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1.
Exp Psychol ; 67(3): 161-168, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32900298

RESUMO

Dynamic visual noise (DVN) selectively impairs memory for some types of stimuli (e.g., colors, textures, concrete words), but not for others (e.g., matrices, Chinese characters, simple shapes). According to the image definition hypothesis, the key difference is whether the stimulus leads to images that are ill-defined or well-defined. The former will be affected because the addition of noise quickly reduces the usefulness of the image in supplying information about the item's identity. The image definition hypothesis predicts that fonts should lead to ill-defined images and therefore should be affected by DVN, and although three previous studies appear to show this result, they lack a key control condition and report only proportion correct. Two experiments reassessed whether DVN affects memory for fonts, but, unlike the previous studies, both included a static visual noise condition and both were analyzed using signal detection measures. There was no evidence that DVN affected memory for font information, thus disconfirming a prediction of the original version of image definition hypothesis. We suggest a revised version that focuses on redintegration can explain the results.


Assuntos
Memória de Curto Prazo/fisiologia , Ruído , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
2.
PLoS One ; 15(8): e0219233, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32790667

RESUMO

Our aim was to examine the effect of a smartphone's presence on learning and memory among undergraduates. A total of 119 undergraduates completed a memory task and the Smartphone Addiction Scale (SAS). As predicted, those without smartphones had higher recall accuracy compared to those with smartphones. Results showed a significant negative relationship between phone conscious thought, "how often did you think about your phone", and memory recall but not for SAS and memory recall. Phone conscious thought significantly predicted memory accuracy. We found that the presence of a smartphone and high phone conscious thought affects one's memory learning and recall, indicating the negative effect of a smartphone proximity to our learning and memory.


Assuntos
Telefone Celular/tendências , Aprendizagem/fisiologia , Memória/fisiologia , Atenção/fisiologia , Cognição , Dependência Psicológica , Feminino , Humanos , Masculino , Memória de Curto Prazo/fisiologia , Smartphone , Estudantes , Inquéritos e Questionários , Adulto Jovem
3.
PLoS Comput Biol ; 16(8): e1008128, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32785228

RESUMO

Many cognitive processes involve transformations of distributed representations in neural populations, creating a need for population-level models. Recurrent neural network models fulfill this need, but there are many open questions about how their connectivity gives rise to dynamics that solve a task. Here, we present a method for finding the connectivity of networks for which the dynamics are specified to solve a task in an interpretable way. We apply our method to a working memory task by synthesizing a network that implements a drift-diffusion process over a ring-shaped manifold. We also use our method to demonstrate how inputs can be used to control network dynamics for cognitive flexibility and explore the relationship between representation geometry and network capacity. Our work fits within the broader context of understanding neural computations as dynamics over relatively low-dimensional manifolds formed by correlated patterns of neurons.


Assuntos
Modelos Neurológicos , Redes Neurais de Computação , Biologia Computacional , Humanos , Memória de Curto Prazo/fisiologia , Neurônios/fisiologia
4.
Nat Commun ; 11(1): 4250, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32843635

RESUMO

A mechanistic understanding of core cognitive processes, such as working memory, is crucial to addressing psychiatric symptoms in brain disorders. We propose a combined psychophysical and biophysical account of two symptomatologically related diseases, both linked to hypofunctional NMDARs: schizophrenia and autoimmune anti-NMDAR encephalitis. We first quantified shared working memory alterations in a delayed-response task. In both patient groups, we report a markedly reduced influence of previous stimuli on working memory contents, despite preserved memory precision. We then simulated this finding with NMDAR-dependent synaptic alterations in a microcircuit model of prefrontal cortex. Changes in cortical excitation destabilized within-trial memory maintenance and could not account for disrupted serial dependence in working memory. Rather, a quantitative fit between data and simulations supports alterations of an NMDAR-dependent memory mechanism operating on longer timescales, such as short-term potentiation.


