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1.
Nat Commun ; 14(1): 4371, 2023 08 08.
Artigo em Inglês | MEDLINE | ID: mdl-37553346

RESUMO

The recent emergence of a causal link between Epstein-Barr virus (EBV) and multiple sclerosis has generated considerable interest in the development of an effective vaccine against EBV. Here we describe a vaccine formulation based on a lymph node targeting Amphiphile vaccine adjuvant, Amphiphile-CpG, admixed with EBV gp350 glycoprotein and an engineered EBV polyepitope protein that includes 20 CD8+ T cell epitopes from EBV latent and lytic antigens. Potent gp350-specific IgG responses are induced in mice with titers >100,000 in Amphiphile-CpG vaccinated mice. Immunization including Amphiphile-CpG also induces high frequencies of polyfunctional gp350-specific CD4+ T cells and EBV-specific CD8+ T cells that are 2-fold greater than soluble CpG and are maintained for >7 months post immunization. This combination of broad humoral and cellular immunity against multiple viral determinants is likely to provide better protection against primary infection and control of latently infected B cells leading to protection against the development of EBV-associated diseases.


Assuntos
Infecções por Vírus Epstein-Barr , Herpesvirus Humano 4 , Camundongos , Animais , Infecções por Vírus Epstein-Barr/prevenção & controle , Linfócitos T CD8-Positivos , Epitopos de Linfócito T , Linfonodos , Vacinas de Subunidades Antigênicas
2.
Sci Adv ; 9(22): eadg6802, 2023 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-37267368

RESUMO

While freshwater and anadromous fish have been critical economic resources for late prehistoric and modern Native Americans, the origin and development of fishing is not well understood. We document the earliest known human use of freshwater and anadromous fish in North America by 13,000 and 11,800 years ago, respectively, from primary anthropogenic contexts in central Alaska (eastern Beringia). Fish use appears conditioned by broad climatic factors, as all occurrences but one are within the Younger Dryas chronozone. Earlier Bølling-Allerød and later early Holocene components, while exhibiting similar organic preservation, did not yield evidence of fishing, suggesting that this was a response to changing environmental factors, perhaps reductions in higher ranked resources such as large terrestrial mammals. Late Pleistocene and recent Indigenous peoples harvested similar fish taxa in the region (salmon, burbot, whitefish, and pike). We characterize late Pleistocene fishing in interior Beringia as an important element of broad-spectrum foraging rather than the intensive communal fishing and storage common among recent peoples.


Assuntos
Água Doce , Caça , Animais , Humanos , Alaska , América do Norte , Salmão , Mamíferos
3.
J Immunother Cancer ; 10(11)2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-36343976

RESUMO

BACKGROUND: Novel therapies are urgently needed for ovarian cancer (OC), the fifth deadliest cancer in women. Preclinical work has shown that DNA methyltransferase inhibitors (DNMTis) can reverse the immunosuppressive tumor microenvironment in OC. Inhibiting DNA methyltransferases activate transcription of double-stranded (ds)RNA, including transposable elements. These dsRNAs activate sensors in the cytoplasm and trigger type I interferon (IFN) signaling, recruiting host immune cells to kill the tumor cells. Adenosine deaminase 1 (ADAR1) is induced by IFN signaling and edits mammalian dsRNA with an A-to-I nucleotide change, which is read as an A-to-G change in sequencing data. These edited dsRNAs cannot be sensed by dsRNA sensors, and thus ADAR1 inhibits the type I IFN response in a negative feedback loop. We hypothesized that decreasing ADAR1 editing would enhance the DNMTi-induced immune response. METHODS: Human OC cell lines were treated in vitro with DNMTi and then RNA-sequenced to measure RNA editing. Adar1 was stably knocked down in ID8 Trp53-/- mouse OC cells. Control cells (shGFP) or shAdar1 cells were tested with mock or DNMTi treatment. Tumor-infiltrating immune cells were immunophenotyped using flow cytometry and cell culture supernatants were analyzed for secreted chemokines/cytokines. Mice were injected with syngeneic shAdar1 ID8 Trp53-/- cells and treated with tetrahydrouridine/DNMTi while given anti-interferon alpha and beta receptor 1, anti-CD8, or anti-NK1.1 antibodies every 3 days. RESULTS: We show that ADAR1 edits transposable elements in human OC cell lines after DNMTi treatment in vitro. Combining ADAR1 knockdown with DNMTi significantly increases pro-inflammatory cytokine/chemokine production and sensitivity to IFN-ß compared with either perturbation alone. Furthermore, DNMTi treatment and Adar1 loss reduces tumor burden and prolongs survival in an immunocompetent mouse model of OC. Combining Adar1 loss and DNMTi elicited the most robust antitumor response and transformed the immune microenvironment with increased recruitment and activation of CD8+ T cells. CONCLUSION: In summary, we showed that the survival benefit from DNMTi plus ADAR1 inhibition is dependent on type I IFN signaling. Thus, epigenetically inducing transposable element transcription combined with inhibition of RNA editing is a novel therapeutic strategy to reverse immune evasion in OC, a disease that does not respond to current immunotherapies.


