Mental images in episodic memory

Episodic memory, i.e. memorization of information within a
spatiotemporal environment, is affected by Alzheimer's disease (AD)
but its loss may also occur in the normal aging process. The
purpose of this study is to analyze and evaluate episodic memory in
patients with AD by examining their cognitive skills in episodic
memory through the introspection technique. A new method was used,
wherein we assessed mental images of the subject's own past
recalled in the mind like projected pictures and movies. Experiment
1 is designed to determine the effect and process of normal and
pathological aging on cognitive skills in episodic memory using the
introspection technique. Two groups were observed towards this
purpose: 21 patients with AD and 19 normal control subjects. All
subjects were chosen from ages from 55 to 70 and were administered
standardized neuropsychological tests (K-DRS and MMSE-K). All
subjects were asked to retrieve their episodic memory of the
previous day, week, month, and a day remote from testing day. The
answers were analyzed, focusing on their specific features such as
emotional state, color, and time order. In the following day, the
subjects were tasked to recall again all images that they
reproduced in the previous day's test in order to observe
impairment of anterograde memory. Results showed that patients
failed to arrange the retrieved images in time order and their
images of the previous day were unclear in color and were
stationary like photographs, even when they reproduced the mental
images at as much quantity as controls. They also could not
remember particular events of yesterday, only their general
occurrence. These results suggest that in the early stage of AD,
difficulties in the retrieval of recent episodic memory begin to
occur, and qualitative impairment happens earlier than
quantitative. The third chapter supports these results with further
evidence, analyzing from a clinical viewpoint 3 patients with AD, 1
patient with mild depression and 2 controls. In Experiment 2 the
emotional intensity of episodic memory within different categories
of memory (yesterday, week, month, and remote) was investigated by
comparing healthy elderly people and AD patients. The subjects’
voice intonations were estimated by 8 valuators. As a result, the
emotional intensity of AD patient was evaluated lower than
controls. It appears that patients in the early stage of AD are
impaired in the ability to express emotions during emotional
episodic memory retrieval compared to healthy elderly adults.