Assuntos
Encefalite Antirreceptor de N-Metil-D-Aspartato/fisiopatologia , Memória de Curto Prazo/fisiologia , Esquizofrenia/fisiopatologia , Sinapses/fisiologia , Adolescente , Adulto , Encefalite Antirreceptor de N-Metil-D-Aspartato/psicologia , Feminino , Humanos , Masculino , Modelos Neurológicos , Rede Nervosa/fisiopatologia , Plasticidade Neuronal , Córtex Pré-Frontal/fisiopatologia , Receptores de N-Metil-D-Aspartato/fisiologia , Psicologia do Esquizofrênico , Adulto Jovem
5.
Psychol Aging ; 35(5): 614-626, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32744845

RESUMO

Capacity-limited working memory (WM) systems have been known to degrade in older age. In line with inhibition-deficit theories of aging, WM deficits in older individuals have been attributed to failures in the ability to suppress the processing of task irrelevant, distracting information. Yet, other cognitive mechanisms underlying age-related WM deficits have been observed, including failures in WM with increasing memory load. Moreover, both distracting information and high memory load have been shown to trigger adjustments in cognitive control leading to subsequent performance benefits on later trials. However, no studies have characterized these dynamic adjustments across the life span or examined their contribution to WM deficits in older adults. We investigated the contribution of distracter interference, memory load, and dynamic adjustments in cognitive control on WM performance in 505 individuals with ages ranging from adolescence to older adulthood. Distracter interference and memory load were parametrically manipulated (high vs. low) in a delayed-recognition WM task, and accuracy was examined as a function of current (N) and previous (N-1) trial demands. Curvilinear models revealed that performance differs over the life span depending on specific WM task demands. Specifically, the ability to suppress task irrelevant distracters was greater in adulthood compared with adolescence, but worse in later life. In contrast, memory load resulted in performance deficits with increasing age, which were exacerbated when high load and interference demands combined. Dynamic adjustments in cognitive control was spared, in part, with memory-load triggered sequential trial effects maintained across the life span, but interference-triggered benefits observable up to middle age. (PsycInfo Database Record (c) 2020 APA, all rights reserved).


Assuntos
Cognição/fisiologia , Memória de Curto Prazo/fisiologia , Adolescente , Adulto , Idoso , Envelhecimento , Feminino , Voluntários Saudáveis , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
6.
Health Psychol ; 39(9): 815-825, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32833483

RESUMO

Low income and low educational attainment are among the strongest predictors of both smoking prevalence and lapse (i.e., return) to smoking after cessation attempts. Treatment refinement is limited by inadequate knowledge of the specific lapse- or relapse-relevant vulnerabilities characteristic of populations that should be the target of treatment. In the context of a randomized clinical trial design, we describe an experimental medicine approach for evaluating the role of 2 specific lapse-relevant targets relative to the higher stress characteristic of low-socioeconomic contexts: low distress tolerance and low working memory capacity. Furthermore, we use an innovative approach for understanding risk of smoking lapse in smokers undergoing a quit attempt to examine candidate mechanistic targets assessed not only during nicotine use, but also during the conditions smokers will face upon a cessation attempt-during stressful nicotine-deprivation windows. This study is designed to show the incremental value of assessments during deprivation windows, in part because of the way in which specific vulnerabilities are modified by, and interact with, the heightened stress and withdrawal symptoms inherent to nicotine-deprivation states. Specifically, the study is designed to evaluate whether a novel mindfulness intervention (mindfulness combined with interoceptive exposure) can improve upon existing mindfulness interventions and extend therapeutic gains to the modification of mechanistic targets assessed in high-stress or negative affectivity contexts. The overall goal is to validate mechanistic targets and associated interventions for the purpose of expanding treatment options for at-risk smokers. (PsycInfo Database Record (c) 2020 APA, all rights reserved).


