Do the medial temporal lobes resolve perceptual interference?

Editor's Note: These short, critical reviews of recent papers in the Journal, written exclusively by graduate students or postdoctoral fellows, are intended to summarize the important findings of the paper and provide additional insight and commentary. For more information on the format and purpose of the Journal Club, please see The role of the medial temporal lobes (MTLs) in memory was first clearly established with the case of patient HM, who suffered from an inability to form new memories following surgical removal of bilateral MTLs (Scoville and Milner, 1957). Subsequent work in humans and animals revealed that memory impairment associated with MTL damage was related to a set of subcortical and cortical structures including the hippocampus, en-torhinal, perirhinal, and parahippocampal cortex. Recent studies have shown that some of these subregions are domain sensitive with evidence indicating that the para-hippocampal gyrus and hippocampus are involved in scene recognition, whereas the perirhinal cortex is involved in recognition of individual objects (Taylor et al., 2007; Sta-resina et al., 2011). Despite these considerable advances in our understanding of this brain region over the last 60 years, there remain unresolved questions regarding the fundamental role the MTL plays in perception and memory. One current controversy rests on evidence that MTL damage impairs perceptual discrimination in tasks that place no or minimal demands on memory. Many studies have reported domain-specific patterns of perceptual impairment following damage to different MTL subregions with object and scene discrimination impairments associated with perirhinal and hippocampal damage respectively (Lee et al., 2005; Saksida and Bussey, 2010). Importantly , the perceptual deficits reported in these studies were only apparent under conditions where stimuli shared many features, suggesting that MTL subregions differentially support complex representations that are recruited to distinguish highly similar objects and scenes. Evidence that MTL damage impairs high-level vision seemingly conflicts with the notion that the MTL is a " memory system " that has no role in cogni-tion outside the mnemonic domain. Under representational accounts of MTL function, amnesia associated with MTL damage is reframed as a representa-tional deficit where forgetting occurs due to a failure in resolving perceptual interference (Bartko et al., 2010; Graham et al., 2010; Barense et al., 2012). These models borrow ideas from interference theories of amnesia (Warrington and Weiskrantz, 1974) which propose that successful recognition judgments occur when there is sufficient overlap in the features perceived during initial and subsequent encounters with a stimulus. …