RESUMO
Previous research has shown that after adapting to a thin body, healthy participants (HP) perceive pictures of their own bodies as being fatter and vice versa. This aftereffect might contribute to the development of perceptual body image disturbances in eating disorders (ED).In the present study, HP and ED completed a behavioral experiment to rate manipulated pictures of their own bodies after adaptation to thin or fat body pictures. After adapting to a thin body, HP judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. ED only showed such an adaptation effect when they adapted to fat body pictures.The reported results indicate a relationship between body image distortion in ED and visual body image adaptation. It can be suspected that due to a pre-existing, long-lasting adaptation to thin body shapes in ED, an additional visual adaption to thin body shapes cannot be induced. Hence this pre-existing adaptation to thin body shapes could induce perceptual body image distortions in ED.
Assuntos
Adaptação Fisiológica/fisiologia , Imagem Corporal/psicologia , Transtornos da Alimentação e da Ingestão de Alimentos/psicologia , Percepção Visual/fisiologia , Adulto , Feminino , Humanos , Adulto JovemRESUMO
Previous studies in electrophysiology have provided consistent evidence for a relationship between neural oscillations in different frequency bands and the maintenance of information in working memory (WM). While the amplitude and cross-frequency coupling of neural oscillations have been shown to be modulated by the number of items retained during WM, interareal phase synchronization has been associated with the integration of distributed activity during WM maintenance. Together, these findings provided important insights into the oscillatory dynamics of cortical networks during WM. However, little is known about the cortical regions and frequencies that underlie the specific maintenance of behaviorally relevant information in WM. In the current study, we addressed this question with magnetoencephalography and a delayed match-to-sample task involving distractors in 25 human participants. Using spectral analysis and beamforming, we found a WM load-related increase in the gamma band (60-80 Hz) that was localized to the right intraparietal lobule and left Brodmann area 9 (BA9). WM-load related changes were also detected at alpha frequencies (10-14 Hz) in Brodmann area 6, but did not covary with the number of relevant WM-items. Finally, we decoded gamma-band source activity with a linear discriminant analysis and found that gamma-band activity in left BA9 predicted the number of target items maintained in WM. While the present data show that WM maintenance involves activity in the alpha and gamma band, our results highlight the specific contribution of gamma band delay activity in prefrontal cortex for the maintenance of behaviorally relevant items.
Assuntos
Mapeamento Encefálico/métodos , Ondas Encefálicas/fisiologia , Memória de Curto Prazo/fisiologia , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Adolescente , Adulto , Feminino , Humanos , Magnetoencefalografia/métodos , Masculino , Estimulação Luminosa/métodos , Adulto JovemRESUMO
Visual perception can be strongly biased due to exposure to specific stimuli in the environment, often causing neural adaptation and visual aftereffects. In this study, we investigated whether adaptation to certain body shapes biases the perception of the own body shape. Furthermore, we aimed to evoke neural adaptation to certain body shapes. Participants completed a behavioral experiment (n = 14) to rate manipulated pictures of their own bodies after adaptation to demonstratively thin or fat pictures of their own bodies. The same stimuli were used in a second experiment (n = 16) using functional magnetic resonance imaging (fMRI) adaptation. In the behavioral experiment, after adapting to a thin picture of the own body participants also judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. The fusiform body area (FBA) and the right middle occipital gyrus (rMOG) show neural adaptation to specific body shapes while the extrastriate body area (EBA) bilaterally does not. The rMOG cluster is highly selective for bodies and perhaps body parts. The findings of the behavioral experiment support the existence of a perceptual body shape aftereffect, resulting from a specific adaptation to thin and fat pictures of one's own body. The fMRI results imply that body shape adaptation occurs in the FBA and the rMOG. The role of the EBA in body shape processing remains unclear. The results are also discussed in the light of clinical body image disturbances.
