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The rostromedioventral striatum is critical for behavior dependent on evaluating rewards. We asked what contribution tonically active neurons (TANs), the putative striatal cholinergic interneurons, make in coding reward value in this part of the striatum. Two female monkeys were given the option to accept or reject an offered reward in each trial, the value of which was signaled by a visual cue. Forty-five percent of the TANs use temporally modulated activity to encode information about discounted value. These responses were significantly better represented using principal component analysis than by just counting spikes. The temporal coding is straightforward: the spikes are distributed according to a sinusoidal envelope of activity that changes gain, ranging from positive to negative according to discounted value. Our results show that the information about the relative value of an offered reward is temporally encoded in neural spike trains of TANs. This temporal coding may allow well tuned, coordinated behavior to emerge.SIGNIFICANCE STATEMENT Ever since the discovery that neurons use trains of pulses to transmit information, it seemed self-evident that information would be encoded into the pattern of the spikes. However, there is not much evidence that spike patterns encode cognitive information. We find that a set of interneurons, the tonically active neurons (TANs) in monkeys' striatum, use temporal patterns of response to encode information about the discounted value of offered rewards. The code seems straightforward: a sinusoidal envelope that changes gain according to the discounted value of the offer, describes the rate of spiking across time. This temporal modulation may provide a means to synchronize these interneurons and the activity of other neural elements including principal output neurons.
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Comportamento Animal/fisiologia , Interneurônios/fisiologia , Recompensa , Estriado Ventral/fisiologia , Animais , Feminino , Macaca mulattaRESUMO
To review the emerging role of transcranial MR-guided focused ultrasound as a treatment and research modality for functional neurological disorders, we summarize recent clinical and preclinical studies. Clinical trials have investigated the safety and efficacy of thermal lesions created by transcranial, high-intensity focused ultrasound. Preclinical work has additionally investigated the ability to disrupt the blood-brain barrier and to produce reversible neuromodulation with focused ultrasound utilizing lower intensities. We discuss ongoing trials and future avenues of investigation. © 2016 International Parkinson and Movement Disorder Society.
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Ablação por Ultrassom Focalizado de Alta Intensidade/métodos , Imageamento por Ressonância Magnética/métodos , Doenças do Sistema Nervoso/cirurgia , Procedimentos Neurocirúrgicos/métodos , Cirurgia Assistida por Computador/métodos , Animais , Ablação por Ultrassom Focalizado de Alta Intensidade/tendências , Humanos , Imageamento por Ressonância Magnética/tendências , Procedimentos Neurocirúrgicos/tendências , Cirurgia Assistida por Computador/tendênciasRESUMO
Because the complex functions of the basal ganglia have been increasingly studied over the past several decades, the understanding of the role of the subthalamic nucleus (STN) in motor and cognitive functions has evolved. The traditional role in motor function ascribed to the STN, based on its involvement in the cortico-striato-thalamo-cortical motor loops, the pathologic STN activity seen in Parkinson's disease, and the benefits in motor symptoms following STN lesions and deep brain stimulation, has been revised to include wider cognitive functions. The increased attention focused on such nonmotor functions housed within the STN partially arose from the observed cognitive and affective side effects seen with STN deep brain stimulation. The multiple modalities of research have corroborated these findings and have provided converging evidence that the STN is critically involved in cognitive processes. In particular, numerous experiments have demonstrated the involvement of the STN in high-conflict decisions. The different STN functions appear to be related to activity in anatomically distinct subregions, with the ventral STN contributing to high-conflict decision-making through its role in the hyperdirect pathway involving the prefrontal cortex.
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Cognição/fisiologia , Núcleo Subtalâmico/fisiologia , Animais , HumanosRESUMO
Astroblastomas are exceedingly rare central nervous system tumors. Surgical resection is the standard initial treatment for astroblastomas. Still, some astroblastomas that have been completely resected recur. The optimal treatment for these lesions is unclear. There are no previous reports of the use of Gamma Knife radiosurgery in the treatment of astroblastomas. The patient is a 58 year old woman who had undergone resection of a left parieto-occipital tumor at an outside hospital in 2002, with repeat resection for recurrences in 2005 and 2007. Pathologic analysis at the Mayo Clinic demonstrated the tumor to be a low-grade astroblastoma. Repeat imaging in 2008 again demonstrated recurrence, and the patient was referred to our center for Gamma Knife radiosurgery. Pre and post-contrast T1 stereotactic MR images were obtained and imported into the treatment planning system for the Gamma Knife Perfexion. Two foci of tumor consistent with the patient's known left parietal astroblastoma were identified. A prescription dose of 18.00 Gy to the 50% isodose was delivered, and 16 isocenters were used. Follow-up imaging 17 months post-radiosurgery demonstrated a decrease in tumor size. Gamma Knife radiosurgery represents a useful treatment modality for recurrent astroblastomas. While surgical resection of low grade astroblastomas can be curative, Gamma Knife radiosurgery may be beneficial in cases where gross total resection is not feasible.