Assuntos
Neoplasias Ovarianas , Edição de RNA , Feminino , Humanos , Animais , Camundongos , Microambiente Tumoral , Metilação de DNA , Elementos de DNA Transponíveis , Proteínas de Ligação a RNA/genética , Proteínas de Ligação a RNA/metabolismo , RNA de Cadeia Dupla/uso terapêutico , Carcinoma Epitelial do Ovário/genética , Neoplasias Ovarianas/terapia , Neoplasias Ovarianas/tratamento farmacológico , Citocinas/metabolismo , Mamíferos/genética , Mamíferos/metabolismo
4.
NPJ Vaccines ; 7(1): 128, 2022 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-36307453

RESUMO

Despite the success of currently authorized vaccines for the reduction of severe COVID-19 disease risk, rapidly emerging viral variants continue to drive pandemic waves of infection, resulting in numerous global public health challenges. Progress will depend on future advances in prophylactic vaccine activity, including advancement of candidates capable of generating more potent induction of cross-reactive T cells and durable cross-reactive antibody responses. Here we evaluated an Amphiphile (AMP) adjuvant, AMP-CpG, admixed with SARS-CoV-2 Spike receptor binding domain (RBD) immunogen, as a lymph node-targeted protein subunit vaccine (ELI-005) in mice and non-human primates (NHPs). AMP-mediated targeting of CpG DNA to draining lymph nodes resulted in comprehensive local immune activation characterized by extensive transcriptional reprogramming, inflammatory proteomic milieu, and activation of innate immune cells as key orchestrators of antigen-directed adaptive immunity. Prime-boost immunization with AMP-CpG in mice induced potent and durable T cell responses in multiple anatomical sites critical for prophylactic efficacy and prevention of severe disease. Long-lived memory responses were rapidly expanded upon re-exposure to antigen. In parallel, RBD-specific antibodies were long-lived, and exhibited cross-reactive recognition of variant RBD. AMP-CpG-adjuvanted prime-boost immunization in NHPs was safe and well tolerated, while promoting multi-cytokine-producing circulating T cell responses cross-reactive across variants of concern (VOC). Expansion of RBD-specific germinal center (GC) B cells in lymph nodes correlated to rapid seroconversion with variant-specific neutralizing antibody responses exceeding those measured in convalescent human plasma. These results demonstrate the promise of lymph-node adjuvant-targeting to coordinate innate immunity and generate robust adaptive responses critical for vaccine efficacy.

5.
Nano Res ; 15(3): 2300-2314, 2022 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36089987

RESUMO

Despite the promise of immunotherapy such as the immune checkpoint inhibitors (ICIs) anti-PD-1 and anti-CTLA-4 for advanced melanoma, only 26%-52% of patients respond, and many experience grade III/IV immune-related adverse events. Motivated by the need for an effective therapy for patients non-responsive to clinically approved ICIs, we have developed a novel nanoimmunotherapy that combines locally administered Prussian blue nanoparticle-based photothermal therapy (PBNP-PTT) with systemically administered agonistic anti-CD137 monoclonal antibody therapy (aCD137). PBNP-PTT was administered at various thermal doses to melanoma cells in vitro, and was combined with aCD137 in vivo to test treatment effects on melanoma tumor progression, animal survival, immunological protection against tumor rechallenge, and hepatotoxicity. When administered at a melanoma-specific thermal dose, PBNP-PTT elicits immunogenic cell death (ICD) in melanoma cells and upregulates markers associated with antigen presentation and immune cell co-stimulation in vitro. Consequently, PBNP-PTT eliminates primary melanoma tumors in vivo, yielding long-term tumor-free survival. However, the antitumor immune effects generated by PBNP-PTT cannot eliminate secondary tumors, despite significantly slowing their growth. The addition of aCD137 enables significant abscopal efficacy and improvement of survival, functioning through activated dendritic cells and tumor-infiltrating CD8+ T cells, and generates CD4+ and CD8+ T cell memory that manifests in the rejection of tumor rechallenge, with no long-term hepatotoxicity. This study describes for the first time a novel and effective nanoimmunotherapy combination of PBNP-PTT with aCD137 mAb therapy for melanoma.

