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Kimron Shapiro, Zhao Fan, Steve Johnston, Suresh Muthukumaraswamy, Krish Singh; Serial chaining of two cognitive operations: An fMRI and MEG study. Journal of Vision 2010;10(7):293. doi: 10.1167/10.7.293.
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© ARVO (1962-2015); The Authors (2016-present)
A fundamental process in human cognition is to perform chained sequential operations in which the second task requires an input from the first. In this study, we used two consecutive tasks requiring line segment completion to explore the brain mechanisms of serial chaining by combing the strength of fMRI and MEG approaches. Behavioural results from both neural imaging approaches consistently demonstrated an additional serial chaining cost, over and above classical dual-task PRP costs where chaining was not required. The extra chaining cost is reflected by an altered distribution of response times (particularly for Task 2) as revealed by an increased mean and variance at short SOAs (100ms, 350ms) but not at the long SOA (650ms). MEG data in both sensor and source space reveal a Sustained Posterior Component (SPC) beginning from 300ms after Task 2 onset, lasting for approximately 500ms. This sustained component arises primarily from the left hemisphere and is linked with serial chaining rather than task difficulty or switching of spatial location. Preliminary fMRI results confirm both the pattern of left hemispheric lateralization and the sustained activity during serial chaining. Localization analyses from both MEG and fMRI suggest a source lying in the boundary between left temporal, parietal and occipital regions that is linked with serial chaining. MEG results and preliminary fMRI results thus provide evidence to suggest that serial chaining involves two unique components relative to two independent sequential operations, i.e., a component of planning and execution, and another component of information buffering and result-passing.
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