RESUMO
Cardiovascular rhythms representing functional states of the autonomic nervous system (ANS) are insufficiently reflected by the current physiological model based on low and high frequency bands (LF, HF, resp.). An intermediate (IM) frequency band generated by a brainstem pacemaker was included in systemic physiological ANS analyses of forehead skin perfusion (SP), ECG, and respiration. Data of 38 healthy participants at T0 and T1 (+1 week) before, during, and following osteopathic cranial vault hold (CVH) stimulation were analyzed including momentary frequencies of highest amplitude, amplitudes in low (0.05-0.12 Hz), IM (0.12-0.18 Hz), and high (0.18-0.4 Hz) frequency bands, and established heart rate variability (HRV) metrics. During CVH, LF interval durations increased, whereas IM/HF band durations decreased significantly. Amplitudes increased significantly in all frequency bands. A cluster analysis found one response pattern dominated by IM activity (47% of participants) with highly stable 0.08 Hz oscillation to CVH, and one dominated by LF activity (0.10 Hz) at T0, increasing to IM activity at T1. Showing frequency ratios at ≈3:1, respiration was not responsible for oscillations in PPG during CVH. HRV revealed no significant responses. Rhythmic patterns in SP and respiration matched previous findings on a reticular "0.15 Hz rhythm". Involvement of baroreflex pathways is discussed as alternative explanation.
Assuntos
Sistema Nervoso Autônomo , Sistema Cardiovascular , Humanos , Pressão Sanguínea/fisiologia , Sistema Nervoso Autônomo/fisiologia , Respiração , Barorreflexo , Frequência Cardíaca/fisiologiaRESUMO
Intermediate (IM) band physiology in skin blood flow exhibits parallels with the primary respiratory mechanism (PRM) or cranial rhythmic impulse (CRI), controversial concepts of osteopathy in the cranial field (OCF). Owing to inconsistent manual palpation results, validity of evidence of PRM/CRI activity has been questionable. We therefore tried to validate manual palpation combining instrumented tracking and algorithmic objectivation of frequencies, amplitudes, and phases. Using a standard OCF intervention, cranial vault hold (CVH), two OCF experts palpated and digitally marked CRI frequencies in 25 healthy adults. Autonomic nervous system (ANS) activity in low frequency (LF) and IM band in photoplethysmographic (PPG) forehead skin recordings was probed with momentary frequency of highest amplitude (MFHA) and wavelet amplitude spectra (WAS) in examiners and participants. Palpation errors and frequency expectation bias during CVH were analyzed for phases of MFHA and CRI. Palpated CRI frequencies (0.05-0.08 Hz) correlated highly with mean MFHA frequencies with 1:1 ratio in 77% of participants (LF-responders; 0.072 Hz) and with 2:1 ratio in 23% of participants (IM-responders; 0.147 Hz). WAS analysis in both groups revealed integer number (harmonic) waves in (very) low and IM bands in > 98% of palpated intervals. Phase analyses in participants and examiners suggested synchronization between MFHA and CRI in a subset of LF-responders. IM band physiology in forehead PPG may offer a sensible physiological correlate of palpated CRI activity. Possible coordination or synchronization effects with additional physiological signals and between examiners and participants should be investigated in future studies.
