Executive Functions in Aging: An Experimental and Computational Study of the Wisconsin Card Sorting and Brixton Spatial Anticipation Tests.

In order to explore the effect of normal aging on executive function, we tested 25 younger adults and 25 neurologically healthy older adults on the Wisconsin Card Sorting Test (WCST) and the Brixton Spatial Anticipation Test (BRXT), two classic tests of executive function. We found that older participants were more likely than younger participants to err on both tasks, but the additional errors of older participants tended to be related to task set maintenance and rule inference rather than perseveration. We further found that the tendency to perseverate (across all participants) on the WCST was related to the tendency to produce stimulus or response perseverations on the BRXT, rather than any tendency to perseverate on BRXT rule application. Finally, on both tasks, older participants were also slower, particularly on trials following an error, than younger participants. To explore the neurocomputational basis for the observed behaviours we then extended an existing model of schema-modulated action selection on the WCST to the BRXT. We argue on the basis of the model that the performance of older participants on both tasks reflects a slower update of schema thresholds within the basal ganglia, coupled with a decrease in sensitivity to feedback.

On Simulating Neural Damage in Connectionist Networks.

A key strength of connectionist modelling is its ability to simulate both intact cognition and the behavioural effects of neural damage. We survey the literature, showing that models have been damaged in a variety of ways, e.g. by removing connections, by adding noise to connection weights, by scaling weights, by removing units and by adding noise to unit activations. While these different implementations of damage have often been assumed to be behaviourally equivalent, some theorists have made aetiological claims that rest on nonequivalence. They suggest that related deficits with different aetiologies might be accounted for by different forms of damage within a single model. We present two case studies that explore the effects of different forms of damage in two influential connectionist models, each of which has been applied to explain neuropsychological deficits. Our results indicate that the effect of simulated damage can indeed be sensitive to the way in which damage is implemented, particularly when the environment comprises subsets of items that differ in their statistical properties, but such effects are sensitive to relatively subtle aspects of the model's training environment. We argue that, as a consequence, substantial methodological care is required if aetiological claims about simulated neural damage are to be justified, and conclude more generally that implementation assumptions, including those concerning simulated damage, must be fully explored when evaluating models of neurological deficits, both to avoid over-extending the explanatory power of specific implementations and to ensure that reported results are replicable. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s42113-020-00081-z) contains supplementary material, which is available to authorized users.

A neurally plausible schema-theoretic approach to modelling cognitive dysfunction and neurophysiological markers in Parkinson's disease.

The cognitive mechanisms underlying sequential action selection in routine or everyday activities may be understood in terms of competition within a hierarchically organised network of action schemas. We present a neurobiologically plausible elaboration of an existing schema-based cognitive model of action selection in which the basal ganglia implements an activation-based selection process that mediates between assumed cortical representations of rule-based schemas. More specifically, the model employs a network of basal ganglia units with computations performed by individual BG nuclei, embedded in a corticothalamic loop that disinhibits schemas according to the received feedback. We provide bridging assumptions for linking the operation of the model with ERP components that describe the error-related negativity (ERN) and the parietal switch positivity (PSP), and evaluate the model against behavioural and neural markers of performance of the Wisconsin Card Sorting Test by healthy control participants and Parkinson's Disease patients.

Medical teleconsultation to general practitioners reduces the medical error vulnerability of internal medicine patients.

BACKGROUND: e-Health strategies are supposed to improve the performance of national health systems. Medical teleconsultation (MT) is an important component of such e-Health strategies. OBJECTIVES: The outcome of MT was evaluated with regard to the impact on the medical error vulnerability (MEV) of internal medicine patients. METHODS: A team of internal medicine doctors plus a network of forty specialists was set-up in one health district belonging to a unified and universal national health system of a country of Western Europe, in order to provide free-of-charge MT to support general practitioners in solving internal medicine cases. In this observational study, the case series of 2013 is reviewed. RESULTS: a) Only 21% of the MT fell short to the general practitioner's expectations about the case solving focus; b) throughout the medical care process of the patient, 49% of the cases met with one or more of the five MEVs, namely: 1) clinical test mishandling; 2) inaccurate differential diagnosis; 3) inadequate information flow between health providers at different levels of care (transition care); 4) poor coordination between health providers; and 5) poor reconciliation of medications or hazardous therapies. c) MT canceled or prevented MEVs in 56% and mitigate MEVs in 15% of the cases; d) MT canceled or prevented 85% of MEV caused by poor information exchange in transition care, therefore improving patient referral and counter-referral. CONCLUSIONS: MT reduces MEV and therefore, whenever implemented to a large extent, may improve the quality of health care delivery and the performance of national health systems.