Hierarchical Organization of Scripts: Converging Evidence from fMRI and Frontotemporal Degeneration

Abstract

The present study examined the organization of complex familiar activities, known as "scripts" (e.g., "going fishing"). We assessed whether events in a script are processed in a linear-sequential manner or clustered-hierarchical manner, and we evaluated the neural basis for this processing capacity. Converging evidence was obtained from functional neuroimaging in healthy young adults and from behavioral and structural magnetic resonance imaging (MRI) data in patients with focal neurodegenerative disease. In both studies, participants judged the order of consecutive event pairs taken from a script. Event pairs either were clustered together within a script or were from different clusters within the script. Controls judged events more accurately and quickly if taken from the same cluster within a script compared with different clusters, even though all event pairs were consecutive, consistent with the hierarchical organization of a script. Functional magnetic resonance imaging associated this with bilateral inferior frontal activation. Patients with progressive nonfluent aphasia or behavior-variant frontotemporal dementia did not distinguish between event pairs from the same cluster or from different clusters within a script. Structural MRI associated this deficit with significant frontal cortical atrophy. Our findings suggest that frontal cortex contributes to clustering events during script comprehension, underlining the role of frontal cortex in the hierarchical organization of a script.

Processing structure in language and music: a case for shared reliance on cognitive control

“…The role inferior frontal regions (and especially Broca's area) play in structural processing is controversial (see , for discussion from the language perspective); LIFG, in particular, has been associated with cognitive control and working memory, but also has been claimed to support syntax-specific processes (at least in language; e.g., Grodzinsky & Santi, 2008) and/or more general types of complex hierarchical relationships such as action sequences (e.g., Farag et al, 2010;Fitch & Martins, 2014;Koechlin & Jubault, 2006) and mathematical structure (Friedrich & Friederici, 2009;Maruyama, Pallier, Jobert, Sigman, & Dehaene, 2012). Thus, these frontal regions that may be associated with shared musical/linguistic processing likely reflect a variety of underlying cognitive processes; a greater understanding of the ways in which linguistic and musical manipulations involve LIFG (and its right-hemisphere homologue) will likely add important data to this debate.…”

Neural networks for harmonic structure in music perception and action

“…Interestingly, IFG has 101 been associated not only with structural integration and prediction of musical sequences, but 5 also with structuring of complex actions (Fuster, 2001;Koechlin and Summerfield, 2007) 103 outside the music domain. Lesions of the left IFG cause impairment in sequencing pictures 104 representing human actions (Fazio et al, 2009), and bilateral IFG are involved in evaluating 105 whether constituent acts belong to the same or separate sub-goals (Farag et al, 2010).…”

Narrative discourse deficits in amyotrophic lateral sclerosis

“…13,14 To elucidate the neuroanatomical basis of narrative discourse deficits in ALS, we related performance to high-resolution GM and WM structural imaging in a subset of patients. Based on previous fMRI work in healthy adults and nonaphasic patients with behavioral variant frontotemporal dementia (bvFTD), [15][16][17] we expected the narrative disorder in ALS to be related in part to their prefrontal disease.…”

“…Previous fMRI studies of healthy adults and correlation studies in nonaphasic patients relate narrative performance to hierarchical organization and planning. 15,16 By comparison, recalling the overall purpose of the story may be relatively preserved in ALS because this depends on memory of a single element rather than on the organizational demands of narrative expression.…”