High field structural MRI reveals specific episodic memory correlates in the subfields of the hippocampus S.G. Travis a , Y. Huang a , E. Fujiwara a,b , A. Radomski b , F. Olsen c , R. Carter b , P. Seres c , N.V. Malykhin a,b,c,n a Centre for Neuroscience, University of Alberta, Edmonton, Alberta, Canada b Department of Psychiatry, University of Alberta, Edmonton, Alberta, Canada c Department of Biomedical Engineering, University of Alberta, Edmonton, Alberta, Canada T6G 2V2 article info Article history: Received 20 June 2013 Received in revised form 22 November 2013 Accepted 23 November 2013 Available online 1 December 2013 Keywords: Hippocampus Episodic memory Structural MRI Wechsler Memory Scale Medial temporal lobe Subfields abstract The involvement of the hippocampus (HC) in episodic memory is well accepted; however it is unclear how each subfield within the HC contributes to memory function. Recent magnetic resonance imaging (MRI) studies suggest differential involvement of hippocampal subfields and subregions in episodic memory. However, most structural MRI studies have examined the HC subfields within a single subregion of the HC and used specialised experimental memory paradigms. The purpose of the present study was to determine the association between volumes of HC subfields throughout the entire HC structure and performance on standard neuropsychological memory tests in a young, healthy population. We recruited 34 healthy participants under the age of 50. MRI data was acquired with a fast spin echo (FSE) sequence yielding a 0.52 Â 0.68 Â 1.0 mm 3 native resolution. The HC subfields – the cornu ammonis 1–3 (CA), dentate gyrus (DG), and subiculum (SUB) – were segmented manually within three hippocampal subregions using a previously defined protocol. Participants were administered the Wechsler Memory Scale, 4th edition (WMS-IV) to assess performance in episodic memory using verbal (Logical Memory, LM) and visual (Designs, DE; visual-spatial memory, DE-Spatial; visual-content memory, DE-Content) memory subtests. Working memory subtests (Spatial Addition, SA; and Symbol Span, SSP) were included as well. Working memory was not associated with any HC volumes. Volumes of the DG were correlated with verbal memory (LM) and visual-spatial memory (DE-Spatial). Posterior CA volumes correlated with both visual-spatial and visual-object memory (DE-Spatial, DE-Content). In general, anterior subregion volumes (HC head) correlated with verbal memory, while some anterior and many posterior HC subregion volumes (body and tail) correlated with visual memory scores (DE-Spatial, DE-Content). In addition, while verbal memory showed left-lateralized associations with HC volumes, visual memory was associated with HC volumes bilaterally. This the first study to examine the associations between hippocampal subfield volumes across the entire hippocampal formation with performance in a set of standard memory tasks. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction It has been over half a century since the famous case of patient H.M. and his bilateral medial temporal lobe (MTL) resections gave psychologists strong evidence that the MTL is required for learning and memory (Scoville & Milner, 1957). Subsequent studies of the hippocampus (HC) – a bilateral structure within the MTL – have found that volumetric measurements taken via Magnetic Reso- nance Imaging (MRI) can predict performance on a number of common neuropsychological tests and episodic memory para- digms. This is true for healthy controls with intact HC tissue (Foster, Meikle, & Goodson, 1999; Hackert et al., 2002; Convit, Wolf, Tarshish, & de Leon, 2003; and Rosen et al., 2003) and in patients with temporal lobectomies (Scoville & Milner, 1957; Loring et al., 1993). This relationship can also be seen in patholo- gical instances where reduced HC volume is highly correlated with poorer memory performance, such as in Alzheimer's disease; (Köhler et al., 1998), schizophrenia (Seidman et al., 2002; and O’Driscoll et al., 2001), and hippocampal sclerosis observed in temporal lobe epilepsy (Lencz et al., 1992; Baxendale, Thompson, & Van Paesschen, 1998; Pegna et al., 2002; Griffith et al., 2003; Griffith, Pyzalski, Seidenberg, & Hermann, 2004). In healthy populations with intact HC tissue, however, the correlation Contents lists available at ScienceDirect journal homepage: www.elsevier.com/locate/neuropsychologia Neuropsychologia 0028-3932/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.neuropsychologia.2013.11.016 n Correspondence to: Department of Biomedical Engineering, Faculty of Medicine & Dentistry, University of Alberta, Edmonton, Alberta, Canada T6G 2V2. Tel.: þ1 780 248 1120; fax: þ1 780 492 8259. E-mail address: nikolai@ualberta.ca (N.V. Malykhin). Neuropsychologia 53 (2014) 233–245