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1.
Biol Psychol ; 132: 133-142, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-29246813

RESUMO

The speed of visual processing is central to our understanding of face perception. Yet the extent to which early visual processing influences later processing in distributed face processing networks, and the top-down modulation of such bottom-up effects, remains unclear. We used simultaneous EEG-fMRI to investigate cortical activity that showed unique covariation with ERP components of face processing (C1, P1, N170, P3), while manipulating sustained attention and transient cognitive conflict employing an emotional face-word Stroop task. ERP markers of visual processing within 100 ms after stimulus onset showed covariation with brain activation in precuneous, posterior cingulate gyrus, left middle temporal gyrus, left inferior frontal gyrus and frontal operculum, and a left lateral parietal-occipital cluster, illustrating the impact of early stage processing on higher-order mechanisms. Crucially, this covariation depended on sustained attentional focus and was absent for incongruent trials, suggesting flexible top-down gating of bottom-up processing.


Assuntos
Atenção/fisiologia , Eletroencefalografia/métodos , Reconhecimento Facial/fisiologia , Imageamento por Ressonância Magnética/métodos , Mapeamento Encefálico , Córtex Cerebral/diagnóstico por imagem , Emoções/fisiologia , Feminino , Humanos , Masculino , Rede Nervosa/diagnóstico por imagem , Teste de Stroop , Adulto Jovem
2.
Ann Neurol ; 73(6): 762-73, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23447373

RESUMO

OBJECTIVE: The importance of the cholinergic system for cognitive function has been well documented in animal and human studies. The objective of this study was to elucidate the cognitive and functional connectivity changes associated with enhanced acetylcholine levels. We hypothesized that older adults with mild memory deficits would show behavioral and functional network enhancements with an acetylcholinesterase inhibitor treatment (donepezil) when compared to a placebo control group. METHODS: We conducted a 3-month, double-blind, placebo-controlled study on the effects of donepezil in 27 older adults with mild memory deficits. Participants completed a delayed recognition memory task. Functional magnetic resonance imaging (fMRI) scans were collected at baseline prior to treatment and at 3-month follow-up while subjects were on a 10mg daily dose of donepezil or placebo. RESULTS: Donepezil treatment significantly enhanced the response time for face and scene memory probes when compared to the placebo group. A group-by-visit interaction was identified for the functional network connectivity of the left fusiform face area (FFA) with the hippocampus and inferior frontal junction, such that the treatment group showed increased connectivity over time when compared to the placebo group. Additionally, the enhanced functional network connectivity of the FFA and hippocampus significantly predicted memory response time at 3-month follow-up in the treatment group. INTERPRETATION: These findings suggest that increased cholinergic transmission improves goal-directed neural processing and cognitive ability and may serve to facilitate communication across functionally-connected attention and memory networks. Longitudinal fMRI is a useful method for elucidating the neural changes associated with pharmacological modulation and is a potential tool for monitoring intervention efficacy in clinical trials.


Assuntos
Encéfalo/fisiopatologia , Inibidores da Colinesterase/uso terapêutico , Disfunção Cognitiva/tratamento farmacológico , Disfunção Cognitiva/psicologia , Rede Nervosa/fisiologia , Regulação para Cima/fisiologia , Idoso , Idoso de 80 Anos ou mais , Encéfalo/efeitos dos fármacos , Disfunção Cognitiva/fisiopatologia , Donepezila , Método Duplo-Cego , Feminino , Humanos , Indanos/uso terapêutico , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Rede Nervosa/efeitos dos fármacos , Estimulação Luminosa/métodos , Piperidinas/uso terapêutico , Tempo de Reação/efeitos dos fármacos , Tempo de Reação/fisiologia , Regulação para Cima/efeitos dos fármacos
3.
J Neurophysiol ; 107(5): 1257-9, 2012 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22072509

RESUMO

A recent study (Di Lazzaro et al. J Neurophysiol 105: 2150-2156, 2011) describes the findings from a rigorous comparison on the effects of several popular variations of transcranial magnetic stimulation (TMS) protocols. The results demonstrate that excitatory and inhibitory neural networks may be independently modulated based on TMS protocol selection. Moreover, the within-group replication of multiple between-group experiments suggests that independent evaluations of TMS parameters will continue to inform and guide future TMS research.