7.
Oncologist ; 26(12): e2136-e2142, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34427023

RESUMO

LESSONS LEARNED: Entinostat at the selected dose levels in combination with a standard dose of enzalutamide showed a promising safety profile in this small phase I study BACKGROUND: Entinostat inhibits prostate cancer (PCa) growth and suppresses Treg cell function in vitro and in vivo. METHODS: This was a phase I study to explore the safety and preliminary efficacy of entinostat (3 and 5 mg orally per week) in combination with enzalutamide in castration resistant PCa (CRPC). The study was carried out in an open-label two-cohort design. Patients who had developed disease progression on or were eligible for enzalutamide were enrolled in the study. The safety profile of the combination therapy, Prostate specific antigen (PSA) levels, the pharmacokinetics of enzalutamide after entinostat administration, peripheral T-cell subtype (including Treg quantitation), and mononuclear cell (PBMC) histone H3 acetylation were analyzed. RESULTS: Six patients with metastatic CRPC were enrolled. There was no noticeable increment of fatigue related to entinostat. Toxicities possibly or probably related to entinostat or the combination therapy included grade 3 anemia 1/6 (17%), grade 2 white blood cell (WBC) decrease 1/6 (17%), and other self-limiting grade 1 adverse events (AEs). Median duration of treatment with entinostat was 18 weeks. Entinostat did not affect the steady plasma concentration of enzalutamide. Increased PBMC histone H3 acetylation was observed in blood samples. No evident T-cell subtype changes were detected, including in Treg quantitation. CONCLUSION: Entinostat 5 mg weekly in combination with enzalutamide showed an acceptable safety profile in this small phase I study. A planned phase II part of the trial was terminated because of sponsor withdrawal.


Assuntos
Neoplasias de Próstata Resistentes à Castração , Benzamidas , Humanos , Leucócitos Mononucleares , Masculino , Nitrilas , Feniltioidantoína , Neoplasias de Próstata Resistentes à Castração/tratamento farmacológico , Piridinas
8.
Cancer Res ; 80(17): 3649-3662, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32605998

RESUMO

Despite the outstanding clinical results of immune checkpoint blockade (ICB) in melanoma and other cancers, clinical trials in breast cancer have reported low responses to these therapies. Current efforts are now focused on improving the treatment efficacy of ICB in breast cancer using new combination designs such as molecularly targeted agents, including histone deacetylase inhibitors (HDACi). These epigenetic drugs have been widely described as potent cytotoxic agents for cancer cells. In this work, we report new noncanonical regulatory properties of ultra-selective HDAC6i over the expression and function of epithelial-mesenchymal transition pathways and the invasiveness potential of breast cancer. These unexplored roles position HDAC6i as attractive options to potentiate ongoing immunotherapeutic approaches. These new functional activities of HDAC6i involved regulation of the E-cadherin/STAT3 axis. Pretreatment of tumors with HDAC6i induced critical changes in the tumor microenvironment, resulting in improved effectiveness of ICB and preventing dissemination of cancer cells to secondary niches. Our results demonstrate for the first time that HDAC6i can both improve ICB antitumor immune responses and diminish the invasiveness of breast cancer with minimal cytotoxic effects, thus departing from the cytotoxicity-centric paradigm previously assigned to HDACi. SIGNIFICANCE: Ultraselective HDAC6 inhibitors can reduce tumor growth and invasiveness of breast cancer by noncanonical mechanisms unrelated to the previously cytotoxic properties attributed to HDAC inhibitors.


