Craig P. McFarland

Frontal lobe involvement in a task of time-based prospective memory

Time-based prospective memory (PM) has been found to be negatively affected by aging, possibly as a result of declining frontal lobe (FL) function. Despite a clear retrospective component to PM tasks, the medial temporal lobes (MTL) are thought to play only a secondary role in successful task completion. The present study investigated the role of the FLs and MTLs in time-based PM, as well as their involvement in clock monitoring, plan generation, and time estimation, each of which may play a role in the execution of time-based PM tasks. Based upon their scores on composite measures of FL and MTL function, 32 older adults were divided into four groups, and were then tested on a time-based laboratory PM task. Overall age effects were also assessed and each of the four groups was compared to a group of 32 younger adults. High-frontal functioning participants demonstrated better prospective memory than low-frontal functioning participants, and were not distinguishable from younger adults. Older adults with high-MTL scores performed significantly better than those with low-MTL scores, but only if they were also high in FL function. FL function, but not MTL function, predicted patterns of clock monitoring, quality of plans generated to assist in time-based PM performance, and the accuracy of time estimation. Again, on each of these measures the performance of the high-frontal group was equivalent to that of the younger adults. The results of this study suggest that it is not aging per se that disrupts PM performance, but it is instead primarily the diminished frontal function seen in a subset of older adults.

Implementation intentions and imagery: individual and combined effects on prospective memory among young adults

Prospective memory (PM) has been found to benefit from implementation intentions (i.e., “when I see X, I will do Y”). However, to date, it is unclear whether implementation intentions must incorporate imagery in order to produce a positive effect on PM, or whether the verbal statement alone is sufficient. It is also equivocal whether the use of visual imagery alone improves PM, absent an intentional statement. The present study investigated the individual influences of implementation intentions and imagery, as well as their combined effect, on PM. A total of 64 undergraduates were placed into one of four instructional conditions—read-only, implementation intention, imagery, or combined—and were then tested on a laboratory PM task. The results revealed that participants in the implementation intention, imagery, and combined groups completed significantly more PM tasks than did participants in the read-only group, but they did not differ from one another. Combining implementation intentions and imagery, however, did not improve PM performance over either strategy alone. Additionally, the implementation intention and imagery groups outperformed the read-only group on a secondary ongoing digit detection task. The results of this study suggest that implementation intentions do not require imagery to be effective in improving PM, and that imagery alone has positive effects on PM. Finally, the results of the ongoing digit detection task suggest that the use of implementation intentions and imagery might provide for automatic identification and processing of environmental cues.

Effects of emotion on item and source memory in young and older adults.

Emotional experiences are easier to remember than neutral ones, but whether memory for all aspects of an experience is improved by emotion remains unclear. Some researchers have argued that the influence of emotion on memory is different for item than for source information, whereas others have argued that emotion affects both similarly. Also, whether item and source memory are affected by emotion in older people in the same way as in young people is currently unclear. We examined item and source memory for emotional and neutral materials in young and older adults. Memory for emotional items was superior to memory for neutral items, whereas there was no difference in source memory. Overall, item and source memory were poorer in older people than in young people, but emotion seemed to have a similar effect on both age groups. Although emotional content was remembered better than neutral content, this benefit did not apply to source memory. However, varying the emotionality of the source (i.e., the voice in Experiment 3) improved memory for the source, and this effect was greater in young than in older people. Tone of voice had no effect on item memory in older people, but the effect was variable in the young and may depend on the extent to which the tone of voice moderates the interpretation of the content.

Implementation intentions and prospective memory among older adults: An investigation of the role of frontal lobe function

ABSTRACT Prospective memory (PM) among older adults has been shown to be influenced by frontal lobe (FL) function. An implementation intention (e.g., ‘if situation X occurs, I will do Y’) is a mnemonic strategy that may be particularly beneficial for individuals with low-FL function, as it has been suggested that implementation intentions produce heightened accessibility to environmental cues, and automatic triggering of previously formed intentions. The present study investigated the effectiveness of implementation intentions among 32 older adults characterized as possessing high- or low-FL function. Participants were placed into one of two conditions: Read-Only or Implementation Intentions, before being tested on a laboratory prospective memory task. Results indicated that older adults with high-FL composite scores demonstrated better PM than those with low-FL scores, and that those who made implementation intentions outperformed those who simply read task instructions. Of particular interest is the finding that high-FL participants benefited from implementation intentions, suggesting that implementation intentions may improve PM of all older adults regardless of FL function. Theoretical underpinnings of implementation intentions are discussed in the context of FL function.

