Impaired recollection and initially preserved familiarity in a patient with bilateral fornix transection following third ventricle colloid cyst removal: A two-year follow-up study

Abstract

Objective

Recognition memory is widely accepted as a dual process-based model, namely familiarity and recollection. However, the location of their specific neurobiological substrates remains unclear. Similar to hippocampal damage, fornix damage has been associated with recollection memory but not familiarity memory deficits. To understand the neural basis of recognition memory, determining the importance of the fornix and its hippocampal connections is essential.

Methods

Recognition memory was examined in a 45-year-old male who underwent a complete bilateral fornix section following the removal of a third ventricle colloid cyst. The application of familiarity and recollection for recognition memory decisions was investigated via an immediate and delayed associative recognition test and an immediate and delayed forced-choice task in the patient and a control group (N = 15) over a two-year follow-up period. Complete demographic, neuropsychological, neuropsychiatric, and neuroradiological characterizations of this patient were performed.

Results

Persistent immediate and delayed verbal recollection memory deficits were observed in the patient. Moreover, delayed familiarity-based recognition memory declined gradually over the follow-up period, immediate familiarity-based recognition memory was unaffected, and reduced non-verbal memory improved.

Conclusion

The present findings support models that the extended hippocampal system, including the fornices, does not appear to play a role in familiarity memory but is particularly important for recollection memory. Moreover, our study suggests that bilateral fornix transection may be associated with relatively functional recovery of non-verbal memory.

Keywords:

• Bilateral fornix transection
• colloid cyst
• familiarity
• fornix
• hippocampus
• non-verbal memory
• recognition memory
• recollection

Acknowledgments

This article is dedicated to Mr. DR. and his wife for their contribution and their valuable cooperation. The authors thank Ana Pagá Casanova for her expert technical assistance. We also wish to thank our colleagues of the Department of Psychology of the University of Valencia and the Department of Geriatrics of the Caritas-Klinik Dominikus, Berlin-Reinickendorf for discussions and comments concerning the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.