Assuntos
Memória de Curto Prazo/fisiologia , Abandono do Hábito de Fumar/métodos , Adolescente , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pobreza , Abandono do Hábito de Fumar/psicologia , Adulto Jovem
7.
Proc Natl Acad Sci U S A ; 117(30): 17667-17674, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32651280

RESUMO

Noncompliance with social distancing during the early stage of the coronavirus disease 2019 (COVID-19) pandemic poses a great challenge to the public health system. These noncompliance behaviors partly reflect people's concerns for the inherent costs of social distancing while discounting its public health benefits. We propose that this oversight may be associated with the limitation in one's mental capacity to simultaneously retain multiple pieces of information in working memory (WM) for rational decision making that leads to social-distancing compliance. We tested this hypothesis in 850 United States residents during the first 2 wk following the presidential declaration of national emergency because of the COVID-19 pandemic. We found that participants' social-distancing compliance at this initial stage could be predicted by individual differences in WM capacity, partly due to increased awareness of benefits over costs of social distancing among higher WM capacity individuals. Critically, the unique contribution of WM capacity to the individual differences in social-distancing compliance could not be explained by other psychological and socioeconomic factors (e.g., moods, personality, education, and income levels). Furthermore, the critical role of WM capacity in social-distancing compliance can be generalized to the compliance with another set of rules for social interactions, namely the fairness norm, in Western cultures. Collectively, our data reveal contributions of a core cognitive process underlying social-distancing compliance during the early stage of the COVID-19 pandemic, highlighting a potential cognitive venue for developing strategies to mitigate a public health crisis.


Assuntos
Infecções por Coronavirus/epidemiologia , Infecções por Coronavirus/psicologia , Tomada de Decisões , Individualidade , Relações Interpessoais , Memória de Curto Prazo/fisiologia , Pneumonia Viral/epidemiologia , Pneumonia Viral/psicologia , Distância Social , Betacoronavirus/isolamento & purificação , Cognição , Infecções por Coronavirus/virologia , Humanos , Pandemias , Pneumonia Viral/virologia , Estados Unidos/epidemiologia
8.
Prax Kinderpsychol Kinderpsychiatr ; 69(4): 305-320, 2020 Jul.
Artigo em Alemão | MEDLINE | ID: mdl-32615892

RESUMO

The Effect of a Short-Term Mindfulness Program on Memory Performance in School-Aged Children A one-week mindfulness-based intervention designed to improve 8- to 10-year-old children's memory performance was investigated. Seventy-three children were quasi-randomly assigned either to one of two mindfulness-based intervention groups (breathing meditation or yoga), or to an active control group. The sessions were held on six consecutive days. Prior to intervention and after completing the intervention, children's short-term and long-term memory performance were assessed. In confirmation of prior studies, breathing meditation and yoga showed positive effects on memory performance when compared with the control group. Moreover, differences in the effectiveness of breathing meditation and yoga were found: While both interventions had comparable effects on long-term memory, only breathing meditation showed improvements in short-term memory performance. The present study provides valuable evidence on the effectiveness of meditation on cognitive functions in childhood and shows that school-aged children can already benefit from short-term meditation programs.


Assuntos
Memória/fisiologia , Atenção Plena , Criança , Cognição/fisiologia , Humanos , Meditação , Memória de Curto Prazo/fisiologia , Instituições Acadêmicas , Ioga
9.
PLoS One ; 15(7): e0222688, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32706780

RESUMO

We present the results of a study investigating whether there is an effect of Anodal-Transcranial Direct Current Stimulation (A-tDCS) on working memory (WM) performance. The relative effectiveness of A-tDCS on WM is investigated using a 2-back test protocol using two commonly used memory visual stimuli (shapes and letters). In a double-blinded, randomised, crossover, sham-controlled experiment, real A-tDCS and sham A-tDCS were applied separately to the left dorsolateral prefrontal cortex (L-DLPFC) of twenty healthy subjects. There was a minimal interval of one week between sham and real A-tDCS sessions. For the letters based stimulus experiment, 2-back test recall accuracy was measured for a set of English letters (A-L) which were presented individually in a randomised order where each was separated by a blank interval. A similar 2-back protocol was used for the shapes based stimuli experiment where instead of letters, a set of 12 geometric shapes were used. The working memory accuracy scores measured appeared to be significantly affected by memory stimulus type used and by the application of A-tDCS (repeated measures ANOVA p<0.05). A large effect size (d = 0.98) and statistical significance between sham and real A-tDCS WM scores (p = 0.01) was found when shapes were used as a visual testing stimulus, while low (d = 0.38) effect size and insignificant difference (p = 0.15) was found when letters were used. This results are important as they show that recollection different stimuli used in working memory can be affected differently by A-tDCS application. This highlights the importance of considering using multiple methods of WM testing when assessing the effectiveness of A-tDCS.