Assuntos
Adaptação Fisiológica , Mapeamento Encefálico , Corpo Humano , Lobo Occipital/irrigação sanguínea , Reconhecimento Visual de Modelos/fisiologia , Adulto , Animais , Viés , Índice de Massa Corporal , Feminino , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Lobo Occipital/fisiologia , Estimulação Luminosa , Adulto JovemRESUMO
BACKGROUND: Body image distortion is a key symptom of eating disorders. In behavioral research two components of body image have been defined: attitudes towards the body and body size estimation. Only few fMRI-studies investigated the neural correlates of body image in bulimia; those are constrained by the lack of a direct distinction between these different body image components. METHODS: The present study investigates the neural correlates of two aspects of the body image using fMRI: satisfaction rating and size estimation of distorted own body photographs in bulimia nervosa patients (15) and controls (16). RESULTS: Patients were less satisfied with their current body shape than controls and preferred to be thinner. The amount of insula activity reflects the pattern of the satisfaction rating for patients and controls. Patients also overestimated their own body size. For control subjects, an activated cluster in lateral occipital cortex was sensitive for body size distortions, whereas bulimic patients did not demonstrate such a modulation. Furthermore, bulimic subjects did not recruit the middle frontal gyrus (MFG) in contrast to controls during the body size estimation task, maybe indicating a reduced spatial manipulation capacity. Therefore, this activation pattern of lateral occipital cortex and MFG might be responsible for body size overestimation in bulimia. CONCLUSIONS: The present results show that bulimic patients exhibit two distinct deficits in body image representations similar to anorectic patients and that specifically associated neuronal correlates can be identified. Concludingly, our study support psychotherapeutic strategies specifically targeting these two aspects of body image distortions.
Assuntos
Imagem Corporal , Tamanho Corporal/fisiologia , Bulimia Nervosa/fisiopatologia , Bulimia Nervosa/psicologia , Encéfalo/fisiologia , Interpretação Estatística de Dados , Manual Diagnóstico e Estatístico de Transtornos Mentais , Feminino , Humanos , Imageamento por Ressonância Magnética , Lobo Occipital/fisiologia , Lobo Parietal/fisiologia , Satisfação Pessoal , Estimulação Luminosa , Córtex Pré-Frontal/fisiologia , Desempenho Psicomotor/fisiologia , Autoimagem , Inquéritos e Questionários , Adulto JovemRESUMO
The ability to integrate different types of information (e.g., object identity and spatial orientation) and maintain or manipulate them concurrently in working memory (WM) facilitates the flow of ongoing tasks and is essential for normal human cognition. Research shows that object and spatial information is maintained and manipulated in WM via separate pathways in the brain (object/ventral versus spatial/dorsal). How does the human brain coordinate the activity of different specialized systems to conjoin different types of information? Here we used functional magnetic resonance imaging to investigate conjunction- versus single-task manipulation of object (compute average color blend) and spatial (compute intermediate angle) information in WM. Object WM was associated with ventral (inferior frontal gyrus, occipital cortex), and spatial WM with dorsal (parietal cortex, superior frontal, and temporal sulci) regions. Conjoined object/spatial WM resulted in intermediate activity in these specialized areas, but greater activity in different prefrontal and parietal areas. Unique to our study, we found lower temporo-occipital activity and greater deactivation in temporal and medial prefrontal cortices for conjunction- versus single-tasks. Using structural equation modeling, we derived a conjunction-task connectivity model that comprises a frontoparietal network with a bidirectional DLPFC-VLPFC connection, and a direct parietal-extrastriate pathway. We suggest that these activation/deactivation patterns reflect efficient resource allocation throughout the brain and propose a new extended version of the biased competition model of WM.
Assuntos
Encéfalo/fisiologia , Cognição/fisiologia , Memória de Curto Prazo/fisiologia , Percepção Espacial/fisiologia , Percepção Visual/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , MasculinoRESUMO
We examined the neural signatures of stimulus features in visual working memory (WM) by integrating functional magnetic resonance imaging (fMRI) and event-related potential data recorded during mental manipulation of colors, rotation angles, and color-angle conjunctions. The N200, negative slow wave, and P3b were modulated by the information content of WM, and an fMRI-constrained source model revealed a progression in neural activity from posterior visual areas to higher order areas in the ventral and dorsal processing streams. Color processing was associated with activity in inferior frontal gyrus during encoding and retrieval, whereas angle processing involved right parietal regions during the delay interval. WM for color-angle conjunctions did not involve any additional neural processes. The finding that different patterns of brain activity underlie WM for color and spatial information is consistent with ideas that the ventral/dorsal "what/where" segregation of perceptual processing influences WM organization. The absence of characteristic signatures of conjunction-related brain activity, which was generally intermediate between the 2 single conditions, suggests that conjunction judgments are based on the coordinated activity of these 2 streams.
