RESUMEN
Effective cognitive training must improve cognition beyond the trained domain (show a transfer effect) and be applicable to dementia-risk populations, e.g., amnesic mild cognitive impairment (aMCI). Theories suggest training should target processes that 1) show robust engagement, 2) are domain-general, and 3) reflect long-lasting changes in brain organization. Brain regions that connect to many different networks (i.e., show high participation coefficient; PC) are known to support integration. This capacity is 1) relatively preserved in aMCI, 2) required across a wide range of cognitive domains, and 3) trait-like. In 49 individuals with aMCI that completed a 6-week visual speed of processing training (VSOP) and 28 active controls, enhancement in PC was significantly more related to transfer to working memory at global and network levels in VSOP compared to controls, particularly in networks with many high-PC nodes. This suggests that enhancing brain integration may provide a target for developing effective cognitive training.
Asunto(s)
Trastornos del Conocimiento , Disfunción Cognitiva , Encéfalo , Cognición , Disfunción Cognitiva/psicología , Disfunción Cognitiva/terapia , Humanos , Memoria a Corto Plazo , Pruebas NeuropsicológicasRESUMEN
A major challenge in the cognitive training field is inducing broad, far-transfer training effects. Thus far, little is known about the neural mechanisms underlying broad training effects. Here, we tested a set of competitive hypotheses regarding the role of brain integration versus segregation underlying the broad training effect. We retrospectively analyzed data from a randomized controlled trial comparing neurocognitive effects of vision-based speed of processing training (VSOP) and an active control consisting of mental leisure activities (MLA) in older adults with MCI. We classified a subset of participants in the VSOP as learners, who showed improvement in executive function and episodic memory. The other participants in the VSOP (i.e., VSOP non-learners) and a subset of participants in the MLA (i.e., MLA non-learners) served as controls. Structural brain networks were constructed from diffusion tensor imaging. Clustering coefficients (CCs) and characteristic path lengths were computed as measures of segregation and integration, respectively. Learners showed significantly greater global CCs after intervention than controls. Nodal CCs were selectively enhanced in cingulate cortex, parietal regions, striatum, and thalamus. Among VSOP learners, those with more severe baseline neurodegeneration had greater improvement in segregation after training. Our findings suggest broad training effects are related to enhanced segregation in selective brain networks, providing insight into cognitive training related neuroplasticity.
Asunto(s)
Amnesia , Corteza Cerebral/patología , Disfunción Cognitiva , Remediación Cognitiva , Red Nerviosa/patología , Tálamo/patología , Anciano , Anciano de 80 o más Años , Amnesia/diagnóstico por imagen , Amnesia/patología , Amnesia/fisiopatología , Amnesia/terapia , Corteza Cerebral/diagnóstico por imagen , Disfunción Cognitiva/diagnóstico por imagen , Disfunción Cognitiva/patología , Disfunción Cognitiva/fisiopatología , Disfunción Cognitiva/terapia , Cuerpo Estriado , Imagen de Difusión Tensora , Femenino , Humanos , Masculino , Persona de Mediana Edad , Red Nerviosa/diagnóstico por imagen , Plasticidad Neuronal/fisiología , Desempeño Psicomotor/fisiología , Estudios Retrospectivos , Tálamo/diagnóstico por imagenRESUMEN
Adaptation capacity is critical for maintaining cognition, yet it is understudied in groups at risk for dementia. Autonomic nervous system (ANS) is critical for neurovisceral integration and is a key contributor to adaptation capacity. To determine the central nervous system's top-down regulation of ANS, we conducted a mechanistic randomized controlled trial study, using a 6-week processing speed and attention (PS/A)-targeted intervention. Eighty-four older adults with amnestic mild cognitive impairment (aMCI) were randomized to a 6-week PS/A-targeted intervention or an active control without PS/A. Utilizing repeated measures (i.e., PS/A test different from the intervention, resting and cognitive task-based ECG, and resting fMRI) at baseline, immediately post-intervention (post-test), and 6-month follow-up, we aimed to test whether PS/A causally influences vagal control of ANS via their shared central neural pathways in aMCI. We indexed vagal control of ANS using high-frequency heart rate variability (HF-HRV) extracted from ECG data. Functional brain connectivity patterns were extracted from fMRI using advanced statistical tools. Compared to the control group, the intervention group showed significant improvement in PS/A, HF-HRV, salience network (SN), central executive network (CEN), and frontal parietal network (FPN) connectivity at post-test; the effect on SN, CEN, and FPN remained at 6-month follow-up. Changes in PS/A and SN connectivity significantly predicted change in HF-HRV from baseline to post-test and/or 6-month-follow-up. Age, neurodegeneration, nor sex did not affect these relationships. This work provides novel support for top-down regulation of PS/A and associated SN on vagal control of ANS. Intervening PS/A may be a viable approach for promoting adaptation capacity in groups at risk for dementia.
