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1.
PLoS Comput Biol ; 14(7): e1006177, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30016315

RESUMO

The combination of Transcranial Magnetic Stimulation (TMS) with Electroencephalography (EEG) exposes the brain's global response to localized and abrupt stimulations. However, large electric artifacts are induced in the EEG by the TMS, obscuring crucial stages of the brain's response. Artifact removal is commonly performed by data processing techniques. However, an experimentally verified physical model for the origin and structure of the TMS-induced discharge artifacts, by which these methods can be justified or evaluated, is still lacking. We re-examine the known contribution of the skin in creating the artifacts, and outline a detailed model for the relaxation of the charge accumulated at the electrode-gel-skin interface due to the TMS pulse. We then experimentally validate implications set forth by the model. We find that the artifacts decay like a power law in time rather than the commonly assumed exponential. In fact, the skin creates a power-law decay of order 1 at each electrode, which is turned into a power law of order 2 by the reference electrode. We suggest an artifact removal method based on the model which can be applied from times after the pulse as short as 2 milliseconds onwards to expose the full EEG from the brain. The method can separate the capacitive discharge artifacts from those resulting from cranial muscle activation, demonstrating that the capacitive effect dominates at short times. Overall, our insight into the physical process allows us to accurately access TMS-evoked EEG responses that directly follow the TMS pulse, possibly opening new opportunities in TMS-EEG research.


Assuntos
Artefatos , Eletroencefalografia/métodos , Modelos Neurológicos , Estimulação Magnética Transcraniana/métodos , Eletrodos , Potencial Evocado Motor/fisiologia , Humanos , Joelho , Músculo Esquelético/fisiologia , Imagens de Fantasmas , Reprodutibilidade dos Testes , Fenômenos Fisiológicos da Pele
2.
Brain Cogn ; 82(3): 243-53, 2013 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-23721994

RESUMO

Functional connectivity was evaluated in patients with schizophrenia (SC) and in patients with Parkinson's disease (PD) during the performance of a local contextual processing paradigm, to investigate the proposition that functional disconnection is involved with contextual processing deficits in these populations. To this end, we utilized event-related EEG signals, synchronization likelihood and graph theoretical analysis. Local context was defined as the occurrence of a predictive sequence of stimuli before the presentation of a target event. In the SC patients, we observed a decrease in path length (L) in the beta band, for the predictive sequence and for predicted and random targets, compared with controls. These abnormalities were associated with weaker frontal-temporal-parietal connections. In the PD patients we found longer L (theta band) for predicted targets, and higher cluster coefficients for both the predictive sequence (theta band) and predicted targets (alpha and theta bands), compared with controls. Detection of predicted targets was associated with weaker frontal-parietal connections in PD. No group differences were found for randomized standard stimuli in both SC and PD patients. These findings provide evidence of task-specific functional connectivity abnormalities within frontal networks during local contextual processing.


Assuntos
Encéfalo/fisiopatologia , Doença de Parkinson/fisiopatologia , Esquizofrenia/fisiopatologia , Adulto , Encéfalo/patologia , Ondas Encefálicas , Sincronização Cortical , Feminino , Humanos , Masculino , Memória de Curto Prazo/fisiologia , Pessoa de Meia-Idade , Doença de Parkinson/patologia , Esquizofrenia/patologia
3.
Brain Res ; 1727: 146543, 2020 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-31712087

RESUMO

The study investigated the underlying mechanisms associated with the ability of patients with major depressive disorder (MDD) to utilize predictive contextual information in order to facilitate detection of predictable versus random targets. To this end we evaluated EEG event-related functional connectivity during the processing of predictive stimuli in MDD and control subjects. A target detection task was used where targets were either preceded by randomized sequences of standards, or by sequences that included a predictive sequence. Functional connectivity was evaluated using synchronization likelihood and graph theory. The cluster coefficient and local efficiency values were greater in MDD compared to controls, during the processing of the three stimuli consisting of the predictive sequence, in the beta frequency band, suggesting an increased structured network organization. These changes were associated with increased functional connectivity within frontal networks in MDD patients compared to controls. However, no significant functional connectivity group-changes were observed for target conditions or randomized standards. These findings suggest that MDD is associated with context-specific functional connectivity abnormalities during the processing of predictive stimuli.