Imagine that: Self-imagination improves prospective memory in memory-impaired individuals with neurological damage

Recent research has demonstrated that “self-imagination” – a mnemonic strategy developed by Grilli and Glisky (2010) – enhances episodic memory in memory-impaired individuals with neurological damage more than traditional cognitive strategies, including semantic elaboration and visual imagery. The present study investigated the effect of self-imagination on prospective memory in individuals with neurologically based memory deficits. In two separate sessions, 12 patients with memory impairment took part in a computerised general knowledge test that required them to answer multiple choice questions (i.e., ongoing task) and press the “1” key when a target word appeared in a question (i.e., prospective memory task). Prior to the start of the general knowledge test in each session, participants attempted to encode the prospective memory task with one of two strategies: self-imagination or rote-rehearsal. The findings revealed a “self-imagination effect (SIE)” in prospective memory as self-imagining resulted in better prospective memory performance than rote-rehearsal. These results demonstrate that the mnemonic advantage of self-imagination extends to prospective memory in memory-impaired individuals with neurological damage and suggest that self-imagination has potential in cognitive rehabilitation.

Decreased white matter integrity in neuropsychologically defined mild cognitive impairment is independent of cortical thinning.

Improved understanding of the pattern of white matter changes in early and prodromal Alzheimer’s disease (AD) states such as mild cognitive impairment (MCI) is necessary to support earlier preclinical detection of AD, and debate remains whether white matter changes in MCI are secondary to gray matter changes. We applied neuropsychologically based MCI criteria to a sample of normally aging older adults; 32 participants met criteria for MCI and 81 participants were classified as normal control (NC) subjects. Whole-head high resolution T1 and diffusion tensor imaging scans were completed. Tract-Based Spatial Statistics was applied and a priori selected regions of interest were extracted. Hippocampal volume and cortical thickness averaged across regions with known vulnerability to AD were derived. Controlling for corticalthic kness, the MCI group showed decreased average fractional anisotropy (FA) and decreased FA in parietal white matter and in white matter underlying the entorhinal and posterior cingulate cortices relative to the NC group. Statistically controlling for cortical thickness, medial temporal FA was related to memory and parietal FA was related to executive functioning. These results provide further support for the potential role of white matter integrity as an early biomarker for individuals at risk for AD and highlight that changes in white matter may be independent of gray matter changes.

Enhancing memory and imagination improves problem solving among individuals with depression

Recent work has revealed links between memory, imagination, and problem solving, and suggests that increasing access to detailed memories can lead to improved imagination and problem-solving performance. Depression is often associated with overgeneral memory and imagination, along with problem-solving deficits. In this study, we tested the hypothesis that an interview designed to elicit detailed recollections would enhance imagination and problem solving among both depressed and nondepressed participants. In a within-subjects design, participants completed a control interview or an episodic specificity induction prior to completing memory, imagination, and problem-solving tasks. Results revealed that compared to the control interview, the episodic specificity induction fostered increased detail generation in memory and imagination and more relevant steps on the problem-solving task among depressed and nondepressed participants. This study builds on previous work by demonstrating that a brief interview can enhance problem solving among individuals with depression and supports the notion that episodic memory plays a key role in problem solving. It should be noted, however, that the results of the interview are relatively short-lived.

Event-based prospective memory among veterans: The role of posttraumatic stress disorder symptom severity in executing intentions

ABSTRACT Objective: Posttraumatic stress disorder (PTSD) has been linked with neuropsychological deficits in several areas, including attention, learning and memory, and cognitive inhibition. Although memory dysfunction is among the most commonly documented deficits associated with PTSD, our existing knowledge pertains only to retrospective memory. The current study investigated the relationship between PTSD symptom severity and event-based prospective memory (PM). Method: Forty veterans completed a computerized event-based PM task, a self-report measure of PTSD, and measures of retrospective memory. Results: Hierarchical regression analysis results revealed that PTSD symptom severity accounted for 16% of the variance in PM performance, F(3, 36) = 3.47, p < .05, after controlling for age and retrospective memory. Additionally, each of the three PTSD symptom clusters was related, to varying degrees, with PM performance. Conclusions: Results suggest that elevated PTSD symptoms may be associated with more difficulties completing tasks requiring PM. Further examination of PM in PTSD is warranted, especially in regard to its impact on everyday functioning.

Prospective Memory in Depression: Review of an Emerging Field†

Depressive disorders have been linked to a variety of neuropsychological deficits, including in the areas of processing speed, memory, and executive functioning. These neurocognitive disturbances may contribute to the impairments in daily functioning often experienced by those suffering with depression. Prospective memory (PM), which refers to remembering to execute a previously formed intention at some point in the future, has been shown to play a critical role in daily functioning and may be particularly relevant in the context of depression. In this review, we synthesize the literature on PM and its relation to depression. We also put forth a new five-phase model of PM through which we frame our discussion of the existing literature on PM and depression. The results of this review reveal that PM deficits emerge in those tasks that place the greatest demands on executive functioning (e.g., monitoring for a PM cue, maintaining an intention over a delay). We conclude the review by highlighting the potential clinical relevance of these findings and proposing directions for future research.