Asunto(s)
Adaptación Fisiológica/fisiología , Atención/fisiología , Sistema Nervioso Autónomo/fisiología , Encéfalo/fisiología , Disfunción Cognitiva/rehabilitación , Vías Nerviosas/fisiología , Anciano , Disfunción Cognitiva/fisiopatología , Femenino , Frecuencia Cardíaca/fisiología , Humanos , Imagen por Resonancia Magnética , Masculino , Nervio Vago/fisiologíaRESUMEN
BACKGROUND: As of April 18, 2020, over 2,000,000 patients had been diagnosed with coronavirus disease-2019 (COVID-19) globally, and more than 140,000 deaths had been reported. The clinical and epidemiological characteristics of adult patients have been documented recently. However, information on pediatric patients is limited. We describe the clinical and epidemiological characteristics of pediatric patients to provide valuable insight into the early diagnosis and assessment of COVID-19 in children. METHODS AND FINDINGS: This retrospective, observational study involves a case series performed at 4 hospitals in West China. Thirty-four pediatric patients with COVID-19 were included from January 27 to February 23, 2020. The final follow-up visit was completed by March 16, 2020. Clinical and epidemiological characteristics were analyzed on the basis of demographic data, medical history, laboratory tests, radiological findings, and treatment information. Data analysis was performed for 34 pediatrics patients with COVID-19 aged from 1 to 144 months (median 33.00, interquartile range 10.00-94.25), among whom 14 males (41%) were included. All the patients in the current study presented mild (18%) or moderate (82%) forms of COVID-19. A total of 48% of patients were noted to be without a history of exposure to an identified source. Mixed infections of other respiratory pathogens were reported in 16 patients (47%). Comorbidities were reported in 6 patients (18%). The most common initial symptoms were fever (76%) and cough (62%). Expectoration (21%), vomiting (12%), and diarrhea (12%) were also reported in a considerable portion of cases. A substantial increase was detected in serum amyloid A for 17 patients (among 20 patients with available data; 85%) and in high-sensitivity C-reactive protein for 17 patients (among 29 patients with available data; 59%), whereas a decrease in prealbumin was noticed in 25 patients (among 32 patients with available data; 78%). In addition, significant increases in the levels of lactate dehydrogenase and α-hydroxybutyrate dehydrogenase were detected in 28 patients (among 34 patients with available data; 82%) and 25 patients (among 34 patients with available data; 74%), respectively. Patchy lesions in lobules were detected by chest computed tomographic scans in 28 patients (82%). Ground-glass opacities, which were a typical feature in adults, were rare in pediatric patients (3%). Rapid radiologic progression and a late-onset pattern of lesions in the lobules were also noticed. Lesions in lobules still existed in 24 (among 32 patients with lesions; 75%) patients that were discharged, although the main symptoms disappeared a few days after treatment. All patients were discharged, and the median duration of hospitalization was 10.00 (8.00-14.25) days. The current study was limited by the small sample size and a lack of dynamic detection of inflammatory markers. CONCLUSIONS: Our data systemically presented the clinical and epidemiological features, as well as the outcomes, of pediatric patients with COVID-19. Stratified analysis was performed between mild and moderate cases. The findings offer new insight into early identification and intervention in pediatric patients with COVID-19.