Assuntos
Memória de Curto Prazo/fisiologia , Estimulação Transcraniana por Corrente Contínua/métodos , Adulto , Estudos Cross-Over , Método Duplo-Cego , Feminino , Voluntários Saudáveis , Humanos , Aprendizagem , Masculino , Córtex Pré-Frontal/fisiologia , Adulto Jovem
10.
Exp Psychol ; 67(2): 132-139, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32729402

RESUMO

Acute stress and chronic stress change the physiology and function of the individual. As one facet, stress and its neuroendocrine correlates - with glucocorticoids in particular - modulate memory in a concerted action. With respect to working memory, impairing effects of acute stress and increased levels of glucocorticoids could be expected, but empirical evidence on moderating effects of cortisol on working memory is ambiguous in human studies. In the current study, we thus aimed to investigate cortisol stress responses and memory performance. Older men and women (32 men, 43 women, aged 61-67 years) underwent the Trier Social Stress Test (TSST) and performed the 2-back task before and after exposure to acute stress. In line with theoretical assumptions, we found that higher cortisol stress responses led to a decline of working memory performance in men. However, the opposite was evident for women, who appeared to benefit from higher stress responses. This effect was evident for accuracy, but not for reaction time. In conclusion, cortisol might mediate working memory alterations with stress in a sex-specific manner in older people. Possible mechanisms and causes for these sex differences put a focus on endocrine changes in the aging population that might lead to differential effects across the lifespan.


Assuntos
Memória de Curto Prazo/fisiologia , Estresse Psicológico/fisiopatologia , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
11.
Exp Psychol ; 67(3): 178-185, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32684147

RESUMO

The process of spontaneous refreshing plays a central role in current models of working memory but is yet to be observed directly. In a recent study, Rey, Versace, and Plancher (2018) introduced a novel approach to investigate the mechanisms underlying refreshing: They presented tones previously associated with a visual mask during the free time of a complex span task and found that this impaired memory, presumably because reactivation of the masks disrupts refreshing. Here, we aimed to replicate their finding under more controlled settings with more observations per participant. We failed to replicate the previous findings, thereby questioning the robustness of the original effect.


Assuntos
Rememoração Mental/fisiologia , Adulto , Feminino , Humanos , Masculino , Memória de Curto Prazo/fisiologia
12.
Acta Psychol (Amst) ; 209: 103089, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32629207

RESUMO

Self-directed learning (SDL) is a rapidly developing trend in schools, although its prerequisites, such as children's skills and abilities to plan and monitor their own learning, have not been investigated in detail. Due to additional cognitive load it induces, SDL has been in some cases found to be detrimental for learning, especially for students with a lower cognitive capacity. With this study, we explored some of the causes for the variability in learning gains. We examined 111 middle school students' self-directed category learning using an exploratory web-task for autonomous learning, focusing on their information search (browsing a taxonomy of unknown dinosaurs) and their memorization of respective category labels. We were interested to detect whether students' performance in a complex span task (Ospan) was also reflected in their search and learning behavior. Results revealed different learning gain trajectories in the latter task, where higher WMC students were more confident about their learning. Also, the students with lower WMC were found to search the taxonomy by repeatedly searching the same (basic type of) dinosaur exemplar. In line with prior findings about human mental capacity restrictions and cognitive load theory, the present work evidenced the important role of students' resistance to distraction, and its relation to differences in self-directed search and memorizing. The results imply the need to teach metacognitive skills and offer supportive scaffolding in order to avoid cognitive overload in SDL.