Assuntos
Regulação Neoplásica da Expressão Gênica/fisiologia , Desacetilase 6 de Histona/metabolismo , Inibidores de Checkpoint Imunológico/farmacologia , Neoplasias Mamárias Experimentais/patologia , Neoplasias de Mama Triplo Negativas/patologia , Animais , Proliferação de Células/efeitos dos fármacos , Proliferação de Células/fisiologia , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Transição Epitelial-Mesenquimal/fisiologia , Feminino , Neoplasias Mamárias Experimentais/imunologia , Neoplasias Mamárias Experimentais/metabolismo , Camundongos , Invasividade Neoplásica/patologia , Neoplasias de Mama Triplo Negativas/imunologia , Neoplasias de Mama Triplo Negativas/metabolismo
9.
Transl Oncol ; 13(10): 100823, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32652470

RESUMO

High-risk neuroblastoma, which is associated with regional and systemic metastasis, is a leading cause of cancer-related mortality in children. Responding to this need for novel therapies for high-risk patients, we have developed a "nanoimmunotherapy," which combines photothermal therapy (PTT) using CpG oligodeoxynucleotide-coated Prussian blue nanoparticles (CpG-PBNPs) combined with anti-CTLA-4 (aCTLA-4) immunotherapy. Our in vitro studies demonstrate that in addition to causing ablative tumor cell death, our nanoimmunotherapy alters the surface levels of co-stimulatory, antigen-presenting, and co-inhibitory molecules on neuroblastoma tumor cells. When administered in a syngeneic, murine model of neuroblastoma bearing synchronous Neuro2a tumors, the CpG-PBNP-PTT plus aCTLA-4 nanoimmunotherapy elicits complete tumor regression in both primary (CpG-PBNP-PTT-treated) and secondary tumors, and long-term survival in a significantly higher proportion (55.5%) of treated-mice compared with the controls. Furthermore, the surviving, nanoimmunotherapy-treated animals reject Neuro2a rechallenge, suggesting that the therapy generates immunological memory. Additionally, the depletion of CD4+, CD8+, and NK+ populations abrogate the observed therapeutic responses of the nanoimmunotherapy. These findings demonstrate the importance of concurrent PTT-based cytotoxicity and the antitumor immune effects of PTT, CpG, and aCTLA-4 in generating a robust abscopal effect against neuroblastoma.

10.
PLoS One ; 15(6): e0234745, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32544213

RESUMO

PCR inhibitors are a formidable problem to the study of aged, degraded, and/or low copy number DNA. As a result, there is a need to find alternate methods that ameliorate the efficacy of PCR. In this study, we attempted to use genetic methods to identify the species of salmonid (Oncorhynchus spp.) remains recovered from archaeological sites along the Feather River located in northern California, United States. In the process of doing so, we compared the efficacy of a PCR enhancer cocktail called "PEC-P" and a reagent rich PCR recipe called "rescue PCR" over standard PCR. Across all treatments (full concentration and 1:10 dilute eluates subjected to standard PCR, PEC-P, and rescue PCR) species identification was possible for 74 of 93 archaeological fish specimens (79.6%). Overall, six of the 93 samples (6.5%) consistently yielded species identification across all treatments. The species of ten specimens (10.8%) were uniquely identified from amplicons produced with either PEC-P or rescue PCR or both. Notably, the species of seven samples (7.5%) were uniquely identified with standard PCR over the alternative treatments. Considering both full concentration and 1:10 dilute eluates (N = 186), standard PCR performed as well as PEC-P (p = 0.1451) and rescue (p = 0.6753). Yet, considering results from full concentration eluates alone (N = 93), PEC-P (60.2%) outperformed both standard PCR (44.1%; p = 0.0277) and rescue PCR (40.9%; p = 0.0046). Stochasticity observed in our study cautions us against choosing a "best" performing method of those explored here and suggests their respective potentials to improve success may be sample dependent. When working with samples compromised by PCR inhibitors, it is useful to have alternative methodologies for subduing the problem. Both PEC-P and rescue PCR represent useful alternative methods for the study of aged, degraded, and/or low copy number DNA samples compromised by PCR inhibitors.