Assuntos
Percepção de Cores/fisiologia , Lobo Frontal/fisiologia , Memória de Curto Prazo/fisiologia , Lobo Parietal/fisiologia , Percepção Espacial/fisiologia , Córtex Visual/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados , Feminino , Lobo Frontal/anatomia & histologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Vias Neurais , Lobo Parietal/anatomia & histologia , Estimulação Luminosa , Córtex Visual/anatomia & histologia , Adulto JovemRESUMO
Previous studies have shown that prolonged inspection of a tilted visual pattern leads to changes in perception ("tilt after-effect", TAE), as well as to a reduction of the neural activation evoked by this pattern ("neural adaptation"). In this fMRI study, we investigated whether such perceptual and neural adaptation can be induced solely by mental imagination. The subjects were asked to mentally generate tilted lines, after which they were presented test lines oriented in the same or the direction orthogonal to the mentally tilted lines. Subjects showed a TAE even after mental imagery ("mental TAE"). Furthermore, a significant orientation-specific adaptation occurred in extrastriate visual areas (V3-V4), showing a decreasing gradient of adaptation from areas V4 to V1. Both this neural adaptation and the individual size of the mental TAE correlated with performance in a behavioural task probing mental imagery. Thus, orientation-selective neurons in visual areas seem to be recruited by mental imagery, and the amount of recruitment correlates with the degree of success of mental imagery operations. The influence of mental imagery on perception and on the neural activity in extrastriate visual areas provides evidence for analogue coding of mental images.
Assuntos
Imaginação/fisiologia , Orientação/fisiologia , Córtex Visual/fisiologia , Adaptação Fisiológica/fisiologia , Análise de Variância , Encéfalo/fisiologia , Feminino , Humanos , Modelos Lineares , Imageamento por Ressonância Magnética , Masculino , Estimulação Luminosa , Percepção Visual/fisiologia , Adulto JovemRESUMO
BACKGROUND: Ultraviolet (UV) light, especially UVC, is germicidal but its ability to penetrate layers of protein containing solutions is poor. This hampers its use to inactivate pathogens in therapeutic fresh plasma (FP). STUDY DESIGN AND METHODS: FP units were spiked with lipid-enveloped or nonenveloped viruses. Others were used without spiking. The units were transferred into UV-transparent bags and irradiated with UVB or UVC light from both sides. The bags either were clamped between quartz plates or remained loose. In addition they were agitated at different speeds. Before and after irradiation virus titers or plasma variables were measured. RESULTS: Virus inactivation by UV irradiation was marginal when the FP units were not agitated or when the irradiation bags were fixed between quartz plates. It was strongly enhanced when they remained unfixed and were intensively agitated during treatment. At 100 rpm and UVC doses of approximately 1 J/cm(2), with the exception of human immunodeficiency virus Type 1, all viruses used were effectively inactivated. UVB up to 2.5 J/cm(2) was less effective. At 1 J/cm(2) UVC or 2.5 J/cm(2) UVB the activities of the clotting factors tested in general were reduced by approximately 10% to 20% compared to untreated plasma. More sensitive was clotting factor XI whose activity was lowered by approximately 23 and 29%, respectively. No further reductions were determined after storage of UVC-treated FP for 3 months at 30 degrees C or less. CONCLUSIONS: Pathogen inactivation of FP by UV light becomes effective when the unfixed irradiation bags are strongly agitated. The decrease in some clotting factor activities could be acceptable.
Assuntos
Preservação de Sangue/métodos , Plasma/efeitos da radiação , Plasma/virologia , Esterilização/métodos , Raios Ultravioleta , Proteínas Sanguíneas/efeitos da radiação , Humanos , Imunoensaio , Vírus/crescimento & desenvolvimento , Vírus/efeitos da radiaçãoRESUMO
BACKGROUND: Bacterial contamination of platelet concentrates (PCs) is recognized as a serious threat to transfusion safety. We developed a simple method for sterilization of PCs with short-wave ultraviolet light (UVC). The effects of treatment on the sterility of contaminated PCs and in vitro platelet (PLT) variables were evaluated. STUDY DESIGN AND METHODS: Plasma-reduced PCs were prepared from pools of five buffy coats. Irradiation with UVC (wavelength, 254 nm) under vigorous agitation was from both sides of the irradiation bags. Kinetics of the inactivation of Bacillus cereus, Propionibacterium acnes, and Staphylococcus epidermidis were determined. PCs spiked with approximately 10 to 100 colony-forming units (CFUs)/mL of 10 bacteria species (n = 12/species) were irradiated with UVC doses between 0.25 and 0.4 J/cm(2) and tested for sterility by a commercially available bacterial detection system (BacT/ALERT, bioMérieux) after storage at 22 degrees C for 3 or 6 days. The influence of a dose of 0.3 J/cm(2) on PLT variables was investigated on Days 1, 4, and 6 after irradiation. RESULTS: At 0.3 J/cm(2) all bacteria species tested were inactivated by more than 4 log. At this dose the influence of UVC on in vitro PLT variables was marginal; the storage stability for up to 6 days after treatment was maintained. PCs spiked with approximately 10 to 100 CFUs/mL were reproducibly sterilized in the dose range tested. In individual experiments with the spore former B. cereus, PCs were, however, unsterile after treatment. CONCLUSION: Irradiation at UVC doses not detrimental to in vitro PLT variables sterilizes PCs contaminated with a wide range of different bacteria species.