Assuntos
Atenção/fisiologia , Cognição/fisiologia , Função Executiva/fisiologia , Aprendizagem , Memória de Longo Prazo/fisiologia , Memória de Curto Prazo/fisiologia , Estudantes/psicologia , Adolescente , Feminino , Humanos , Masculino , Testes Neuropsicológicos
13.
PLoS Biol ; 18(6): e3000769, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32598358

RESUMO

We used functional magnetic resonance imaging (fMRI) to investigate the neural codes for representing stimulus information held in different states of priority in working memory. Human participants (male and female) performed delayed recall for 2 oriented gratings that could appear in any of several locations. Priority status was manipulated by a retrocue, such that one became the prioritized memory item (PMI) and another the unprioritized memory item (UMI). Using inverted encoding models (IEMs), we found that, in early visual cortex, the orientation of the UMI was represented in a neural representation that was rotated relative to the PMI. In intraparietal sulcus (IPS), we observed the analogous effect for the representation of the location of the UMI. Taken together, these results provide evidence for a common remapping mechanism that may be responsible for representing stimulus identity and stimulus context with different levels of priority in working memory.


Assuntos
Encéfalo/fisiologia , Memória de Curto Prazo/fisiologia , Percepção Visual/fisiologia , Comportamento , Feminino , Humanos , Imagem por Ressonância Magnética , Masculino , Modelos Neurológicos , Estimulação Luminosa , Análise e Desempenho de Tarefas , Fatores de Tempo , Adulto Jovem
14.
Exp Psychol ; 67(3): 169-177, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32552545

RESUMO

Abstract. A large literature suggests that the way we process information is influenced by the categories that we have learned. We examined whether, when we try to uniquely encode items in working memory, the information encoded depends on the other stimuli being simultaneously learned. Participants were required to memorize unknown aliens, presented one at the time, for immediate recognition of their features. Some aliens, called twins, were organized into pairs that shared every feature (nondiscriminative feature) except one (discriminative feature), while some other aliens, called hermits, did not share feature. We reasoned that if people develop unsupervised categories by creating a category for a pair of aliens, we should observe better feature identification performance for nondiscriminative features compared to hermit features, but not compared to discriminative features. On the contrary, if distinguishing features draw attention, we should observe better performance when a discriminative rather than nondiscriminative feature was probed. Overall, our results suggest that when items share features, people code items in working memory by focusing on similarities between items, establishing clusters of items in an unsupervised fashion not requiring feedback on cluster membership.


Assuntos
Memória de Curto Prazo/fisiologia , Reconhecimento Psicológico/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
15.
Neuron ; 107(3): 509-521.e7, 2020 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-32492366

RESUMO

Post-tetanic potentiation (PTP) is an attractive candidate mechanism for hippocampus-dependent short-term memory. Although PTP has a uniquely large magnitude at hippocampal mossy fiber-CA3 pyramidal neuron synapses, it is unclear whether it can be induced by natural activity and whether its lifetime is sufficient to support short-term memory. We combined in vivo recordings from granule cells (GCs), in vitro paired recordings from mossy fiber terminals and postsynaptic CA3 neurons, and "flash and freeze" electron microscopy. PTP was induced at single synapses and showed a low induction threshold adapted to sparse GC activity in vivo. PTP was mainly generated by enlargement of the readily releasable pool of synaptic vesicles, allowing multiplicative interaction with other plasticity forms. PTP was associated with an increase in the docked vesicle pool, suggesting formation of structural "pool engrams." Absence of presynaptic activity extended the lifetime of the potentiation, enabling prolonged information storage in the hippocampal network.


