Cognitive stimulation of the default-mode network modulates functional connectivity in healthy aging

A cognitive-stimulation tool was created to regulate functional connectivity within the brain Default-Mode Network (DMN). Computerized exercises were designed based on the hypothesis that repeated task-dependent coactivation of multiple DMN regions would translate into regulation of resting-state network connectivity. Forty seniors (mean age: 65.90 years; SD: 8.53) were recruited and assigned either to an experimental group (n = 21) who received one month of intensive cognitive stimulation, or to a control group (n = 19) who maintained a regime of daily-life activities explicitly focused on social interactions. An MRI protocol and a battery of neuropsychological tests were administered at baseline and at the end of the study. Changes in the DMN (measured via functional connectivity of posterior-cingulate seeds), in brain volumes, and in cognitive performance were measured with mixed models assessing group-by-timepoint interactions. Moreover, regression models were run to test gray-matter correlates of the various stimulation tasks. Significant associations were found between task performance and gray-matter volume of multiple DMN core regions. Training-dependent up-regulation of functional connectivity was found in the posterior DMN component. This interaction was driven by a pattern of increased connectivity in the training group, while little or no up-regulation was seen in the control group. Minimal changes in brain volumes were found, but there was no change in cognitive performance. The training-dependent regulation of functional connectivity within the posterior DMN component suggests that this stimulation program might exert a beneficial impact in the prevention and treatment of early AD neurodegeneration, in which this neurofunctional pathway is progressively affected by the disease

Up-regulation of DMN connectivity in mild cognitive impairment via network-based cognitive training

BACKGROUND: Previous work designed a network-based protocol of cognitive training. This programme exploits a mechanism of induced task-oriented co-activation of multiple regions that are part of the default mode network (DMN), to induce functional rewiring and increased functional connectivity within this network. OBJECTIVE: In this study, the programme was administered to patients with a diagnosis of mild cognitive impairment to test its effects in a clinical sample. METHOD: Twenty-three patients with mild cognitive impairment (mean age: 73.74 years, standard deviation 5.13, female/male ratio 13/10) allocated to the experimental condition underwent one month of computerised training, while fourteen patients (mean age: 73.14 years, standard deviation 6.16, female/male ratio 7/7) assigned to the control condition underwent a regime of intense social engagement. Patients were in the prodromal stage of Alzheimer's disease (AD) as confirmed by clinical follow ups for at least two years. The DMN was computed at baseline and retest, together with other, control patterns of connectivity, grey matter maps, and neuropsychological profiles. RESULTS: A condition-by-timepoint interaction indicating increased connectivity triggered by the programme was found in left parietal DMN regions. No decreases as well as no changes in the other networks or morphology were found. Although between-condition cognitive changes did not reach statistical significance, they correlated positively with changes in DMN connectivity in the left parietal region, supporting the hypothesis that parietal changes were beneficial. CONCLUSION: This programme of cognitive training up-regulates a pattern of connectivity which is pathologically down-regulated in AD. We argue that, when cognitive interventions are conceptualised as tools to induce co-activation repeatedly, it can lead to clinically-relevant improvements in brain functioning, and can be of aid in support of pharmacological and other interventions in the earliest stages of AD

Diagnosi neuropsicologica e tecniche di neuroimaging in un caso complesso di sindrome di Balint

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Reading compounds in neglect dyslexia: the headedness effect

Reading compound words was studied in neglect dyslexia in order to assess the influence of \u2018head- edness\u2019. The \u2018head\u2019 of a compound is the component that determines the grammatical category, the syntactic (e.g., the gender) and the semantic properties of the compound as a whole. For example, in the word \u2018blackberry\u2019 berry is the compound\u2019s head. The question was addressed of whether or not the privileged status of the head constituent influences processing and determines behavioural patterns in the breakdown of spatial attention in neglect. Italian right-headed (e.g. capobanda, band leader) and left-headed compounds (e.g. astronave, spaceship) were administered to 18 participants affected by neglect dyslexia. Left-headed compounds were read better than right-headed compounds. This result was not due to factors such as frequency, familiarity, age of acquisition or imageability, since these effects were controlled. It is suggested that attention is captured by the head component after implicit reading of the whole word. The head would require a relatively lighter processing load than the modifier and benefit from top-down facilitation. \ufff