Assuntos
DNA/análise , Oncorhynchus/genética , Reação em Cadeia da Polimerase/métodos , Animais , Arqueologia , Osso e Ossos/metabolismo , DNA/metabolismo , DNA Mitocondrial/análise , DNA Mitocondrial/metabolismo , Fatores de Tempo
11.
Sci Rep ; 10(1): 3470, 2020 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-32103105

RESUMO

Novel therapies are urgently needed for ovarian cancer, the deadliest gynecologic malignancy. Ovarian cancer has thus far been refractory to immunotherapies that stimulate the host immune system to recognize and kill cancer cells. This may be because of a suppressive tumor immune microenvironment and lack of recruitment and activation of immune cells that kill cancer cells. Our previous work showed that epigenetic drugs including DNA methyltransferase inhibitors and histone deacetylase 6 inhibitors (DNMTis and HDAC6is) individually increase immune signaling in cancer cells. We find that combining DNMTi and HDAC6i results in an amplified type I interferon response, leading to increased cytokine and chemokine expression and higher expression of the MHC I antigen presentation complex in human and mouse ovarian cancer cell lines. Treating mice bearing ID8 Trp53-/- ovarian cancer with HDAC6i/DNMTi led to an increase in tumor-killing cells such as IFNg+ CD8, NK, and NKT cells and a reversal of the immunosuppressive tumor microenvironment with a decrease in MDSCs and PD-1hi CD4 T cells, corresponding with an increase in survival. Thus combining the epigenetic modulators DNMTi and HDAC6i increases anti-tumor immune signaling from cancer cells and has beneficial effects on the ovarian tumor immune microenvironment.


Assuntos
DNA (Citosina-5-)-Metiltransferases/antagonistas & inibidores , Inibidores Enzimáticos/farmacologia , Desacetilase 6 de Histona/antagonistas & inibidores , Transdução de Sinais/efeitos dos fármacos , Microambiente Tumoral/efeitos dos fármacos , Animais , Antígeno B7-H1/genética , Antígeno B7-H1/metabolismo , Linfócitos T CD4-Positivos/citologia , Linfócitos T CD4-Positivos/imunologia , Linfócitos T CD4-Positivos/metabolismo , Linfócitos T CD8-Positivos/citologia , Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , DNA (Citosina-5-)-Metiltransferases/metabolismo , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Inibidores Enzimáticos/uso terapêutico , Feminino , Desacetilase 6 de Histona/metabolismo , Inibidores de Histona Desacetilases/farmacologia , Inibidores de Histona Desacetilases/uso terapêutico , Humanos , Interferon gama/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Células T Matadoras Naturais/citologia , Células T Matadoras Naturais/imunologia , Células T Matadoras Naturais/metabolismo , Neoplasias Ovarianas/tratamento farmacológico , Neoplasias Ovarianas/imunologia , Neoplasias Ovarianas/mortalidade , Neoplasias Ovarianas/patologia , Taxa de Sobrevida
13.
Sci Rep ; 9(1): 6136, 2019 04 16.
Artigo em Inglês | MEDLINE | ID: mdl-30992475

RESUMO

Histone deacetylases (HDACs) are involved in diverse cellular regulatory mechanisms including non-canonical functions outside the chromatin environment. Several publications have demonstrated that selective HDAC inhibitors (HDACi) can influence tumor immunogenicity and the functional activity of specific immune cells. In particular, the selective inhibition of HDAC6 has been reported to decrease tumor growth in several malignancies. However, there is still no clarity about the cellular components mediating this effect. In this study, we evaluated the HDAC6i Nexturastat A as a priming agent to facilitate the transition of the tumor microenvironment from "cold" to "hot", and potentially augment immune check-point blockade therapies. This combination modality demonstrated to significantly reduce tumor growth in syngeneic melanoma tumor models. Additionally, we observed a complete neutralization of the up-regulation of PD-L1 and other immunosuppressive pathways induced by the treatment with anti-PD-1 blockade. This combination also showed profound changes in the tumor microenvironment such as enhanced infiltration of immune cells, increased central and effector T cell memory, and a significant reduction of pro-tumorigenic M2 macrophages. The evaluation of individual components of the tumor microenvironment suggested that the in vivo anti-tumor activity of HDAC6i is mediated by its effect on tumor cells and tumor-associated macrophages, and not directly over T cells. Overall, our results indicate that selective HDAC6i could be used as immunological priming agents to sensitize immunologically "cold" tumors and subsequently improve ongoing immune check-point blockade therapies.