Assuntos
Memória de Curto Prazo/fisiologia , Fibras Musgosas Hipocampais/metabolismo , Plasticidade Neuronal/fisiologia , Células Piramidais/metabolismo , Sinapses/metabolismo , Vesículas Sinápticas/metabolismo , Potenciais de Ação/fisiologia , Animais , Região CA3 Hipocampal/citologia , Giro Denteado/citologia , Camundongos , Microscopia Eletrônica , Fibras Musgosas Hipocampais/fisiologia , Fibras Musgosas Hipocampais/ultraestrutura , Técnicas de Patch-Clamp , Células Piramidais/fisiologia , Células Piramidais/ultraestrutura , Ratos , Sinapses/fisiologia , Potenciais Sinápticos/fisiologia
16.
Dev Neuropsychol ; 45(3): 118-128, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32412307

RESUMO

This study used a novel approach that combined the latency and accuracy scores to examine the relative involvement of inhibition and working memory in two measures of cognitive flexibility - mixing cost and switch cost in 110 Nigerian adolescents. Results showed that inhibition was significantly associated with switch cost. On the other hand, working memory was negatively associated with mixing cost. These findings support the assumption that cognitive flexibility skills are dependent on inputs from inhibition and working memory processes. Inhibition is involved in the deactivation of irrelevant stimuli during switching trials while working memory is essential to maintain the current rule in sets that require no shifting.


Assuntos
Cognição/fisiologia , Inibição Psicológica , Memória de Curto Prazo/fisiologia , Adolescente , Adulto , Criança , Feminino , Humanos , Masculino , Nigéria , Adulto Jovem
17.
Neuron ; 107(2): 283-291.e6, 2020 07 22.
Artigo em Inglês | MEDLINE | ID: mdl-32392472

RESUMO

Episodic memory requires linking events in time, a function dependent on the hippocampus. In "trace" fear conditioning, animals learn to associate a neutral cue with an aversive stimulus despite their separation in time by a delay period on the order of tens of seconds. But how this temporal association forms remains unclear. Here we use two-photon calcium imaging of neural population dynamics throughout the course of learning and show that, in contrast to previous theories, hippocampal CA1 does not generate persistent activity to bridge the delay. Instead, learning is concomitant with broad changes in the active neural population. Although neural responses were stochastic in time, cue identity could be read out from population activity over longer timescales after learning. These results question the ubiquity of seconds-long neural sequences during temporal association learning and suggest that trace fear conditioning relies on mechanisms that differ from persistent activity accounts of working memory.


Assuntos
Aprendizagem por Associação/fisiologia , Hipocampo/fisiologia , Memória Episódica , Rede Nervosa/fisiologia , Animais , Comportamento Animal , Região CA1 Hipocampal/fisiologia , Condicionamento Operante , Sinais (Psicologia) , Medo/psicologia , Hipocampo/citologia , Processamento de Imagem Assistida por Computador , Memória de Curto Prazo/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Neurônios/fisiologia , Optogenética
18.
PLoS One ; 15(5): e0223941, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32469952

RESUMO

Expert behavior is characterized by rapid information processing abilities, dependent on more structured schemata in long-term memory designated for their domain-specific tasks. From this understanding, expertise can effectively reduce cognitive load on a domain-specific task. However, certain tasks could still evoke different gradations of load even for an expert, e.g., when having to detect subtle anomalies in dental radiographs. Our aim was to measure pupil diameter response to anomalies of varying levels of difficulty in expert and student dentists' visual examination of panoramic radiographs. We found that students' pupil diameter dilated significantly from baseline compared to experts, but anomaly difficulty had no effect on pupillary response. In contrast, experts' pupil diameter responded to varying levels of anomaly difficulty, where more difficult anomalies evoked greater pupil dilation from baseline. Experts thus showed proportional pupillary response indicative of increasing cognitive load with increasingly difficult anomalies, whereas students showed pupillary response indicative of higher cognitive load for all anomalies when compared to experts.


