Improving visual spatial working memory in younger and older adults: effects of cross-modal cues.

Spatially informative auditory and vibrotactile (cross-modal) cues can facilitate attention but little is known about how similar cues influence visual spatial working memory (WM) across the adult lifespan. We investigated the effects of cues (spatially informative or alerting pre-cues vs. no cues), cue modality (auditory vs. vibrotactile vs. visual), memory array size (four vs. six items), and maintenance delay (900 vs. 1800 ms) on visual spatial location WM recognition accuracy in younger adults (YA) and older adults (OA). We observed a significant interaction between spatially informative pre-cue type, array size, and delay. OA and YA benefitted equally from spatially informative pre-cues, suggesting that attentional orienting prior to WM encoding, regardless of cue modality, is preserved with age.  Contrary to predictions, alerting pre-cues generally impaired performance in both age groups, suggesting that maintaining a vigilant state of arousal by facilitating the alerting attention system does not help visual spatial location WM.

Effects of practice and delays on learning and retention of skilled tool use in Parkinson's disease.

Previous research has shown that individuals with Parkinson's disease (PD) show preserved learning of tool-related motor skills, while retention was impaired after a three-week delay, possibly as a result of striatal dysfunction. The goal of the current study was to identify if shorter delays and more extensive practice might reduce retention deficits related to complex tool use in PD. PD participants and healthy age and education-matched controls were trained to use novel tools across four sessions, spaced one-day, one-week, and three-weeks apart. Recall of tool attributes (e.g., function) and skilled motor performance using tools was investigated by examining patterns of learning and forgetting over time. Results showed that tool attribute recall was unimpaired in PD participants relative to controls. For motor skill performance, PD participants were unimpaired in motor skill learning within sessions, but they did not retain these skills across one-week and three-week delays between sessions. This dissociation suggests that the striatum plays a critical role in retention of motor skills needed in skilled tool use performance. Finally, in spite of forgetting, individuals with PD still demonstrated improvement across sessions with additional training, suggesting that people with PD may benefit from extensive practice when learning motor skills.

Effects of dividing attention on memory for declarative and procedural aspects of tool use.

Tool-related knowledge and skills are supported by a complex set of memory processes that are not well understood. Some aspects of tools are mediated by either declarative or procedural memory, while other aspects may rely on an interaction of both systems. Although motor skill learning is believed to be primarily supported by procedural memory, there is debate in the current literature regarding the role of declarative memory. Growing evidence suggests that declarative memory may be involved during early stages of motor skill learning, although findings have been mixed. In the current experiment, healthy, younger adults were trained to use a set of novel complex tools and were tested on their memory for various aspects of the tools. Declarative memory encoding was interrupted by dividing attention during training. Findings showed that dividing attention during training was detrimental for subsequent memory for tool attributes as well as accurate demonstration of tool use and tool grasping. However, dividing attention did not interfere with motor skill learning, suggesting that declarative memory is not essential for skill learning associated with tools.

Naturalistic Action Performance Distinguishes Amnestic Mild Cognitive Impairment from Healthy Aging.

Individuals with amnestic mild cognitive impairment (aMCI) show minor decrements in their instrumental activities of daily living (IADL). Sensitive measures of IADL performance are needed to capture the mild difficulties observed in aMCI groups. Routine naturalistic actions (NAs) are familiar IADL-type activities that require individuals to enact everyday tasks such as preparing coffee. In the current study we examined the extent to which NAs could be used to help facilitate differential diagnosis of aMCI relative to composite measures of episodic memory, semantic knowledge, and executive function. Healthy older adults (n=24) and individuals with aMCI (n=24) enacted two highly familiar NAs and completed tests of episodic memory, semantic knowledge, and executive function. Binary logistic regression was used to predict group membership (aMCI vs. control participants). The regression analyses indicated that NA performance could reliably predict group membership, over and above measures of cognitive functioning. These findings indicated that NA performance can be used to help facilitate differential diagnosis of healthy aging and aMCI and used as an outcome measure in intervention studies.

Compromised naturalistic action performance in amnestic mild cognitive impairment.

