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1.
J Cogn Neurosci ; : 1-9, 2019 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-31659925

RESUMO

An auditory event is often accompanied by characteristic visual information. For example, the sound level produced by a vigorous handclap may be related to the speed of hands as they move toward collision. Here, we tested the hypothesis that visual information about the intensity of auditory signals are capable of altering the subsequent neurophysiological response to auditory stimulation. To do this, we used EEG to measure the response of the human brain (n = 28) to the audiovisual delivery of handclaps. Depictions of a weak handclap were accompanied by auditory handclaps at low (65 dB) and intermediate (72.5 dB) sound levels, whereas depictions of a vigorous handclap were accompanied by auditory handclaps at intermediate (72.5 dB) and high (80 dB) sound levels. The dependent variable was the amplitude of the initial negative component (N1) of the auditory evoked potential. We find that identical clap sounds (intermediate level; 72.5 dB) elicited significantly lower N1 amplitudes when paired with a video of a weak clap, compared with when paired with a video of a vigorous clap. These results demonstrate that intensity predictions can affect the neural responses to auditory stimulation at very early stages (<100 msec) in sensory processing. Furthermore, the established sound-level dependence of auditory N1 amplitude suggests that such effects may serve the functional role of altering auditory responses in accordance with visual inferences. Thus, this study provides evidence that the neurally evoked response to an auditory event results from a combination of a person's beliefs with incoming auditory input.

2.
Artigo em Inglês | MEDLINE | ID: mdl-31399393

RESUMO

Speaking-induced suppression (SIS) is the phenomenon that the sounds one generates by overt speech elicit a smaller neurophysiological response in the auditory cortex than comparable sounds that are externally generated. SIS is a specific example of the more general phenomenon of self-suppression. SIS has been well established in nonhuman animals and is believed to involve the action of corollary discharges. This review summarizes, first, the evidence for SIS in heathy human participants, where it has been most commonly assessed with electroencephalography and/or magnetoencephalography using an experimental paradigm known as "Talk-Listen"; and second, the growing number of Talk-Listen studies that have reported subnormal levels of SIS in patients with schizophrenia. This result is theoretically significant, as it provides a plausible explanation for some of the most distinctive and characteristic symptoms of schizophrenia, namely the first-rank symptoms. In particular, while the failure to suppress the neural consequences of self-generated movements (such as those associated with overt speech) provides a prima facie explanation for delusions of control, the failure to suppress the neural consequences of self-generated inner speech provides a plausible explanation for certain classes of auditory-verbal hallucinations, such as audible thoughts. While the empirical evidence for a relationship between SIS and the first-rank symptoms is currently limited, I predict that future studies with more sensitive experimental designs will confirm its existence. Establishing the existence of a causal, mechanistic relationship would represent a major step forward in our understanding of schizophrenia, which is a necessary precursor to the development of novel treatments.

3.
Artigo em Inglês | MEDLINE | ID: mdl-31264785

RESUMO

BACKGROUND AND AIMS: The notion of basic self-disturbance has been proposed as a core feature of schizophrenia-spectrum disorders and as an indicator of future transition to psychosis in high-risk populations. However, the relation of this notion to many clinical characteristics has not been explored. The aim of this study was: (a) to investigate the distribution of self-disturbance and other symptoms dimensions in ultra-high risk (UHR), first-episode psychosis (FEP) and healthy control groups; and (b) to explore the association of self-disturbance with a history of self-harm, suicidal attempt, eating disorder symptomatology, school bullying victimization and sexual or physical abuse. METHODS: Patients with UHR status (n = 38) or FEP (n = 26) and healthy controls (n = 33) were assessed with the Examination of Anomalous Self-Experience (EASE) and the Comprehensive Assessment of at Risk Mental States (CAARMS). The clinical-historical variables were assessed through medical records. RESULTS: The FEP group scored significantly higher on the EASE than the UHR group, which scored significantly higher than the healthy control group, which had a very low score. Multivariate logistic regression analyses revealed that higher EASE score was significantly associated with a history of self-harm, disordered eating and bullying victimization (but not with suicide attempts or sexual/physical abuse) after controlling for positive, negative and depressive symptoms. CONCLUSION: These novel findings suggest that self-disturbance may be related to a history of school bullying victimization, self-harm and eating disorder symptomatology in patients with or at-risk of psychosis. If further confirmed, these findings are potentially relevant to clinical risk assessment and therapy.

