What can human lesion studies tell us about the function of the claustrum?

Objectives/AimsThe claustrum is a sheet-like bilateral brain region whose function remains unknown. We comprehensively examined cases of human claustrum lesions to assess their support for various hypotheses of function. To do so we searched the following terms on PubMed and Scopus: ‘claustrum AND (lesion OR contusion OR in- jury OR trauma)’.ResultsIn total our search uncovered 103 cases, which were then screened for confirmed damage to the claustrum by neuroimaging. Thirty-eight individual cases and 14 cohort studies were included. Our results suggest human claustral lesions do not selectively impair a singular domain. Instead, they argue that human claustrum may have a more general function. The high incidence of seizures following claustral lesions suggests this may involve maintenance of excitation-inhibition balance.ConclusionsThe wide range of symptoms observed following claustral lesions do not provide compelling evidence to support prominent current theories of claustrum function such as spatial navigation, attentional allocation, cognition, multisensory integration, and salience computation. Conversely, the lesions studies support the hypothesis that the claustrum regulates cortical excitability.