http://www.nitrc.org/forum/forum.php?forum_id=5178 <table border="0" width="100%"><tr><td align="left"/></tr></table> <p><b>An fMRI investigation into the effect of preceding stimuli during visual oddball tasks.</b></p> <p>J Neurosci Methods. 2015 May 16;</p> <p>Authors: Fajkus J, Mikl M, Shaw DJ, Brázdil M</p> <p>Abstract<br/> BACKGROUND: This study investigates the modulatory effect of stimulus sequence on neural responses to novel stimuli. A group of 34 healthy volunteers underwent event-related functional magnetic resonance examination while performing a three-stimulus visual oddball task, involving randomly presented frequent stimuli and two types of infrequent stimuli-targets and distractors. New Method: We developed a modified categorization of rare stimuli that incorporated the type of preceding rare stimulus and analyzed the event-related functional data according to this sequence categorization; specifically, we explored hemodynamic response modulation associated with increasing rare-to-rare stimulus interval.<br/> RESULTS: For two consecutive targets, a modulation of brain function was evident throughout posterior midline and lateral temporal cortex, while responses to targets preceded by distractors were modulated in a widely distributed fronto-parietal system. As for distractors that follow targets, brain function was modulated throughout a set of posterior brain structures. For two successive distractors, however, no significant modulation was observed, which is consistent with previous studies and our prime hypothesis. Comparison with existing methods: The involvement of aforementioned technique extends the possibilities of conventional oddball task analysis and enables to explore the effects in the whole range of rare stimuli intervals.<br/> CONCLUSION: This methodology can be efficiently applied to study wide range of associated cognitive mechanisms, such as decision making, expectancy and attention.<br/> </p><p>PMID: 25989317 [PubMed - as supplied by publisher]</p> en-us Copyright 2000-2026 NITRC OSI Sat, 02 May 2026 13:09:53 GMT http://blogs.law.harvard.edu/tech/rss NITRC RSS generator