4.
Neuroimage ; 198: 170-180, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31002966

RESUMO

When we move our articulator organs to produce overt speech, the brain generates a corollary discharge that acts to suppress the neural and perceptual responses to our speech sounds. Recent research suggests that inner speech - the silent production of words in one's mind - is also accompanied by a corollary discharge. Here, we show that this corollary discharge contains information about the temporal and physical properties of inner speech. In two experiments, participants produced an inner phoneme at a precisely-defined moment in time. An audible phoneme was presented 300 ms before, concurrently with, or 300 ms after participants produced the inner phoneme. We found that producing the inner phoneme attenuated the N1 component of the event-related potential - an index of auditory cortex processing - but only when the inner and audible phonemes occurred concurrently and matched on content. If the audible phoneme was presented before or after the production of the inner phoneme, or if the inner phoneme did not match the content of the audible phoneme, there was no attenuation of the N1. These results suggest that inner speech is accompanied by a temporally-precise and content-specific corollary discharge. We conclude that these results support the notion of a functional equivalence between the neural processes that underlie the production of inner and overt speech, and may provide a platform for identifying inner speech abnormalities in disorders in which they have been putatively associated, such as schizophrenia.

5.
Neurosci Biobehav Rev ; 101: 85-112, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30878499

RESUMO

BACKGROUND: Typically, we try to protect our own bodies and this is supported by internal representations that specify one's body identity, spatial parameters, and bodily sensations, but in self-harm the body becomes the target. First acts of self-harm are typically reported in adolescence. At this age, the body also becomes more salient to one's self-concept. It may be possible that disturbances in representations of one's own body and its sensations contribute to self-harm. METHODS: To investigate these links, we conducted a systematic review critically examining the potential role of body representation and sensation disturbances in self-harm (non-suicidal or suicidal) in adolescents and young adults (12-25 years). RESULTS: The search strategy identified 64 studies (275,183 participants) and overall, young people engaging in self-harm reported greater levels of body dissatisfaction, body disownership, and deficits in the experience and evaluation of bodily sensations compared to non-injuring control groups; however, there was subscale variability and gender differences. CONCLUSION: Our results emphasise the strong link between body representations and self-protection, as well as a need for investigating self-harm interventions that take body image and awareness into account.


Assuntos
Imagem Corporal , Comportamento Autodestrutivo/psicologia , Estudos Transversais , Emoções , Humanos , Interocepção , Estudos Longitudinais , Comportamento Autodestrutivo/epidemiologia , Suicídio/psicologia , Suicídio/estatística & dados numéricos
6.
Schizophr Res ; 208: 293-299, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30738699

RESUMO

Decreased brain activity in the frontal region, as indicated by increased slow wave EEG power measured by electrodes place on the skull over this area, in association with negative symptoms has previously been shown to distinguish ultra-high risk (UHR) individuals who later transitioned to psychosis (UHR-P) from those who did not transition (UHR-NP). The aims of the current study were to: 1) replicate these results and 2) investigate whether similar association between increased frontal slow wave activity and functioning shows any value in the prediction of transition to psychosis in UHR individuals. The brain activity, recorded using EEG, of 44 UHR individuals and 38 healthy controls was included in the analyses. Symptom severity was assessed in UHR participants and functioning was measured in both groups. The power in the theta frequency band in the frontal region of UHR individuals was higher than in controls. However, there was no difference between the UHR-P and the UHR-NP groups, and no change in slow frequency power following transition to psychosis. The correlation between delta frequency power and negative symptoms previously observed was not present in our UHR cohort, and there was no association between frontal delta or theta and functioning in either group. Increased delta power was rather correlated with depressive symptoms in the UHR group. Future research will be needed to better understand when, in the course of the illness, does the slow wave activity in the frontal area becomes impaired.