Assuntos
Encéfalo/fisiopatologia , Transtorno Depressivo Maior/fisiopatologia , Percepção Visual/fisiologia , Adulto , Ritmo beta , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Vias Neurais/fisiopatologia , Estimulação Luminosa
4.
Stud Health Technol Inform ; 132: 475-80, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18391348

RESUMO

BACKGROUND: Virtual Reality is an interactive three-dimensional computer generated environment. Providing a complex and multi-modal environment, VR can be particularly useful for the study of complex cognitive functions and brain disorders. Here we used a VR world to measure the distortion in reality perception in schizophrenia patients. METHODS: 43 schizophrenia patients and 29 healthy controls navigated in a VR environment and were asked to detect incoherencies, such as a cat barking or a tree with red leaves. RESULTS: Whereas the healthy participants reliably detected incoherencies in the virtual experience, 88% of the patients failed in this task. The patients group had specific difficulty in the detection of audio-visual incoherencies; this was significantly correlated with the hallucinations score of the PANSS. CONCLUSIONS: By measuring the distortion in reality perception in schizophrenia patients, we demonstrated that Virtual Reality can serve as a powerful experimental tool to study complex cognitive processes.


Assuntos
Percepção , Psicologia do Esquizofrênico , Interface Usuário-Computador , Adulto , Feminino , Humanos , Imageamento Tridimensional , Israel , Masculino
5.
Schizophr Res ; 93(1-3): 334-44, 2007 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-17433627

RESUMO

Transcranial Magnetic Stimulation (TMS) is rapidly gaining acceptance as a non-invasive probe into brain functionality. We utilize TMS to study the connectivity of a simple motor network in patients of schizophrenia (N=19), and in healthy control subjects (N=9). TMS was used in an externally paced finger tapping task, perturbing the internal network oscillations invoked by the finger motion as it keeps pace with a metronome. TMS perturbations were synchronized to the metronome and applied to the network at the level of the primary motor cortex (M1). Contrary to initial expectations, TMS did not affect the sensorimotor synchronization of subjects with schizophrenia or their tapping accuracy. TMS did cause extreme deviations in the finger's trajectory, and altered the timing perceptions of subjects with schizophrenia. Additionally, it invoked high-level deficiencies related to attention and volition in the form of lapses, implying that the connectivity between modules in the brain that underlie motor control, sensorimotor synchronization, timing perception and awareness of action, can be disrupted by TMS in subjects with schizophrenia, but not in healthy subjects. The ability to disrupt high level network functions with perturbations to the lower level of M1 supports models describing deficits in connectivity of distributed networks in the brains of schizophrenia patients. It also demonstrates the use of TMS to probe connectivity between components of such networks.


Assuntos
Cognição/fisiologia , Córtex Motor/fisiopatologia , Rede Nervosa/fisiologia , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Estimulação Magnética Transcraniana , Adulto , Atenção/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Motivação , Atividade Motora/fisiologia , Esquizofrenia/diagnóstico , Percepção do Tempo/fisiologia
6.
Am J Psychiatry ; 163(3): 512-20, 2006 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-16513875

RESUMO

OBJECTIVE: The authors' goal was to improve the diagnosis of schizophrenia by using virtual reality technology to build a complex, multimodal environment in which cognitive functions can be studied (and measured) in parallel. METHOD: The authors studied sensory integration within working memory by means of computer navigation through a virtual maze. The simulated journey consisted of a series of rooms, each of which included three doors. Each door was characterized by three features (color, shape, and sound), and a single combination of features--the door-opening rule--was correct. Subjects had to learn the rule and use it. The participants were 39 schizophrenic patients and 21 healthy comparison subjects. RESULTS: Upon completion, each subject was assigned a performance profile, including various error scores, response time, navigation ability, and strategy. A classification procedure based on the subjects' performance profile correctly predicted 85% of the schizophrenic patients (and all of the comparison subjects). Several performance variables showed significant correlations with scores on a standard diagnostic measure (Positive and Negative Syndrome Scale), suggesting potential use of these measurements for the diagnosis of schizophrenia. On the other hand, the patients did not show unusual repetition of response despite stimulus cessation (called "perseveration" in classical studies of schizophrenia), which is a common symptom of the disease. This deficit appeared only when the subjects did not receive proper explanation of the task. CONCLUSIONS: The ability to study multimodal performance simultaneously by using virtual reality technology opens new possibilities for the diagnosis of schizophrenia with objective procedures.


