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Lesions affecting the parahippocampal cortex yield spatial memory deficits in humans.
C J Ploner1, B M Gaymard, S Rivaud-Péchoux
1INSERM U 289, Service d'Exploration Fonctionelles du Système Nerveux, Service de Neurologie I, Service de Neurochirurgie, H opital de la Salpêtrière, Paris, France. christoph.ploner@charite.de
Cerebral Cortex (New York, N.Y. : 1991)
|November 14, 2000
Summary
The parahippocampal cortex (PHC) is crucial for human spatial memory. Lesions affecting the PHC, but not the perirhinal cortex (PRC), significantly impair spatial memory-guided eye movements.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Neuroanatomy
Background:
- Primate studies suggest the parahippocampal cortex (PHC) is involved in spatial tasks.
- Functional imaging and lesion studies in humans implicate the medial temporal neocortex in spatial cognition.
- Specific evidence for the PHC's specialized role in spatial memory has been limited.
Purpose of the Study:
- To investigate the spatial memory functions of the human perirhinal cortex (PRC) and PHC.
- To determine if the PHC plays a critical role in spatial memory.
- To differentiate the roles of PRC and PHC in spatial memory.
Main Methods:
- Studied patients with lesions affecting the PRC (sparing PHC) and patients with lesions affecting both PRC and PHC.
- Utilized an oculomotor delayed response task with variable memory delays (up to 30s).
- Compared performance of patient groups to healthy controls.
Main Results:
- Patients with combined PRC and PHC lesions exhibited significant delay-dependent inaccuracies in memory-guided eye movements contralateral to the lesion.
- Patients with PRC lesions only (sparing PHC) did not show significant spatial memory inaccuracies.
- These findings highlight the PHC's specific contribution to spatial memory.
Conclusions:
- The PHC is a critical component for spatial memory in humans.
- Extrahippocampal spatial memory functions in the medial temporal lobe are likely concentrated in the PHC.
- Spatial memory deficits observed with PHC lesions are not attributable to damage in connections with rostral temporal lobe regions.