Abnormal Categorization and Perceptual Learning in Patients with Hippocampal Damage

The perirhinal cortex (PRh) is widely accepted as having an important role in object recognition memory in humans and animals. Contrary to claims that PRh mediates declarative memory exclusively, previous evidence suggests that PRh has a role in the perceptual processing of complex objects. In the present study, we conducted an examination of the possible role of PRh in perceptual function in rats. We examined whether bilateral excitotoxic lesions of PRh or PPRh (perirhinal plus postrhinal cortices) in the rat would cause deficits in a zero-delay object-recognition task and a simultaneous oddity discrimination task. Both of these tasks measured spontaneous (untrained, unrewarded) behavior, and the stimuli in these experiments were manipulated to produce varying levels of perceptual difficulty. As predicted by simulations using a computational model, rats with PPRh lesions were impaired in object recognition when the stimuli to be discriminated were manipulated to share many features in common. Furthermore, rats with PPRh and PRh lesions were impaired in a simultaneous oddity discrimination task when the stimuli to be discriminated were manipulated explicitly to be more perceptually similar. These findings provide support for the idea that PRh in the rat is important for the perceptual processing of complex objects, in addition to its well established role in memory.

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“…Our view is that perceptual learning can indeed occur in PRh. Evidence suggests it also does in the hippocampus (Graham et al, 2006).…”

Section: Discussionmentioning

confidence: 99%

Perceptual Functions of Perirhinal Cortex in Rats: Zero-Delay Object Recognition and Simultaneous Oddity Discriminations

Bartko¹,

Winters²,

Cowell³

et al. 2007

J. Neurosci.

Self Cite

168

172

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“…During perception, the hippocampus binds together visual elements of an image (Olsen et al, 2012;Warren et al, 2012;Zeidman et al, 2015), which is especially important for scene stimuli (Lee et al, 2005a,b;Graham et al, 2006;Hodgetts et al, 2016) and then stores this representation into long-term memory (Ryan and Cohen, 2004). As we become familiar with an environment, the hippocampus builds a map of the spatial relationships between visual landmarks, which is critical for navigation (Morgan et al, 2011).…”

Section: The Memory and Navigation Networkmentioning

confidence: 99%

Two distinct scene processing networks connecting vision and memory

Baldassano

Esteva

Beck

et al. 2016

Preprint

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Visual AbstractA number of regions in the human brain are known to be involved in processing natural scenes, but the field has lacked a unifying framework for understanding how these different regions are organized and interact. We provide evidence from functional connectivity and meta-analyses for a new organizational principle, in which scene processing relies upon two distinct networks that split the classically defined parahippocampal place area (PPA). The first network of strongly connected regions consists of the occipital place area/transverse occipital sulcus and posterior PPA, which contain retinotopic maps and are not strongly coupled to the hippocampus at rest. The second network consists of the caudal inferior parietal lobule, retrosplenial complex, and anterior PPA, which connect to the hippocampus (especially anterior hippocampus), and are implicated in both visual and nonvisual tasks, including episodic memory and navigation. We propose that these two distinct networks capture the primary functional division among scene-processing regions, between those that process visual features from the current view of a scene and those that connect information from a current scene view with a much broader temporal and spatial context. This new framework for understanding the neural substrates of scene-processing bridges results from many lines of research, and makes specific functional predictions. Key words: memory; networks; scene; vision Significance StatementThere are a number of brain regions that only show high levels of activity for full photographic scenes, not individual objects. By examining their relationships to each other and the rest of the brain, we argue that there are two types of scene-processing regions that belong to two separate networks. One network, which overlaps most of the visual system, processes visual features of the current view of the world, such as spatial layout. Another network, which is connected to long-term memory, puts this moment-by-moment information in context, allowing us to navigate through environments and remember past events in familiar locations. These two groups of brain regions cooperate to help us understand the world and our place in it.

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“…Recent findings in monkeys and in humans with perirhinal cortex lesions have been taken to indicate that perirhinal cortex is needed for visual discrimination tasks when the test items have a high degree of feature ambiguity (Bussey et al 2002;Barense et al 2005Barense et al , 2007Lee et al 2005a,b; but see Clark et al 2011). It has also been suggested that the hippocampus is needed when spatial processing is required, for example, in visual discriminations involving scenes (Lee et al 2005a;Graham et al 2006). The challenge is to decide whether impaired performance reflects impaired perception or impaired memory (for reviews of this growing literature, see Hampton 2005;Buckley and Gaffan 2006;Baxter 2009;Suzuki 2009;Graham et al 2010).…”

Section: Visual Discrimination Tasksmentioning

confidence: 99%

“…In some studies in monkeys and also in humans (e.g., Barense et al 2005;Graham et al 2006), discrimination learning involved the same stimulus materials over multiple trials. In these cases, impaired performance could reflect a deficit, not in perception, but in associative learning or long-term memory for the repeated material (Hampton 2005;Suzuki 2009;Wixted and Squire 2011).…”

Section: Visual Discrimination Tasksmentioning

confidence: 99%

Working memory, long-term memory, and medial temporal lobe function

Jeneson¹,

Squire²

2011

Learn. Mem.

316

250

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Early studies of memory-impaired patients with medial temporal lobe (MTL) damage led to the view that the hippocampus and related MTL structures are involved in the formation of long-term memory and that immediate memory and working memory are independent of these structures. This traditional idea has recently been revisited. Impaired performance in patients with MTL lesions on tasks with short retention intervals, or no retention interval, and neuroimaging findings with similar tasks have been interpreted to mean that the MTL is sometimes needed for working memory and possibly even for visual perception itself. We present a reappraisal of this interpretation. Our main conclusion is that, if the material to be learned exceeds working memory capacity, if the material is difficult to rehearse, or if attention is diverted, performance depends on long-term memory even when the retention interval is brief. This fundamental notion is better captured by the terms subspan memory and supraspan memory than by the terms short-term memory and long-term memory. We propose methods for determining when performance on short-delay tasks must depend on long-term (supraspan) memory and suggest that MTL lesions impair performance only when immediate memory and working memory are insufficient to support performance. In neuroimaging studies, MTL activity during encoding is influenced by the memory load and correlates positively with long-term retention of the material that was presented. The most parsimonious and consistent interpretation of all the data is that subspan memoranda are supported by immediate memory and working memory and are independent of the MTL.

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Abnormal Categorization and Perceptual Learning in Patients with Hippocampal Damage

Cited by 98 publications

References 62 publications

Perceptual Functions of Perirhinal Cortex in Rats: Zero-Delay Object Recognition and Simultaneous Oddity Discriminations

Perceptual Functions of Perirhinal Cortex in Rats: Zero-Delay Object Recognition and Simultaneous Oddity Discriminations

Two distinct scene processing networks connecting vision and memory

Working memory, long-term memory, and medial temporal lobe function

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