8 - Less well-characterized memory disorders

Summary

Research on short-term memory disorders, disorders of well-established memory, frontal memory disorders, and organic amnesia is still in a very open stage of development. Hypotheses about the functional deficits underlying these deficits as well as the lesions that cause them may well undergo a sea change in the face of new discoveries over the next few years. All the interpretations advanced in previous chapters are tentative suggestions that seem plausible in the light of available evidence. Currently, it is unwise to become strongly attached to hypotheses about the bases of organic memory disorders, but quite a bit has been learnt about their main features. The same cannot be said about disorders of the kinds of implicit memory that are probably preserved in organic amnesics. Nor can it be said about the memory disorders that form an often variable part of certain complex psychiatric and neurological disturbances, such as schizophrenia and Parkinson's disease. This chapter considers first the small amount of research that has been directed at exploring whether brain damage can cause selective impairments of priming, skill acquisition and retention, and conditioning (all kinds of implicit memory in which the evidence of remembering is indirect rather than direct). The evidence concerning the memory deficits associated with the complex psychiatric and neurological syndromes is then briefly reviewed in order to ascertain whether the memory deficits reported in these conditions can be interpreted as compounds of the elementary memory disorders, discussed earlier in the book.