Source memory in Parkinson's disease

Pilot Study to Examine the Use of Self-Generation to Improve Learning and Memory in People With Traumatic Brain Injury

People with traumatic brain injury (TBI) experience memory and learning difficulties. Difficulty in the initial acquisition of information is a primary reason people with TBI experience difficulties in learning and memory. Treatment focusing on improving the acquisition of information will likely improve both recall and recognition performance. In the “generation effect,” items self-generated are remembered better than items read or otherwise provided. The purpose of this study was to examine the application of the generation effect in improving memory for functional activities. The study used a within-subjects design and included 10 participants with TBI and 15 healthy control participants. Results demonstrated that material learned under the generated learning conditions was recalled better than when generated under provided learning conditions. This finding was true in both the TBI and the control groups. These results provide initial evidence supporting the use of self-generation to improve new learning of functional tasks for people with TBI.

HIV-associated episodic memory impairment: evidence of a possible differential deficit in source memory for complex visual stimuli

HIV infection is often associated with frontal systems pathology and related deficits in the strategic encoding and retrieval aspects of episodic memory. However, no prior HIV studies have explicitly examined source memory, which refers to recall of information regarding the context in which a declarative memory was formed. Source memory is heavily reliant on frontal systems and strategic cognitive processes and is singly dissociable from the content of the memory (i.e., item memory), which is more dependent on medial temporal systems and automatic processes. The present study examined item and source memory in 60 individuals with HIV infection and 35 demographically similar seronegative participants. The primary finding of interest was a significant HIV effect on source (but not item) memory for complex visual stimuli. Follow-up correlational analyses showed a significant association between visual source memory errors and impairment on measures of executive functions, working memory, and higher-level list learning encoding strategies. These findings extend the hypothesized profile of strategic encoding and retrieval deficits in HIV to the construct of source memory, which may be differentially affected relative to item memory for complex visual stimuli.

Self-generation to improve learning and memory of functional activities in persons with multiple sclerosis: meal preparation and managing finances

OBJECTIVE

To examine the utility of using a self-generation strategy to improve learning and performance of everyday functional tasks in persons with multiple sclerosis (MS).

DESIGN

Mixed-design with both a within- and between-subject factor.

SETTING

Nonprofit rehabilitation research institution.

PARTICIPANTS

Participants (n=20) with MS and healthy controls (n=18).

INTERVENTIONS

Participants completed 2 meal preparation and 2 financial management tasks. One task in each area was presented in the provided condition, in which all instructions were provided to and read by the participants, and the other task was presented in the generated condition, in which participants were asked to generate (fill in the blank) the necessary items needed to perform each step of the task.

MAIN OUTCOME MEASURES

Correct recall of task items and step sequence immediately and 1 week after initial learning and correct performance of task items and step sequence 30 minutes after initial learning. The maximum possible score in each of the recall tests was 24.

RESULTS

Although the MS and healthy groups did not differ in overall items recalled, in both groups tasks learned in the generated condition enhanced memory performance significantly for the tasks used when compared with similar tasks learned in the provided condition.

CONCLUSIONS

Self-generation during learning can significantly improve subsequent recall of information and performance of activities of daily living for persons with MS. Implications of these findings for cognitive rehabilitation in MS are discussed.

The psychological refractory period in Parkinson's disease

The Psychological Refractory Period paradigm was used to investigate whether patients with Parkinson's disease showed disproportional deficits in regulating responses to two sequential presented stimuli. The first task required a speeded key-press response to an auditory stimulus, and the second task required a speeded key-press response to a visual stimulus. The stimulus onset asynchrony (SOA) between Task 1 and Task 2 was 50 msec., 150 msec., and 650 msec. According to the bottleneck model, the SOA manipulation should not affect performance on Task 1, but reaction time for Task 2 should increase as the SOA between the two tasks decreased. The increase in reaction time for Task 2 was referred to as the Psychological Refractory Period. In this study, both patients with Parkinson's disease and normal controls showed classical effects. More importantly, although the 22 patients with Parkinison's disease took longer to respond to both Tasks 1 and 2 than the 20 normal controls, the effects of the Psychological Refractory Period for the two groups were of the same magnitude. The results suggest that Parkinson's disease affects only the response-execution stages rather than the response-selection stages, based on the central bottleneck model.