Many studies over the past decades suggested an important role of the hippocampus for navigation and orientation. A study by Maguire et al. (1997) found an enlarged hippocampus in London taxi drivers who through
functional imaging, and Morris et al. (1982) even found impairments in
navigation in rats with a damaged hippocampus.
A study by Teng and Squire (1999) however,
examined a patient with virtually complete bilateral damage to the hippocampus.
Patient E.P. (76 years) had amnesia in 1992 and moved to a new city in 1993. As
expected, it was impossible for him to retrieve any information about the city
he is currently living in. However, observing his virtually navigation skills
for remote memories of the city he grew up in, showed no difference to controls.
Teng and Squire concluded, that the hippocampus is necessary for the encoding
of long-term declarative memories but seems to be spared in their retrieval.
It can be criticised however that E.P was
asked 10 questions about navigating to different locations whereas controls
were only asked a mean of 9.5 questions. More questions can improve an overall
performance. Moreover, results of controls are given as rages, without stating
a mean or SD. In the case of outliers, comparing E.P.’s performance with the
controls can lead to misinterpretation (213 words).
Nevertheless, it is shown that navigation
cannot be located in the hippocampus completely, since E.P was able to complete
most of the given tasks without impairment.
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