Gatsby Computational Neuroscience Unit Alexandra House, 17 Queen Square, LONDON, WC1N 3AR, UK, Tel: +44 (0) 20 7679 1176, Fax +44 (0) 20 7679 1173 abla@gatsby.ucl.ac.uk, www.gatsby.ucl.ac.uk   ABSTRACTS Venue B10 Seminar Room, Alexandra House, 17 Queen Square London, WC1N 3AR Supported by The Gatsby Foundation |Index|Objective|Attendees|Programme|Travel information|Accommodation| Cholinergic Neurotransmission and Systems Level Neural Modulation: Insights from Functional Imaging Studies Maura Furey Section on Neuroimaging in Mood and Anxiety Disorders National Institute of Mental Health (NIH), USA The study of human cognition with functional brain imaging in conjunction with pharmacologic probes that alter cognitive functions provides an opportunity to examine another dimension of the organization of human neural systems.  In addition to identifying the anatomical structures that participate in specific cognitive functions, this approach can reveal how different neurotransmitter systems modulate processing in those structures.  Additionally, as our findings have demonstrated, pharmacologically induced modulation of activity in one region can influence the contribution of other regions that also participate in a complex function like attention and memory.  Thus, by integrating functional brain imaging and psychopharmacology we can explore the role of neuromodulation in systems level neural functions. This talk will focus on results from PET and fMRI studies that evaluate the role of cholinergic enhancement in the context of working memory/attention paradigms.   The results will demonstrate pharmacologically-induced, systems level modulation of neural responses, and will support the hypothesis that the cholinergic neurotransmitter system modulates cognitive processes via attentional mechanisms in which neural responses to salient stimuli are enhanced via signal-to-noise processing.