Assuntos
Cognição/fisiologia , Movimentos Oculares/fisiologia , Memória de Curto Prazo/fisiologia , Percepção Visual/fisiologia , Adulto , Atenção/fisiologia , Feminino , Humanos , Aprendizagem/fisiologia , Masculino , Pessoa de Meia-Idade , Pupila/fisiologia , Radiografia Dentária/psicologia , Radiografia Panorâmica/psicologia
19.
Psychol Aging ; 35(6): 866-880, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32406709

RESUMO

For the first time, we quantify capacities of working memory in young and older adults in a dual-task situation, addressing whether older adults have diminished central or peripheral capacity in working memory. Across 2 experiments, 63 young and 63 old adult participants studied visual arrays of colored squares and sequences of unfamiliar tones in quick succession and were instructed to attend to one or both modalities. Memory was assessed with a single-probe change-detection task. We used a recently developed capacity-estimate model to partition participants' overall working memory capacity into 3 components: a peripheral component dedicated to visual information regardless of attention instruction; a peripheral component similarly dedicated to auditory information; and a central component allocated to either modality, or shared between both, depending on attention instruction. Capacity estimates of the peripheral components were consistently smaller in the older adults than in the young adults, but the central component was stable across both age groups. We contend that older adults are impaired in their ability to strategically encode information in ways that younger adults use to increase peripheral storage, a kind of storage that is immune to loss through bimodal attention costs. (PsycInfo Database Record (c) 2020 APA, all rights reserved).


Assuntos
Envelhecimento/psicologia , Atenção/fisiologia , Memória de Curto Prazo/fisiologia , Tempo de Reação/fisiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Envelhecimento/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
20.
Brain ; 143(4): 1158-1176, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32243506

RESUMO

It is well established that chronic cognitive problems after traumatic brain injury relate to diffuse axonal injury and the consequent widespread disruption of brain connectivity. However, the pattern of diffuse axonal injury varies between patients and they have a correspondingly heterogeneous profile of cognitive deficits. This heterogeneity is poorly understood, presenting a non-trivial challenge for prognostication and treatment. Prominent amongst cognitive problems are deficits in working memory and reasoning. Previous functional MRI in controls has associated these aspects of cognition with distinct, but partially overlapping, networks of brain regions. Based on this, a logical prediction is that differences in the integrity of the white matter tracts that connect these networks should predict variability in the type and severity of cognitive deficits after traumatic brain injury. We use diffusion-weighted imaging, cognitive testing and network analyses to test this prediction. We define functionally distinct subnetworks of the structural connectome by intersecting previously published functional MRI maps of the brain regions that are activated during our working memory and reasoning tasks, with a library of the white matter tracts that connect them. We examine how graph theoretic measures within these subnetworks relate to the performance of the same tasks in a cohort of 92 moderate-severe traumatic brain injury patients. Finally, we use machine learning to determine whether cognitive performance in patients can be predicted using graph theoretic measures from each subnetwork. Principal component analysis of behavioural scores confirm that reasoning and working memory form distinct components of cognitive ability, both of which are vulnerable to traumatic brain injury. Critically, impairments in these abilities after traumatic brain injury correlate in a dissociable manner with the information-processing architecture of the subnetworks that they are associated with. This dissociation is confirmed when examining degree centrality measures of the subnetworks using a canonical correlation analysis. Notably, the dissociation is prevalent across a number of node-centric measures and is asymmetrical: disruption to the working memory subnetwork relates to both working memory and reasoning performance whereas disruption to the reasoning subnetwork relates to reasoning performance selectively. Machine learning analysis further supports this finding by demonstrating that network measures predict cognitive performance in patients in the same asymmetrical manner. These results accord with hierarchical models of working memory, where reasoning is dependent on the ability to first hold task-relevant information in working memory. We propose that this finer grained information may be useful for future applications that attempt to predict long-term outcomes or develop tailored therapies.


Assuntos
Lesões Encefálicas Traumáticas/fisiopatologia , Encéfalo/fisiopatologia , Memória de Curto Prazo/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiopatologia , Adulto , Transtornos Cognitivos/fisiopatologia , Conectoma , Imagem de Tensor de Difusão , Feminino , Humanos , Aprendizado de Máquina , Masculino , Pessoa de Meia-Idade , Resolução de Problemas/fisiologia
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