Connectivity of the frontal and anterior insular network: a cortico-cortical evoked potential study

Abstract

OBJECT The frontal and insular fiber network in humans remains largely unknown. This study investigated the connectivity of the frontal and anterior insular network in humans using cortico-cortical evoked potential (CCEP). METHODS This retrospective analysis included 18 patients with medically intractable focal epilepsy who underwent stereoelectroencephalography and CCEP. Alternating 1-Hz electrical stimuli were delivered to parts of the frontal lobe and anterior insula (prefrontal cortex [PFC], ventrolateral and dorsolateral premotor area [vPM and dPM, respectively], presupplementary motor area [pre-SMA], SMA, frontal operculum, and anterior insula). A total of 40–60 stimuli were averaged in each trial to obtain CCEP responses. The distribution of CCEP was evaluated by calculating the root mean square of CCEP responses. RESULTS Stimulation of the PFC elicited prominent CCEP responses in the medial PFC and PMs over the ipsilateral hemisphere. Stimulation of the vPM and dPM induced CCEP responses in the ipsilateral frontoparietal areas. Stimulation of the pre-SMA induced CCEP responses in the ipsilateral medial and lateral frontal areas and contralateral pre-SMA, whereas stimulation of the SMA induced CCEP responses in the bilateral frontoparietal areas. Stimulation of the frontal operculum induced CCEP responses in the ipsilateral insula and temporal operculum. CCEPs were observed in the ipsilateral medial, lateral frontal, and frontotemporal operculum in the anterior insular stimulation. Stimulation of the vPM and SMA led to the network in the dominant hemisphere being more developed. CONCLUSIONS Various regions within the frontal lobe and anterior insula were linked to specific ipsilateral and contralateral regions, which may reflect distinct functional roles.

Strong coupling between slow oscillations and wide fast ripples in children with epileptic spasms: Investigation of modulation index and occurrence rate

“…Analysis of corticocortical evoked potential (CCEP) has demonstrated epileptic networks 35,36 in patients with focal epilepsy. Analysis of corticocortical evoked potential (CCEP) has demonstrated epileptic networks 35,36 in patients with focal epilepsy.…”

“…Stereotactic EEG has the potential to delineate subcortical electrophysiological activity in ES in the future. Analysis of corticocortical evoked potential (CCEP) has demonstrated epileptic networks 35,36 in patients with focal epilepsy. There are no reports investigating ES using CCEP.…”

The frontal aslant tract (FAT) and its role in speech, language and executive function

“…Finally, a small number of studies have provided electrophysiological evidence of a monosynaptic connection between IFG and medial superior frontal gyrus (Enatsu et al, 2016;Matsumoto et al, 2007;Ookawa et al, 2017;Swann et al, 2012). Enatsu and colleagues (2016) investigated 18 patients using cortico-cortical evoked potentials (CCEP) and found that stimulation of the pre-SMA induces a robust response in IFG.…”

Considerations in performing and analyzing the responses of cortico‐cortical evoked potentials in stereo‐EEG

“…In CCEPs, stimulation frequencies such as 1 Hz, 0.5 Hz, 0.33 Hz, 0.2 Hz, 0.1 Hz, and 0.067 Hz have been used in the past (Table ). Only one study has looked at effects of stimulation frequency on response morphology— little difference in responses to 2 and 1 Hz stimulation in Heschl's gyrus was shown; however, there was a marked change between 2 and 5 Hz …”

“…Monophasic pulses have been shown to be efficient AP generators, but have shown to be more damaging than charge‐balanced waveforms . Alternating monophasic waveforms have been used in many CCEPs studies, both in SEEG and ECoG; these waveforms are able to efficiently generate APs, reverse many electrochemical reactions and simultaneously mitigate stimulation artifact when averaged. Monophasic pulses may also produce different physiologic effects.…”