Assuntos
Antineoplásicos Imunológicos/uso terapêutico , Desacetilase 6 de Histona/antagonistas & inibidores , Inibidores de Histona Desacetilases/uso terapêutico , Macrófagos/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Animais , Anti-Inflamatórios/uso terapêutico , Antígeno B7-H1/imunologia , Desacetilase 6 de Histona/imunologia , Tolerância Imunológica/efeitos dos fármacos , Macrófagos/imunologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Neoplasias/imunologia , Receptor de Morte Celular Programada 1/imunologia , Microambiente Tumoral/efeitos dos fármacos
14.
J Cancer Surviv ; 11(2): 246-255, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-27873046

RESUMO

PURPOSE: The goal of this RCT was to examine the efficacy and safety of a web-based program to improve cardiovascular and bone health outcomes, among 35 BRCA1/2+ breast cancer survivors who underwent prophylactic oophorectomy and thus experienced premature surgical menopause. METHODS: A 12-month commercially available web-based lifestyle modification program (Precision Nutrition Coaching) was utilized. Cardiovascular fitness, dietary intake, leisure time activity, body composition, bone mineral density, bone structure, and muscle strength were assessed. RESULTS: Average adherence to all program components was 74.8 %. Women in the intervention group maintained their cardiovascular fitness level over the 12 months (1.1 ± 7.9 %), while the control group significantly decreased fitness capacity (-4.0 ± 7.5 %). There was a significant difference between groups in percent change of whole body bone area (-0.8 ± 2.5 control and 0.5 ± 1.30 intervention). We also observed decreased BMI (-4.7 ± 6.2 %) and fat mass (-8.6 ± 12.7 %) in the intervention group due to significant concomitant decreases in caloric intake and increases in caloric expenditure. The control group demonstrated decreased caloric intake and decreased lean tissue mass. CONCLUSIONS: In this population at high risk for detrimental cardiovascular and bone outcomes, a commercially available lifestyle intervention program mitigated a decline in cardiovascular health, improved bone health, and decreased weight through fat loss. IMPLICATIONS FOR CANCER SURVIVORS: Precision Nutrition Coaching has shown benefit in breast cancer survivors for reduced risk of deleterious cardiovascular and bone outcomes.


Assuntos
Proteína BRCA2/metabolismo , Terapia Comportamental/métodos , Neoplasias da Mama/complicações , Estilo de Vida , Ovariectomia/métodos , Ubiquitina-Proteína Ligases/metabolismo , Adolescente , Adulto , Neoplasias da Mama/mortalidade , Feminino , Humanos , Pessoa de Meia-Idade , Comportamento de Redução do Risco , Sobreviventes , Adulto Jovem
15.
Neuroimage ; 48(4): 717-25, 2009 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-19559802

RESUMO

According to the sensorimotor theory of lexicosemantic organization, semantic representations are neurally distributed and anatomically linked to category-specific sensory areas. Previous functional neuroimaging studies have demonstrated category specificity in lexicosemantic representations. However, little evidence is available from word generation paradigms, which provide access to semantic representations while minimizing confounds resulting from low-level perceptual features of stimulus presentation. In this study, 13 healthy young adults underwent fMRI scanning while performing a word generation task, generating exemplars to nine different semantic categories. Each semantic category was assigned to one of three superordinate category types, based upon sensorimotor modalities (visual, motor, somatosensory) presumed to predominate in lexical acquisition. For word generation overall, robust activation was seen in left inferior frontal cortex. Analyses by sensorimotor modality categories yielded activations in brain regions related to perceptual and motor processing: Visual categories activated extrastriate cortex, motor categories activated the intraparietal sulcus and posterior middle temporal cortex, and somatosensory categories activated postcentral and inferior parietal regions. Our results are consistent with the sensorimotor theory, according to which lexicosemantic representations are distributed across brain regions participating in sensorimotor processing associated with the experiential components of lexicosemantic acquisition.


Assuntos
Encéfalo/fisiologia , Linguística , Processos Mentais/fisiologia , Fala/fisiologia , Adulto , Mapeamento Encefálico , Vias Eferentes/fisiologia , Feminino , Humanos , Testes de Linguagem , Imageamento por Ressonância Magnética , Masculino , Modelos Psicológicos , Córtex Somatossensorial/fisiologia , Vias Visuais/fisiologia , Vocabulário , Adulto Jovem
16.
J Int Neuropsychol Soc ; 14(6): 990-1003, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18954479

