• Utilized electric cortical stimulation to identify FEFs in seven patients with intractable focal epilepsy.
• Employed diffusion tensor imaging (DTI) with regions of interest in the FEF and contralateral paramedian pontine reticular formation (PPRF).
• Functional mapping was performed using 50 Hz electric stimulation.

Main Results:

• FEFs were localized to the superior precentral sulcus (pre-CS) and superior frontal gyrus (SFG).
• DTI successfully identified subcortical fibers connecting FEFs to contralateral PPRFs, traversing the internal capsule.
• These FEF tracts were found adjacent to the subthalamic nucleus (STN) and globus pallidus internus (GPi).

Conclusions:

• This study characterized the distinct subcortical networks of the FEF.
• The identified FEF fiber tracts are critical considerations for neurosurgeons performing DBS of the STN or GPi.
• Awareness of these pathways can help mitigate risks and improve patient outcomes in neurosurgical procedures.