Assuntos
Transtornos Cognitivos/diagnóstico , Esquizofrenia/diagnóstico , Psicologia do Esquizofrênico , Interface Usuário-Computador , Adulto , Atenção , Transtornos Cognitivos/psicologia , Simulação por Computador , Humanos , Masculino , Aprendizagem em Labirinto , Memória/fisiologia , Transtornos da Memória/diagnóstico , Testes Neuropsicológicos , Escalas de Graduação Psiquiátrica/estatística & dados numéricos , Psicometria/instrumentação , Tempo de Reação , Percepção Espacial , Análise e Desempenho de Tarefas , Jogos de Vídeo
7.
Eur Neuropsychopharmacol ; 16(8): 572-9, 2006 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-16713194

RESUMO

A large body of literature indicates that disturbances of central serotonin (5-HT) function play an important role in aggressive behavior. Results from open-label and placebo-controlled trials as well as the reported inverse relationship between 5-HT function and aggression in human subjects, suggest that reduced 5-HT activity is associated with aggressive behavior. The activity of the 5-HT transporter (5-HTT), as determined by [(3)H]5-HT uptake to blood lymphocytes, was measured in 20 currently aggressive and 20 non-aggressive male schizophrenia patients. In addition, the pharmacodynamic characteristics of platelet 5-HTT were assessed by [(3)H]citalopram binding. There were no significant differences in the density (B(max)) of platelet [(3)H]citalopram binding sites between the two groups. Similarly, the dissociation constant (K(d)) values were indistinguishable. The maximum uptake velocity (V(max)) of [(3)H]5-HT to fresh lymphocytes and the K(m) values of the 5-HT to the transporter were significantly higher in currently aggressive compared to the non-aggressive schizophrenia patients. The association of high V(max) values with current aggressive behavior provides further support to the involvement of the 5-HTT in aggressive behavior as well as to the efficacy of 5-HTT blockers in the control of aggression. The role of the various components of the serotonergic system in the pathophysiology and treatment of aggressive behavior in schizophrenia needs to be further evaluated.


Assuntos
Agressão , Plaquetas/metabolismo , Linfócitos/metabolismo , Esquizofrenia/sangue , Proteínas da Membrana Plasmática de Transporte de Serotonina/sangue , Adulto , Humanos , Masculino , Serotonina/metabolismo , Trítio/metabolismo
8.
Eur Neuropsychopharmacol ; 16(6): 429-36, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16431091

RESUMO

A rapidly growing body of data suggests that abnormalities in serotonergic function might be involved in the pathophysiology of schizophrenia and that serotonergic mechanisms play a role in the therapeutic effects of antipsychotics. The activity of the serotonin transporter (5-HTT), as determined by [(3)H]5-HT uptake to blood lymphocytes, was measured in 38 medicated schizophrenia patients (15 of them treated with typical antipsychotics and 23 treated with atypical antipsychotics) and 15 healthy control subjects. In addition, the pharmacodynamic characteristics of platelet 5-HTT were assessed by [(3)H]citalopram binding. There were no significant differences in the density (B(max)) of platelet [(3)H]citalopram binding sites between the three groups. Similarly, the dissociation constant (K(d)) values were indistinguishable. There were no significant differences in the maximal uptake velocity (V(max)) of [(3)H]5-HT to fresh lymphocytes between the three groups. The affinity (K(m)) values of 5-HT to the 5-HTT were significantly higher in schizophrenia patients treated with typical antipsychotics compared with control subjects. The K(m) values in schizophrenia patients treated with atypical antipsychotics were significantly lower compared with those observed in the group of schizophrenia patients treated with typical antipsychotics; however, they were comparable to values in the control group. The high values of K(m) associated with typical antipsychotic treatment may be relevant to the high risk of developing extrapyramidal side effects (EPS). The role of the various components of the serotonergic system in the etiopathology of schizophrenia and the mechanisms by which antipsychotics achieve their therapeutic effects need to be further evaluated.