Asunto(s)
Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/fisiopatología , Pulmón/diagnóstico por imagen , Neumonía Viral/epidemiología , Neumonía Viral/fisiopatología , Betacoronavirus , Proteína C-Reactiva/metabolismo , COVID-19 , Niño , Preescolar , China/epidemiología , Coinfección/epidemiología , Infecciones por Coronavirus/diagnóstico por imagen , Infecciones por Coronavirus/metabolismo , Tos/epidemiología , Tos/fisiopatología , Diarrea/epidemiología , Diarrea/fisiopatología , Femenino , Fiebre/epidemiología , Fiebre/fisiopatología , Humanos , Hidroxibutirato Deshidrogenasa/metabolismo , Lactante , L-Lactato Deshidrogenasa/metabolismo , Tiempo de Internación/estadística & datos numéricos , Masculino , Pandemias , Neumonía Viral/diagnóstico por imagen , Neumonía Viral/metabolismo , Prealbúmina/metabolismo , Estudios Retrospectivos , SARS-CoV-2 , Proteína Amiloide A Sérica/metabolismo , Índice de Severidad de la Enfermedad , Tomografía Computarizada por Rayos X , Vómitos/epidemiología , Vómitos/fisiopatologíaRESUMEN
Effective learning in old age, particularly in those at risk for dementia, is essential for prolonging independent living. Individual variability in learning, however, is remarkable; that is, months of cognitive training to improve learning may be beneficial for some individuals but not others. So far, little is known about which neurophysiological mechanisms account for the observed variability in learning induced by cognitive training in older adults. By combining Lövdén et al.'s (2010, A theoretical framework for the study of adult cognitive plasticity. Psychological Bulletin, 136, 659-676) framework proposing the role of adaptation capacity in neuroplasticity and a neurovisceral integration model of the relationship between autonomic nervous system (ANS) and brain with a novel shapelet analytical approach that allows for accurate and interpretable analysis of time series data, we discovered an acute, ECG-derived ANS segment in response to cognitive training tasks at baseline that predicted learning outcomes from a 6-week cognitive training intervention. The relationship between the ANS segment and learning was robust in both cross-participant and cross-task analyses among a group of older adults with amnestic mild cognitive impairment. Furthermore, the revealed ANS shapelet significantly predicted training-induced neuroplasticity in the dorsal anterior cingulate cortex and select frontal regions during task fMRI. Across outcome measures, individuals were less likely to prospectively benefit from the cognitive training if their ECG data were more similar to this particular ANS segment at baseline. Our findings are among the first empirical evidence to confirm that adaptation capacity, indexed by ANS flexibility, predicts individual differences in learning and associated neuroplasticity beyond individual characteristics (e.g., age, education, neurodegeneration, total training).
Asunto(s)
Adaptación Fisiológica/fisiología , Envejecimiento/fisiología , Sistema Nervioso Autónomo/fisiopatología , Aprendizaje/fisiología , Plasticidad Neuronal/fisiología , Anciano , Anciano de 80 o más Años , Método Doble Ciego , Electrocardiografía , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Práctica PsicológicaRESUMEN
Prior neuroimaging and neuropsychological research indicates that the left inferior parietal lobule in the human brain is a critical substrate for representing object manipulation knowledge. In the present functional MRI study we used multivoxel pattern analyses to test whether action similarity among objects can be decoded in the inferior parietal lobule independent of the task applied to objects (identification or pantomime) and stimulus format in which stimuli are presented (pictures or printed words). Participants pantomimed the use of objects, cued by printed words, or identified pictures of objects. Classifiers were trained and tested across task (e.g., training data: pantomime; testing data: identification), stimulus format (e.g., training data: word format; testing format: picture) and specific objects (e.g., training data: scissors vs. corkscrew; testing data: pliers vs. screwdriver). The only brain region in which action relations among objects could be decoded across task, stimulus format and objects was the inferior parietal lobule. By contrast, medial aspects of the ventral surface of the left temporal lobe represented object function, albeit not at the same level of abstractness as actions in the inferior parietal lobule. These results suggest compulsory access to abstract action information in the inferior parietal lobe even when simply identifying objects.