Assuntos
Osteopatia , Palpação , Adulto , Humanos , Crânio/fisiologia , Testa , PeleRESUMO
AIMS: Patients with schizophrenia frequently show insufficient vitamin D levels, which are associated with somatic comorbidity and may contribute to psychopathology. For many reasons, vitamin D supplementation may be indicated for this patient cohort. However, there is growing evidence for a vitamin D-mediated increase of drug metabolism by induction of cytochrome P450 (CYP) 3A4. Hence, this study aimed to assess vitamin D's impact on both antipsychotic drug concentrations and psychopathology in a non-interventional manner. METHODS: Totals of 107 serum concentrations of different antipsychotic drugs (amisulpride, aripiprazole, clozapine, olanzapine, quetiapine and risperidone), 80 serum concentrations of vitamin D and psychopathological assessments were obtained from 80 patients with schizophrenia. The impact of Vitamin D on antipsychotic drug concentrations and symptomatology was assessed using a generalized linear model, path and correlation analyses. RESULTS: We observed a negative relationship between vitamin D and dose-adjusted antipsychotic drug concentrations, which was particularly pronounced for drugs which are predominantly metabolized via CYP3A4 (i.e., aripiprazole and quetiapine). A path analysis suggested a relieving effect of vitamin D on symptomatology which was, however, counteracted by its negative impact on antipsychotic drug levels. Finally, patients with vitamin D levels above the median exhibited a significantly higher proportion of therapeutically insufficient dose-normalized drug concentrations of aripiprazole and quetiapine. CONCLUSION: Despite vitamin D's potential benefits on physical and mental health, clinicians should be aware of its negative impact on blood concentrations of antipsychotics metabolized by CYP3A4 in patients with schizophrenia. Therefore, when considering its supplementation, therapeutic drug monitoring should be applied to guide dose adjustment.
Assuntos
Antipsicóticos , Esquizofrenia , Antipsicóticos/efeitos adversos , Aripiprazol/efeitos adversos , Benzodiazepinas/efeitos adversos , Citocromo P-450 CYP3A , Humanos , Fumarato de Quetiapina/uso terapêutico , Esquizofrenia/tratamento farmacológico , Vitamina DRESUMO
Brain-computer interfaces (BCIs) can be used in real-time fMRI neurofeedback (rtfMRI NF) investigations to provide feedback on brain activity to enable voluntary regulation of the blood-oxygen-level dependent (BOLD) signal from localized brain regions. However, the temporal pattern of successful self-regulation is dynamic and complex. In particular, the general linear model (GLM) assumes fixed temporal model functions and misses other dynamics. We propose a novel data-driven analyses approach for rtfMRI NF using intersubject covariance (ISC) analysis. The potential of ISC was examined in a reanalysis of data from 21 healthy individuals and nine patients with post-traumatic stress-disorder (PTSD) performing up-regulation of the anterior cingulate cortex (ACC). ISC in the PTSD group differed from healthy controls in a network including the right inferior frontal gyrus (IFG). In both cohorts, ISC decreased throughout the experiment indicating the development of individual regulation strategies. ISC analyses are a promising approach to reveal novel information on the mechanisms involved in voluntary self-regulation of brain signals and thus extend the results from GLM-based methods. ISC enables a novel set of research questions that can guide future neurofeedback and neuroimaging investigations.
Assuntos
Neurorretroalimentação , Transtornos de Estresse Pós-Traumáticos , Tonsila do Cerebelo , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância MagnéticaRESUMO
Real-time functional magnetic resonance imaging-based neurofeedback (rt-fMRI NF) is a recent technique used to train self-regulation of circumscribed brain areas or networks. For clinical applications in depression, NF training targets brain areas with disturbed activation patterns, such as heightened reactivity of amygdala in response to negative stimuli, in order to normalize the neurophysiology and their behavioral correlates. Recent studies have targeted emotion processing areas such as the amygdala, the salience network, and top-down control areas such as the lateral prefrontal cortex. Different methods of rt-fMRI-based NF in depression, their potential for clinical improvement, and most recent advancements of this technology are discussed considering their role for future clinical applications. Initial findings of randomized controlled trials show promising results. However, for lasting treatment effects, clinical efficiency and optimal target regions, tasks, control conditions, and duration of training need to be established.
Assuntos
Neurorretroalimentação , Tonsila do Cerebelo , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Depressão/diagnóstico por imagem , Depressão/terapia , Imageamento por Ressonância MagnéticaRESUMO
Real-time fMRI guided neurofeedback training has gained increasing interest as a noninvasive brain regulation technique with the potential to modulate functional brain alterations in therapeutic contexts. Individual variations in learning success and treatment response have been observed, yet the neural substrates underlying the learning of self-regulation remain unclear. Against this background, we explored potential brain structural predictors for learning success with pooled data from three real-time fMRI data sets. Our analysis revealed that gray matter volume of the right putamen could predict neurofeedback learning success across the three data sets (n = 66 in total). Importantly, the original studies employed different neurofeedback paradigms during which different brain regions were trained pointing to a general association with learning success independent of specific aspects of the experimental design. Given the role of the putamen in associative learning this finding may reflect an important role of instrumental learning processes and brain structural variations in associated brain regions for successful acquisition of fMRI neurofeedback-guided self-regulation.
