An fMRI investigation of the neuroanatomical correlates of script processing in healthy subjects

Jennifer L. Gallo

doi:10.17918/etd-840

Scripts are over-learned motor programs for routine, goal-directed activities. Script knowledge includes the actions, objects, and sequence of steps associated with reaching the goal of an activity. Errors in script activities have been studied almost exclusively in neurologically impaired patients, which can lead to misguided assumptions about the source of errors in script activities. Using functional brain imaging, this research gathered data on 9 undergraduate students asked to read a series of brief descriptions of script activities embedded with either semantic or sequencing errors. Semantic errors were associated with problems involving the knowledge of objects and actions pertinent to achieving the goal of a script activity. Scripts suggestive of semantic errors included either substitution with an inappropriate object or an inappropriate action. Sequencing errors were associated with errors related to the order in which script steps are completed. Scripts suggestive of sequencing errors included an order of steps that made the script either physically impossible or conceptually inappropriate to perform in the presented order. Subject-level and group-level analyses were conducted with a series of volumetric t-tests using statistic parametric mapping. In general, when participants viewed scripts, semantic errors activated more posterior cortical and subcortical networks, and sequencing errors activated more anterior cortical networks. More specifically, with respect to semantic aspects of script processing, action errors resulted in more bilateral activation of primary occipital, inferior and middle temporal, and prefrontal cortex, as well as lentiform nucleus, and object errors resulted in more right than left hemisphere activation of parietal, premotor, prefrontal, and limbic cortex, as well as parahippocampal gyrus and cerebellum. With respect to sequential aspects of script processing, physical errors resulted in right hemisphere activation of prefrontal cortex and cingulate gyrus plus left angular gyrus, and conceptual errors resulted in right hemisphere activation of prefrontal cortex and posterior commissure. Though not without limitations, these results suggest that neurologically intact individuals engage diffuse yet distinct neural networks when they encounter different types of script errors, and that regional activations associated with script errors may be best understood in relation to activation associated with correct script processing.

An fMRI investigation of the neuroanatomical correlates of script processing in healthy subjects

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An fMRI investigation of the neuroanatomical correlates of script processing in healthy subjects

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