Ž . Brain Research Reviews 26 1998 106–112 Functional magnetic resonance imaging of mental rotation and memory scanning: a multidimensional scaling analysis of brain activation patterns 1 Georgios A. Tagaris a,b,c,2 Wolfgang Richter d,e , Seong-Gi Kim d,e , Giuseppe Pellizzer a,b , Peter Andersen d,e , Kamil Ugurbil d,e , Apostolos P. Georgopoulos a,b,c,f, ) ˇ a ( ) Brain Sciences Center 11B , Veterans Affairs Medical Center, Minneapolis, MN 55417, USA b Department of Physiology, UniÕersity of Minnesota Medical School, Minneapolis, MN, USA c Department of Neurology, UniÕersity of Minnesota Medical School, Minneapolis, MN, USA d Center for Magnetic Resonance Research, UniÕersity of Minnesota Medical School, Minneapolis, MN, USA e Department of Radiology, UniÕersity of Minnesota Medical School, Minneapolis, MN, USA f Department of Psychiatry, UniÕersity of Minnesota Medical School, Minneapolis, MN, USA Keywords: Magnetic; Imaging; Memory; Brain Contents 1. Introduction ........................................................................ 106 2. Materials and methods .................................................................. 107 2.1. Tasks ......................................................................... 107 2.2. Functional MRI ................................................................... 109 2.3. Multidimensional scaling .............................................................. 109 3. Results and discussion .................................................................. 109 4. Conclusions ........................................................................ 111 Acknowledgements...................................................................... 112 References .......................................................................... 112 1. Introduction w x w x Mental rotation 6,18,19 and memory scanning 4,12,20 are typical examples of cognitive operations presumably wx involved in various tasks 7 . The original tasks involved ) Ž . Corresponding author. Fax: q1 612 725-2291; E-mail: omega@maroon.tc.umn.edu 1 Published on the World Wide Web on 24 February 1998. 2 Current address: Department of Neurology, General Athens Hospital, Athens, Greece. w x judgements to be indicated by key presses 18,19 or verbal w x w x responses 20 , whereas recent variants 4,6,12 required directed movements as responses. The cardinal sign of both mental rotation and memory scanning tasks is the increase of the response time with task demands, namely w x the angle of rotation 6,18,19 or of the number of items in w x the list scanned 4,12,20 . The rates of processing informa- w x tion in these two kinds of tasks are uncorrelated 12 , which suggests that different brain mechanisms may be involved. In contrast, the rates of rotation of a figure or a w x movement direction are positively correlated 12 , which 0165-0173r98r$19.00 q 1998 Elsevier Science B.V. All rights reserved.