Assuntos
Antipsicóticos/sangue , Plaquetas/metabolismo , Linfócitos/sangue , Esquizofrenia/sangue , Proteínas da Membrana Plasmática de Transporte de Serotonina/sangue , Adulto , Antipsicóticos/farmacologia , Antipsicóticos/uso terapêutico , Plaquetas/efeitos dos fármacos , Citalopram/sangue , Feminino , Humanos , Linfócitos/efeitos dos fármacos , Masculino , Pessoa de Meia-Idade , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Esquizofrenia/tratamento farmacológico
9.
Med Hypotheses ; 67(4): 941-6, 2006.
Artigo em Inglês | MEDLINE | ID: mdl-16698189

RESUMO

The current psychiatric diagnostic system, the diagnostic statistic manual, has recently come under increasing criticism. The major reason for the shortcomings of the current psychiatric diagnosis is the lack of a scientific brain-related etiological knowledge about mental disorders. The advancement toward such knowledge is further hampered by the lack of a theoretical framework or "language" that translates clinical findings of mental disorders to brain disturbances and insufficiencies. Here such a theoretical construct is proposed based on insights from neuroscience and neural-computation models. Correlates between clinical manifestations and presumed neuronal network disturbances are proposed in the form of a practical diagnostic system titled "Brain Profiling". Three dimensions make-up brain profiling, "neural complexity disorders", "neuronal resilience insufficiency", and "context-sensitive processing decline". The first dimension relates to disturbances occurring to fast neuronal activations in the millisecond range, it incorporates connectivity and hierarchical imbalances appertaining typically to psychotic and schizophrenic clinical manifestations. The second dimension relates to disturbances that alter slower changes namely long-term synaptic modulations, and incorporates disturbances to optimization and constraint satisfactions within relevant neuronal circuitry. Finally, the level of internal representations related to personality disorders is presented by a "context-sensitive process decline" as the third dimension. For practical use of brain profiling diagnosis a consensual list of psychiatric clinical manifestations provides a "diagnostic input vector", clinical findings are coded 1 for "detection" and 0 for "non-detection", 0.5 is coded for "questionable". The entries are clustered according to their presumed neuronal dynamic relationships and coefficients determine their relevance to the specific related brain disturbance. Relevant equations calculate and normalize the different values attributed to relevant brain disturbances culminating in a three-digit estimation representing the three diagnostic dimensions. brain profiling has the promise for a future brain-related diagnosis. It offers testable predictions about the etiology of mental disorders because being brain-related it lends readily to brain imaging investigations. Being presented also as a one-point representation in a three-dimensional space, multiple follow-up diagnoses trace a trajectory representing an easy-to-see clinical history of the patient. Additional, more immediate, advantages involve reduced stigma because it relaters the disorder to the brain not the person, in addition the three-digit diagnostic code is clinically informative unlike the DSM codes that have no clinical relevance. To conclude, brain profiling diagnosis of mental disorders could be a bold new step toward a "clinical-neuroscience" substituting "psychiatry".


Assuntos
Encéfalo/fisiopatologia , Transtornos Mentais/diagnóstico , Neurociências , Humanos , Transtornos Mentais/fisiopatologia , Modelos Neurológicos
10.
Med Hypotheses ; 65(5): 947-52, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15996829

RESUMO

In 1895 Freud tried to explain mental disorders using the neurophysiological knowledge of his time. He soon abandoned this attempt realizing it was immature considering the neuroscientific knowledge available to him. For the rest of his career he limited himself to psychological formulations. Along the same lines, lacking etiology for mental disorders, the diagnostic system of psychiatry is exclusively descriptive. The need for a brain related diagnosis of mental disorders is important for developing better treatments and more reliable diagnosis. Today with the development of neuroscience it is time to go back to Freud's initial attempts and explain mental disorders as altered neuronal organizations in the brain. The neural network level is chosen as the relevant description level for mental functions. Plasticity is chosen as a general concept for neuronal dynamics explaining neuropathology of psychiatric disorders. Plasticity is divided according to timescales into "fast plasticity," "slow plasticity" and "stable plasticity". It is proposed that normal mental functions require optimal balance among all the plasticity timescales. Mental disorders arise when such balance is disturbed, thus mental disorders could be reformulated as deficiencies of the different plasticity processes. Changes in coherence synchrony and phase-locking membrane potentials in cortically spread neuronal ensembles are all expressions of fast plasticity. Synaptogenic and neurogenic processes, such as brain derived neurotrophic factor-dependent processes, are defined as slow plasticity. Finally those synaptic and neuronal pathways that consolidated into long lasting circuits are referred to as stable plasticity. With the aid of a neural network model simulating the plasticity imbalance, a mathematical formulation could be realized for mental disorders. Once achieved this mathematical formulation could form a guiding framework for interpreting brain-imaging data collected from psychiatric patients. Such a model is realized using interconnected "modules" each simulating the relevant plasticity dynamics relevant for the model. Diagnosing plasticity imbalance has some advantages over current descriptive psychiatric diagnosis. It is brain-related thus less stigmatising in the sense that mental disorders are brain disorders and not "person" disorders. The diagnostic system is much more flexible allowing for a high degree of variations and combinations in the description of the disorders thus naturally accounting for comorbidities. Most importantly, this diagnostic model is brain-related offering research targets for intervention and a theoretical framework guiding such interventions.