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Neoplasias Encefálicas/cirurgia , Recidiva Local de Neoplasia/cirurgia , Neoplasias Neuroepiteliomatosas/cirurgia , Radiocirurgia/métodos , Feminino , Humanos , Imageamento por Ressonância Magnética , Pessoa de Meia-Idade , Tomografia Computadorizada por Raios X , Resultado do TratamentoRESUMO
BACKGROUND: To study the feasibility of utilizing intracortical electroencephalography (ICE) including quantitative EEG (qEEG) analysis for the detection of vasospasm in five consecutive poor-grade SAH patients. METHODS: Intracortical electroencephalography (ICE) was obtained via a single miniature parenchymal 8-contact depth electrode placed at the bedside. Quantitative EEG parameters, calculated on surface EEG and ICE, included alpha/delta ratio (ADR), mean amplitude, suppression percent, and total power. Percent changes between averaged values over 4-6 h of baseline EEG and EEG prior to angiography were calculated. The entire continuous qEEG recording for each patient was then reviewed to determine optimal automated alarm criteria. RESULTS: ICE ADR was the most accurate for predicting angiographic vasospasm (5/5). ICE ADR decreased between baseline and follow-up by 42% (from 0.56 ± 0.07 to 0.32 ± 0.03) for those with vasospasm (N = 3) compared to 17% (0.62 ± 0.06 to 0.51 ± 0.03) for those without (N = 2). A sustained decrease in the ICE ADR from baseline (>25% for ≥ 4 h) occurred in all three patients with angiographically confirmed vasospasm and not in the two without; this decline occurred 1-3 days prior to angiographic confirmation. CONCLUSIONS: Intracortical EEG is promising for detecting ischemia from vasospasm in poor-grade SAH patients, may be superior to scalp EEG, and allow automated detection, particularly using the ADR. Larger studies are needed to better define the effectiveness of this approach.
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Isquemia Encefálica/diagnóstico , Eletroencefalografia/métodos , Monitorização Fisiológica/métodos , Hemorragia Subaracnóidea/complicações , Vasoespasmo Intracraniano/diagnóstico , Adulto , Idoso , Ritmo alfa , Isquemia Encefálica/etiologia , Isquemia Encefálica/fisiopatologia , Cuidados Críticos/métodos , Ritmo Delta , Estudos de Viabilidade , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Monitorização Fisiológica/instrumentação , Estudos Retrospectivos , Índice de Gravidade de Doença , Hemorragia Subaracnóidea/fisiopatologia , Vasoespasmo Intracraniano/etiologia , Vasoespasmo Intracraniano/fisiopatologiaRESUMO
Subjective cognitive side effects (CSEs) are common in patients taking antiepileptic drugs (AEDs). The objective of this study was to predict which patients are at risk for CSEs, and compare the CSE profiles of all commonly used AEDs. In this nonrandomized retrospective study, medical records of 1694 adult outpatients with epilepsy seen at our center over a 5-year period who had taken one or more AEDs were examined. Non-AED predictors of CSEs were investigated, and rates of AED-related CSEs were compared in 1189 patients (546 on monotherapy) newly started on an AED at our center. The average rate of AED-related intolerable CSEs (leading to dosage change or discontinuation) was 12.8%. On multivariate analysis, no significant non-AED predictors of CSEs were found. Significantly more intolerable CSEs were attributed to topiramate (21.5% of 130 patients) than to most other AEDs, including carbamazepine (9.9%), gabapentin (7.3%), levetiracetam (10.4%), lamotrigine (8.9%), oxcarbazepine (11.6%), and valproate (8.3%). CSE rates with zonisamide (14.9%) were significantly higher than those for gabapentin and lamotrigine. After exclusion of CSEs during the first 8 weeks of therapy, rates of CSEs were lower, but relative differences remained unchanged. In monotherapy, significantly more intolerable CSEs occurred with topiramate (11.1% of 18 patients) than with carbamazepine or valproate, and both phenytoin and zonisamide were associated with more CSEs than valproate. From this study, it can be concluded that intolerable patient-reported CSEs are most common with topiramate, followed by zonisamide, phenytoin, and oxcarbazepine. They are least likely to be reported with gabapentin, valproate, lamotrigine, carbamazepine, and levetiracetam.
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Anticonvulsivantes/efeitos adversos , Transtornos Cognitivos/induzido quimicamente , Transtornos Cognitivos/psicologia , Adulto , Transtornos Cognitivos/epidemiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Pacientes Ambulatoriais , Valor Preditivo dos TestesRESUMO
Pneumocephalus in the absence of a recent intracranial or intrathecal procedure is a significant radiographic finding and may be clinically relevant. Pneumocephalus secondary to intravenous catheterization may be a more common finding than previously expected. Although pneumocephalus is often associated with pathological conditions, recognition of a characteristic pattern of intravenous pneumocephalus in the presence of intravenous catheterization may aid the clinician in determining a patient's underlying condition. This unexpected radiographic finding should not necessarily be cause for alarm, and there is no evidence that intravenous pneumocephalus alone is harmful. We present a patient with intravenous pneumocephalus and a review of the literature.