RESUMO

Although previous studies have shown that individuals with autism spectrum disorder (ASD) excel at visual search, underlying neural mechanisms remain unknown. This study investigated the neurofunctional correlates of visual search in children with ASD and matched typically developing (TD) children, using an event-related functional magnetic resonance imaging design. We used a visual search paradigm, manipulating search difficulty by varying set size (6, 12, or 24 items), distractor composition (heterogeneous or homogeneous) and target presence to identify brain regions associated with efficient and inefficient search. While the ASD group did not evidence accelerated response time (RT) compared with the TD group, they did demonstrate increased search efficiency, as measured by RT by set size slopes. Activation patterns also showed differences between ASD group, which recruited a network including frontal, parietal, and occipital cortices, and the TD group, which showed less extensive activation mostly limited to occipito-temporal regions. Direct comparisons (for both homogeneous and heterogeneous search conditions) revealed greater activation in occipital and frontoparietal regions in ASD than in TD participants. These results suggest that search efficiency in ASD may be related to enhanced discrimination (reflected in occipital activation) and increased top-down modulation of visual attention (associated with frontoparietal activation).


Assuntos
Atenção/fisiologia , Transtorno Autístico/patologia , Transtorno Autístico/fisiopatologia , Encéfalo/patologia , Encéfalo/fisiopatologia , Movimentos Oculares/fisiologia , Percepção Visual/fisiologia , Adolescente , Encéfalo/irrigação sanguínea , Mapeamento Encefálico , Criança , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Oxigênio , Tempo de Reação/fisiologia
17.
Neuropsychologia ; 45(8): 1697-706, 2007 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-17292926

RESUMO

Verbal fluency is a widely used neuropsychological paradigm. In fMRI implementations, conventional unpaced (self-paced) versions are suboptimal due to uncontrolled timing of responses, and overt responses carry the risk of motion artifact. We investigated the behavioral and neurofunctional effects of response pacing and overt speech in semantic category-driven word generation. Twelve right-handed adults (8 females), ages 21-37 were scanned in four conditions each: paced-overt, paced-covert, unpaced-overt, and unpaced-covert. There was no significant difference in the number of exemplars generated between overt versions of the paced and unpaced conditions. Imaging results for category-driven word generation overall showed left-hemispheric activation in inferior frontal cortex, premotor cortex, cingulate gyrus, thalamus, and basal ganglia. Direct comparison of generation modes revealed significantly greater activation for the paced compared to unpaced conditions in right superior temporal, bilateral middle frontal, and bilateral anterior cingulate cortex, including regions associated with sustained attention, motor planning, and response inhibition. Covert (compared to overt) conditions showed significantly greater effects in right parietal and anterior cingulate, as well as left middle temporal and superior frontal regions. We conclude that paced overt paradigms are useful adaptations of conventional semantic fluency in fMRI, given their superiority with regard to control over and monitoring of behavioral responses. However, response pacing is associated with additional non-linguistic effects related to response inhibition, motor preparation, and sustained attention.


Assuntos
Mapeamento Encefálico , Encéfalo/irrigação sanguínea , Imageamento por Ressonância Magnética , Semântica , Fala/fisiologia , Comportamento Verbal/fisiologia , Adulto , Encéfalo/fisiologia , Feminino , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Oxigênio/sangue , Estimulação Luminosa/métodos , Tempo de Reação , Percepção da Fala/fisiologia , Fatores de Tempo
18.
Neuron ; 50(5): 799-812, 2006 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-16731517

RESUMO

When performing tasks, humans are thought to adopt task sets that configure moment-to-moment data processing. Recently developed mixed blocked/event-related designs allow task set-related signals to be extracted in fMRI experiments, including activity related to cues that signal the beginning of a task block, "set-maintenance" activity sustained for the duration of a task block, and event-related signals for different trial types. Data were conjointly analyzed from mixed design experiments using ten different tasks and 183 subjects. Dorsal anterior cingulate cortex/medial superior frontal cortex (dACC/msFC) and bilateral anterior insula/frontal operculum (aI/fO) showed reliable start-cue and sustained activations across all or nearly all tasks. These regions also carried the most reliable error-related signals in a subset of tasks, suggesting that the regions form a "core" task-set system. Prefrontal regions commonly related to task control carried task-set signals in a smaller subset of tasks and lacked convergence across signal types.


Assuntos
Mapeamento Encefálico , Córtex Cerebral/fisiologia , Imageamento por Ressonância Magnética , Processos Mentais/fisiologia , Adolescente , Adulto , Potenciais Evocados/fisiologia , Lobo Frontal/fisiologia , Giro do Cíngulo/fisiologia , Humanos , Lobo Parietal/fisiologia
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