1,721,018 research outputs found
Transcranial brain stimulation studies of episodic memory in young adults, elderly adults and individuals with memory dysfunction: A review.
No full textTranscranial magnetic and electric stimulation studies examining episodic memory in young participants have established the role of the left prefrontal cortex during encoding and the right prefrontal cortex during episodic retrieval. Furthermore, these techniques have been used to verify the reduction in functional asymmetry in the prefrontal cortex that occurs with ageing, at least during encoding, suggesting the existence of compensatory adjustments for the structural and neurotransmitter loss that occurs with physiological ageing. Nevertheless, it has been shown that several factors can modulate performance based on the type of material or strategy used. It is important to note that although numerous studies have addressed the role of the prefrontal cortex in episodic memory, a number of studies have also demonstrated the involvement of a more distributed neural network sustaining this function involving the temporal lobes and parietal cortices. Finally, it is evident that the use of transcranial stimulation techniques might represent a powerful tool not only for investigating the involvement of cerebral areas in a specific cognitive task but also for designing interventional therapies for individuals with memory impairment
Compensatory networks to counteract the effects of ageing on language
No full textBACKGROUND:
Word-retrieval difficulties are a common consequence of healthy ageing and are associated with a reduction in asymmetrical recruitment of the dorsolateral prefrontal cortex (DLPFC), although the significance of this reduction has not yet been clarified. Using repetitive transcranial magnetic stimulation (rTMS) it has been demonstrated that an asymmetrical involvement of the DLPFC during action naming in young subjects, whereas bilateral involvement was shown in elderly participants. By using rTMS during a naming task in a group of elderly subjects, the aim of the present work was to investigate whether the magnitude of DLPFC asymmetry (left-right rTMS effect) during action naming correlates with task performance, proving the presence of a compensation strategy in some but not all elderly participants.
METHODS:
We aimed to test if there was a correlation between DLPFC asymmetry (left-right rTMS effect) and naming performance in a group of elderly subjects.
RESULTS:
The results show that rTMS affects action naming differently according to individual naming ability. In particular, the predominance of a left vs. right DLPFC effect was observed only in the low-performing older adults, while an asymmetric reduction was selectively shown in the high-performing group. Interestingly, high-performing older adults also displayed better performances on a phonemic fluency test.
CONCLUSION:
The present data suggest that successful ageing is linked to less prefrontal asymmetry, an efficient strategy for counteracting age-related declines in cognitive function
Empathy and emotion recognition in semantic dementia: a case report.
No full textRecent studies have demonstrated that patients suffering from frontotemporal lobar degeneration (FTLD) show impairments in empathy and emotional processing. In this study, we examined two different aspects of these abilities in a patient with semantic dementia (SD), a variant of FTLD. The first aspect was the assessment of the cognitive and emotional components of empathy through the Interpersonal Reactivity Index. The second was the naming and comprehension of emotions using the Ekman 60 Faces Test. The patient's emotion word knowledge was spared and the emotional aspects of empathy preserved. Conversely, the patient performed below average for all of the basic emotions when an emotion word had to be matched with a picture. When picture-to-picture matching was tested, however, the patient was able to recognize happiness. This case is a good example of a dissociation of covert and overt emotional functioning in SD. Results are discussed in terms of the impaired empathic behavior and emotional functioning in FTLD
The role of the dorsolateral prefrontal cortex in retrieval from long-term memory depends on strategies: an rTMS study
No full textThe ability to associate a name to a face is a crucially relevant task in daily life. In this study, we investigated the neuronal basis of face-name retrieval in young subjects using repetitive transcranial magnetic stimulation (rTMS) over the left or right dorsolateral prefrontal cortex (DLPFC). The experimental task was composed of two study phases: an encoding phase and a retrieval phase. During the encoding phase, subjects saw a face (familiar or unfamiliar) followed by a name. During the retrieval phase, they saw the face together with two names and had to choose the name that was correctly associated with the face. rTMS was delivered only during retrieval. In addition, we evaluated the use of memory strategies during the task. Accordingly, subjects were subdivided into two groups: strategy users (SU) and no-strategy users (NSU). No rTMS effects were present for familiar face-name pairs, probably due to a ceiling effect. However, for unfamiliar face-name pairs, the different use of memory strategies resulted in different rTMS effects. The SU group showed a selective interference effect after right DLPFC stimulation, whereas the NSU group showed an effect after left DLPFC stimulation. Importantly, the overall performance of the two groups was comparable. We suggest that during memory retrieval the left DLPFC might be recruited when the subject does not apply deliberately a retrieval strategy whereas there is a shift to the right DLPFC if cognitive control processes that are engaged by strategies are needed to guide episodic retrieval
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Successful physiological aging and episodic memory: a brain stimulation study
No full textFunctional neuroimaging studies have shown that younger adults tend to asymmetrically recruit specific regions of an hemisphere in an episodic memory task (Hemispheric Encoding Retrieval Asymmetry-HERA model). In older adults, this hemispheric asymmetry is generally reduced as suggested by the Hemispheric Asymmetry Reduction for OLDer Adults-HAROLD-model. Recent works suggest that while low-performing older adults do not show this reduced asymmetry, high-performing older adults counteract age-related neural decline through a plastic reorganization of cerebral networks that results in reduced functional asymmetry. However, the issue of whether high- and low-performing older adults show different degrees of asymmetry and the relevance of this process for counteracting aging have not been clarified. We used transcranial magnetic stimulation (TMS) to transiently interfere with the function of the dorsolateral prefrontal cortex (DLPFC) during encoding or retrieval of associated and non-associated word pairs. A group of healthy older adults was studied during encoding and retrieval of word pairs. The subjects were divided in two subgroups according to their experimental performance (i.e., high- and low-performing). TMS effects on retrieval differed according to the subject's subgroup. In particular, the predominance of left vs. right DLPFC effects during encoding, predicted by the HERA model, was observed only in low-performing older adults, while the asymmetry reduction predicted by the HAROLD model was selectively shown for the high-performing group. The present data confirm that older adults with higher memory performance show less prefrontal asymmetry as an efficient strategy to counteract age-related memory decline
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