CONEUR-885; NO. OF PAGES 6 Please cite this article in press as: Vann SD, Albasser MM. Hippocampus and neocortex: recognition and spatial memory, Curr Opin Neurobiol (2011), doi:10.1016/j.conb.2011.02.002 Available online at www.sciencedirect.com Hippocampus and neocortex: recognition and spatial memory Seralynne D Vann and Mathieu M Albasser Recognition and spatial memory are typically associated with the perirhinal cortex and hippocampal formation, respectively. Solely focusing on these structures for these specific mnemonic functions may, however, be limiting progress in the field. The distinction between these subdivisions of memory is becoming less defined as, for example, hippocampal cells traditionally considered to encode locations also encode place–object associations. There is increasing evidence for the involvement of overlapping networks of brain structures for aspects of both spatial and recognition memory. Future models of spatial and recognition memory will have to extend beyond the hippocampus and perirhinal cortex to incorporate a wider network of cortical and subcortical structures. Address School of Psychology, Cardiff University, Cardiff, UK Corresponding author: Vann, Seralynne D (vannsd@cardiff.ac.uk) Current Opinion in Neurobiology 2011, 21:1–6 This review comes from a themed issue on Behavioral and cognitive neuroscience Edited by Ann Graybiel and Richard Morris 0959-4388/$ – see front matter # 2011 Elsevier Ltd. All rights reserved. DOI 10.1016/j.conb.2011.02.002 Introduction The neural processes that allow us to form episodic memories, that is, remember events we experience throughout our lives, are still far from fully understood. Neuropsychological studies have been pivotal in identi- fying those brain structures that are necessary for forming new memories but typically studies in animals are required to investigate these mnemonic processes with higher anatomical resolution. There continues to be a debate as to whether the term episodic memory can even be applied to non-humans; this is particularly relevant when considering vivid experiences where remembering can give a sense of ‘re-living’ the event in a way that has been likened to mental-time travel (see [1]). Whether or not episodic memory is directly comparable across species, there are certainly aspects of episodic memory that can be assessed in animals such as memory for objects, spatial routes and locations, and spatiotemporal context. The recent use of convergent approaches to assess the neural substrates of both recognition memory and spatial learning, including electrophysiological recordings, immediate-early gene imaging, and lesion disconnection studies, has identified an interactive net- work of regions that support these functions. In this review, we will discuss findings from recent studies that have shed light on aspects of object recognition, spatial memory, and how these two forms of memory are brought together. Recent findings will be put into the context of a more unified model of memory that focuses on inter- actions, rather than dissociations, between brain regions. Recognition memory One component of memory is recognising whether you have encountered someone or something before. This ability can be assessed non-verbally by using a prefer- ential viewing paradigm that builds on the innate pre- ference of animals, including humans, to look at, or explore, something novel. In rats, the spontaneous object recognition task has been used to assess the neural sub- strates of recognition memory [2] (see Figure 1). While there is an ongoing debate about the extent to which the hippocampus is required for animals to exhibit normal levels of novel object exploration (see [3,4]), there is a general consensus that the perirhinal cortex contributes to recognition memory [5,6]. The inability of perirhinal lesion rats to discriminate new objects from previously seen objects had been thought to result from animals not remembering the old object. In contrast, however, McTighe et al. [7] recently proposed that the poor per- formance was in fact a result of rats having a false memory for the novel object, that is, acting as if the novel object had been previously experienced, therefore exploring it less. The authors argue that the loss of the perirhinal cortex leaves animals unable to use the unique complex features associated with the whole object and instead are limited to using simpler stimulus features that are more likely shared across objects thus resulting in false recog- nition [7]; this explanation is consistent with recent models that question the perceived dichotomy between memory and perception (for a review see [8]). However, if perirhinal lesion rats do treat novel objects as familiar, this should also be demonstrated during the sample phase where the animals are presented with previously unseen objects. In fact, perirhinal lesion rats in both this study [7] and previous studies (e.g. [9,10]) correctly behave as if the objects are novel as they show comparable levels of object exploration to control rats during the sample phase; this ‘false memory’ account cannot, therefore, provide a gen- eral mechanism for perirhinal lesion effects. Extending the substrates of recognition memory Although object recognition in rats has typically been considered in terms of the visual domain, recent studies www.sciencedirect.com Current Opinion in Neurobiology 2011, 21:1–6