7.
PLoS One ; 13(12): e0208152, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30566534

RESUMO

The thalamus is believed to play crucial role in processing viscero-sensory information, and regulating the activity of amygdala in patients with panic disorder (PD). Previous functional neuroimaging studies have detected abnormal activation in the thalamus in patients with PD compared with healthy control subjects (HC). Very few studies, however, have investigated for volumetric abnormalities in the thalamus in patients with PD. Furthermore, to the best of our knowledge, no previous study has investigated for shape abnormalities in the thalamus in patients with PD. Twenty-five patients with PD and 25 HC participants (all female) were recruited for the study. A voxel-wise volume comparison analysis and a vertex-wise shape analysis were conducted to evaluate structural abnormalities in the PD patients compared to HC. The patients with PD demonstrated significant gray matter volume reductions in the thalamus bilaterally, relative to the HC. The shape analysis detected significant inward deformation in some thalamic regions in the PD patients, including the anterior nucleus, mediodorsal nucleus, and pulvinar nucleus. PD patients showed shape deformations in key thalamic regions that are believed to play a role in regulating emotional and cognitive functions.


Assuntos
Núcleos Anteriores do Tálamo/patologia , Núcleo Mediodorsal do Tálamo/patologia , Transtorno de Pânico/patologia , Pulvinar/patologia , Adulto , Núcleos Anteriores do Tálamo/diagnóstico por imagem , Estudos de Casos e Controles , Feminino , Voluntários Saudáveis , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imagem por Ressonância Magnética/métodos , Masculino , Núcleo Mediodorsal do Tálamo/diagnóstico por imagem , Pessoa de Meia-Idade , Tamanho do Órgão , Transtorno de Pânico/diagnóstico por imagem , Pulvinar/diagnóstico por imagem , Adulto Jovem
8.
Psychiatry Res ; 270: 915-921, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30551344

RESUMO

Individuals with elevated hoarding symptoms report elevated symptoms of ADHD and these symptoms are related to impaired daily functioning. Neuropsychological studies have found specific deficits in attention, and a recent review of attentional data from numerous hoarding studies concluded that inattention likely represents an etiological factor in hoarding, rather than a comorbidity. Our study aimed to examine which symptoms of ADHD, inattention or hyperactivity, are related to hoarding symptom severity, and whether individuals with hoarding symptoms display a neurophysiological marker of poor attention (Theta/Beta Ratio; THBR) that might explain these associations. The THBR indexes theta power relative to beta power in the frontal cortex and is often atypical in individuals with ADHD. We hypothesised that individuals would report more severe problems with inattention and would exhibit an elevated theta/beta ratio relative to a healthy control group. We also predicted that any relationship between hoarding and inattention would be independent of anxiety and depression symptoms. 17 hoarding-symptomatic participants and 16 healthy control participants completed self-report measures relating to ADHD, hoarding and general psychopathology, and then underwent resting measures of electroencephalography (EEG). Individuals with hoarding symptoms reported greater difficulties with inattention and hyperactivity, however they did not exhibit an elevated theta/beta ratio. When taking into account recent anxiety and depression, only inattention predicted hoarding symptom severity. Further investigations may help clarify this association and help inform attention-based treatments for hoarding.


Assuntos
Transtorno do Deficit de Atenção com Hiperatividade/fisiopatologia , Transtorno do Deficit de Atenção com Hiperatividade/psicologia , Eletroencefalografia , Colecionismo/fisiopatologia , Colecionismo/psicologia , Adulto , Ansiedade/psicologia , Ritmo beta/fisiologia , Depressão/psicologia , Feminino , Lobo Frontal/fisiopatologia , Humanos , Masculino , Autorrelato , Ritmo Teta/fisiologia
9.
Brain Res ; 2018 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-30391305

