Back to the high school days: an abnormal remembering characterized by concurrent as well as alternating feeling to be in the past and present

摘要

After the successful treatment of a hypothalamic germinoma, a 31-year-old right-handed male developed a difficulty in memory and admitted to our department for detailed evaluation. Neuropsychologically he showed no personality change, confabulation, misidentification, delusion or disorientation to physical time. Neither aphasia, dementia or frontal lobe dysfunction was found. However, he showed a moderate degree of anterograde amnesia and a retrograde amnesia for the last 5 years judged by a public events test. Moreover, his temporal markings of a correctly remembered event in the post high school days shifted strongly toward the high school days. This temporal location abnormality was largely limited to the events from the days of his graduation from the high school to the period 5 years prior to the present incident. He felt personal events happened during this period as if they had occurred in the high school days, although he well knew that they actually happened much later. At the same time he felt that memories of the high school days were abnormally vivid and recent. Most interestingly, he was found to have been experiencing a funny feeling that he was living in the high school days and the present at the same time. The feeling occurred either simultaneously or alternatively. In the latter instance, he would suddenly start behaving as if he were a high school student. He would start urging his wife to go to the school together immediately. This behavior would be over in several minutes. His consciousness was clear in these instances and there was no amnesia for these periods. A brain MRI with gadolinium enhancement showed a lesion extending in the hypothalamus, anterior thalamus, basal forebrain and midbrain bilaterally. After eight months this abnormality of temporal sensation disappeared. However, tendency to make the date of public event nearer to the high school period persisted. We hypothesize that impaired temporal estimation for an event recalled from the retrograde memory store and mis-arousal of familiarity evoked at the time of spontaneous recollection are responsible for double feeling of time of an experience. These phenomenon might be attributable to the partial destruction of the Papez' and the basolateral limbic circuits.