Probing hippocampal stimulation in experimental temporal lobe epilepsy with functional MRI

Area of Science:

• Neuroscience
• Epilepsy Research
• Medical Imaging

Background:

• Electrical neurostimulation is a current epilepsy management strategy, but optimal protocols remain unclear.
• Simultaneous deep brain stimulation (DBS)-fMRI in patients is limited, hindering systematic investigation of stimulation parameters.
• Mesial temporal lobe epilepsy (mTLE) models are crucial for understanding brain responses to neurostimulation.

Purpose of the Study:

• To systematically examine brain-wide responses to electrical neurostimulation in an epilepsy mouse model using fMRI.
• To compare fMRI responses between epileptic and control mice during septal hippocampus stimulation.
• To investigate the effects of varying stimulation amplitude and frequency on brain activation patterns.

Main Methods:

• Utilized the intrahippocampal kainate mouse model of mesial temporal lobe epilepsy (mTLE).
• Employed functional MRI (fMRI) to assess brain-wide responses to electrical stimulation in the septal hippocampus.
• Compared fMRI responses across different stimulation amplitudes (80-230 μA) and frequencies (1-100 Hz), including prolonged 1 Hz stimulation.

Main Results:

• Epileptic mice showed distinct fMRI responses compared to controls, with stronger ipsilateral hippocampal activation and wider spread to cortical areas.
• Stimulation frequency was the key determinant of activation spread, while amplitude had minimal effect.
• Prolonged 1 Hz stimulation resulted in a slight reduction in local excitability in epileptic mice.

Conclusions:

• Electrical stimulation frequency is a critical parameter for modulating brain activation in epilepsy.
• Findings provide a better understanding of neurostimulation paradigms for epilepsy management.
• This study highlights the utility of fMRI in systematically evaluating neurostimulation strategies in epilepsy models.