Assuntos
Preservação de Sangue/métodos , Esterilização/métodos , Raios Ultravioleta , Bacillus cereus/crescimento & desenvolvimento , Bacillus cereus/efeitos da radiação , Plaquetas/microbiologia , Plaquetas/efeitos da radiação , Propionibacterium acnes/efeitos da radiação , Staphylococcus epidermidis/efeitos da radiaçãoRESUMO
BACKGROUND: A fully automated single-tube assay with tubes (BD TruCOUNT, BD Biosciences) for absolute counting of residual cells in freshly prepared plasma by flow cytometry was developed (BD Plasma Count). STUDY DESIGN AND METHODS: The nucleic acid dye thiazole orange stains white blood cells (WBCs). The monoclonal antibodies anti-CD41a-peridinin chlorophyll protein-Cy5.5 and anti-glycophorin A-fluorescein isothiocyanate label platelets (PLTs) and red blood cells (RBCs), respectively. No fixation, permeabilization, or washing steps were required. Validation was done according to guidelines of the International Conference on Harmonization and the National Committee for Clinical Laboratory Standards. Cell-free plasma was spiked with each cell type for accuracy, reproducibility, and linearity measurements. RESULTS: Results showed no carryover or drift under automated sample acquisition conditions. Nonspecific background was fewer than 0.3 cells per microL for residual WBCs (rWBCs), fewer than 2.7 cells per microL for rRBCs, and fewer than 85 cells per microL for rPLTs. Determinations of rWBC and rPLT counts were linear with a coefficient of variation of less than 12 percent for the imprecision. Owing to cross-linking of the anti-glycophorin A antibody, linearity and precision for rRBCs diverged up to 21 percent at a count of 6000 rRBCs per microL. In a 2-year period, five operators investigated 2666 quality control (QC) samples of fresh-frozen plasma on 108 working days. Maximum cell numbers found were 196 for rWBCs, 3960 for rRBCs, and 28,952 for rPLTs per microL. In 31 cases (1.2%) rWBCs were out of specification. No outlier was observed for rRBCs and rPLTs. Residual RBC cell numbers determined were always within the acceptable concentration range of the assay. CONCLUSION: These data demonstrate that the single-tube test is suitable for routine QC assessment of the cellular contaminants of therapeutic plasma according to the European recommendations.
Assuntos
Contagem de Eritrócitos , Citometria de Fluxo/métodos , Contagem de Leucócitos , Plasma/citologia , Contagem de Plaquetas , Humanos , Controle de QualidadeRESUMO
BACKGROUND: Transfusion of platelet concentrates (PCs) is the basic treatment for severe platelet disorders. PCs carry the risk of pathogen transmission, especially bacteria. Pathogen reduction (PR) by addition of photochemical reagents and irradiation with visible or ultraviolet (UV) light can significantly reduce this risk. We present a novel approach for PR in PCs employing UVC light alone. STUDY DESIGN AND METHODS: UVC PR was evaluated by bacteria and virus infectivity assays. PC quality was investigated by measuring pH, lactate, glucose, hypotonic shock response, platelet aggregation, CD62P expression, and annexin V binding as in vitro parameters. The impact of UVC PR on the platelet proteome was assessed by differential in-gel electrophoresis and compared with changes caused by UVB and gamma-irradiation, respectively. RESULTS: Vigorous agitation of loosely placed PCs generated thin fluid layers that allow penetration of UVC light for inactivation of the six bacteria and six of the seven virus species tested. HIV-1 was only moderately inactivated. UVC light at the dose used (0.4 J/cm(2)) had a minor impact on in vitro parameters and on storage stability of treated PCs. Proteome analysis revealed a common set of 92 (out of 793) protein spots being affected by all three types of irradiation. Specific alterations were most pronounced for gamma-irradiation (45 spots), followed by UVB (11 spots) and UVC (2 spots). CONCLUSION: UVC irradiation is a potential new method for pathogen reduction in PCs. The data obtained until now justify further development of this process.