Assuntos
Potencial Evocado Motor/fisiologia , Rede Nervosa/fisiologia , Inibição Neural/fisiologia , Estimulação Magnética Transcraniana/métodos , Humanos , Estimulação Magnética Transcraniana/normas
5.
Proc Natl Acad Sci U S A ; 108(17): 7212-7, 2011 Apr 26.
Artigo em Inglês | MEDLINE | ID: mdl-21482762

RESUMO

Multitasking negatively influences the retention of information over brief periods of time. This impact of interference on working memory is exacerbated with normal aging. We used functional MRI to investigate the neural basis by which an interruption is more disruptive to working memory performance in older individuals. Younger and older adults engaged in delayed recognition tasks both with and without interruption by a secondary task. Behavioral analysis revealed that working memory performance was more impaired by interruptions in older compared with younger adults. Functional connectivity analyses showed that when interrupted, older adults disengaged from a memory maintenance network and reallocated attentional resources toward the interrupting stimulus in a manner consistent with younger adults. However, unlike younger individuals, older adults failed to both disengage from the interruption and reestablish functional connections associated with the disrupted memory network. These results suggest that multitasking leads to more significant working memory disruption in older adults because of an interruption recovery failure, manifest as a deficient ability to dynamically switch between functional brain networks.


Assuntos
Encéfalo/fisiologia , Memória/fisiologia , Resolução de Problemas/fisiologia , Adulto , Idoso , Humanos , Masculino , Pessoa de Meia-Idade
6.
Nat Neurosci ; 14(5): 656-61, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21441920

RESUMO

Selective attention filters information to limit what is encoded and maintained in working memory. Although the prefrontal cortex (PFC) is central to both selective attention and working memory, the underlying neural processes that link these cognitive abilities remain elusive. Using functional magnetic resonance imaging to guide repetitive transcranial magnetic stimulation with electroencephalographic recordings in humans, we perturbed PFC function at the inferior frontal junction in participants before they performed a selective-attention, delayed-recognition task. This resulted in diminished top-down modulation of activity in posterior cortex during early encoding stages, which predicted a subsequent decrement in working memory accuracy. Participants with stronger fronto-posterior functional connectivity displayed greater disruptive effects. Our data further suggests that broad alpha-band (7-14 Hz) phase coherence subserved this long-distance top-down modulation. These results suggest that top-down modulation mediated by the prefrontal cortex is a causal link between early attentional processes and subsequent memory performance.


Assuntos
Mapeamento Encefálico , Potenciais Evocados/fisiologia , Memória de Curto Prazo/fisiologia , Vias Neurais/fisiologia , Córtex Pré-Frontal/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Análise de Variância , Atenção/fisiologia , Eletroencefalografia/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Vias Neurais/irrigação sanguínea , Testes Neuropsicológicos , Oxigênio/sangue , Estimulação Luminosa/métodos , Córtex Pré-Frontal/irrigação sanguínea , Reconhecimento Psicológico/fisiologia , Estatística como Assunto , Fatores de Tempo , Estimulação Magnética Transcraniana/métodos , Adulto Jovem
7.
Neuropsychologia ; 49(6): 1466-75, 2011 May.
Artigo em Inglês | MEDLINE | ID: mdl-21272595

RESUMO

Memory performance can be enhanced by expectations regarding the appearance of ensuing stimuli. Here, we investigated the influence of stimulus-category expectation on memory performance in aging, and used fMRI to explore age-related alterations in associated neural mechanisms. Unlike younger adults, who demonstrated both working memory (WM) and long-term memory (LTM) performance benefits for face stimuli when this stimulus category was expected, older adults did not exhibit these memory benefits. Concordantly, older adults did not exhibit expectation-period activity modulation in visual association cortex (i.e., fusiform face area (FFA)), unlike younger adults. However, within the older population, individuals who demonstrated face-expectation memory benefits also exhibited expectation-period FFA activity modulation equivalent to younger adults. The older cohort also displayed diminished expectation-related functional connectivity between regions of the prefrontal cortex and the FFA, relative to younger adults, suggesting that network alterations underlie the absence of expectation-mediated cortical modulation and memory benefits. This deficit may have broader consequences for the effective utilization of predictive cues to guide attention and engender optimal cognitive performance in older individuals.


