Source amnesia in patients with frontal lobe damage.
Creators: name: Gow, Catherine Ann.
Publisher: name: Université d'Ottawa / University of Ottawa
Year: 1994
Subjects: subject: Biology, Neuroscience.

description: Frontal lobe lesions do not produce a classical amnesia syndrome, although such damage has been associated with some forms of disordered memory processing. This study examined the phenomena of source amnesia in patients with frontal lobe damage. Patients with focal lesions to the frontal lobe, and age- and education-matched normal control subjects were compared on two memory tasks for their recall of both fact and source. In the first experiment, subjects learned fictitious facts about famous and nonfamous individuals and were tested for their recall of both the fact and the source following a 15 minute, and one week delay. In the second experiment, subjects were tested for their recall of the placement of objects on two surfaces under both plain and enhanced conditions. Subjects' ability to recall the board, as well as the exact placement of the objects on the board was tested. Additionally, subjects were required to discriminate experimental objects, from those not seen during the learning session. In both experiments, patients' ability to recall the facts, and the overall placement of objects was as good as that of normal control subjects, but the patients tended to commit more source errors than the normal control subjects. Results from experiment 1 indicated that some patients with lesions of the right hemisphere tended to have more difficulty recalling the presenter source (intra-experimental source) while some patients with left hemisphere damage tended to have more difficulty recalling where they had learned a fact (extra-experimental source). Subtle language impairments were found to be associated with acquisition but not delayed recall of the verbal material. Intra-experimental source errors were related to poor performance on the WCST, while extra-experimental source errors were related to non-verbal measures such as WMS-R, Visual Memory Index, and WAIS-R, PIQ. The data suggest that recall of contextual features such as the modality of presentation and time and place of a learned event can be dissociated from the contents of the learning episode, and that source recall may be disproportionately impaired in some patients with frontal lobe damage. The second experiment revealed deficits in the ability of patients, particularly those with left hemisphere damage, to determine the exact placement of objects on the board to the left. The use of color to enhance learning did not result in increased recall for any of the subjects, however, the patients with damage to the left hemisphere were more likely to incorrectly attempt to place an object under these conditions. Recall of object placement was associated with classical frontal lobe measures, while discrimination of the sets of objects, and placing an object on the wrong board were related to the BNT in the enhanced condition. In fact, although significant correlations were found between the spatial memory measures in the plain condition and the Visual Memory Index, these measures were correlated with the Verbal Memory Index. The results suggest that enhanced context does not increase the accuracy of recall in either patients or normal control subjects. However, the addition of color to the learning situation increased erroneous attempts at placement in the group of patients with left hemisphere damage. This propensity was attributed to a combined effect of use of verbal strategies in the enhanced condition, and poor language decoding abilities in the left hemisphere damaged-patients.