Assuntos
Bacteriemia/prevenção & controle , Preservação de Sangue/métodos , Plaquetoferese , Esterilização/métodos , Raios Ultravioleta , Viremia/prevenção & controle , Bacteriemia/sangue , Bactérias/crescimento & desenvolvimento , Bactérias/efeitos da radiação , Plaquetas/microbiologia , Plaquetas/virologia , Humanos , Modelos Biológicos , Proteoma , Viremia/sangue , Vírus/crescimento & desenvolvimento , Vírus/efeitos da radiaçãoRESUMO
BACKGROUND: Methylene blue (MB) / light treatment is a well-known procedure for the inactivation of pathogens in fresh frozen plasma (FFP). Aim of the current study was to investigate the thrombin generation (TG) characteristics and quality of MB plasma prepared by the Theraflex MB Plasma System. METHODS: Single donor plasma units (n = 18) were MB/light-treated, with sampling before and after processing. Preparation included leukocyte depletion, addition of MB pill prior to illumination, and depletion of MB and photoproducts by filtration. Different plasma parameters and TG were measured. TG additionally was determined in solvent/detergent plasma (n = 8). RESULTS: MB/light treatment significantly affected factors V, VIII and XI, which were decreased by 9-18%. While the antigen level was not affected, fibrinogen according to Clauss was decreased by 7%, correlating with a 12% prolongation of TT and RT. The total amount of free thrombin generated, given as 'area under the curve' (AUC), was comparable for untreated (93 +/- 18% of normal plasma) and MB/light-treated plasma (95 +/- 20%). Also peak thrombin concentration was not significantly affected by treatment (94 +/- 11% (untreated) vs. 96 +/- 12% (treated)). The 'time to peak' value (TTP) was 105% of normal plasma for untreated FFP and 89% for MB-treated plasma. CONCLUSION: For plasma treated with the Theraflex MB Plasma System no profound influence of MB/ light treatment on the characteristics of thrombin generation was detected. In concordance with data from the literature, coagulation factors V, VIII and XI were decreased due to MB/ light treatment. Decrease was less than 20%.
RESUMO
It is a prevalent notion that borderline personality disorder (BPD) is characterized by deficits in executive functions (EF) like inhibition. Yet experimental studies yield inconsistent results. However, despite emotional dysregulation being a core feature of BPD, most paradigms did not control for emotional state or comorbid mental disorders. In the present study, subjects with BPD and comorbid MDD (BPD+MDD), with major depression (MDD) and healthy controls (HC) partook in a social exclusion paradigm combined with an inhibition task. We expected inhibition to be more strongly impaired in BPD+MDD than in depression and HC when experiencing negative emotions. Respecting inhibition, depressed patients performed best while (BPD+MDD) patients performed worst. Surprisingly, MDD & HC participants' performance improved during social exclusion, but this was not the case for BPD+MDD. Inhibition deficits were correlated with childhood trauma. These results challenge the hypothesis that an induction of negative emotion results in inferior inhibition in (BPD+MDD). Instead, patients with (BPD+MDD) seem to suffer from a more general inhibitory dysfunction. Importantly, (BPD+MDD) patients were not able to improve their performance during social exclusion like HC and MDD patients did. These findings need to be investigated further, particularly regarding the efficiency of neural networks regulating inhibition and effects of trauma.
