Academic diss.--Helsinki. / Includes bibliographical references.

No description available.

The experiments reported in the present dissertation investigated the contribution of the mammillary region to several classes of learning and memory: spatial memory, nonspatial memory, and conditioned aversion learning. It was demonstrated that such lesions impair performance on tasks that require memory for spatial information but that the deficit depends on both the amount of damage within the region as well as the degree of difficulty of the task. A dissociation in the effect of such lesions on performance of comparable spatial and nonspatial memory tasks was shown. In contrast to the severe deficits observed on spatial memory tasks, the acquisition and retention of a complex nonspatial memory task was not impaired after extensive damage to the mammillary region. Such lesions also did not impair performance on two conditioned aversion tasks. These experiments suggest that the mammillary region may be selectively involved in spatial learning and memory. The relevance of these findings to Korsakoff's syndrome is discussed.

No description available.

D.Litt. et Phil. / The present work set out to evaluate whether the division on a neuropsychological basis between Korsakoff's amnesia and Kevin Walsh's Adaptive Behavioural Syndrome (ABS) was justified (Walsh, 1989). The research took the approach that the supposed agents responsible for the ABS (neurotoxicity of alcohol) and Korsakoff's syndrome (thiamine avitaminosis) had not been proven to produce site-specific lesions. Using Bowden (1990) as a point of departure, Luria's (1973) classic discussion of the hierarchical nature of brain functioning was used to generate the hypothesis that the two topographical areas of the brain are both subject to stimulation via the arousal mechanisms of the reticular activating system of the brainstem, and that this might well result in cortical arousal deficiencies giving rise to the frontal and axial deficits seen in alcohol related syndromes. Evidence was found, using techniques of analysis developed by the Boston group (Kaplan, 1980), that in fact the frontally-based ABS was less vulnerable to brainstem dysfunction, and that when arousal levels began to increase, as in the arousing neuropsychological evaluation environment, signs of frontal dysfunction waned, whilst signs of axial mnemonic difficulties did not. This discrepancy was explained using Luria's information that the frontal cortical areas are richly supplied with connections to the reticular activating system of the brainstem, whereas the axial structures are not so richly endowed. The conclusion was reached that the ASS and l(orsakoff's dysfunctions are two sides of the same coin, and that the division between the two is both an artifact of research designs in the past that have excluded those with signs of alcohol dementia ('pure' amnesias), and the heretofore invisible moderating influence of the acetaldehyde-damaged noradrenergic pathways of the brainstem. The post-traumatic amnesias seen following closed head injury and acute stress were discussed as contributing to the generalisability of the conclusions, and the role of neuropsychologists in the future within the field was discussed.