Assuntos
Conectoma , Aprendizagem/fisiologia , Rede Nervosa/fisiologia , Neurorretroalimentação/fisiologia , Putamen/anatomia & histologia , Putamen/fisiologia , Autocontrole , Adulto , Córtex Cerebral/diagnóstico por imagem , Córtex Cerebral/fisiologia , Conjuntos de Dados como Assunto , Feminino , Neuroimagem Funcional , Humanos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/diagnóstico por imagem , Putamen/diagnóstico por imagem , Adulto JovemRESUMO
Auditory mismatch processing is accompanied by activation of a distributed brain network which can be detected by fMRI. However, the impact of different experimental designs such as event-related or block designs and different stimulus characteristics on the auditory mismatch response and the activity of this network remains controversial. In the present study, we applied five auditory mismatch paradigms with standard experimental designs and recorded fMRI in 31 healthy participants. Brain activity was analyzed using general linear models as well as classification approaches. The results stress a greater role of the type of the applied deviant stimulus compared to the experimental design. Moreover, the absolute number of the deviants as well as the length of the experimental run seems to play a greater role than the experimental design. The present study promotes optimization of experimental paradigms in the context of mismatch research. In particular, our findings contribute to designing auditory mismatch paradigms for application in clinical settings.
Assuntos
Percepção Auditiva/fisiologia , Potenciais Evocados Auditivos , Imageamento por Ressonância Magnética , Estimulação Acústica , Adulto , Mapeamento Encefálico , Feminino , Humanos , MasculinoRESUMO
The mismatch negativity is a cortical response to auditory changes and its reduction is a consistent finding in schizophrenia. Recent evidence revealed that the human brain detects auditory changes already at subcortical stages of the auditory pathway. This finding, however, raises the question where in the auditory hierarchy the schizophrenic deficit first evolves and whether the well-known cortical deficit may be a consequence of dysfunction at lower hierarchical levels. Finally, it should be resolved whether mismatch profiles differ between schizophrenia and affective disorders which exhibit auditory processing deficits as well. We used functional magnetic resonance imaging to assess auditory mismatch processing in 29 patients with schizophrenia, 27 patients with major depression, and 31 healthy control subjects. Analysis included whole-brain activation, region of interest, path and connectivity analysis. In schizophrenia, mismatch deficits emerged at all stages of the auditory pathway including the inferior colliculus, thalamus, auditory, and prefrontal cortex. In depression, deficits were observed in the prefrontal cortex only. Path analysis revealed that activation deficits propagated from subcortical to cortical nodes in a feed-forward mechanism. Finally, both patient groups exhibited reduced connectivity along this processing stream. Auditory mismatch impairments in schizophrenia already manifest at the subcortical level. Moreover, subcortical deficits contribute to the well-known cortical deficits and show specificity for schizophrenia. In contrast, depression is associated with cortical dysfunction only. Hence, schizophrenia and major depression exhibit different neural profiles of sensory processing deficits. Our findings add to a converging body of evidence for brainstem and thalamic dysfunction as a hallmark of schizophrenia.
