Effect of conceptual and lexical errorless versus trial-and-error learning in amnestic mild cognitive impairment

The impact of reward and punishment sensitivity on memory and executive performance in individuals with amnestic mild cognitive impairment

Amnestic mild cognitive impairment (aMCI) is defined by memory impairment but executive function (EF) deficits could be also a common feature. This study examined the underlying neurocognitive processes associated with executive function (EF) deficits in patients with aMCI using the Wisconsin Card Sorting Test (WCST) and computational modeling. Forty-two patients with aMCI and thirty-eight matched Controls performed the WSCT and underwent neurocognitive assessment. The Attentional Learning Model was applied the WCST. Patients with aMCI demonstrated deficits in feedback-learning. More specifically, patients showed increased Reward-Sensitivity and reduced Punishment-Sensitivity. These alterations were associated with poor WSCT performance and deficits in EF and Memory. Goal-directed deficits in aMCI, as observed in the WCST, are associated with difficulties in updating attention after feedback as its changes too rapidly following positive feedback and too slowly following negative feedback. Consequently, memory and EF deficits interact and reinforce each other generating performance deficits in patients with aMCI.

Learning capacity in early-stage Alzheimer's disease: The role of feedback during learning on memory performance

Alzheimer's disease is characterized by a decline in episodic memory and executive functioning, hampering learning ability. Insight into outcome-based learning capacity may be relevant for optimizing the learning potential of these patients. To date, mixed results have been found in studies in which cognitively impaired participants have to learn based on positive and negative outcomes. In this study, we investigated the role of negative and positive feedback on memory performance and participants' ability to adjust their behaviour accordingly in a sample of 23 early-stage AD patients and 23 matched healthy controls. We administered a novel computerized object-location memory task, in which participants were instructed to learn and memorize the locations of different everyday objects following errorless learning (EL) and trial-and-error learning (TEL). A separate probabilistic TEL task was employed in which participants had to learn how to adjust their behaviour based on positive and negative feedback. EL had a beneficial general effect on memory performance for object locations. However, this effect was not larger in early-stage AD patients compared to controls and error frequency during acquisition of object locations was unrelated to later recall performance. No group differences were found on the probabilistic learning task with respect to learning performance over time and based on positive and negative feedback. Although the error monitoring system seems intact in patients with early-stage AD, errors during learning are likely acting as a source of interference causing difficulty in storage or retrieval of object locations.

Errorful learning improves recognition memory for new vocabulary for people living with memory and dysexecutive impairment following brain injury

A widely accepted view is that errorless learning is essential for supporting new learning in people with anterograde amnesia, but findings are mixed for those with a broader range of memory impairments. People at a chronic stage of recovery from brain injury (BI) with impaired memory and executive function (N = 26) were compared with adults in a comparison group without any known risks to brain function (N = 25). Learning techniques were compared using a "Generate-and-correct" and "Read-only" condition when learning novel word pairs. At test, both groups scored above chance and showed benefits of Generate-and-correct (errorful learning). Poor learners in the BI group were classified from "flat" learning slopes extracted from an independent word-pair learning task. Critically, poor learners showed no benefit, but also no decrement to learning, using the Generate-and-correct method. No group was harmed by errorful learning; all, except the poorest learners, benefitted from errorful learning. This study indicates, that in some rehabilitation settings, encouraging clients to guess the meaning of unfamiliar material (e.g., from cards, magazines, newspapers) and then correct their errors, could have benefits for recognition memory. Determining when and how errorful learning benefits learning is a key aim for future research.

State of the science on mild cognitive impairment (MCI)

Mild cognitive impairment (MCI) represents a transitional stage between healthy aging and dementia, and affects 10-15% of the population over the age of 65. The failure of drug trials in Alzheimer's disease (AD) treatment has shifted researchers' focus toward delaying progression from MCI to dementia, which would reduce the prevalence and costs of dementia profoundly. Diagnostic criteria for MCI increasingly emphasize the need for positive biomarkers to detect preclinical AD. The phenomenology of MCI comprises lower quality-of-life, greater symptoms of depression, and avoidant coping strategies including withdrawal from social engagement. Neurobiological features of MCI are hypoperfusion and hypometabolism in temporoparietal cortices, medial temporal lobe atrophy particularly in rhinal cortices, elevated tau and phosphorylated tau and decreased Aβ42 in cerebrospinal fluid, and brain Aβ42 deposition. Elevated tau can be identified in MCI, particularly in the entorhinal cortex, using positron emission tomography, and analysis of signal complexity using electroencephalography or magnetoencephalography holds promise as a biomarker. Assessment of MCI also relies on cognitive screening and neuropsychological assessment, but there is an urgent need for standardized cognitive tests to capitalize on recent discoveries in cognitive neuroscience that may lead to more sensitive measures of MCI. Cholinesterase inhibitors are frequently prescribed for MCI, despite the lack of evidence for their efficacy. Exercise and diet interventions hold promise for increasing reserve in MCI, and group psychoeducational programs teaching practical memory strategies appear effective. More work is needed to better understand the phenomenology and neurobiology of MCI, and how best to assess it and delay progression to dementia.