Comparative neuropsychology and Korsakoff's syndrome. II.--Two-choice visual discrimination learning.
Explore the source record for details and available documents.
Biomedical subjects
Publications and source records attributed to M Oscar-Berman.
Explore the source record for details and available documents.
Nine patients 55 to 74 years old with Parkinson's disease were tested before and after treatment with 50 to 225 mg dimepramine fumarate (CIBA G-31406) for about three weeks daily in order to determine the drug's effects on electrodermal responsiveness to a series of unpredictably occurring loud sounds. Twelve control subjects were tested and retested with the same procedure. In addition, the Parkinson patients received a number of cognitive tests before and after drug treatment. Results indicated that the drug tends to decrease autonomic arousal responses as measured by resting conductance levels, number of fluctuations in skin conduction per minute, orienting response, and habituation rate. These decreases in measures of arousal generally were accompanied by lowered performance scores on several tests of memory and temporal discrimination ability.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Subjects with formal musical training were tested tachistoscopically in order to obtain thresholds for recognizing single notes a staff, presented successively to the lateral visual fields. They were also tested on backward visual making of the same stimuli to determine the interstimllus interval needed to escape the masking effect (critical ISI). Response requirements in threshold and ISI conditions were nonverbal (depressing an organ key), or verbal (indicating the stimulus by name). Recognition threshold for notes were lower in the right visual field than in the left, and verbal responses were easier than manual responses in the threshold condition. However, critical ISIs were lower in the left field than in the right, and ISIs from the left visual field were lower with manual responses than with verbal responses. These findings support the idea that (a) threshold and ISI represent separate levels of perceptual processing, and (b) in trained subjects, the ability to recognize musical symbols may be governed by the left hemisphere, while the information-processing stage of iconic storage may occur in the right hemisphere.
Performance of 10 alcoholic Korsakoff patients was compared to that of 10 normal and 10 alcoholic control subjects on each of three different schedules of spatial probability learning (50:50, 70:30, and 30:70) using monetary reinforcement and a correction procedure. There was some evidence that the Korsakoff patients were less sensitive than normals to the effects of reward: Although on all three schedules, choice ratios by normal subjects approximated the reinforcement ratios, the choice ratios of Korsakoffs on the second and third schedules remained close to the reinforcement ratio acquired with the first schedule. In addition, the Korsakoffs made an abnormal number of perseverative errors early in training. On most measures, performance by alcoholic controls fell between that of the other two groups.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
This paper reviews five separate experimental studies concerning the acute or chronic effects of alcohol on late ERP components related to cognitive processes. The studies are evaluated for their adequacy in two arenas: (a) task relevance from a behavioral viewpoint, and (b) their ability to clarify the functional significance of alcohol-related ERP changes. Based upon the general trends of the results reported from the five individual laboratories conducting the investigations, it can be concluded that the P3 component is the most consistently altered of the four late ERP components considered (N1, N2, P2, P3). The finding of a reduced P3 amplitude was more reliable than the finding of increased P3 latency. Alterations in ERP components, when they did occur, occurred under the acute influence of ethanol, as well as in abstinent chronic alcoholics. All of the ERP findings reported were obtained using variations of signal detection procedures. Changes in ERP components did not always parallel performance changes, suggesting that aspects of psychological processes (e.g., attention and stimulus evaluation), presumed to underly ERPs' functional significance, did not directly reflect these processes.
Explore the source record for details and available documents.