Assuntos
Córtex Auditivo/fisiopatologia , Vias Auditivas/fisiopatologia , Percepção Auditiva/fisiologia , Conectoma , Transtorno Depressivo Maior/fisiopatologia , Colículos Inferiores/fisiopatologia , Córtex Pré-Frontal/fisiopatologia , Esquizofrenia/fisiopatologia , Tálamo/fisiopatologia , Adulto , Córtex Auditivo/diagnóstico por imagem , Vias Auditivas/diagnóstico por imagem , Transtorno Depressivo Maior/diagnóstico por imagem , Feminino , Humanos , Colículos Inferiores/diagnóstico por imagem , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Córtex Pré-Frontal/diagnóstico por imagem , Esquizofrenia/diagnóstico por imagem , Tálamo/diagnóstico por imagemRESUMO
BACKGROUND: Traumatic experiences are associated with neurofunctional dysregulations in key regions of the emotion regulation circuits. In particular, amygdala responsivity to negative stimuli is exaggerated while engagement of prefrontal regulatory control regions is attenuated. Successful application of emotion regulation (ER) strategies may counteract this disbalance, however, application of learned strategies in daily life is hampered in individuals afflicted by posttraumatic stress disorder (PTSD). We hypothesized that a single session of real-time fMRI (rtfMRI) guided upregulation of prefrontal regions during an emotion regulation task enhances self-control during exposure to negative stimuli and facilitates transfer of the learned ER skills to daily life. METHODS: In a cross-over design, individuals with a PTSD diagnosis after a single traumatic event (nâ¯=â¯20) according to DSM-IV-TR criteria and individuals without a formal psychiatric diagnosis (nâ¯=â¯21) underwent a cognitive reappraisal training. In randomized order, all participants completed two rtfMRI neurofeedback (NF) runs targeting the left lateral prefrontal cortex (lPFC) and two control runs without NF (NoNF) while using cognitive reappraisal to reduce their emotional response to negative scenes. During the NoNF runs, two %%-signs were displayed instead of the two-digit feedback (FB) to achieve a comparable visual stimulation. The project aimed at defining the clinical potential of the training according to three success markers: (1) NF induced changes in left lateral prefrontal cortex and bilateral amygdala activity during the regulation of aversive scenes compared to cognitive reappraisal alone (primary registered outcome), (2) associated changes on the symptomatic and behavioral level such as indicated by PTSD symptom severity and affect ratings, (3) clinical utility such as indicated by perceived efficacy, acceptance, and transfer to daily life measured four weeks after the training. RESULTS: In comparison to the reappraisal without feedback, a neurofeedback-specific decrease in the left lateral PFC (dâ¯=â¯0.54) alongside an attenuation of amygdala responses (dâ¯=â¯0.33) emerged. Reduced amygdala responses during NF were associated with symptom improvement (râ¯=â¯-0.42) and less negative affect (râ¯=â¯-0.63) at follow-up. The difference in symptom scores exceeds requirements for a minimal clinically important difference and corresponds to a medium effect size (dâ¯=â¯0.64). Importantly, 75% of individuals with PTSD used the strategies in daily life during a one-month follow-up period and perceived the training as efficient. CONCLUSION: Our findings suggest beneficial effects of the NF training indicated by reduced amygdala responses that were associated with improved symptom severity and affective state four weeks after the NF training as well as patient-centered perceived control during the training, helpfulness and application of strategies in daily life. However, reduced prefrontal involvement was unexpected. The study suggests good tolerability of the training protocol and potential for clinical use in the treatment of PTSD.
Assuntos
Neurorretroalimentação , Transtornos de Estresse Pós-Traumáticos , Tonsila do Cerebelo/diagnóstico por imagem , Mapeamento Encefálico , Cognição , Estudos Cross-Over , Emoções , Humanos , Imageamento por Ressonância Magnética , Transtornos de Estresse Pós-Traumáticos/diagnóstico por imagem , Transtornos de Estresse Pós-Traumáticos/terapiaRESUMO
BACKGROUND: The experience of auditory verbal hallucinations in schizophrenia is associated with changes in brain network function. In particular, studies indicate altered functional coupling between nodes of the language and default mode networks. Neurofeedback based on real-time functional magnetic resonance imaging (rtfMRI) can be used to modulate such aberrant network connectivity. METHODS: We investigated resting-state connectivity changes after neurofeedback (NF) in 21 patients with schizophrenia and 35 healthy individuals. All participants underwent two days of neurofeedback training of important nodes of the left-hemispheric language network including the inferior frontal gyrus (IFG) and posterior superior temporal gyrus (pSTG). In a double-blind randomized cross-over design, participants learned to down- and up-regulate their brain activation in the designated target regions based on NF. Prior to and after each training day, a resting state measurement took place. RESULTS: Coupling between nodes of the language and the default mode network (DMN) selectively increased after down-as compared to up-regulation NF. Network analyses revealed more pronounced increases in functional connectivity between nodes of the language network and the DMN in patients compared to healthy individuals. In particular, down-regulation NF led to increased coupling between nodes of the language network and bilateral inferior parietal lobe (IPL) as well as posterior cingulate cortex (PCC)/precuneus in patients. Up-regulation strengthened connectivity with the medial prefrontal cortex (mPFC). Improved well-being four weeks after the training predicted increased functional coupling between the left IFG and left IPL. CONCLUSION: Modulatory effects emerged as increased internetwork communication, indicating that down-regulation NF selectively enhances coupling between language and DM network nodes in patients with AVH. RtfMRI NF may thus be used to modulate brain network function that is relevant to the phenomenology of AVH. Specific effects of self-regulation on symptom improvement have to be explored in therapeutic interventions.
