Functional MRI evidence for the decline of word retrieval and generation during normal aging

International audienceThis fMRI study aimed to explore the effect of normal aging on word retrieval and generation. The question addressed is whether lexical production decline is determined by a direct mechanism, which concerns the language operations or is rather indirectly induced by a decline of executive functions. Indeed, the main hypothesis was that normal aging does not induce loss of lexical knowledge, but there is only a general slowdown in retrieval mechanisms involved in lexical processing , due to possible decline of the executive functions. We used three tasks (verbal fluency, object naming , and semantic categorization). Two groups of participants were tested (Young, Y and Aged, A), without cognitive and psychiatric impairment and showing similar levels of vocabulary. Neuropsychological testing revealed that older participants had lower executive function scores, longer processing speeds, and tended to have lower verbal fluency scores. Additionally, older participants showed higher scores for verbal automa-tisms and overlearned information. In terms of behav-ioral data, older participants performed as accurate as younger adults, but they were significantly slower for the semantic categorization and were less fluent for verbal fluency task. Functional MRI analyses suggested that older adults did not simply activate fewer brain regions involved in word production, but they actually showed an atypical pattern of activation. Significant correlations between the BOLD (Blood Oxygen Level Dependent) signal of aging-related (A > Y) regions and cognitive scores suggested that this atypical pattern of the activation may reveal several compensatory mechanisms (a) to overcome the slowdown in retrieval, due to the decline of executive functions and processing speed and (b) to inhibit verbal automatic processes. The BOLD signal measured in some other aging-dependent regions did not correlate with the behavioral and neuro-psychological scores, and the overactivation of these uncorrelated regions would simply reveal dedifferentia-tion that occurs with aging. Altogether, our results suggest that normal aging is associated with a more difficult access to lexico-semantic operations and representations by a slowdown in executive functions, without any conceptual loss

The functional anatomy of semantic retrieval is influenced by gender, menstrual cycle, and sex hormones

This study examines the neurobiology of semantic retrieval and describes the influence of gender, menstrual cycle, and sex hormones on semantic networks. Healthy right-handed subjects (12 men, 12 women) were investigated with 3T-fMRI during synonym generation. Behavioral performance and sex hormone levels were assessed. Women were examined during the early follicular and midluteal cycle phase. The activation pattern in all groups involved left frontal and temporal as well as bilateral medial frontal, cingulate, occipital, basal ganglia, and cerebellar regions. Men showed greater left frontal activation than women in both menstrual cycle phases. Women yielded high correlations of left prefrontal activation with estradiol in the midluteal phase and with progesterone in both phases. Testosterone levels correlated highly with left prefrontal activation in all three groups. In all, we describe a cerebral network involved in semantic processing and demonstrate that it is significantly affected by gender and sex steroid hormones

Social exclusion of older persons: a scoping review and conceptual framework

As a concept, social exclusion has considerable potential to explain and respond to disadvantage in later life. However, in the context of ageing populations, the construct remains ambiguous. A disjointed evidence-base, spread across disparate disciplines, compounds the challenge of developing a coherent understanding of exclusion in older age. This article addresses this research deficit by presenting the findings of a two-stage scoping review encompassing seven separate reviews of the international literature pertaining to old-age social exclusion. Stage one involved a review of conceptual frameworks on old-age exclusion, identifying conceptual understandings and key domains of later-life exclusion. Stage two involved scoping reviews on each domain (six in all). Stage one identified six conceptual frameworks on old-age exclusion and six common domains across these frameworks: neighbourhood and community; services, amenities and mobility; social relations; material and financial resources; socio-cultural aspects; and civic participation. International literature concentrated on the first four domains, but indicated a general lack of research knowledge and of theoretical development. Drawing on all seven scoping reviews and a knowledge synthesis, the article presents a new definition and conceptual framework relating to old-age exclusion

Implanted material tolerance studies for a multiple-channel cochlear prosthesis

Publisher’s permission requested and denied.We have performed a number of temporal bone and animal studies in order to evaluate the histopathological effects of intracochlear electrode implantation and chronic electrical stimulation. Our results indicate that (a) the insertion of a free-fit scala tympani array results in minimal damage to the membranous labyrinth; (b) the materials used in the electrode array evoke mild tissue reactions when implanted subcutaneously, in muscle, or within the scala tympani; (c) intracochlear electrical stimulation for periods of 500 to 2000 hours, using carefully controlled biphasic pulses, does not adversely affect the population or neural activity of the primary auditory neurones; (d) labyrinthine infection severely reduces the number of viable spiral ganglion cells; (e) an adequate fibrous tissue seal of the round window can prevent the spread of infection from the bulla to the implanted cochlea in cats, following inoculation of the bulla cavity with bacteria; (f) bone growth is not associated with electrical stimulation per se; (g) the electrode arrays show minimal platinum dissolution and no apparent degradation of the Silastic® carrier following periods of long-term intracochlear electrical stimulation

Potentially Stressful Life Events and Emotional Closeness Between Grandparents and Adult Grandchildren

The purpose of this study is to explore the variation in emotional closeness in the adult grandchild and grandparent relationship in relation to the occur-rence of potentially stressful life events in childhood. A sample of university students (N = 119) completed a questionnaire measuring elements of inter-generational solidarity. Comparisons were made on emotional closeness between groups that had and had not experienced a life event, revealing it was the grandparent’s enactment of normative solidarity, as perceived by the adult grandchild, that produced greater emotional closeness. Complementing the findings of Bengston and Roberts, this research supports the theoretical view that high levels of normative solidarity lead to greater affectual solidarity, which in turn produces higher associational solidarity

Simulation-based UAS Swarm Selection for Monitoring and Detection of Migrant Border Crossings

The European migration crisis reached critical levels in 2015 due to a major influx of migrants taking the journey across the Mediterranean to Italy, Greece, and other European coasts. Migration flow rates across the Mediterranean have dropped in recent years, but fatalities have increased and border pressure is still high. Recent operations by local governments, international agencies, and NGO organizations have saved many lives and improved data collection practices, yet they have not been fully successful in responding to the high volume of travel and unexpected rate spikes in migrant trips. Different Operational Constructs and asset strategies have been studied resulting in relevant organizations investing in Unmanned Aerial Systems (UAS) for monitoring and detection. However, many questions about the most effective deployment of these assets still remain. This study is centered on the development of a modeling and simulation environment, as well as a decision support tool for conducting system-of-systems comparisons of UAS swarm and surface fleet asset combinations. The environment is an agent-based simulation built in the In-House tool Janus, which leverages the NASAWorld-Wind SDK. The simulation tool and dashboard provide a trade-off environment for parametric analysis of swarm capabilities. A case study is performed for operations by the Italian Coast Guard off the coast of Libya. Results confirm the success of implementing UAS and coordinated swarm systems. Further analysis examines the trade-off of mission effectiveness and cost, with consideration of the resilience and robustness of the system-of-systems