Assuntos
Encéfalo/fisiopatologia , Transtornos Mentais/diagnóstico , Transtornos Mentais/fisiopatologia , Modelos Neurológicos , Plasticidade Neuronal , Neurociências/métodos , Psiquiatria/métodos , Pesquisa Biomédica/métodos , Humanos , Transtornos Mentais/psicologia , Rede Nervosa/fisiopatologia
11.
Stud Health Technol Inform ; 111: 508-14, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15718788

RESUMO

Our goal is to develop a new family of automatic tools for the diagnosis of schizophrenia, using Virtual Reality Technology (VRT). VRT is specifically suitable for this purpose, because it allows for multi-modal stimulation in a complex setup, and the simultaneous measurement of multiple parameters. In this work we studied sensory integration within working memory, in a navigation task through a VR maze. Along the way subjects pass through multiple rooms that include three doors each, only one of which can be used to legally exit the room. Specifically, each door is characterized by three features (color, shape and sound), and only one combination of features -- as determined by a transient opening rule -- is legal. The opening rule changes over time. Subjects must learn the rule and use it for successful navigation throughout the maze. 39 schizophrenic patients and 21 healthy controls participated in this study. Upon completion, each subject was assigned a performance profile, including various error scores, response time, navigation ability and strategy. We developed a classification procedure based on the subjects' performance profile, which correctly predicted 85% of the schizophrenic patients (and all the controls). We observed that a number of parameters showed significant correlation with standard diagnosis scores (PANSS), suggesting the potential use of our measurements for future diagnosis of schizophrenia. On the other hand, our patients did not show unusual repetition of response despite stimulus cessation (called perseveration in classical studies of schizophrenia), which is usually considered a robust marker of the disease. Interestingly, this deficit only appeared in our study when subjects did not receive proper explanation of the task.


Assuntos
Esquizofrenia/diagnóstico , Interface Usuário-Computador , Estudos de Casos e Controles , Feminino , Humanos , Israel , Masculino
12.
PLoS One ; 10(4): e0123033, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25837521

RESUMO

Electroencephalographic (EEG) analysis has emerged as a powerful tool for brain state interpretation and diagnosis, but not for the diagnosis of mental disorders; this may be explained by its low spatial resolution or depth sensitivity. This paper concerns the diagnosis of schizophrenia using EEG, which currently suffers from several cardinal problems: it heavily depends on assumptions, conditions and prior knowledge regarding the patient. Additionally, the diagnostic experiments take hours, and the accuracy of the analysis is low or unreliable. This article presents the "TFFO" (Time-Frequency transformation followed by Feature-Optimization), a novel approach for schizophrenia detection showing great success in classification accuracy with no false positives. The methodology is designed for single electrode recording, and it attempts to make the data acquisition process feasible and quick for most patients.


Assuntos
Ondas Encefálicas/fisiologia , Encéfalo/fisiologia , Eletroencefalografia/métodos , Esquizofrenia/diagnóstico , Esquizofrenia/fisiopatologia , Algoritmos , Eletrodos , Humanos , Índice de Gravidade de Doença , Processamento de Sinais Assistido por Computador
13.
Schizophr Res ; 64(2-3): 157-63, 2003 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-14613680

RESUMO

The rubber-hand illusion (RHI), an illusion in which tactile sensations are referred to a synthetic alien limb, is enhanced in schizophrenia patients. Somatosensory evoked responses of the illusion were compared between schizophrenia patients and normal control subjects. Schizophrenia patients had significant alterations in long latency evoked responses during the illusion. These findings support the hypothesis of alterations in associative higher-level neuronal activity in schizophrenia. The findings support previous results pointing to alterations in associative brain regions in schizophrenia.