Assuntos
Córtex Cerebral/fisiopatologia , Conectoma/métodos , Alucinações/fisiopatologia , Idioma , Rede Nervosa/fisiopatologia , Neurorretroalimentação/fisiologia , Esquizofrenia/fisiopatologia , Adulto , Córtex Cerebral/diagnóstico por imagem , Método Duplo-Cego , Feminino , Alucinações/diagnóstico por imagem , Alucinações/etiologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Rede Nervosa/diagnóstico por imagem , Esquizofrenia/complicações , Esquizofrenia/diagnóstico por imagemRESUMO
Task performance depends on ongoing brain activity which can be influenced by attention, arousal, or motivation. However, such modulating factors of cognitive efficiency are unspecific, can be difficult to control, and are not suitable to facilitate neural processing in a regionally specific manner. Here, we non-pharmacologically manipulated regionally specific brain activity using technically sophisticated real-time fMRI neurofeedback. This was accomplished by training participants to simultaneously control ongoing brain activity in circumscribed motor and memory-related brain areas, namely the supplementary motor area and the parahippocampal cortex. We found that learned voluntary control over these functionally distinct brain areas caused functionally specific behavioral effects, i.e. shortening of motor reaction times and specific interference with memory encoding. The neurofeedback approach goes beyond improving cognitive efficiency by unspecific psychological factors such as attention, arousal, or motivation. It allows for directly manipulating sustained activity of task-relevant brain regions in order to yield specific behavioral or cognitive effects.
Assuntos
Imageamento por Ressonância Magnética/métodos , Neurorretroalimentação/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Atenção/fisiologia , Encéfalo/fisiologia , Feminino , Hipocampo/fisiologia , Humanos , Aprendizagem/fisiologia , Masculino , Memória/fisiologia , Córtex Motor/fisiologia , Tempo de Reação/fisiologia , Adulto JovemRESUMO
Deficits in emotion regulation are a prominent feature of psychiatric conditions and a promising target for treatment. For instance, cognitive reappraisal is regarded as an effective strategy for emotion regulation. Neurophysiological models have established the lateral prefrontal cortex (LPFC) as a key structure in the regulation of emotion processing through modulations of emotion-eliciting structures such as the amygdala. Feedback of the LPFC activity by real-time functional magnetic resonance (fMRI) may thus enhance the efficacy of cognitive reappraisal. During cognitive reappraisal of aversive visual stimuli, LPFC activity was fed back to the experimental group, whereas control participants received no such information. As a result, during reappraisal, amygdala activity was lower in the experimental group than in the controls. Furthermore, an increase of inter-hemispheric functional connectivity emerged in the feedback group. The current study extends the neurofeedback literature by suggesting that fMRI feedback can modify brain activity during a given task.