Assuntos
Envelhecimento/fisiologia , Atenção/fisiologia , Cognição/fisiologia , Memória/fisiologia , Enquadramento Psicológico , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Sinais (Psicologia) , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Vias Neurais/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Reconhecimento Psicológico/fisiologia , Valores de Referência , Adulto Jovem
8.
J Neurosci ; 30(43): 14399-410, 2010 Oct 27.
Artigo em Inglês | MEDLINE | ID: mdl-20980597

RESUMO

Expectations generated by predictive cues increase the efficiency of perceptual processing for complex stimuli (e.g., faces, scenes); however, the impact this has on working memory (WM) and long-term memory (LTM) has not yet been investigated. Here, healthy young adults performed delayed-recognition tasks that differed only in stimulus category expectations, while behavioral and functional magnetic resonance imaging data were collected. Univariate and functional-connectivity analyses were used to examine expectation-driven, prestimulus neural modulation, networks that regulate this modulation, and subsequent memory performance. Results revealed that predictive category cueing was associated with both enhanced WM and LTM for faces, as well as baseline activity shifts in a face-selective region of the visual association cortex [i.e., fusiform face area (FFA)]. In addition, the degree of functional connectivity between FFA and right inferior frontal junction (IFJ), middle frontal gyrus (MFG), inferior frontal gyrus, and intraparietal sulcus correlated with the magnitude of prestimulus activity modulation in the FFA. In an opposing manner, prestimulus connectivity between FFA and posterior cingulate cortex, a region of the default network, negatively correlated with FFA activity modulation. Moreover, whereas FFA connectivity with IFJ and the precuneus predicted enhanced expectation-related WM performance, FFA connectivity with MFG predicted LTM improvements. These findings suggest a model of expectancy-mediated neural biasing, in which a single node (e.g., FFA) can be dynamically linked or disconnected from different brain regions depending on prestimulus expectations, and the strength of distinct connections is associated with WM or LTM benefits.


Assuntos
Córtex Cerebral/fisiologia , Memória de Curto Prazo/fisiologia , Rememoração Mental/fisiologia , Vias Neurais/fisiologia , Adolescente , Adulto , Interpretação Estatística de Dados , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Lobo Occipital/fisiologia , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Reconhecimento Psicológico/fisiologia , Análise de Regressão , Percepção Visual/fisiologia , Adulto Jovem
9.
Neuroimage ; 53(2): 736-45, 2010 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-20600999

RESUMO

Distinct areas within the visual association cortex are specialized for representing specific stimulus features, such as V4 for color and V5/hMT+ for motion. Recent studies have demonstrated that areas associated with attended features exhibit enhanced cortical activity, whereas those associated with ignored features elicit reduced activity. However, the source of this attentional (or top-down) modulation remains uncertain. A network of fronto-parietal cortical regions has been proposed as the prime candidate underlying this top-down modulation. Here, we evaluate whether there are distinct or overlapping top-down network regions for attention to different stimulus features. To this end, we explored functional magnetic resonance imaging (fMRI) functional connectivity data, electroencephalographic (EEG) source localization, and phase coherence that were obtained while participants attended or ignored motion and color stimuli. Functional connectivity analysis indicated that attention to color relies strongly on prefrontal regions, whereas attention to motion recruits both prefrontal and parietal areas. Although these networks are generally topologically segregated, both color and motion processes recruit right inferior frontal junction (IFJ). However, the IFJ may be more critical for color processing, as only connectivity with V4 predicted the degree of attentional modulation. Source localization at the time range of attentional modulation of the event related potential corroborated the role of the right IFJ and indicated that feature-based, top-down modulation occurs early during processing (< 200ms post-stimulus onset). Furthermore, long-distance alpha (8-12Hz) phase coherence between the IFJ and visual cortices may serve as a mechanism underlying anticipatory, top-down modulation of color feature processing.