Asunto(s)
Lóbulo Parietal/fisiología , Reconocimiento Visual de Modelos/fisiología , Desempeño Psicomotor/fisiología , Mapeo Encefálico/métodos , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Adulto JovenRESUMEN
The appropriate use of everyday objects requires the integration of action and function knowledge. Previous research suggests that action knowledge is represented in frontoparietal areas while function knowledge is represented in temporal lobe regions. Here we used multivoxel pattern analysis to investigate the representation of object-directed action and function knowledge while participants executed pantomimes of familiar tool actions. A novel approach for decoding object knowledge was used in which classifiers were trained on one pair of objects and then tested on a distinct pair; this permitted a measurement of classification accuracy over and above object-specific information. Region of interest (ROI) analyses showed that object-directed actions could be decoded in tool-preferring regions of both parietal and temporal cortex, while no independently defined tool-preferring ROI showed successful decoding of object function. However, a whole-brain searchlight analysis revealed that while frontoparietal motor and peri-motor regions are engaged in the representation of object-directed actions, medial temporal lobe areas in the left hemisphere are involved in the representation of function knowledge. These results indicate that both action and function knowledge are represented in a topographically coherent manner that is amenable to study with multivariate approaches, and that the left medial temporal cortex represents knowledge of object function.
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Encéfalo/fisiología , Destreza Motora , Desempeño Psicomotor , Comportamiento del Uso de la Herramienta/fisiología , Adulto , Mapeo Encefálico , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Corteza Sensoriomotora/fisiología , Adulto JovenRESUMEN
The format of high-level object representations in temporal-occipital cortex is a fundamental and as yet unresolved issue. Here we use fMRI to show that human lateral occipital cortex (LOC) encodes novel 3-D objects in a multisensory and part-based format. We show that visual and haptic exploration of objects leads to similar patterns of neural activity in human LOC and that the shared variance between visually and haptically induced patterns of BOLD contrast in LOC reflects the part structure of the objects. We also show that linear classifiers trained on neural data from LOC on a subset of the objects successfully predict a novel object based on its component part structure. These data demonstrate a multisensory code for object representations in LOC that specifies the part structure of objects.
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Lóbulo Occipital/fisiología , Percepción del Tacto/fisiología , Percepción Visual/fisiología , Mapeo Encefálico/métodos , Circulación Cerebrovascular/fisiología , Femenino , Humanos , Modelos Lineales , Imagen por Resonancia Magnética/métodos , Masculino , Pruebas Neuropsicológicas , Lóbulo Occipital/diagnóstico por imagen , Oxígeno/sangre , Estimulación Física , Adulto JovenRESUMEN
Sensory cortices of individuals who are congenitally deprived of a sense can exhibit considerable plasticity and be recruited to process information from the senses that remain intact. Here, we explored whether the auditory cortex of congenitally deaf individuals represents visual field location of a stimulus-a dimension that is represented in early visual areas. We used functional MRI to measure neural activity in auditory and visual cortices of congenitally deaf and hearing humans while they observed stimuli typically used for mapping visual field preferences in visual cortex. We found that the location of a visual stimulus can be successfully decoded from the patterns of neural activity in auditory cortex of congenitally deaf but not hearing individuals. This is particularly true for locations within the horizontal plane and within peripheral vision. These data show that the representations stored within neuroplastically changed auditory cortex can align with dimensions that are typically represented in visual cortex.
