MEMORY, DISEASES OF
MEMORY, DISEASES OF. Memory, or the power of reproducing mental impressions, is impaired by age, wounds, or injuries to the head or nervous system, fevers, intemperance, and various physical conditions. It is perhaps affected in all kinds of mental derangement, but is in a most signal manner obliterated or enfeebled in Dementia. There are, however, examples of recollection surviving all other faculties, and preserving a clear and extensive notion of long and complicated series of events amid the general darkness and ruin of mind. Incoherence owes some of its features to defective or irregular memory. Cases of so marvelous an exaltation and extension of this capacity, as where a whole parliamentary debate could be recalled, suggest the suspicion of unhealthy action. There appear, however, to be special affections of the faculty. It may be suspended while the intelligence remains intact. Periods of personal or general history may elude the grasp, and even that continuity of impressions which goes far to constitute the feeling of personal identity, is broken Up, and a duality or multiplicity of experiences may appear to be conjoined. The converse of this may happen, and knowledge that had completely faded away may, under excitement or cerebral disease, return. There are, besides, states in which this power is partially affected, as in the instances where the numbers 5 and 7 were lost, and where a highly educated man could not retain any conception of the letter F; secondly, where, it appears perverted, recalling images inappropriately, and in an erroneous sequence of order or time, and different from what are desired; and thirdly, where, while the written or printed signs of ideas can be used, the oral or articulate signs are utterly forgotten. All these deviations from health appear to depend upon changes generally of an apoplectic nature in the anterior lobes of the brain.—Crichton on Mental Derangement; Teuchtersleben, Medical Psychology; Ribot, Les Maladies de la Memoire (1881).