Claustral Lesions Delay Amygdaloid Kindling in the Rat

Abstract

Summary:Purpose: Lesions of the claustrum in cats and primates have been shown to disrupt the development and expression of amygdaloid-kindled seizures in cats and primates. Because the structure and connectivity of the claustrum can vary between species, we wanted to examine the effects of claustral lesions on kindling in rats.Methods: One group of rats received bilateral radiofrequency lesions of both anterior and posterior regions of the claustrum before amygdaloid kindling. Another group of rats received bilateral anterior and posterior radiofrequency lesions of the claustrum after amygdaloid kindling. Some rats were tested for transfer of kindling to the contralateral amygdala after claustral lesions.Results: Small lesions that destroyed 13% of the claustrum were capable of delaying, but not blocking, amygdaloid kindling. The delay in kindling was due to an increase in the stimulation trials required to kindle to stage 5 seizures. The lesions had no effect on established kindled seizures or on transfer to the contralateral amygdala.Conclusions: As in other species, the claustrum in the rat appears to play a role in kindling from the amygdala. Because of the restricted size of our claustral lesions, however, we were unable to conclusively assess the full extent of the claustrum's participation in limbic kindling.

Functional Specificity of Claustrum Connections in the Rat: Interhemispheric Communication between Specific Parts of Motor Cortex

“…Regardless of whether the intra-claustral connections represent the axons of interneurons or the collaterals of claustrocortical projections, either type of connection could synchronize extensive parts of the claustrum. This view is consistent with data indicating that the claustrum is susceptible to kindling and plays a role in the development of epileptiform activity (Mohapel et al, 2000, 2001). If many claustral neurons converge on overlapping cortical regions, synchronization of these neurons should effectively activate their cortical targets.…”

Susceptibility to Kindling and Neuronal Connections of the Anterior Claustrum

“…Similar results have also been observed in monkeys (Wada and Tsuchimochi, 1997). Radio-frequency (RF) lesions of the posterior claustrum delay amygdaloid kindling in rats (Mohapel et al, 2001). The results are not conclusive, however, because electrolytic and RF lesions can also damage fibers of passage.…”

“…The fact that stimulation of claustrum or perirhinal cortex produces more rapid kindling than focal stimulation of frontal/motor cortex itself (Seidel and Corcoran, 1986) presumably reflects the broad anatomical connections of claustrum (present results) and perirhinal cortex with cortex and other structures, which would allow widespread recruitment of discharge throughout the network. In support of this hypothesis, bilateral frontal lesions damaging the insula, orbital cortex, and anterior portions of the perirhinal cortex retard amygdaloid kindling (Corcoran et al, 1976), as do small bilateral lesions of the claustrum (Mohapel et al, 2001).…”

A case study in connectomics: the history, mapping, and connectivity of the claustrum

“…It is thought that epileptoform propagation from limbic sites may be linked to the motor cortex via the claustrum (Mohapel et al, 2000). A case study was conducted on a 12-year-old girl who presented with status epilepticus (multiple, repeated complex partial and myoclonic seizures occurred in the upper extremities and face with orofacial automatisms, eye deviation, and nystagmus) displaying psychotic behavior with agitation, severe cognitive impairment and temporary loss of vision, hearing and speech, as well as loss of orientation in time and place.…”