The fractionation of retrograde amnesia

This single case study describes our investigations of the retrograde memory deficit of a patient who became severely and selectively amnesic after an encephalitic illness. On clinical assessment his retrograde deficit for both personal and public events appeared to encompass his entire adult life. However, he retained knowledge of words introduced into the vocabulary during the retrograde period. The experimental investigation documented his inability to recall, recognize, and place in temporal order the names and faces of famous people for all time periods sampled. By contrast, his recall of either a famous face or a famous name was significantly facilitated by the verbal cue of the person's first name and initial of the surname (i.e., Margaret T...). His performance on a test of "familiarity" that required him to select the famous name or the famous face from two distractors (unknown) was within normal limits. It is argued that names and faces of famous people are represented in more than one system: both in a vocabulary-like fact memory system that is preserved and also in a congnitively mediated schemata that in this case is functionally inoperative.     

Consolidation theory and retrograde amnesia in humans

Recent research on the cognitive dysfunctions experienced by human anmesic patients indicates that very long term (multidecade) changes may occur in memory.Flat retrograde amnesia (RA), consisting of a uniform memory deficit for information from all preamnesia time periods, indicates a simple, monolithic retrieval problem, whereasgraded RA, with greater memory deficits for information from recent as opposed to remote time periods, suggests the presence of a gradual long-term encoding, or consolidation, process. An evaluation of 247 outcomes from 61 articles provides strong evidence of graded RA across different cerebral injuries, materials, and test procedures, as well as in measures of both absolute and relative (patient vs. control) performance. Future conceptualizations of human memory should address the possibility that memories increase in resistance to forgetting, or reduction in trace fragility, across many decades.     

Mental shock can produce retrograde amnesia

Subjects in three experiments saw a short film of a mentally shocking event in which a young boy is violently shot in the face. Compared to other subjects who saw a nonviolent version of the same film, those who saw the mentally shocking version showed poorer retention of the details of the film. Retention was poorer whether measured by recognition or recall. Furthermore, impaired memory occurred only when the event was mentally upsetting, and not when it was merely unexpected but not upsetting. These results suggest that mentally shocking episodes may disrupt the lingering processing necessary for full storage of information in memory.     

Emotion-induced retrograde amnesia and trait anxiety

Emotional arousal can both enhance and impair memory. Considering that both emotional memory and trait anxiety (TA) have been associated with adrenergic activity, the authors investigated whether there is an association between 2 opposite emotional memory biases and the TA. The authors used a procedure recently put forward by B. A. Strange, R. Hurlemann, and R. J. Dolan (2003) to elicit an emotion-induced retrograde amnesia (ERA) coupled to an emotional memory enhancement (EME). The authors contrasted the association between these emotional memory biases and the TA in several conditions involving different levels of encoding and types of recall. The results presented here indicated a significant interaction of the TA with EME and ERA and the dependency of these biases on the consciously controlled use of memory.     

Focal retrograde amnesia and the episodic-semantic distinction

This article reports a review of focal retrograde amnesia (FRA), or the phenomenon of organically based severe memory loss restricted to retrograde, or pretraumatic, memory. Cases of FRA are classified according to the type of memory loss: episodic, semantic, or both. A few different clusters of the disorder were identified. Lesions to either the anterior temporal lobes or the posterior/visual cortex can result in an FRA that devastates retrograde episodic memory, while having smaller effects on semantic memory. A number of left-hemisphere patients have FRA confined to semantic memory. There are several additional examples of FRA following minor cerebral trauma that disrupts either episodic memory alone or both episodic and semantic memory that are not accompanied by evidence of structural brain lesions. We discuss these different profiles of FRA and their implications for the understanding of memory retrieval.     

Impaired acquisition of temporal information in retrosplenial amnesia

In this paper we describe the performance of an amnesic with a left retrosplenial lesion on three memory tasks assessing his ability to judge when a previously learned event had occurred. This patient was dramatically impaired in acquiring temporal information about new stimuli, and this defect could not be attributed to recognition failures or to frontal lobe dysfunction. In contrast to his impaired acquisition of temporal information, he had no difficulty judging the temporal order of remote historical events. The pattern of performance displayed by this patient suggests a specific defect in "time-tagging" of new incoming information.     

Substance p reversal of electroconvulsive shock and cycloheximide-induced retrograde amnesia

Subcutaneous post-trial administration of the neuropeptide substance P was found to reverse the amnestic effects of both electroconvulsive shock and cycloheximide. Substance P was observed to reverse the amnestic effects of cycloheximide in both C57B1/6J and heterogeneous strain (HS) mice. Substance P was found to reverse the amnestic effects of electroconvulsive seizures in C57B1/6J animals. Peripheral injections of substance P were also found to facilitate the retention of a single-trial passive avoidance habit in animals of both genotypes, provided a weak footshock was used during training.     

Syndromes of retrograde amnesia: a conceptual and empirical synthesis

This article attempts a synthesis of the range of disorders that have been subsumed under the rubric of retrograde amnesia. At a functional level, it is possible to make distinctions between various forms of retrograde amnesia, including a distinction between episodic amnesia for personally experienced events and semantic retrograde amnesia for components of knowledge, such as those relating to people and events. At an anatomical level, discrete lesions to limbic-diencephalic structures usually result in a limited degree of retrograde amnesia. Marked episodic or marked semantic retrograde amnesia is usually associated with significant involvement of cortical and neocortical structures. Retrograde amnesia is a functionally heterogeneous rather than a unitary phenomenon. Discontinuities and dissociations found in published studies point to the potential fractionation of retrograde amnesia into component disorders, each with its own neural profile.     

The retrieval hypothesis as an explanation of induced retrograde amnesia

The present experiment tested the hypothesis that retrograde induced amnesia is due to retrieval failure and anterograde induced amnesia to encoding failure by providing recall cues which were expected to eliminate retrograde amnesia but worsen or have no effect on anterograde amnesia. The 80 subjects received auditory presentation of 10 lists, each composed of 15 four-letter words presented at a rate of 2s/item at 75 dB in a free-recall task, followed by a 72 s recall period. The amnesia-producing event was an outstanding item in serial position 8 presented at 115 dB (about the intensity of a loud shout) on half the lists. During the first half of the recall period subjects free-recalled, but during the last half they were given a list of the first (single cue) or the first two (double cue) letters of each word, to be used as aids to recall. To demonstrate induced amnesia, lists containing a loud item were compared to those not containing one. First half free recall performance indicated that large retrograde and anterograde effects were present for both cue conditions. Second half cued recall performance indicated that in the double cue condition retrograde amnesia disappeared and anterograde amnesia became larger. Cueing had much smaller effects in the single cue condition.     

Priming of semantic autobiographical knowledge: a case study of retrograde amnesia

The case of a 36-year-old man who suffers dense retrograde and anterograde amnesia as a result of closed-head injury that caused extensive damage to his left frontal-parietal and right parieto-occipital lobes is described. Patient K.C. has normal intelligence and relatively well-preserved perceptual, linguistic, short-term memory, and reasoning abilities. He possesses some fragmentary general knowledge about his autobiographical past, but he does not remember a single personal event or happening from any time of his life. He has some preserved expert knowledge related to the work he did for 3 years before the onset of amnesia, although he has no personal recollections from that period. Some features of K.C.'s retrograde amnesia can be interpreted in terms of the distinction between episodic and semantic memory, and in terms of the distinction between episodic and semantic autobiographical knowledge. K.C.'s semantic knowledge, but not his episodic knowledge, showed progressive improvement, or priming, in the course of the investigation.