Assuntos
Tonsila do Cerebelo/fisiologia , Cognição/fisiologia , Emoções/fisiologia , Imageamento por Ressonância Magnética , Neurorretroalimentação/fisiologia , Adulto , Mapeamento Encefálico/métodos , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Percepção Visual/fisiologiaRESUMO
While impairments in emotion recognition are consistently reported in schizophrenia, there is some debate on the experience of emotion. Only few studies investigated neural correlates of emotional experience in schizophrenia. The present functional magnetic resonance imaging study compared a standard visual mood induction paradigm with an audiovisual method aimed at eliciting emotions more automatically. To investigate the interplay of sensory, cognitive and emotional mechanisms during emotion experience, we examined connectivity patterns between brain areas. Sixteen schizophrenia patients and sixteen healthy subjects participated in two different mood inductions (visual and audiovisual) that were administered for different emotions (happiness, sadness and neutral). Confirming the dissociation of behavioral and neural correlates of emotion experience, patients rated their mood similarly to healthy subjects but showed differences in neural activations. Sensory brain areas were activated less, increased activity emerged in higher cortical areas, particularly during audiovisual stimulation. Connectivity was increased between primary and secondary sensory processing areas in schizophrenia. These findings support the hypothesis of a deficit in filtering and processing sensory information alongside increased higher-order cognitive effort compensating for perception deficits in the affective domain. This may suffice to recover emotion experience in ratings of clinically stable patients but may fail during acute psychosis.
Assuntos
Afeto/fisiologia , Percepção Auditiva/fisiologia , Encéfalo/fisiopatologia , Esquizofrenia/fisiopatologia , Psicologia do Esquizofrênico , Percepção Visual/fisiologia , Estimulação Acústica , Adulto , Mapeamento Encefálico , Expressão Facial , Feminino , Felicidade , Humanos , Imageamento por Ressonância Magnética , Masculino , Música , Vias Neurais/fisiologia , Testes Neuropsicológicos , Estimulação LuminosaRESUMO
Mental imagery is a complex cognitive process that resembles the experience of perceiving an object when this object is not physically present to the senses. It has been shown that, depending on the sensory nature of the object, mental imagery also involves correspondent sensory neural mechanisms. However, it remains unclear which areas of the brain subserve supramodal imagery processes that are independent of the object modality, and which brain areas are involved in modality-specific imagery processes. Here, we conducted a functional magnetic resonance imaging study to reveal supramodal and modality-specific networks of mental imagery for auditory and visual information. A common supramodal brain network independent of imagery modality, two separate modality-specific networks for imagery of auditory and visual information, and a common deactivation network were identified. The supramodal network included brain areas related to attention, memory retrieval, motor preparation and semantic processing, as well as areas considered to be part of the default-mode network and multisensory integration areas. The modality-specific networks comprised brain areas involved in processing of respective modality-specific sensory information. Interestingly, we found that imagery of auditory information led to a relative deactivation within the modality-specific areas for visual imagery, and vice versa. In addition, mental imagery of both auditory and visual information widely suppressed the activity of primary sensory and motor areas, for example deactivation network. These findings have important implications for understanding the mechanisms that are involved in generation of mental imagery.
Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Imaginação/fisiologia , Rede Nervosa/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica , Adulto , Atenção , Mapeamento Encefálico , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Memória , Estimulação Luminosa , SemânticaRESUMO
Real-time fMRI allows analysis and visualization of the brain activity online, i.e. within one repetition time. It can be used in neurofeedback applications where subjects attempt to control an activation level in a specified region of interest (ROI) of their brain. The signal derived from the ROI is contaminated with noise and artifacts, namely with physiological noise from breathing and heart beat, scanner drift, motion-related artifacts and measurement noise. We developed a Bayesian approach to reduce noise and to remove artifacts in real-time using a modified Kalman filter. The system performs several signal processing operations: subtraction of constant and low-frequency signal components, spike removal and signal smoothing. Quantitative feedback signal quality analysis was used to estimate the quality of the neurofeedback time series and performance of the applied signal processing on different ROIs. The signal-to-noise ratio (SNR) across the entire time series and the group event-related SNR (eSNR) were significantly higher for the processed time series in comparison to the raw data. Applied signal processing improved the t-statistic increasing the significance of blood oxygen level-dependent (BOLD) signal changes. Accordingly, the contrast-to-noise ratio (CNR) of the feedback time series was improved as well. In addition, the data revealed increase of localized self-control across feedback sessions. The new signal processing approach provided reliable neurofeedback, performed precise artifacts removal, reduced noise, and required minimal manual adjustments of parameters. Advanced and fast online signal processing algorithms considerably increased the quality as well as the information content of the control signal which in turn resulted in higher contingency in the neurofeedback loop.
