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Two experiments examined the extent to which retrograde amnesia (RA) is attenuated by prior learning experiences. In Experiment 1, rats initially received either passive avoidance training in a step-through apparatus, exposure to the apparatus, or noncontingent footshock. When training on a second but different passive avoidance task was followed by hypothermia treatment, RA was obtained only in the latter two groups. In Experiment 2, one-way active avoidance training, yoked noncontingent shocks, or apparatus exposure constituted the initial experience. Subsequent step-down passive avoidance training and amnestic treatment resulted in memory loss for the prior apparatus exposure group, but not for either of the preshocked conditions. These experiments demonstrate that certain types of prior aversive experience can substantially modify the magnitude of RA, and, in conjunction with other familiarization studies, emphasize a paradox for interpretations of RA based solely upon CNS disruption. The possibility that hypothermia treatment serves as an important contextual or encoding cue necessary for memory retrieval was considered. It was suggested that prior experience may block RA by enabling rats to differentiate training and treatment conditions.

The author, by giving an outline of one particular case as well as a survey of the relevant literature on transient global amnesia, describes the characteristic clinical picture that is characterized by a sudden loss of what is known as the short-time memory, which usually lasts for several hours, as well as by retrograde amnesia which sometimes dates back to many years. The condition gradually fades away within a few hours or during a night's sleep, and what remains is lack or loss of memory for the episodic period or sometimes retrograde amnesia. Relapses were not observed in the majority of patients. The disease usually develops in people in their sixth to eighth decades of life. The cause of the disease is not yet fully understood. Accordingly, it is justified to use such terms as autochthonous or cryptogenic amnestic episodes. The disease is also discussed from a differential diagnosis point of view.

To analyze disorders of memory functions, observations were made in healthy test subjects after administration of psychotropic drugs and anesthetics. In isolated cases amnesic episodes were recorded and in 8 of the subjects accurate measurements of the retrograde amnesia after propanidid anesthesia were made. The observations provided arguments for the delimitation of the immediate memory (ultra-short-term memory, one minute memory) from short-term memory and long-term memory of the conventional terminology. As a result of our investigations we came to the thesis that the transformation of the non-specific biochemical and electrophysiological processes underlying the immediate memory into the specific processes underlying the short-term memory is more susceptible to disturbances than that of reproduction and the processes serving for perception. With regard to forensic assessment, it is significant that behaviour foreign to the personality could not be observed in amnesic episodes.