Assuntos
Córtex Pré-Frontal/fisiologia , Percepção Visual/fisiologia , Adulto , Atenção/fisiologia , Mapeamento Encefálico , Cor , Eletroencefalografia , Potenciais Pós-Sinápticos Excitadores , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Percepção de Movimento/fisiologia , Rede Nervosa/fisiologia , Lobo Parietal/fisiologia , Estimulação Luminosa , Desempenho Psicomotor/fisiologia , Limiar Sensorial/fisiologia , Adulto Jovem
10.
J Neurosci ; 30(25): 8541-50, 2010 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-20573901

RESUMO

Filtering information on the basis of what is relevant to accomplish our goals is a critical process supporting optimal cognitive performance. However, it is not known whether exposure to irrelevant environmental stimuli impairs our ability to accurately retrieve long-term memories. We hypothesized that visual processing of irrelevant visual information would interfere with mental visualization engaged during recall of the details of a prior experience, despite goals to direct full attention to the retrieval task. In the current study, we compared performance on a cued-recall test of previously studied visual items when participants' eyes were closed to performance when their eyes were open and irrelevant visual stimuli were presented. A behavioral experiment revealed that recollection of episodic details was diminished in the presence of the irrelevant information. A functional magnetic resonance imaging experiment using the same paradigm replicated the behavioral results and found that diminished recollection was associated with the disruption of functional connectivity in a network involving the left inferior frontal gyrus, hippocampus and visual association cortex. Network connectivity supported recollection of contextual details based on visual imagery when eyes were closed, but declined in the presence of irrelevant visual information. We conclude that bottom-up influences from irrelevant visual information interfere with top-down selection of episodic details mediated by a capacity-limited frontal control region, resulting in impaired recollection.


Assuntos
Atenção/fisiologia , Encéfalo/fisiologia , Rememoração Mental/fisiologia , Rede Nervosa/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Neurônios/fisiologia , Estimulação Luminosa , Tempo de Reação/fisiologia , Retenção Psicológica/fisiologia , Percepção Visual/fisiologia
11.
Cereb Cortex ; 20(4): 859-72, 2010 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-19648173

RESUMO

The negative impact of external interference on working memory (WM) performance is well documented; yet, the mechanisms underlying this disruption are not sufficiently understood. In this study, electroencephalogram and functional magnetic resonance imaging (fMRI) data were recorded in separate experiments that each introduced different types of visual interference during a period of WM maintenance: distraction (irrelevant stimuli) and interruption (stimuli that required attention). The data converged to reveal that regardless of the type of interference, the magnitude of processing interfering stimuli in the visual cortex (as rapidly as 100 ms) predicted subsequent WM recognition accuracy for stored items. fMRI connectivity analyses suggested that in the presence of distraction, encoded items were maintained throughout the delay period via connectivity between the middle frontal gyrus and visual association cortex, whereas memoranda were not maintained when subjects were interrupted but rather reactivated in the postinterruption period. These results elucidate the mechanisms of external interference on WM performance and highlight similarities and differences of distraction and multitasking.


Assuntos
Atenção/fisiologia , Córtex Cerebral/fisiologia , Transtornos da Memória/fisiopatologia , Memória de Curto Prazo/fisiologia , Adolescente , Adulto , Mapeamento Encefálico , Córtex Cerebral/irrigação sanguínea , Sinais (Psicologia) , Eletroencefalografia/métodos , Potenciais Evocados/fisiologia , Face , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento por Ressonância Magnética/métodos , Masculino , Transtornos da Memória/patologia , Testes Neuropsicológicos , Oxigênio/sangue , Estimulação Luminosa/métodos , Tempo de Reação/fisiologia , Adulto Jovem
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