RESUMO

The human brain is an efficient, adaptive, and predictive machine, constructing a generative model of the environment that we then perceive and become conscious of. Here, we show that different types of prediction-errors - the discrepancies between top-down expectations and bottom-up sensory input - are integrated across processing levels and sensory modalities of the cortical hierarchy. We designed a novel, hybrid protocol in which five prediction-establishing sounds were played in rapid succession (e.g., "meow", "meow", "meow", etc.), followed by either a standard (e.g., "meow") or a deviant (e.g., "woof") prime sound, then a visual target word that was either congruent or incongruent (e.g., "cat" or "dog") with the prime sound. We found that the deviants elicited a more negative voltage than the standards at about 150 ms - the mismatch negativity (MMN), an event-related potential (ERP) sensitive to low-level perceptual violations - and that the incongruent words elicited a more negative voltage than the congruent words at about 350 ms - the N400, an ERP sensitive to high-level semantic violations. We also found that the N400 was context-dependent: the N400 was larger when the target words were preceded by a standard than a deviant. Our results suggest that perceptual prediction-errors modulate subsequent semantic prediction-errors. We conclude that our results are consistent with one of the most important assumptions of predictive coding theories: hierarchical prediction-error processing.

10.
PLoS One ; 13(11): e0207163, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30403747

RESUMO

The amygdala plays an important functional role in fear and anxiety. Abnormalities in the amygdala are believed to be involved in the neurobiological basis of panic disorder (PD). Previous structural neuroimaging studies have found global volumetric and morphological abnormalities in the amygdala in patients with PD. Very few studies, however, have explored for structural abnormalities in various amygdala sub-regions, which consist of various sub-nuclei, each with different functions. This study aimed to evaluate for volumetric abnormalities in the amygdala sub-nuclei, in order to provide a better understanding neurobiological basis of PD. Thirty-eight patients with PD and 38 matched healthy control (HC) participants underwent structural MRI scanning. The volume of the whole amygdala, as well as its consistent sub-nuclei, were calculated using FreeSurfer software. Relative volumes of these amygdala sub-regions were compared between the two groups. Results showed significantly smaller volumes in the right lateral and basal nuclei in the patients with PD compared with the HC. Lateral and basal nuclei are thought to play crucial role for processing sensory information related with anxiety and fear. Our results suggest that these particular amygdala sub-regions play a role in the development of PD symptoms.

11.
J Affect Disord ; 240: 199-202, 2018 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30077161

RESUMO

BACKGROUND: Panic disorder (PD), an anxiety disorder characterized by the recurrence of panic attacks, has been reported to be associated with volumetric changes in several brain regions. There are, however, very few studies investigating abnormalities in cortical thickness, and little is known about the relationship between cortical thickness and social dysfunction in PD. METHODS: Thirty-eight patients with PD and 38 healthy control participants (HC) were recruited for this study. A whole-brain analysis was performed to evaluate groupwise differences in cortical thickness using the FreeSurfer software. Symptom severity and social functioning were evaluated with the Panic Disorder Severity Scale (PDSS) and the Global Assessment of Functioning (GAF) scale. RESULTS: The patients with PD demonstrated a significant reduction in cortical thickness in the left rostral middle frontal cortex (MFC), compared with the HC. Correlational analyses revealed that cortical thickness in the left rostral MFC showed a significant negative relationship with PDSS score and a significant positive relationship with GAF scores in the PD patients. LIMITATIONS: All the patients received medication. CONCLUSION: PD patients showed reduced cortical thickness in the left rostral MFC compared with HC. Furthermore, cortical thickness in this region was associated with patients' symptom severity and degree of social dysfunction.

12.
Artigo em Inglês | MEDLINE | ID: mdl-29968972

RESUMO

AIM: The Inventory of Psychotic-Like Anomalous Self-Experiences (IPASE) is a self-report measure of minimal self-disturbance. The aim of the current report was to assess the construct validity of the scale by examining its convergent validity with the gold-standard measure of minimal self-disturbance, the Examination of Anomalous Self-Experience (EASE), and its discriminant validity. METHOD: The sample consisted of 46 participants (21 ultra-high risk for psychosis patients, 14 first episode psychosis patients, 11 healthy controls). Correlations between the clinical instruments were examined. RESULTS: The IPASE correlated strongly with general psychopathology and positive psychotic symptoms, moderately with negative symptoms, and weakly with manic symptoms. The strongest correlation (r = 0.92) was apparent between IPASE and EASE total scores. CONCLUSION: These preliminary data indicate construct validity of the IPASE, demonstrating both convergent and discriminant validity. The IPASE may be suitable as a screener measure for minimal self-disturbance, but should not be used as a replacement to measure the construct of minimal self-disturbance, which requires considerable psychopathological sophistication.

