The Claustrum in Relation to Seizures and Electrical Stimulation

Abstract

The neural mechanisms of altered consciousness that accompanies most epileptic seizures are not known. We have reported alteration of consciousness resulting from electrical stimulation of the claustrum via a depth electrode in a woman with refractory focal epilepsy. Additionally, there are reports that suggest possible claustral involvement in focal epilepsy, including MRI findings of bilaterally increased T2 signal intensity in patients with status epilepticus (SE). Although its cytoarchitecture and connectivity have been studied extensively, the precise role of the claustrum in consciousness processing, and, thus, its contribution to the semiology of dyscognitive seizures are still elusive. To investigate the role of the claustrum in rats, we studied the effect of high-frequency stimulation (HFS) of the claustrum on performance in the operant chamber. We also studied the inter-claustral and the claustro-hippocampal connectivity through cerebro-cerebral evoked potentials (CCEPs), and investigated the involvement of the claustrum in kainate (KA)-induced seizures. We found that HFS of the claustrum decreased the performance in the operant task in a manner that was proportional to the current intensity used. In this article, we present previously unpublished data about the effect of stimulating extra-claustral regions in the operant chamber task as a control experiment. In these animals, stimulation of the corpus callosum, the largest interhemispheric commissure, as well as the orbitofrontal cortex in the vicinity of the claustrum did not produce that same effect as with claustral stimulation. Additionally, CCEPs established the presence of effective connectivity between both claustra, as well as between the claustrum and bilateral hippocampi indicating that these connections may be part of the circuitry involved in alteration of consciousness in limbic seizures. Lastly, some seizures induced by KA injections showed an early involvement of the claustrum with later propagation to the hippocampi. Further work is needed to clarify the exact role of the claustrum in mediating alteration of consciousness during epileptic seizures.

The Claustrum is Involved in Cognitive Processes Related to the Classical Conditioning of Eyelid Responses in Behaving Rabbits

“…Since the original proposal of the claustrum (CL) as a structure involved in the integration of many different cortical and subcortical neural centers in order to generate conscious sensations ( Crick 1994 ), we have seen a notable increase in the number of structural and hodological studies dealing with its peculiar central place in the brain and regarding its putative integrative role in higher brain functions. So far, the CL has been related to consciousness ( Crick and Koch 2005 ; Kurada et al. 2019 ), salience detection ( Smythies et al.…”

A Role for the Claustrum in Salience Processing?

“…The claustrum (CLA) is a subcortical structure whose precise function remains unknown, but has been implicated in various mechanisms involved in directing attention (Mathur, 2014; Goll et al, 2015; Atlan et al, 2018; White et al, 2018), salience detection (Smythies et al, 2012), multisensory integration (Edelstein and Denaro, 2004), cross-modal transfer (Hadjikhani and Roland, 1998), perceptual binding (Crick and Koch, 2005), cognition (Jackson et al, 2018), and consciousness (Koubeissi et al, 2014; Stiefel et al, 2014; Kurada et al, 2019). In support of this view, the rodent CLA has extensive interhemispheric connections linking modality-related regions of sensory and motor cortex that control exploratory behaviors, such as visual cortex and the frontal eye fields that control visual search (Smith and Alloway, 2010; Smith et al, 2012, 2018; Alloway et al, 2014).…”

The mystery of claustral neural circuits and recent updates on its role in neurodegenerative pathology

“…In contrast to the cortex, the claustrum does not exhibit a layered organization. There is relatively simple and uniform cytoarchitecture within a small number of cell types specific to the claustrum [ 37 ]. As such, the claustrum is mostly composed of glutamatergic neurons [ 38 ] evenly distributed across the claustrum.…”

“…The claustrum is therefore ideally suited as a monitoring structure for sleep–wake cycle control and has been shown to be involved in sleep regulating neural circuits in reptiles and mammals [ 36 , 90 ]. The claustrum may mediate integration of cortical and subcortical neural networks to produce conscious sensations [ 37 ]. Hodologic research studies depicted the salience detection and segregation of attention as another significant function mediated by claustrum [ 51 , 56 , 66 ].…”