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Corteza Auditiva/patología , Sordera/fisiopatología , Plasticidad Neuronal , Corteza Visual/patología , Campos Visuales , Adolescente , Adulto , Mapeo Encefálico , Femenino , Humanos , Imagen por Resonancia Magnética , Masculino , Análisis Multivariante , Adulto JovenRESUMEN
In human lateral temporal cortex, some regions show specific sensitivity to human motion. Here we examine whether such effects reflect a general biological-nonbiological organizational principle or a process specific to human-agent processing by comparing processing of human, animal, and tool motion in a functional magnetic resonance imaging (fMRI) experiment with healthy participants and a voxel-based lesion-symptom mapping (VLSM) study of patients with brain damage (77 stroke patients). The fMRI experiment revealed that in the lateral temporal cortex, the posterior superior temporal sulcus shows a preference for human and animal motion, whereas the middle part of the right superior temporal sulcus/gyrus (mSTS/STG) shows a preference for human and functional tool motion. VLSM analyses also revealed that damage to this right mSTS/STG region led to more severe impairment in the recognition of human and functional tool motion relative to animal motion, indicating the causal role of this brain area in human-agent motion processing. The findings for the right mSTS/STG cannot be reduced to a preference for articulated motion or processing of social variables since neither factor is involved in functional tool motion recognition. We conclude that a unidimensional biological-nonbiological distinction cannot fully explain the visual motion effects in lateral temporal cortex. Instead, the results suggest the existence of distinct components in right posterior temporal cortex and mSTS/STG that are associated, respectively, with biological motion and human-agent motion processing.
Asunto(s)
Mapeo Encefálico , Corteza Cerebral/fisiología , Percepción de Movimiento , Lóbulo Temporal/fisiología , Adolescente , Adulto , Anciano , Estudios de Casos y Controles , Corteza Cerebral/fisiopatología , Femenino , Humanos , Masculino , Persona de Mediana Edad , Accidente Cerebrovascular/fisiopatología , Lóbulo Temporal/fisiopatologíaRESUMEN
The recent development of 1D nanomaterials of controllable size, composition, and structure has opened up enormous possibilities for engineering catalysts with enhanced activity and selectivity. Herein, we report a one-step strategy for the fabrication of versatile silver nanomaterials. Tailored structures, such as nanobelts, nanowires, and nanocables, were conveniently synthesized by adjusting the reaction conditions. The novelty of this synthesis is in a one-pot procedure that combines the sequential formation of precursor nucleation, in situ polymerization, and crystal shaping under mild conditions. The as-synthesized cables consisted of a metallic core (Ag) and an organic outer shell (poly(o-anisidine), POA). Control experiments demonstrated that the introduced organic monomer (OA) not only acted as the nanoreactor and capping agent, but also a modest reducer for controlled crystal growth at the hydrophilic interface. Electrocatalytic tests showed enhanced stability and activity towards the reduction of oxygen, which was believed to be closely associated with the core-shell structural characteristics of the nanomaterials. Their electrocatalytic performance and tunable structure makes such silver nanobelts promising candidates for applications in catalysis and as sensors in nanoelectrochemical devices.
Asunto(s)
Nanoestructuras/química , Oxígeno/química , Polímeros/química , Plata/química , Compuestos de Anilina/química , Catálisis , Nanocables/química , Oxidación-ReducciónRESUMEN
Purpose: The goal of this study was to assess the clinical efficacy and safety of the arsenic trioxide (ATO)/lipiodol emulsion in the transcatheter arterial chemoembolization (TACE) combined with apatinib in the treatment of advanced hepatocellular carcinoma (HCC). Methods: From December 2015 to February 2017, a total of 87 patients were consecutively enrolled and underwent ATO-TACE (aTACE) combined with apatinib in the treatment of advanced HCC. The treatment response and adverse events were assessed at the first month and third month after aTACE therapy. Progression-free survival (PFS), overall survival (OS), and treatment-related adverse events were also analyzed. Results: 87 patients (57 men; 30 women) were enrolled in the present study. Compared to that at the pre-aTACE examination, the levels of AST and ALT were elevated at the first week after procedure (65.84 U/L ± 22.93 U/L vs. 54.15 U/L ± 19.60 U/L, p=0.032; 63.44 U/L ± 22.50 U/L vs. 51.60 U/L ± 13.89 U/L, p=0.027, respectively). Most of the adverse events were grade 1 or 2 according to National Cancer Institute Common Terminology Criteria for Adverse Event (CTCAE). Of the exception, 4 persons (2%) did have grade 3 hand-foot skin reactions, 1 (1%) had grade 3 diarrhea, 1 (1%) had grade 3 hypertension, and 3 (3%) had grade 3 proteinuria and forced to reduce the dose of apatinib by half. The survival analysis of the combination with aTACE and apatinib therapy found that the median PFS was 10.2 months (95% CI: 8.543-11.857), and the median OS was 23.300 months (95% CI: 20.833-25.767). Additionally, both univariate and multivariate Cox regression revealed that the tumor burden (≤50%) and the patients without portal vein tumor thrombus (PVTT) significantly impacted the patient's PFS and OS and were related to better survival. Conclusion: aTACE combined with apatinib is a safe and promising treatment approach for patients with advanced HCC. Additionally, tumor burden (≤50%) and the patients without PVTT are associated with better PFS and OS.