13.
Cognition ; 179: 14-22, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-29894867

RESUMO

Sensory attenuation refers to reduced brain responses to self-initiated sensations relative to those produced by the external world. It is a low-level process that may be linked to higher-level cognitive tasks such as reality monitoring. The phenomenon is often explained by prediction error mechanisms of universal applicability to sensory modality; however, it is most widely reported for auditory stimuli resulting from self-initiated hand movements. The present series of event-related potential (ERP) experiments explored the generalizability of sensory attenuation to the visual domain by exposing participants to flashes initiated by either their own button press or volitional saccade and comparing these conditions to identical, computer-initiated stimuli. The key results showed that the largest reduction of anterior visual N1 amplitude occurred for saccade-initiated flashes, while button press-initiated flashes evoked an intermediary response between the saccade-initiated and externally initiated conditions. This indicates that sensory attenuation occurs for visual stimuli and suggests that the degree of electrophysiological attenuation may relate to the causal likelihood of pairings between the type of motor action and the modality of its sensory response.

14.
Front Neural Circuits ; 12: 43, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29875638

RESUMO

Predictive coding postulates that the brain continually predicts forthcoming sensory events based on past experiences in order to process sensory information and respond to unexpected events in a fast and efficient manner. Predictive coding models in the context of overt speech are believed to operate along auditory white matter pathways such as the arcuate fasciculus and the frontal aslant. The aim of this study was to investigate whether brain regions that are structurally connected via these white matter pathways are also effectively engaged when listening to externally-generated, temporally-predicable speech sounds. Using Electroencephalography (EEG) and Dynamic Causal Modeling (DCM) we investigated network models that are structurally connected via the arcuate fasciculus from primary auditory cortex to Wernicke's and via Geschwind's territory to Broca's area. Connections between Broca's and supplementary motor area, which are structurally connected by the frontal aslant, were also included. The results revealed that bilateral areas interconnected by indirect and direct pathways of the arcuate fasciculus, in addition to regions interconnected by the frontal aslant best explain the EEG responses to speech that is externally-generated but temporally predictable. These findings indicate that structurally connected brain regions involved in the production and processing of auditory stimuli are also effectively connected.

15.
J Cogn Neurosci ; 30(8): 1145-1156, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29668396

RESUMO

Mechanisms of motor-sensory prediction are dependent on expectations regarding when self-generated feedback will occur. Existing behavioral and electrophysiological research suggests that we have a default expectation for immediate sensory feedback after executing an action. However, studies investigating the adaptability of this temporal expectation have been limited in their ability to differentiate modified expectations per se from effects of stimulus repetition. Here, we use a novel, within-participant procedure that allowed us to disentangle the effect of repetition from expectation and allowed us to determine whether the default assumption for immediate feedback is fixed and resistant to modification or is amenable to change with experience. While EEG was recorded, 45 participants completed a task in which they repeatedly pressed a button to produce a tone that occurred immediately after the button press (immediate training) or after a 100-msec delay (delayed training). The results revealed significant differences in the patterns of cortical change across the two training conditions. Specifically, there was a significant reduction in the cortical response to tones across delayed training blocks but no significant change across immediate training blocks. Furthermore, experience with delayed training did not result in increased cortical activity in response to immediate feedback. These findings suggest that experience with action-sensation delays broadens the window of temporal expectations, allowing for the simultaneous anticipation of both delayed and immediate motor-sensory feedback. This research provides insights into the mechanisms underlying motor-sensory prediction and may represent a novel therapeutic avenue for psychotic symptoms, which are ostensibly associated with sensory prediction abnormalities.

