Map reading, navigating from maps, and the medial temporal lobe

Abstract

We administered map-reading tasks in which participants navigated an array of marks on the floor by following paths on hand-held maps that made up to nine turns. The burden on memory was minimal because the map was always available. Nevertheless, because the map was held in a fixed position in relation to the body, spatial computations were continually needed to transform map coordinates into geographical coordinates as participants followed the maps. Patients with lesions limited to the hippocampus (n = 5) performed similar to controls at all path lengths (experiment 1). They were also intact at executing single moves to an adjacent location, even when trials began by facing in a direction that put the map coordinates and geographical coordinates into conflict (experiment 2). By contrast, one patient with large medial temporal lobe (MTL) lesions performed poorly overall in experiment 1 and poorly in experiment 2 when trials began by facing in the direction that placed the map coordinates and geographical coordinates in maximal conflict. Directly after testing, all patients were impaired at remembering factual details about the task. The findings suggest that the hippocampus is not needed to carry out the spatial computations needed for map reading and navigating from maps. The impairment in map reading associated with large MTL lesions may depend on damage in or near the parahippocampal cortex.hippocampus | memory | spatial navigation T wo views have been central to discussions about the function of the hippocampus. One view grew out of work with humans, and emphasizes the importance of the hippocampus for memory (1, 2). By this view, the hippocampus is important for the formation of long-term (declarative) memory, not for immediate memory or for its maintenance by what is ordinarily termed working memory. The second view grew out of work with rodents, and emphasizes the importance of the hippocampus for spatial navigation (3, 4). The suggestion here is that the hippocampus is needed to perform certain online spatial computations. In one sense, these views are compatible because spatial memory is a type of memory. However, a potential conflict arises when one turns to tasks of spatial navigation that are manageable within working memory. What is the role of the hippocampus in this circumstance?A number of studies have explored the possible importance of the human hippocampus for spatial tasks, including navigation. For example, one study reported hippocampal activity during topographical learning of a real-world environment (through viewing films) but less activity during the learning of events that occurred in the environment (5). Other studies reported that the hippocampus exhibited more activity when participants accurately navigated through familiar, virtual-reality towns than when participants needed only to follow a marked route through the same towns (6, 7). In addition, patients with hippocampal lesions were impaired at navigational tasks involving recently explored environments (8-10).It is notable tha...

Spared Perception of the Structure of Scenes after Hippocampal Damage

“…Thus, in these studies, lesions limited to the hippocampus did not affect the ability to judge the structural coherence of objects, objects embedded in scenes, or scenes themselves. This conclusion is in accord with our earlier findings that the hippocampus is also not needed for a variety of other spatial tasks, so long as the tasks do not depend on long-term memory (Rungratsameetaweemana & Squire, 2018;Urgolites et al, 2016Urgolites et al, , 2017Kim et al, 2011Kim et al, , 2015Kim, Borst, et al, 2013;Kim, Sapiurka, et al, 2013;Shrager et al, 2008).…”

“…In these circumstances, patients with hippocampal lesions might have been disadvantaged due to their memory impairment. In our own studies of spatial tasks, where we attempted to minimize the contribution of long-term memory (by limiting the number of stimuli or by using trial-unique stimuli), hippocampal patients performed as well as controls (path integration, Kim, Sapiurka, Clark, & Squire, 2013;Shrager, Kirwan, & Squire, 2008; visual discrimination of scenes, Kim et al, 2011;spatial imagery, Kim, Borst, et al, 2013; scene construction, Kim, Dede, Hopkins, & Squire, 2015; map reading and navigation, Urgolites, Kim, Hopkins, & Squire, 2016; topographical memory with shifts of viewpoint, Urgolites, Hopkins, & Squire, 2017; scene construction with shifts of viewpoint, Rungratsameetaweemana & Squire, 2018). For a report of impaired performance in a task using trial-unique stimuli, see Lee et al (2005).…”

Are place cells just memory cells? Memory compression leads to spatial tuning and history dependence

“…However, there is an ongoing debate on whether the hippocampus is actually needed to navigate in familiar environments (see e.g. (53)(54)(55)(56)). Several studies indicate that the hippocampus is important primarily in situations of navigation that require the formation of new memories (57).…”

Getting Lost Behavior in Patients with Mild Alzheimer’s Disease: A Cognitive and Anatomical Model

“…The medial temporal region includes the hippocampus, the subicular complex and the parahippocampal cortical regions, which collectively play a critical role in the encoding, storage and active manipulation of cognitive maps ( 38 ). Accordingly, past research has demonstrated that patients with lesions to the medial temporal lobe exhibit deficits with spatial memory, including recalling locations, drawing maps of the environment and making judgments about the distance and proximity of locations ( 39 ). Similar spatial memory deficits have been observed in patients with AD ( 33 ).…”