Assuntos
Atenção/fisiologia , Eletroencefalografia , Potenciais Somatossensoriais Evocados/fisiologia , Mãos/inervação , Ilusões/fisiologia , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Tato/fisiologia , Adulto , Mapeamento Encefálico , Córtex Cerebral/fisiopatologia , Delusões/diagnóstico , Delusões/fisiopatologia , Delusões/psicologia , Feminino , Humanos , Masculino , Rede Nervosa/fisiopatologia , Neurônios/fisiologia , Distorção da Percepção/fisiologia , Escalas de Graduação Psiquiátrica , Tempo de Reação/fisiologia , Esquizofrenia/diagnóstico , Limiar Sensorial/fisiologia , Córtex Somatossensorial/fisiologia
14.
Med Hypotheses ; 63(1): 110-4, 2004.
Artigo em Inglês | MEDLINE | ID: mdl-15193360

RESUMO

There is growing dissatisfaction regarding the available diagnostic systems for psychiatric disorders (DSM, ICD). Psychiatrists acknowledge that though mental disease reflects brain disorders, the descriptive and symptom based nature of psychiatric diagnosis bears no relation to brain functions. According to Helmut's article published in the October 2003 issue of Science, in the coming decade researchers and psychiatrists will be called upon to propose a basis for the psychiatric diagnostic system of the future. I propose a new etiology-oriented diagnostic system for psychiatry by integrating two recently emerging bodies of knowledge, one regarding plasticity and the other involving complex systems. Plasticity refers to all brain processes involved in dynamic alterations within communicating neuronal ensembles or networks, in the brain. Complexity refers to certain formulations from system theories relevant to brain dynamics and plasticity. It is proposed to divide plasticity processes into three types based on time domains: (1) "developmental plasticity", (2) "tuning plasticity" and (3) "fast stabilizing plasticity". Each type of plasticity is related to different complexity models achieved by the brain, developmental plasticity is life-long brain organization, it is related to state-space configurations molded into brain representations internalized via processes such as Hebbian learning. Tuning plasticity is related to "matching complexity" a measure of adaptability between internal configurations in the brain-system and externally originating event stimuli. Fast stabilizing plasticity is related to "neural complexity" a measure of neural network integration in the brain. Neural complexity meets the mental requirement to extract important features from different sensory inputs and to simultaneously generate coherent perceptual and cognitive states, thus balancing specialized segregated brain processes with coherent globally integrated whole brain activity. Mental disorders can be reconceptualized as disorders of plasticity resulting in disturbances of state-space brain configurations, matching and neural complexities. Personality disorders result from altered internal representations of the psychosocial environment. Depression and anxiety have been recently linked to alterations of adaptive neuronal plasticity thus reconceptualized as disorders of matching complexity. Finally, psychoses, including schizophrenia spectrum disorders, are reconceptualized as disturbances of neural complexity resulting in altered fast stabilizing plasticity. The new diagnostic system generates testable predictions regarding diagnosis and treatments of mental disorders which may be the future of psychiatry.


Assuntos
Cognição , Transtornos Mentais/diagnóstico , Transtornos Mentais/psicologia , Plasticidade Neuronal , Psiquiatria/métodos , Psicometria/métodos , Desempenho Psicomotor , Humanos , Transtornos Mentais/fisiopatologia , Escalas de Graduação Psiquiátrica , Índice de Gravidade de Doença
15.
Cyberpsychol Behav ; 6(4): 397-404, 2003 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-14511452

RESUMO

Patients with schizophrenia have thinking disorders such as delusions or hallucinations because they have a deficit in the ability to systematize and integrate information. Therefore, they cannot integrate or systematize visual, auditory, and tactile stimuli. The multimodal integration model of the brain can provide a theoretical background from which one can approach multimodal stimulus integration. In this study, we suggest a virtual reality system for the multi-modal assessment of cognitive ability of schizophrenia patients. The virtual reality system can provide multimodal stimuli, such as visual and auditory stimuli, to the patient and can evaluate the patient's multimodal integration and working memory integration abilities by making the patient interpret and react to multimodal stimuli, which must be remembered for a given period of time. The clinical study showed that the virtual reality program developed is comparable to those of the Wisconsin Card Sorting Test (WCST) and the Standard Progressive Matrices (SPM), and it provides some information related to the schizophrenic patients' behavior in 3D virtual environment.


