Characterizing spatial and temporal features of autobiographical memory retrieval networks: a partial least squares approach Donna Rose Addis, a,b,c, * Anthony R. McIntosh, b,c Morris Moscovitch, b,c Adrian P. Crawley, a,d and Mary Pat McAndrews a,b, * a Toronto Western Research Institute, Toronto, Ontario, Canada b Department of Psychology, University of Toronto, Toronto, Ontario, Canada c Rotman Research Institute, Baycrest Centre for Geriatric Care, Toronto, Ontario, Canada d Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada Received 26 April 2004; revised 21 July 2004; accepted 6 August 2004 Conway (Conway, M.A., 1992. A structural model of autobio- graphical memory. In: Conway, M.A., Spinnler, H., Wagenaar, W.A. (Eds.), Theoretical Perspectives on Autobiological Memory. Kluwer Academic Publishers, Dordrecht, The Netherlands, pp. 167–194) proposed that two types of autobiographical memories (AMs) exist within a hierarchical AM system: unique, specific events and repeated, general memories. There is little research on whether retrieval of these AMs relies on different neural substrates. To investigate this issue, we used a multivariate image analysis technique, spatiotemporal partial least squares (PLS), to identify distributed patterns of activity most related to AM tasks that we have found to be associated with a medial and left-lateralized network. Using PLS, specific and general memories were more strongly associated with different parts of this retrieval network. Specific AM retrieval was associated more with activation of regions involved in imagery in episodic memory, including the left precuneus, left superior parietal lobule and right cuneus, whereas general AM retrieval was associated with activation of the right inferior temporal gyrus, right medial frontal cortex, and left thalamus. These two patterns emerged at different lags after stimulus onset, with the general AM pattern peaking between 2 and 6 s, and the specific AM pattern between 6 and 8 s. These lag differences are consistent with Conway’s theory which posits that general AMs are the preferred level of entry to the AM system. A seed PLS analysis revealed that the regions functionally connected to the hippocampus during retrieval did not differentiate specific from general AM retrieval, which confirms our earlier univariate analysis indicating that some aspects of the memory retrieval network are shared by these memories. D 2004 Elsevier Inc. All rights reserved. Keywords: fMRI; Multivariate; Hippocampus; Specific events; General events What constitutes autobiographical memory (AM) has been debated for at least the past two decades. Traditionally, AM has been defined only as episodic memory for personally experienced events that occurred at a specific place and time. Conway (Conway, 1992, 1996; Conway and Pleydell-Pearce, 2000), however, distinguishes between two types of AMs: AMs for unique, specific events and for repeated, general events. Both neuroimaging (Fink et al., 1996; Gilboa et al., 2004; Maguire and Mummery, 1999; Maguire et al., 2000, 2001; Piefke et al., 2003; Ryan et al., 2001) and lesion studies (e.g., Kopelman et al., 1990; Viskontas et al., 2000; for a review, see Conway and Fthenaki, 2000) have focused on the retrieval of specific AMs, with the virtual exclusion of research exploring the neural correlates of general AMs and whether they differ from those of specific AMs (but see Graham et al., 2003). In this paper, we aim to help rectify this imbalance. Conway (1992, 1996) and Conway and Pleydell-Pearce (2000) conceptualize AM as a personal knowledge base that is organized hierarchically, according to three levels of specificity. dLifetime periodsT are an abstract level of autobiographical knowledge organized by theme and time periods. dGeneral eventsT are composed of events memories which are either repeated or temporally extended, and thus lack temporal specificity. In contrast, specific events, or what Conway terms devent specific knowledgeT, refer to AMs for events that occurred at one specific point in time, and represent what is typically called episodic memory. Conceptually, a repeated, general AM can be thought of 1053-8119/$ - see front matter D 2004 Elsevier Inc. All rights reserved. doi:10.1016/j.neuroimage.2004.08.007 * Corresponding authors. Neuropsychology, 4F-409, Toronto Western Research Institute, University Health Network, 399 Bathurst Street, Toronto, Ontario, Canada, M5T 2S8. Fax: +1 416 603 5321. E-mail addresses: donnad@psych.utoronto.ca (D.R. Addis)8 mcandrws@uhnres.utoronto.ca (M.P. McAndrews). Available online on ScienceDirect (www.sciencedirect.com.) www.elsevier.com/locate/ynimg NeuroImage 23 (2004) 1460 – 1471