DISORIENTATION IN AMNESIA - A CONFUSION OF MEMORY TRACES

Disorientation is a common phenomenon in delirium and amnesia. It is t hought to have an obvious explanation, i.e. disoriented patients fail to store the information crucial for the maintenance of orientation In this study, We explored whether disorientation was indeed associated with a failure to learn new information or rather with a confusion of information within memory. Twenty-one patients with severe amnesia wer e examined. Orientation was tested with a 20-item questionnaire. Two r uns of a continuous recognition task were used to test the ability to acquire information (first run of the task) and the tendency to confus e the temporal context of information acquisition (comparison of the s econd with the first run). We found that orientation was much better p redicted by the measure of temporal context confusion (r = 0.90) than by the ability to simply acquire information (r = 0.54). Superimpositi on of neuroradiological scans demonstrated that increased temporal con text confusion was associated with medial orbitofrontal or basal foreb rain damage; patients with normal levels of temporal context confusion did not have damage to these areas. We conclude that disorientation m ore often indicates a confusion of memory traces from different events , i.e. increased temporal context confusion, than an inability to lear n new information. Disorientation appears to reflect primarily a failu re of the orbitofrontal contribution to memory.