Assuntos
Artefatos , Mapeamento Encefálico/métodos , Encéfalo/fisiologia , Imageamento por Ressonância Magnética/métodos , Processamento de Sinais Assistido por Computador , Adulto , Teorema de Bayes , Feminino , Humanos , Masculino , Neurorretroalimentação/métodos , Neurorretroalimentação/fisiologia , Razão Sinal-RuídoRESUMO
Supramodal representation of emotion and its neural substrates have recently attracted attention as a marker of social cognition. However, the question whether perceptual integration of facial and vocal emotions takes place in primary sensory areas, multimodal cortices, or in affective structures remains unanswered yet. Using novel computer-generated stimuli, we combined emotional faces and voices in congruent and incongruent ways and assessed functional brain data (fMRI) during an emotional classification task. Both congruent and incongruent audiovisual stimuli evoked larger responses in thalamus and superior temporal regions compared with unimodal conditions. Congruent emotions were characterized by activation in amygdala, insula, ventral posterior cingulate (vPCC), temporo-occipital, and auditory cortices; incongruent emotions activated a frontoparietal network and bilateral caudate nucleus, indicating a greater processing load in working memory and emotion-encoding areas. The vPCC alone exhibited differential reactions to congruency and incongruency for all emotion categories and can thus be considered a central structure for supramodal representation of complex emotional information. Moreover, the left amygdala reflected supramodal representation of happy stimuli. These findings document that emotional information does not merge at the perceptual audiovisual integration level in unimodal or multimodal areas, but in vPCC and amygdala.
Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Emoções/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica/métodos , Adolescente , Adulto , Mapeamento Encefálico/métodos , Comportamento de Escolha/fisiologia , Simulação por Computador , Expressão Facial , Feminino , Humanos , Imageamento por Ressonância Magnética/métodos , Masculino , Memória de Curto Prazo/fisiologia , Estimulação Luminosa/métodos , Desempenho Psicomotor/fisiologiaRESUMO
Behavioral and electrophysiological data indicate compromised stimulus suppression in schizophrenia. The physiological basis of this effect and its contributions to the etiology of the disease are poorly understood. We examined neural and metabolic measures of P50 suppression in 12 patients with schizophrenia and controls. First, whole-head magnetoencephalography (MEG) assessed amplitudes of left- and right-hemispheric evoked responses and induced oscillations. Secondly, functional magnetic resonance imaging (fMRI) measured the hemodynamic responses to pairs of beeps with a short interval (500ms) as compared with those with a long interval (1500ms). The suppression of alpha power (8-13Hz) time-locked to the stimuli was negatively correlated with the suppression of evoked components and the hemodynamic measures. Remarkably, the suppression of alpha power was reduced in the patients already prior to stimulus onset. Conceivably, alpha oscillations play a central role in stimulus adaptation of neuronal networks and reflect an active mechanism for sensory suppression. The reduced stimulus suppression in schizophrenia seems to be in part due to impaired generation of alpha oscillations in the auditory cortex, resulting in higher metabolic demand as detected by fMRI. Delayed recovery of alpha rhythm may reflect an impaired gating function and contribute to sensory and cognitive deficits in schizophrenia.