Assuntos
Transtorno da Personalidade Borderline/psicologia , Transtorno Depressivo Maior/psicologia , Inibição Psicológica , Distância Psicológica , Adulto , Nível de Alerta , Transtorno da Personalidade Borderline/diagnóstico , Comorbidade , Transtorno Depressivo Maior/diagnóstico , Função Executiva , Feminino , HumanosRESUMO
Working memory, the short-term maintenance and manipulation of information, relies strongly on neural activity in the frontal cortex. Understanding the functional role of this activity is a prerequisite for the understanding of cognitive control mechanisms. Functional imaging studies in human participants have attempted to reveal neural correlates of the subdivision of visual working memory into different processes (maintenance vs manipulation) and according to the type of memorized content. Here, we show, using functional magnetic resonance imaging, a content-specific dissociation of frontal activity, with dorsal premotor areas supporting both maintenance and manipulation of spatial features and more ventral areas supporting maintenance and manipulation of color. Manipulation-specific activity was observed in the anterior middle frontal gyrus, the inferior frontal junction, and the inferior parietal lobe bilaterally. These areas have been implicated in cognitive control, and their activation by the manipulation task conforms to the demand on central executive resources in this condition. We suggest that the enhanced demand on cognitive resources in manipulation compared with maintenance was met by interplay of content- and task-specific modules in a frontoparietal network.
Assuntos
Mapeamento Encefálico/métodos , Percepção de Cores/fisiologia , Lobo Frontal/fisiologia , Memória de Curto Prazo/fisiologia , Percepção Espacial/fisiologia , Análise e Desempenho de Tarefas , Córtex Visual/fisiologia , Tomada de Decisões/fisiologia , Potenciais Evocados Visuais/fisiologia , Humanos , Imageamento por Ressonância Magnética/métodosRESUMO
Phenothiazine-based photosensitisers have been employed in photoantimicrobial research for nearly 80 years, both as lead and novel compounds. However, the main structural variations have mainly involved the auxochromic side chains and little has been reported concerning either peripheral substitution or structures with chromophores other than those of the phenothiazinium or annelated benzo[a]phenothiazinium type. In terms of application, the phenothiazinium series has featured commonly in cytology and cytopathology, as well as in haematological staining. The current work covers the evolution of improved photosensitisers based on the phenothiazine ring system, with particular reference to the field of pathogen inactivation, and the structural alteration of lead compounds such as methylene blue and Nile blue to yield improved photosensitisers for this important aspect of blood product safety.
Assuntos
Patógenos Transmitidos pelo Sangue , Sangue/microbiologia , Viabilidade Microbiana/efeitos dos fármacos , Fenotiazinas/farmacologia , Humanos , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêuticoRESUMO
Many studies have suggested that the intraparietal sulcus (IPS), particularly in the dominant hemisphere, is crucially involved in numerical comparisons. However, this parietal structure has been found to be involved in other tasks that require spatial processing or visuospatial attention as well. fMRI was used to investigate three different magnitude comparisons in an event-related-block design: (a) Which digit is larger in numerical value (e.g., 2 or 5)? (b) Which digit is brighter (e.g., 3 or 3)? (c) Which digit is physically larger (e.g., 3 or 3)? Results indicate a widespread cortical network including a bilateral activation of the intraparietal sulci for all different comparisons. However, by computing contrasts of brain activation between the respective comparison conditions and applying a cortical distance effect as an additional criterion, number-specific activation was revealed in left IPS and right temporal regions. These results indicate that there are both commonalities and differences in the spatial layout of the brain systems for numerical and physical comparisons and that especially the left IPS, while involved in magnitude comparison in general, plays a special role in number comparison.
Assuntos
Encéfalo/irrigação sanguínea , Encéfalo/fisiologia , Imageamento por Ressonância Magnética , Matemática , Percepção Visual/fisiologia , Adulto , Análise de Variância , Encéfalo/anatomia & histologia , Mapeamento Encefálico , Feminino , Lateralidade Funcional/fisiologia , Humanos , Processamento de Imagem Assistida por Computador/métodos , Masculino , Oxigênio/sangue , Estimulação Luminosa/métodos , Tempo de Reação/fisiologiaRESUMO
Patients with schizophrenia show deficits in core cognitive functions as well as in social cognition. The aim of the present study was to test whether deficits in social cognition influence nonsocial, "cold", cognition. Thirty-five patients with recent-onset schizophrenia (SC) and 30 healthy controls (HC) performed a Simon task with social and simple geometric stimuli. We investigated whether the Simon effect, the slowing of reaction times produced by stimulus incongruities in the task-irrelevant spatial domain, differs between patients and healthy participants as a function of the social nature of the cues. The Simon effect was generated by a schematic drawing of human eyes (social cues) or rectangles (nonsocial cues). Overall, patients had longer reaction times than HC. In the eye-like condition, the Simon effect was significantly stronger for HC than for SC. In HC the Simon effect was significantly stronger in the eye-like than in the rectangle condition. In patients, the Simon effect did not differ significantly between both conditions. Thus, the influence of social cues was greatly reduced in the patient group. Current psychopathology or antipsychotic treatment did not influence results. The present study supports earlier findings of altered processing of schematic social cues in patients with schizophrenia, especially when gaze is task-irrelevant.
Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/etiologia , Fixação Ocular , Transtornos da Percepção/etiologia , Esquizofrenia/complicações , Percepção Espacial/fisiologia , Adolescente , Adulto , Análise de Variância , Humanos , Masculino , Testes Neuropsicológicos , Estimulação Luminosa , Escalas de Graduação Psiquiátrica , Tempo de Reação/fisiologia , Adulto JovemRESUMO
Evidence from anatomical and functional imaging studies have highlighted major modifications of cortical circuits during adolescence. These include reductions of gray matter (GM), increases in the myelination of cortico-cortical connections and changes in the architecture of large-scale cortical networks. It is currently unclear, however, how the ongoing developmental processes impact upon the folding of the cerebral cortex and how changes in gyrification relate to maturation of GM/WM-volume, thickness and surface area. In the current study, we acquired high-resolution (3 Tesla) magnetic resonance imaging (MRI) data from 79 healthy subjects (34 males and 45 females) between the ages of 12 and 23 years and performed whole brain analysis of cortical folding patterns with the gyrification index (GI). In addition to GI-values, we obtained estimates of cortical thickness, surface area, GM and white matter (WM) volume which permitted correlations with changes in gyrification. Our data show pronounced and widespread reductions in GI-values during adolescence in several cortical regions which include precentral, temporal and frontal areas. Decreases in gyrification overlap only partially with changes in the thickness, volume and surface of GM and were characterized overall by a linear developmental trajectory. Our data suggest that the observed reductions in GI-values represent an additional, important modification of the cerebral cortex during late brain maturation which may be related to cognitive development.
Assuntos
Giro Denteado/crescimento & desenvolvimento , Substância Cinzenta/crescimento & desenvolvimento , Substância Branca/crescimento & desenvolvimento , Adolescente , Feminino , Humanos , Imageamento por Ressonância Magnética , MasculinoRESUMO
Visual adaptation to certain body shapes alters visual perception of subsequently presented pictures of bodies. We investigated whether these effects can be explained by adaptation to low-level visual objects, ie narrow and wide rectangles. Participants (n = 29) adapted to manipulated photographs of their own bodies, depicting them either unrealistically thin or fat. The perceived shapes of their own bodies were subsequently assessed by an interleaved staircase paradigm. A second experiment (n = 29) used the same design to test for adaptation effects evoked by narrow and wide bars. After adapting to a thin picture of own body, participants also judged a thinner than actual body picture to be the most realistic and vice versa, resembling a typical aftereffect. Importantly, this effect could not be replicated by adaptation to narrow and wide bars, demonstrating that the body-shape aftereffect cannot be explained by adaptation to low-level properties. The results support the existence of a perceptual body-shape aftereffect, resulting from a specific adaptation to thin and fat body shapes.
Assuntos
Adaptação Psicológica/fisiologia , Imagem Corporal/psicologia , Percepção Visual/fisiologia , Adulto , Análise de Variância , Feminino , Pós-Efeito de Figura/fisiologia , Humanos , Julgamento , Masculino , Adulto JovemRESUMO
Visual perception is highly variable and can be influenced by the surrounding world. Previous research has revealed that body perception can be biased due to adaptation to thin or fat body shapes. The aim of the present study was to show that adaptation to certain body shapes and the resulting perceptual biases transfer across different identities of adaptation and test stimuli. We designed two similar adaptation experiments in which healthy female participants adapted to pictures of either thin or fat bodies and subsequently compared more or less distorted pictures of their own body to their actual body shape. In the first experiment (n = 16) the same identity was used as adaptation and test stimuli (i.e. pictures of the participant's own body) while in the second experiment (n = 16) we used pictures of unfamiliar thin or fat bodies as adaptation stimuli. We found comparable adaptation effects in both experiments: After adaptation to a thin body, participants rated a thinner than actual body picture to be the most realistic and vice versa. We therefore assume that adaptation to certain body shapes transfers across different identities. These results raise the questions of whether some type of natural adaptation occurs in everyday life. Natural and predominant exposure to certain bodily features like body shape--especially the thin ideal in Western societies--could bias perception for these features. In this regard, further research might shed light on aspects of body dissatisfaction and the development of body image disturbances in terms of eating disorders.