title: Disruption of Broca's Area Alters Higher-order Chunking Processing during Perceptual Sequence Learning.
abstract: Because Broca's area is known to be involved in many cognitive functions, including language, music, and action processing, several attempts have been made to propose a unifying theory of its role that emphasizes a possible contribution to syntactic processing. Recently, we have postulated that Broca's area might be involved in higher-order chunk processing during implicit learning of a motor sequence. Chunking is an information-processing mechanism that consists of grouping consecutive items in a sequence and is likely to be involved in all of the aforementioned cognitive processes. Demonstrating a contribution of Broca's area to chunking during the learning of a nonmotor sequence that does not involve language could shed new light on its function. To address this issue, we used offline MRI-guided TMS in healthy volunteers to disrupt the activity of either the posterior part of Broca's area (left Brodmann's area [BA] 44) or a control site just before participants learned a perceptual sequence structured in distinct hierarchical levels. We found that disruption of the left BA 44 increased the processing time of stimuli representing the boundaries of higher-order chunks and modified the chunking strategy. The current results highlight the possible role of the left BA 44 in building up effector-independent representations of higher-order events in structured sequences. This might clarify the contribution of Broca's area in processing hierarchical structures, a key mechanism in many cognitive functions, such as language and composite actions.
authors.affiliation: Université catholique de Louvain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Alamia
authors.affiliation: Université catholique de Louvain.
authors.forename: Oleg
authors.initials: O
authors.lastname: Solopchuk
authors.affiliation: Fondazione Istituto Italiano di Tecnologia, Genova, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: D'Ausilio
authors.affiliation: Université catholique de Louvain.
authors.forename: Violette
authors.initials: V
authors.lastname: Van Bever
authors.affiliation: Fondazione Istituto Italiano di Tecnologia, Genova, Italy.|University of Ferrara.
authors.forename: Luciano
authors.initials: L
authors.lastname: Fadiga
authors.affiliation: Université catholique de Louvain.|Fondazione Istituto Italiano di Tecnologia, Genova, Italy.
authors.forename: Etienne
authors.initials: E
authors.lastname: Olivier
authors.affiliation: Université catholique de Louvain.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Zénon
mesh_terms: D000328:Adult; D065711:Broca Area / Q000502:physiology*; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology*; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation / Q000379:methods*; D055815:Young Adult