Facilitation of memory by contextual cues in patients with diencephalic or medial temporal lobe dysfunction

Abstract

Item-context binding is crucial for successful episodic memory formation, and binding deficits have been suggested to underlie episodic-memory deficits. Here, our research investigated the facilitation of cued recall and recognition memory by contextual cues in 20 patients with Korsakoff's amnesia, 20 unilateral medial-temporal lobectomy (MTL) patients and 36 healthy controls. In a computerized task participants had to learn 40 nouns that were randomly combined with a photograph of an everyday scene. Korsakoff patients showed a general memory deficit in both the cued recall and the recognition condition. A less severe memory impairment was found in the patients with medial-temporal lobectomy. Contextual cues facilitated cued recall to an equal extent in unilateral temporal lobectomy patients and healthy controls. However, no facilitation was observed in Korsakoff patients, suggesting an impairment in item-context binding during cued recall tasks. In contrast to the presumed exclusive dependency of recognition memory on item information, all groups equally profited from the contextual cues in recognition tasks. Our findings show that unilateral lesions as with MTL result in normal binding of context and item information, while bilateral dysfunction of the hippocampal-diencephalic system results in impaired context and item binding.