16.
Transl Psychiatry ; 8(1): 21, 2018 01 22.
Artigo em Inglês | MEDLINE | ID: mdl-29353880

RESUMO

Brain white matter abnormalities are evident in individuals with schizophrenia, and also their first-degree relatives, suggesting that some alterations may relate to underlying genetic risk. The ST8 alpha-N-acetyl-neuraminide alpha-2,8-sialyltransferase 2 (ST8SIA2) gene, which encodes the alpha-2,8-sialyltransferase 8B enzyme that aids neuronal migration and synaptic plasticity, was previously implicated as a schizophrenia susceptibility gene. This study examined the extent to which specific haplotypes in ST8SIA2 influence white matter microstructure using diffusion-weighted imaging of individuals with schizophrenia (n = 281) and healthy controls (n = 172), recruited across five Australian sites. Interactions between diagnostic status and the number of haplotype copies (0 or ≥1) were tested across all white matter voxels with cluster-based statistics. Fractional anisotropy (FA) in the right parietal lobe was found to show a significant interaction between diagnosis and ST8SIA2 protective haplotype (p < 0.05, family-wise error rate (FWER) cluster-corrected). The protective haplotype was associated with increased FA in controls, but this effect was reversed in people with schizophrenia. White matter fiber tracking revealed that the region-of-interest was traversed by portions of the superior longitudinal fasciculus, corona radiata, and posterior limb of internal capsule. Post hoc analysis revealed that reduced FA in this regional juncture correlated with reduced IQ in people with schizophrenia. The ST8SIA2 risk haplotype copy number did not show any differential effects on white matter. This study provides a link between a common disease-associated haplotype and specific changes in white matter microstructure, which may relate to resilience or risk for mental illness, providing further compelling evidence for involvement of ST8SIA2 in the pathophysiology of schizophrenia.


Assuntos
Esquizofrenia/genética , Esquizofrenia/fisiopatologia , Sialiltransferases/genética , Substância Branca/patologia , Adolescente , Adulto , Anisotropia , Austrália , Estudos de Casos e Controles , Imagem de Difusão por Ressonância Magnética , Feminino , Haplótipos , Humanos , Masculino , Pessoa de Meia-Idade , Fibras Nervosas Mielinizadas/patologia , Substância Branca/diagnóstico por imagem , Adulto Jovem
17.
Schizophr Bull ; 44(6): 1312-1322, 2018 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-29194516

RESUMO

Self-generated speech produces a smaller N1 amplitude in the auditory-evoked potential than externally generated speech; this phenomenon is known as N1-suppression. Schizophrenia patients show less N1-suppression than healthy controls. This failure to self-suppress may underlie patients' characteristic tendency to misattribute self-generated thoughts and actions to external sources. While the cause of N1-suppression deficits to speech in schizophrenia remains unclear, structural damage to the arcuate fasciculus is a candidate, due to its ostensible role in transmitting the efference copy of the motor plan to speak. Fifty-one patients with early illness schizophrenia (ESZ), 40 individuals at clinical high-risk for psychosis (CHR), and 59 healthy control (HC) participants underwent an electroencephalogram while they spoke and then listened to a recording of their speech. N1-suppression to the spoken sounds was calculated. Participants also underwent a diffusion-tensor imaging (DTI) scan, from which the arcuate fasciculus and pyramidal tract were extracted with deterministic tractography. ESZ patients exhibited significantly less N1-suppression to self-generated speech than HC participants, with CHR participants exhibiting intermediate levels. ESZ patients also exhibited structural abnormalities in the arcuate fasciculus-specifically, reduced fractional anisotropy and increased radial diffusivity-relative to both HC and CHR. There were no between-group differences in the structural integrity of the pyramidal tract. Finally, level of N1-suppression was linearly related to the structural integrity of the arcuate fasciculus, but not the pyramidal tract, across groups. These results suggest that the self-suppression deficits to willed speech consistently observed in schizophrenia patients may be caused, at least in part, by structural damage to the arcuate fasciculus.