Asunto(s)
Carcinoma Hepatocelular , Quimioembolización Terapéutica , Neoplasias Hepáticas , Trióxido de Arsénico , Carcinoma Hepatocelular/tratamiento farmacológico , Quimioembolización Terapéutica/efectos adversos , Emulsiones , Aceite Etiodizado , Femenino , Humanos , Neoplasias Hepáticas/tratamiento farmacológico , Masculino , Piridinas , Resultado del TratamientoRESUMEN
The relationship between Alzheimer's disease (AD) pathology and cognitive decline is an important topic in the aging research field. Recent studies suggest that memory deficits are more susceptible to phosphorylated tau (Ptau) than amyloid-beta. However, little is known regarding the neurocognitive mechanisms linking Ptau and memory-related decline. Here, we extracted data from Alzheimer's Disease Neuroimaging Initiative (ADNI) participants with cerebrospinal fluid (CSF) Ptau collected at baseline, diffusion tensor imaging measure twice, 2 year apart, and longitudinal memory data over 5 years. We defined three age- and education-matched groups: Ptau negative cognitively unimpaired, Ptau positive cognitively unimpaired, and Ptau positive individuals with mild cognitive impairment. We found the presence of CSF Ptau at baseline was related to a loss of structural stability in medial temporal lobe connectivity in a way that matched proposed disease progression, and this loss of stability in connections known to be important for memory moderated the relationship between Ptau accumulation and memory decline.
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Enfermedad de Alzheimer/líquido cefalorraquídeo , Enfermedad de Alzheimer/patología , Trastornos de la Memoria , Vías Nerviosas/patología , Lóbulo Temporal/patología , Proteínas tau/líquido cefalorraquídeo , Anciano , Anciano de 80 o más Años , Progresión de la Enfermedad , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
Making reasonable decisions related to financial and health scenarios is a crucial capacity that can be difficult for older adults to maintain as they age, yet few studies examine neurocognitive factors that are generalizable to different types of everyday decision-making capacity. Here we propose an innovative approach, based on individual risk-taking preference, to identify neural profiles that may help predict older adults' everyday decision-making capacity. Using performance and cognitive arousal information from two gambling tasks, we identified three decision-making preference groups: ambiguity problem-solvers (A), risk-seekers (R), and a control group without strong risk-taking preferences (C). Comparisons of the number of connections within white matter tracts between A vs. C and R vs. C groups resulted in features consistent with the theory of dual neural functional systems involved in decision-making. Unique tracts from the A vs. C contrast were primarily centered in dorsal frontal regions/reflective system; unique tracts from the R vs. C contrast were centered in the ventral frontal regions/impulsive system; and shared tracts from both contrasts were centered in the basal ganglia, coordinating the switch between the two types of decision-making preference. Number of connections from the tracts differentiating A vs. C significantly predicted financial and health/safety decision-making capacity, and the association remained significant after controlling for multiple socioeconomic and cognitive factors. The connectome identified may provide insight into a generic white matter mechanism related to everyday decision-making capacity in older age.
