ORIGINAL PAPER Negative BOLD in Sensory Cortices During Verbal Memory: A Component in Generating Internal Representations? Haim Azulay Æ Ella Striem Æ Amir Amedi Received: 1 February 2009 / Accepted: 16 March 2009 Ó Springer Science+Business Media, LLC 2009 Abstract People tend to close their eyes when trying to retrieve an event or a visual image from memory. However the brain mechanisms behind this phenomenon remain poorly understood. Recently, we showed that during visual mental imagery, auditory areas show a much more robust deactivation than during visual perception. Here we ask whether this is a special case of a more general phenom- enon involving retrieval of intrinsic, internally stored information, which would result in crossmodal deactiva- tions in other sensory cortices which are irrelevant to the task at hand. To test this hypothesis, a group of 9 sighted individuals were scanned while performing a memory retrieval task for highly abstract words (i.e., with low imaginability scores). We also scanned a group of 10 congenitally blind, which by definition do not have any visual imagery per se. In sighted subjects, both auditory and visual areas were robustly deactivated during memory retrieval, whereas in the blind the auditory cortex was deactivated while visual areas, shown previously to be relevant for this task, presented a positive BOLD signal. These results suggest that deactivation may be most prominent in task-irrelevant sensory cortices whenever there is a need for retrieval or manipulation of internally stored representations. Thus, there is a task-dependent balance of activation and deactivation that might allow maximization of resources and filtering out of non relevant information to enable allocation of attention to the required task. Furthermore, these results suggest that the balance between positive and negative BOLD might be crucial to our understanding of a large variety of intrinsic and extrinsic tasks including high-level cognitive functions, sensory processing and multisensory integration. Keywords Multisensory integration Á Negative BOLD Á Intrinsic processing Á Crossmodal brain plasticity Á Verbal memory Á Crossmodal deactivation Introduction People tend to close their eyes or look upward in an unfocused manner when trying to retrieve old or barely recallable items from memory. Interestingly, blind indi- viduals (with a complete absence of vision) seem to have superior memory capabilities (Tillman and Bashaw 1968; Smits and Mommers 1976; Pozar 1982; Pring 1988; Hull and Mason 1995; Ro ¨der et al. 2001; D’Angiulli and Waraich 2002; Raz et al. 2007) including verbal memory capabilities (Tillman and Bashaw 1968; Smits and Mom- mers 1976; Pozar 1982; Pring 1988; Hull and Mason 1995; Amedi et al. 2003; Raz et al. 2007). Similarly, people find it much easier to visually mentally imagine a visual object with their eyes closed (Spanos and Stam 1979). However the brain mechanisms for this phenomenon remain debated and poorly understood. For many years a large body of work emphasized the overlap in the neural substrates supporting perception and This article is published as part of the Special Issue on Multisensory Integration. H. Azulay and E. Striem contributed equally to this work. H. Azulay Á E. Striem Á A. Amedi (&) Department of Medical Neurobiology, Institute of Medical Research Israel-Canada (IMRIC), The Hebrew University of Jerusalem, Jerusalem 91220, Israel e-mail: amir.amedi@ekmd.huji.ac.il URL: http://brain.huji.ac.il/ A. Amedi Cognitive Science Program, The Hebrew University of Jerusalem, Jerusalem 91220, Israel 123 Brain Topogr DOI 10.1007/s10548-009-0089-2