OBJECTIVE: Routine naturalistic actions (NAs) are familiar activities that require the production of several actions in a particular order to achieve a specific goal, such as preparing a meal or paying bills. Given that amnestic mild cognitive impairment (aMCI) has been shown to be a risk factor for dementia, a better understanding of the cognitive processes that mediate NA performance is needed in order to facilitate efforts to promote functional autonomy in this population. METHOD: Performance of 2 highly familiar NAs, and their relationship to measures of episodic memory, semantic knowledge, and executive function was systematically investigated in a sample of healthy older adults (n = 24) and individuals with aMCI (n = 24). RESULTS: In general, measures of executive function were related to commission errors, while episodic memory was associated with the omission of supporting actions. However, both errors of omission and commission appeared to draw on a diverse array of cognitive processes. CONCLUSIONS: The findings provide preliminary evidence that the cognitive correlates of NA errors may not be as process pure as previously hypothesized in neuropsychological models. A more comprehensive understanding of the cognitive underpinnings of NAs in aMCI could lead to more effective intervention programs to promote functional autonomy and delay dementia onset. Furthermore, NAs may be administered in neurocognitive assessments to identify early changes in everyday functioning and facilitate differential diagnosis between healthy aging and aMCI.

Interaction of memory systems during acquisition of tool knowledge and skills in Parkinson's disease.

Previous research suggests that different aspects of tool knowledge are mediated by different memory systems. It is believed that tool attributes (e.g., function, color) are represented as declarative memory while skill learning is supported by procedural memory. It has been proposed that other aspects (e.g., skilled tool use) may rely on an interaction of both declarative and procedural memory. However, the specific form of procedural memory underlying skilled tool use and the nature of interaction between declarative and procedural memory systems remain unclear. In the current study, individuals with Parkinson's disease (PD) and healthy controls were trained over 2 sessions, 3 weeks apart, to use a set of novel complex tools. They were also tested on their ability to recall tool attributes as well as their ability to demonstrate grasp and use of the tools to command. Results showed that, compared to controls, participants with PD showed intact motor skill acquisition and tool use to command within sessions, but failed to retain performance across sessions. In contrast, people with PD showed equivalent recall of tool attributes and tool grasping relative to controls, both within and across sessions. Current findings demonstrate that the frontal-striatal network, compromised in PD, mediates long-term retention of motor skills. Intact initial skill learning raises the possibility of compensation from declarative memory for frontal-striatal dysfunction. Lastly, skilled tool use appears to rely on both memory systems which may reflect a cooperative interaction between the two systems. Current findings regarding memory representations of tool knowledge and skill learning may have important implications for delivery of rehabilitation programs for individuals with PD.

Effects of familiarity and cognitive function on naturalistic action performance.

OBJECTIVE: This study investigated the effects of familiarity on the performance of routine (familiar) naturalistic actions (NAs) that had been performed several times prior to the experiment (e.g., making coffee) and novel (unfamiliar) naturalistic actions (NNAs) that had not been performed prior to instruction (e.g., making a mock volcano). We hypothesized that similar psychological processes were associated with both types of action, but that memory and executive functions would be more important for NNAs. METHOD: In Experiment 1, 18 undergraduates verbally described NAs and NNAs as they observed the tasks being performed. In Experiment 2, stroke patients, impaired (n = 4) or unimpaired (n = 4) on a test of general cognitive function, and 12 controls, physically enacted and arranged in correct order photos of NAs and NNAs. RESULTS: In Experiment 1, the central (crux), but not the noncentral (noncrux) actions, associated with NAs and NNAs were verbally described. In Experiment 2, NA and NNA enactment and photo arrangement performance was lower in the impaired group compared with controls. The impaired group had higher omission (omitting an action) than commission (performing an action incorrectly) crux action error rates for NAs, but the reverse pattern for NNAs. NA performance was more strongly associated with general cognitive function, whereas NNA performance correlated more strongly with executive functioning and memory measures. CONCLUSION: Both types of task involve overlapping cognitive processes. Memory and executive function may be more important for NNAs because these tasks are encoded into memory at study.

Dissociating the memory systems mediating complex tool knowledge and skills.