Assuntos
Transtornos Cognitivos/diagnóstico , Simulação por Computador , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Comportamento Espacial/fisiologia , Interface Usuário-Computador , Adulto , Percepção Auditiva/fisiologia , Transtornos Cognitivos/complicações , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Estimulação Luminosa , Esquizofrenia/complicações , Esquizofrenia/diagnóstico , Percepção Espacial/fisiologia , Percepção Visual/fisiologia
16.
Clin Neurophysiol ; 125(3): 476-83, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24076133

RESUMO

OBJECTIVE: The study investigated local contextual processing in patients with major depressive disorder (MDD). This was defined as the ability to utilize predictive contextual information to facilitate detection of predictable versus random targets. METHOD: We recorded EEG in 15 MDD patients and 14 age-matched controls. Recording blocks consisted of targets preceded by randomized sequences of standards and by sequences of standards that included a predictive sequence signaling the occurrence of a subsequent target event. RESULTS: Both MDD patients and age-matched controls demonstrated a significant reaction time (RT) and P3b latency differences between predicted and random targets. However, patients demonstrated a specific prolongation of these measures during processing of predicted targets, as well as an attenuation of P3b amplitudes for the predictive sequence. In addition, patients target N1 amplitudes were attenuated compared with controls. CONCLUSION: MDD patients were able to utilize predictive context in order to facilitate processing of deterministic targets, however, this ability was limited compared to controls, as demonstrated by context-dependent P3b deficits. SIGNIFICANCE: These findings suggest that patients with major depression have altered processing of local contextual processing.


Assuntos
Compreensão , Transtorno Depressivo Maior/fisiopatologia , Transtorno Depressivo Maior/psicologia , Memória de Curto Prazo/fisiologia , Adolescente , Adulto , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Tempo de Reação/fisiologia
17.
Schizophr Res ; 158(1-3): 204-12, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24998031

RESUMO

This paper tests the hypothesis that patients with schizophrenia have a deficit in selectively attending to predictable events. We used dynamic causal modeling (DCM) of electrophysiological responses - to predictable and unpredictable visual targets - to quantify the effective connectivity within and between cortical sources in the visual hierarchy in 25 schizophrenia patients and 25 age-matched controls. We found evidence for marked differences between normal subjects and schizophrenia patients in the strength of extrinsic backward connections from higher hierarchical levels to lower levels within the visual system. In addition, we show that not only do schizophrenia subjects have abnormal connectivity but also that they fail to adjust or optimize this connectivity when events can be predicted. Thus, the differential intrinsic recurrent connectivity observed during processing of predictable versus unpredictable targets was markedly attenuated in schizophrenia patients compared with controls, suggesting a failure to modulate the sensitivity of neurons responsible for passing sensory information of prediction errors up the visual cortical hierarchy. The findings support the proposed role of abnormal connectivity in the neuropathology and pathophysiology of schizophrenia.


Assuntos
Atenção/fisiologia , Encéfalo/fisiopatologia , Potenciais Evocados/fisiologia , Modelos Neurológicos , Esquizofrenia/fisiopatologia , Percepção Visual/fisiologia , Adolescente , Adulto , Teorema de Bayes , Eletroencefalografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Vias Neurais/fisiopatologia , Neurônios/fisiologia , Testes Neuropsicológicos , Estimulação Luminosa , Esquizofrenia/tratamento farmacológico , Processamento de Sinais Assistido por Computador , Adulto Jovem
18.
Med Hypotheses ; 78(5): 636-40, 2012 May.
Artigo em Inglês | MEDLINE | ID: mdl-22342251

RESUMO

BACKGROUND: As an Ancient Chinese proverb says "The beginning of wisdom is to call things by their right names" thus we must start calling mental disorders by the names of their underlying brain disturbances. Without knowledge of the causes of mental disorders, their cures will remain elusive. METHODS: Neuroanalysis is a literature-based re-conceptualization of mental disorders as disturbances of brain organization. Psychosis and schizophrenia can be re-conceptualized as disturbances to connectivity and hierarchical dynamics in the brain; mood disorders can be re-conceptualized as disturbances to optimization dynamics and free energy in the brain, and finally personality disorders can be re-conceptualized as disordered default-mode networks in the brain. RESULTS AND CONCLUSIONS: Knowledge and awareness of the disease algorithms of mental disorders will become critical because powerful technologies for controlling brain activity are developing and becoming available. The time will soon come when psychiatrists will be asked to define the exact 'algorithms' of disturbances in their psychiatric patients. Neuroanalysis can be a starting point for the response to that challenge.