Assuntos
Relógios Biológicos/fisiologia , Encéfalo/fisiopatologia , Potenciais Evocados Auditivos/fisiologia , Hemodinâmica/fisiologia , Esquizofrenia/fisiopatologia , Estatística como Assunto , Estimulação Acústica , Adolescente , Adulto , Encéfalo/irrigação sanguínea , Eletroencefalografia , Feminino , Lateralidade Funcional , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética/métodos , Magnetoencefalografia , Masculino , Oxigênio/sangue , Esquizofrenia/patologia , Fatores de Tempo , Adulto JovemRESUMO
Perceptual interpretation of the same multisensory stimuli may rely upon influence of attention on multisensory integration. We tested this hypothesis by recording the brain activity using magnetoencephalography in a passing-bouncing illusion with sound. Early activation of the attention-related brain areas and subsequent involvement of the multisensory areas were associated with the bouncing percept. Early activation of the unimodal sensory areas and later involvement of the attention-related areas were associated with the passing percept. Thus, the bouncing percept occurs when early attentional deployment facilitates multisensory integration modulating visual perception. The passing percept results from hierarchical sequence of the perceptual processes: early activation of the unimodal areas and late attentional deployment. Alternation of the perceptual interpretations may depend on spontaneous fluctuation of attention.
Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Mapeamento Encefálico , Córtex Somatossensorial/fisiologia , Percepção Visual/fisiologia , Estimulação Acústica , Adulto , Feminino , Humanos , Magnetoencefalografia , Masculino , Estimulação Luminosa , Processamento de Sinais Assistido por Computador , Adulto JovemRESUMO
BACKGROUND: Pitch identification had yielded unique response patterns compared to other auditory skills. Selecting one out of numerous pitches distinguished this task from detecting a pitch ascent. Encoding of numerous stimuli had activated the intraparietal sulcus in the visual domain. Therefore, we hypothesized that numerosity encoding during pitch identification activates the intraparietal sulcus as well. METHODS: To assess pitch identification, the participants had to recognize a single pitch from a set of four possible pitches in each trial. Functional magnetic resonance imaging (fMRI) disentangled neural activation during this four-pitch-choice task from activation during pitch contour perception, tone localization, and pitch discrimination. RESULTS: Pitch identification induced bilateral activation in the intraparietal sulcus compared to pitch discrimination. Correct responses in pitch identification correlated with activation in the left intraparietal sulcus. Pitch contour perception activated the superior temporal gyrus conceivably due to the larger range of presented tones. The differentiation between pitch identification and tone localization failed. Activation in an ACC-hippocampus network distinguished pitch discrimination from pitch identification. CONCLUSION: Pitch identification is distinguishable from pitch discrimination on the base of activation in the IPS. IPS activity during pitch identification may be the auditory counterpart of numerosity encoding in the visual domain.
Assuntos
Mapeamento Encefálico , Encéfalo/irrigação sanguínea , Imageamento por Ressonância Magnética , Discriminação da Altura Tonal/fisiologia , Percepção da Altura Sonora/fisiologia , Localização de Som/fisiologia , Estimulação Acústica/métodos , Adolescente , Adulto , Atenção/fisiologia , Encéfalo/fisiologia , Comportamento de Escolha , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Masculino , Música , Oxigênio/sangue , Adulto JovemRESUMO
The amygdala plays a key role in emotional processing. The specific contribution of the amygdala during the experience of one's own emotion, however, remains controversial and requires clarification. There is a long-standing debate on hemispheric lateralization of emotional processes, yet few studies to date directly investigated differential activation patterns for the left and right amygdala. Limited evidence supports right amygdala involvement in automatic processes of emotion and left amygdala involvement in conscious and cognitively controlled emotion processing. The present study investigated differential contributions of the left and right amygdala to cognitive and automatic mechanisms of mood induction. Using functional magnetic resonance imaging (fMRI), we examined hemispheric amygdala responses during two mood induction paradigms: a purely visual method presenting face stimuli and an audiovisual method using faces and music. Amygdala responses in 30 subjects (16 females) showed differences in lateralization patterns depending on the processing mode. The left amygdala exhibited comparable activation levels for both methods. The right amygdala, in contrast, showed increased activity only for the audiovisual condition and this activity was increasing over time. The left amygdala showed augmented activity with higher intensity ratings of negative emotional valence. These results support a left-lateralized cognitive and intentional control of mood and a right-sided more automatic induction of emotion that relies less on explicit reflection processes. The modulation of the left amygdala responses by subjective experience may reflect individual differences in the cognitive effort used to induce the mood. Thus, the central role of the amygdala may not be restricted to the perception of emotion in others but also extend into processes involved in regulation of mood.