Asunto(s)
Encéfalo/anatomía & histología , Conectoma , Toma de Decisiones/fisiología , Asunción de Riesgos , Sustancia Blanca/anatomía & histología , Anciano , Estudios Transversales , Imagen de Difusión Tensora , Femenino , Juegos Experimentales , Humanos , Masculino , Vías Nerviosas/anatomía & histología , Pruebas NeuropsicológicasRESUMEN
Studying older adults with excellent cognitive capacities (Supernormals) provides a unique opportunity for identifying factors related to cognitive success - a critical topic across lifespan. There is a limited understanding of Supernormals' neural substrates, especially whether any of them attends shaping and supporting superior cognitive function or confer resistance to age-related neurodegeneration such as Alzheimer's disease (AD). Here, applying a state-of-the-art diffusion imaging processing pipeline and finite mixture modelling, we longitudinally examine the structural connectome of Supernormals. We find a unique structural connectome, containing the connections between frontal, cingulate, parietal, temporal, and subcortical regions in the same hemisphere that remains stable over time in Supernormals, relatively to typical agers. The connectome significantly classifies positive vs. negative AD pathology at 72% accuracy in a new sample mixing Supernormals, typical agers, and AD risk [amnestic mild cognitive impairment (aMCI)] subjects. Among this connectome, the mean diffusivity of the connection between right isthmus cingulate cortex and right precuneus most robustly contributes to predicting AD pathology across samples. The mean diffusivity of this connection links negatively to global cognition in those Supernormals with positive AD pathology. But this relationship does not exist in typical agers or aMCI. Our data suggest the presence of a structural connectome supporting cognitive success. Cingulate to precuneus white matter integrity may be useful as a structural marker for monitoring neurodegeneration and may provide critical information for understanding how some older adults maintain or excel cognitively in light of significant AD pathology.
Asunto(s)
Enfermedad de Alzheimer , Disfunción Cognitiva , Conectoma , Anciano , Enfermedad de Alzheimer/diagnóstico por imagen , Encéfalo/diagnóstico por imagen , Cognición , Disfunción Cognitiva/diagnóstico por imagen , Giro del Cíngulo , HumanosRESUMEN
In this paper, ultrathin (about 2.5 nm) manganite (MnOOH) nanowires were synthesized by a simple wet chemical method at ambient temperature. Temperature-dependent phase transition patterns of the prepared nanowires under different atmospheres were systematically studied with thermogravimetric and differential thermal analysis (TG/DTA). Based on the critical temperatures demonstrated by the phase transition pattern, manganese oxides, such as Mn2O3 and Mn3O4, have been obtained conveniently through calcination. Scanning electron microscope (SEM), transmission electron microscope (TEM) and x-ray diffraction results confirm that the annealed nanowires can both retain their original 1D morphology and show good crystallinity. The electrocatalytic performance of the as-prepared manganese oxides was also explored, which showed good response to the reduction of H2O2 in alkaline media. Among the three manganese oxides, the MnOOH nanowires exhibited the most prominent electrocatalytic efficiency and stability, which provides a good candidate for modern industrial catalysis applications.
RESUMEN
Multivoxel pattern analysis (MVPA) over functional MRI data can distinguish neural representational states that do not differ in their overall amplitude of BOLD contrast. Here we used MVPA to test whether simple intransitive actions can be distinguished in primary motor cortex. Participants rotated and flexed each of their extremities (hands and feet) during fMRI scanning. The primary motor cortex for the hand/wrist was functionally defined in each hemisphere in each subject. Within those subject-specific ROIs, we found that the average amplitude of BOLD contrast for two different movements of the contralateral hand (rotation, flexion) were higher than for the ipsilateral hand, as well as movements by both feet; however, there was no difference in amplitude between the two different types of movements for the contralateral hand. Using multivoxel pattern analysis (linear correlation), we were able to distinguish the two movements for the contralateral hand. These findings demonstrate that simple intransitive actions can be distinguished in primary motor areas using multivoxel pattern analysis.