Assuntos
Transtornos Mentais/diagnóstico , Traumatismos do Nervo Acessório/fisiopatologia , Afeto/fisiologia , Algoritmos , Ansiedade/fisiopatologia , Ansiedade/psicologia , Encéfalo/fisiopatologia , Mapeamento Encefálico , Humanos , Transtornos Mentais/fisiopatologia , Transtornos Mentais/psicologia , Modelos Neurológicos , Plasticidade Neuronal/fisiologia , Transtornos da Personalidade/diagnóstico , Transtornos da Personalidade/fisiopatologia , Transtornos da Personalidade/psicologia , Transtornos Psicóticos/diagnóstico , Esquizofrenia/diagnóstico
19.
Med Hypotheses ; 79(4): 487-92, 2012 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-22832212

RESUMO

How can physical systems of the brain, explain a psychological phenomenon such as personality? Personality is an emergent property of the brain as such it requires interacting elements that generate a whole. Per definition a physical system is a compound whole made of interacting interdependent elements. The brain is composed of multiple levels of elements ranging from single neurons interconnected by axons dendrites and synapses, up to brain regions and neural network ensembles connected by multiple modalities, from direct physical pathways to synchronized functional connectivity. Today we know that the brain develops and wires according to the influences of its environment, this is called "experience dependent plasticity" and follows Hebbian-like algorithms. Such process "embeds" into the brain internal representations in the form of physical attractor configurations distributed within the brain neural-networks. Development entails formation of personal individual-specific network configurations found recently as resting-state networks or "default-mode networks." These internal configurations represent the outer world to us and determine the way we perceive it and react to it. In other words these internal configurations determine our personality styles. The internal representations continuously adapt to the changing worlds offering good adaptability and effective functionality in our changing environments. Personality disorders are reconceptualized in terms of altered disturbed mal-developed default-mode-networks, such that the internal representations are biased, limited, fixated and non-adaptive. In this context therapy of personality disorders can be reconceptualized as experience-depended plasticity therapy.


Assuntos
Encéfalo/fisiopatologia , Transtornos da Personalidade/fisiopatologia , Humanos , Modelos Neurológicos , Modelos Psicológicos , Rede Nervosa/fisiopatologia , Plasticidade Neuronal , Transtornos da Personalidade/psicologia , Transtornos da Personalidade/terapia , Psicofisiologia
20.
Med Hypotheses ; 76(1): 34-49, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-20828937

RESUMO

As early as the end of the 19th century Ernest Bruck declared that the brain is a physical entity and should be studied using the science of mathematics and physics. The brain is an extremely intricate physical entity and we have only recently begun to develop the conceptual tools to decipher this complexity. We can begin to comprehend many of the mental functions and dysfunctions by using insights about brain organization as a developing physical entity of connectivity structures. A comprehensive theoretical framework for the re-conceptualization of mental disorders as real brain-disorders, called "Clinical brain profiling" can be generated to make testable predictions about the etiopathology of psychiatric disorders. If validated, this framework has groundbreaking relevance for psychiatry, not only by providing an etiological diagnostic system, in itself revolutionary, but in its potential to develop effective curative interventions. According to the proposed brain profiling all mental disturbances can be defined in a 3 dimensional space of brain disturbances (1) neural-complexity organization, (2) to neural resilience optimization dynamics and (3) to connectivity constructs for context and internal representations. Neural complexity relates to the ability of the brain to balance connectivity dynamics, neural resilience relates to brain plasticity and changeability for optimizing overall brain dynamics and contextual configurations shape the internal representations of outer world that pattern out reaction and personality styles. Each of these organizational brain functions is predicted to involve a relatively specific neuronal circuitry system in the brain. The circuitry of the nigra-striautum-cortex, are a component of the connectivity balance stabilizers and regulators, a type of neural complexity pacemaker. Thus a patient that rates high on phenomenology related to functional psychosis indicating a disturbance to connectivity balance will have disturbances that will show up in appropriate signal processing imaging of the nigra-striautum-cortex circuitry. The circuitry of thalamus-amygdala-cortex and related pathways are relevant for neuronal matching and constraint frustration. In this respect the patients scoring high on mood and anxiety disorders are predicted to suffer from perturbation shown on appropriate imaging involving the thalamus-amygdala-cortex circuitries. The hippocampus is related to the formation of internal configurations thus those patients rating highest on parameters related to personality organization and maturation will show alterations in the hippocampal organization and activation indicating deficient organizations of internal configurations.


Assuntos
Encéfalo/fisiopatologia , Transtornos Mentais/diagnóstico , Humanos , Transtornos Mentais/fisiopatologia
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