18.
Schizophr Res ; 191: 95-100, 2018 01.
Artigo em Inglês | MEDLINE | ID: mdl-29132815

RESUMO

BACKGROUND: There is evidence to suggest that people with established psychotic disorders show impairments in the mismatch negativity induced by a frequency-deviant sound (fMMN), and that these impairments worsen with the deterioration of psychotic symptoms. This study aimed to test whether individuals at ultra-high risk (UHR) for psychosis show pre-morbid impairments in fMMN, and if so, whether fMMN continues to deteriorate with transition to psychosis. METHOD: fMMN was recorded in a cohort of UHR individuals (n=42) and compared to healthy controls (n=29). Of the 27 UHR participants who returned for a second EEG session, six participants had transitioned to psychosis by 12-month follow-up (UHR-T) and were compared to the 21 participants who did not transition (UHR-NT). RESULTS: fMMN amplitude was significantly reduced, relative to healthy controls, in the UHR cohort. Furthermore, UHR-T individuals showed a significant decrease in fMMN amplitude over the period from baseline to post-transition; this reduction was not observed in UHR-NT. CONCLUSIONS: These results suggest that fMMN is abnormal in UHR individuals, as has repeatedly been found previously in people with established psychotic disorders. The finding that fMMN impairment worsens with transition to psychosis is consistent with the staging model of psychosis; however, caution must be taken in interpreting these findings, given the extremely small sample size of the UHR-T group.


Assuntos
Variação Contingente Negativa/fisiologia , Potenciais Evocados Auditivos/fisiologia , Transtornos Psicóticos/fisiopatologia , Estimulação Acústica , Adolescente , Adulto , Análise de Variância , Eletroencefalografia , Feminino , Humanos , Masculino , Testes Neuropsicológicos , Escalas de Graduação Psiquiátrica , Fatores de Risco , Adulto Jovem
19.
Brain Imaging Behav ; 12(2): 449-458, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-28341872

RESUMO

Diffusion tensor imaging studies report childhood adversity (CA) is associated with reduced fractional anisotropy (FA) in multiple white matter tracts in adults. Reduced FA may result from changes in tissue, suggesting myelin/axonal damage, and/or from increased levels of extracellular free-water, suggesting atrophy or neuroinflammation. Free-water imaging can separately identify FA in tissue (FAT) and the fractional volume of free-water (FW). We tested whether CA was associated with altered FA, FAT, and FW in seven white matter regions of interest (ROI), in which FA changes had been previously linked to CA (corona radiata, corpus callosum, fornix, cingulum bundle: hippocampal projection, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, uncinate fasciculus). Tract-based spatial statistics were performed in 147 psychiatrically healthy adults who had completed a self-report questionnaire on CA primarily stemming from parental maltreatment. ROI were extracted according to the protocol provided by the ENIGMA-DTI working group. Analyses were performed both treating CA as a continuous and a categorical variable. CA was associated with reduced FA in all ROI (although categorical analyses failed to find an association in the fornix). In contrast, CA was only associated with reduced FAT in the corona radiata, corpus callosum, and uncinate fasciculus (with the continuous measure of CA finding evidence of a negative relation between CA and FAT in the fornix). There was no association between CA on FW in any ROI. These results provide preliminary evidence that childhood adversity is associated with changes to the microstructure of white matter itself in adulthood. However, these results should be treated with caution until they can be replicated by future studies which address the limitations of the present study.

20.
Elife ; 62017 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-29199947

RESUMO

Efference copies refer to internal duplicates of movement-producing neural signals. Their primary function is to predict, and often suppress, the sensory consequences of willed movements. Efference copies have been almost exclusively investigated in the context of overt movements. The current electrophysiological study employed a novel design to show that inner speech - the silent production of words in one's mind - is also associated with an efference copy. Participants produced an inner phoneme at a precisely specified time, at which an audible phoneme was concurrently presented. The production of the inner phoneme resulted in electrophysiological suppression, but only if the content of the inner phoneme matched the content of the audible phoneme. These results demonstrate that inner speech - a purely mental action - is associated with an efference copy with detailed auditory properties. These findings suggest that inner speech may ultimately reflect a special type of overt speech.


Assuntos
Encéfalo/fisiologia , Cognição , Fala , Adolescente , Adulto , Eletroencefalografia , Feminino , Voluntários Saudáveis , Humanos , Masculino , Adulto Jovem
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