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Corteza Motora/diagnóstico por imagen , Movimiento/fisiología , Desempeño Psicomotor/fisiología , Mapeo Encefálico , Femenino , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Adulto JovenRESUMEN
A whole-brain network of regions collectively supports the ability to recognize and use objects-the Tool Processing Network. Little is known about how functional interactions within the Tool Processing Network are modulated in a task-dependent manner. We designed an fMRI experiment in which participants were required to either generate object pantomimes or to carry out a picture matching task over the same images of tools, while holding all aspects of stimulus presentation constant across the tasks. The Tool Processing Network was defined with an independent functional localizer, and functional connectivity within the network was measured during the pantomime and picture matching tasks. Relative to tool picture matching, tool pantomiming led to an increase in functional connectivity between ventral stream regions and left parietal and frontal-motor areas; in contrast, the matching task was associated with an increase in functional connectivity among regions in ventral temporo-occipital cortex, and between ventral temporal regions and the left inferior parietal lobule. Graph-theory analyses over the functional connectivity data indicated that the left premotor cortex and left lateral occipital complex were hub-like (exhibited high betweenness centrality) during tool pantomiming, while ventral stream regions (left medial fusiform gyrus and left posterior middle temporal gyrus) were hub-like during the picture matching task. These results demonstrate task-specific modulation of functional interactions among a common set of regions, and indicate dynamic coupling of anatomically remote regions in task-dependent manner.
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Mapeo Encefálico , Encéfalo/fisiología , Fuerza de la Mano/fisiología , Vías Nerviosas/fisiología , Desempeño Psicomotor/fisiología , Adolescente , Encéfalo/diagnóstico por imagen , Femenino , Lateralidad Funcional , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Vías Nerviosas/diagnóstico por imagen , Oxígeno , Muñeca/inervación , Adulto JovenRESUMEN
Recent efforts to characterize visual object representations in the ventral object processing pathway in the human brain have led to contrasting proposals about the causes of neural specificity for different categories. Here we use multivariate techniques in a novel way to relate patterns of functional connectivity to patterns of stimulus preferences. Stimulus preferences were measured throughout the ventral stream to tools, animals, faces and places; separately, we measured the strength of functional connectivity of each voxel in the ventral stream to category-preferring regions outside the ventral stream. Multivariate analyses were then performed over ventral stream voxels, relating 'category-preferences' to 'functional connectivity preferences'. We show that the relation of those two measures doubly dissociates 'tools' and 'places', within what is ostensibly 'place' selective cortex (parahippocampal gyrus). Specifically, in the parahippocampal gyrus, functional connectivity to the left inferior parietal lobule is selectively related to stimulus preferences for tools (and not places), while functional connectivity to retrosplenial cortex is selectively related to place preferences (and not tools preferences). These findings indicate that functional connectivity can be used to index representational content rather than just provide an understanding of 'which regions are talking to which regions'. We suggest that the connectivity of the brain is what drives category-specificity in the ventral stream, and that if this is correct, then understanding the connectivity of the ventral stream will be key to understanding the causes and function of category-specific neural organization.
Asunto(s)
Mapeo Encefálico , Formación de Concepto/fisiología , Lóbulo Parietal/fisiología , Reconocimiento Visual de Modelos/fisiología , Vías Visuales/fisiología , Femenino , Lateralidad Funcional , Humanos , Procesamiento de Imagen Asistido por Computador , Imagen por Resonancia Magnética , Masculino , Oxígeno/sangre , Lóbulo Parietal/diagnóstico por imagen , Vías Visuales/diagnóstico por imagen , Adulto JovenRESUMEN
The observation of other people's actions recruits a network of areas including the inferior frontal gyrus (IFG), the inferior parietal lobule (IPL), and posterior middle temporal gyrus (pMTG). These regions have been shown to be activated through both visual and auditory inputs. Intriguingly, previous studies found no engagement of IFG and IPL for deaf participants during non-linguistic action observation, leading to the proposal that auditory experience or sign language usage might shape the functionality of these areas. To understand which variables induce plastic changes in areas recruited during the processing of other people's actions, we examined the effects of tasks (action understanding and passive viewing) and effectors (arm actions vs. leg actions), as well as sign language experience in a group of 12 congenitally deaf signers and 13 hearing participants. In Experiment 1, we found a stronger activation during an action recognition task in comparison to a low-level visual control task in IFG, IPL and pMTG in both deaf signers and hearing individuals, but no effect of auditory or sign language experience. In Experiment 2, we replicated the results of the first experiment using a passive viewing task. Together, our results provide robust evidence demonstrating that the response obtained in IFG, IPL, and pMTG during action recognition and passive viewing is not affected by auditory or sign language experience, adding further support for the supra-modal nature of these regions.