Previous research has suggested that different components of complex tool knowledge (e.g., attributes of a tool, how it is grasped, how it is used) may be mediated by different memory systems. For instance, while tool attributes may be represented in the declarative memory system, motor skill acquisition has been shown to be represented in the procedural memory system. Still other aspects of tool knowledge such as grasping for use and skilled tool use may rely on an integration of both declarative and procedural memory processes. However, the specific memory representations of different aspects of complex tool knowledge are still unclear. In the current study, D.A., an individual with amnesia, and a sample of matched controls were trained to use a set of novel complex tools. Subsequently, memory for different aspects of tool knowledge including motor skill acquisition, tool attributes, tool grasping, and skilled tool use was tested. Results showed that, in comparison to controls, D.A. was unimpaired in motor skill acquisition. In contrast, D.A. was severely impaired in recall of tool attributes, tool grasping, and skilled tool use, suggesting that these components of tool knowledge, at least in part, rely on declarative memory. Results also showed that providing contextual cues during tests of skilled tool use led to remarkable improvement in D.A.'s demonstration of tool use as well as his subsequent recall of tool functional knowledge. Implications of these findings and future directions are discussed.

The effects of dividing attention on the encoding and performance of novel naturalistic actions.

Novel naturalistic actions (NNAs) are multi-step, goal-directed actions involving the manipulation of objects that are unfamiliar to a person prior to instruction. Experiment 1 investigated the cognitive processes involved with encoding and performing NNAs by selectively interfering with attention during viewing or production of a NNA using the dual-task paradigm (n = 27, healthy adults). Consistent with the central findings from the dual-task memory literature, dividing attention at viewing caused a relatively greater disruptive effect on NNA performance than selectively interfering with attention during enactment. A follow-up experiment (n = 24, healthy adults) increased difficulty of memory retrieval by having participants verbally describe previously viewed NNAs while concurrently performing a secondary task, and it revealed no significant differences between the effects of dividing attention on the verbal description and physical construction of NNAs. The implications of our findings for the processes mediating encoding and enactment of naturalistic actions were presented. As well, the utility of a dynamic technique of inducing error types normally found in neurologically impaired populations was discussed.

A treatment program for individuals with deficient evaluative processing and consequent impaired social and risk judgement.

The current study evaluated the effectiveness of a rehabilitation program developed to assist individuals such as AM who have impaired social and risk judgement. AM's difficulties developed after a severe traumatic brain injury that resulted in bilateral frontal and temporal lobe damage including damage to the amygdala. Previous work (Park et al., 2001) established that AM had impaired automatic processing of negative, but not positive evaluative information, and relatively spared processing of both types of evaluative information when using controlled or strategic processing. In the Strategic Evaluation of Alternatives (SEA) treatment program, AM was trained to compensate for his impairments by explicitly retrieving positive and negative attributes associated with potential actions prior to performing them. The SEA treatment focused specifically on improving AM's ability to obtain financial compensation for his work-related activities. Results showed improved performance on work-related activities and evidence of generalization. Analyses suggested that the process underlying improved performance was compensatory rather than restorative in nature. We discuss the implications of these results for the development of rehabilitation treatment for patients with impaired social and risk judgement.

What do Alzheimer's disease patients know about animals? It depends on task structure and presentation format.

Deficits on tasks requiring semantic memory in Alzheimer's disease (AD) may be due to storage loss, a retrieval deficit, or both. To address this question, we administered multiple tasks involving 9 exemplars of the category "animals," presented as both words and pictures, to 12 AD patients and 12 nondemented individuals. Participants made semantic judgments by class (sorting task), similarity (triadic comparison task), and dimensional attributes (ordering task). Relative to control participants, AD patients were impaired on an unstructured sorting task, but did not differ on a constrained sorting task. On the triadic comparison task, the patients were as likely to make judgments based on size as domesticity attributes, whereas control participants made judgments based primarily on domesticity. The patients' judgments were also less consistent across tasks than those of control participants. On the ordering tasks, performance was generally comparable between groups with pictures but not words, suggesting that pictures enable AD patients to access information from semantic memory that is less accessible with lexical stimuli. These results suggest that AD patients' semantic judgments are impaired when the retrieval context is unstructured, but perform normally under supportive retrieval conditions.