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Cateterismo/efeitos adversos , Embolia Aérea/complicações , Pneumocefalia/etiologia , Humanos , Injeções Intravenosas/efeitos adversos , Masculino , Pessoa de Meia-Idade , Pneumocefalia/diagnóstico por imagem , Tomografia Computadorizada por Raios XRESUMO
Previous studies have shown that perceptual segregation increases after listening to longer tone sequences, an effect known as buildup. More recently, an effect of prior frequency separation (Δƒ) has been discovered: presenting tone sequences with a small Δƒ biases following sequences with an intermediate Δƒ to be segregated into two separate streams, whereas presenting context sequences with a large Δƒ biases following sequences to be integrated into one stream. Here we investigated how attention and task demands influenced these effects of prior stimuli by having participants perform one of three tasks during the context: making streaming judgments on the tone sequences, detecting amplitude modulation in the tones, and performing a visual task while ignoring the tones. Results from two experiments showed that although the effect of prior Δƒ was present across all conditions, the effect was reduced whenever streaming judgments were not made during the context. Experiment 2 showed that streaming was reduced during the beginning of a test sequence only when participants performed the visual task during the context. These experiments suggest that task-based and stimulus-based attention differentially affect distinct influences of prior stimuli, and are consistent with the contribution of distinct levels of processing that affect auditory segregation. (PsycINFO Database Record (c) 2018 APA, all rights reserved).
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Atenção/fisiologia , Percepção Auditiva/fisiologia , Desempenho Psicomotor/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Percepção Visual/fisiologia , Adulto JovemRESUMO
Zebrafish is already one of the most used model organisms in biomedical sciences and other research fields. It is therefore becoming increasingly important to assure that zebrafish maintained in laboratory aquaculture conditions are raised and housed under rigorous standards that promote health and welfare to guarantee the required quality and reproducibility of research data. Specifying the programs each facility is adopting would be the first step to achieve this by allowing other facilities to compare, improve, and discuss their protocols and fish performance. We provide in this article a detailed description of an integrated facility health management program, with protocols and readouts, fully designed and aimed at maximizing fish health, welfare, and performance for research.
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Criação de Animais Domésticos , Aquicultura , Arquitetura de Instituições de Saúde , Oncologia , Neurociências , Peixe-Zebra , Animais , Neoplasias , PesquisaRESUMO
Our experiences, even as adults, shape our brains. Regional differences have been found in experts, with the regions associated with their particular skill-set. Functional differences have also been noted in brain activation patterns in some experts. This study uses multimodal techniques to assess structural and functional patterns that differ between experts and non-experts. Sommeliers are experts in wine and thus in olfaction. We assessed differences in Master Sommeliers' brains, compared with controls, in structure and also in functional response to olfactory and visual judgment tasks. MRI data were analyzed using voxel-based morphometry as well as automated parcellation to assess structural properties, and group differences between tasks were calculated. Results indicate enhanced volume in the right insula and entorhinal cortex, with the cortical thickness of the entorhinal correlating with experience. There were regional activation differences in a large area involving the right olfactory and memory regions, with heightened activation specifically for sommeliers during an olfactory task. Our results indicate that sommeliers' brains show specialization in the expected regions of the olfactory and memory networks, and also in regions important in integration of internal sensory stimuli and external cues. Overall, these differences suggest that specialized expertise and training might result in enhancements in the brain well into adulthood. This is particularly important given the regions involved, which are the first to be impacted by many neurodegenerative diseases.
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OBJECTIVE: To investigate the effect of antiepileptic drug (AED) comedication, including all newer AEDs, on lamotrigine clearance (CL). DESIGN: We reviewed 570 medical charts of outpatients 12 years and older seen at the Columbia Comprehensive Epilepsy Center who received lamotrigine as monotherapy or adjunctive therapy. We investigated whether a given comedication contributed to the lamotrigine serum concentration. In addition, we examined whether the mean lamotrigine CL during comedication with each AED differed from the lamotrigine CL during monotherapy. Finally, we examined whether individuals had significantly different lamotrigine CLs when taking or not taking a particular comedication. RESULTS: Comedication with phenytoin, carbamazepine, and valproate sodium were the major AED predictors of lamotrigine serum concentration. Comedication regimens with felbamate, oxcarbazepine, and phenobarbital were small but significant predictors. The mean lamotrigine CL was 43.2 mL/h per kilogram of body weight with lamotrigine monotherapy, significantly higher with comedication with phenytoin (101.3 mL/h per kilogram) and carbamazepine (59.5 mL/h per kilogram) and significantly lower with valproate (16.9 mL/h per kilogram). Patients had significantly higher lamotrigine CL when taking phenytoin, carbamazepine, and phenobarbital than when not taking those comedications and had significantly lower lamotrigine CL when taking valproate. The mean lamotrigine CL was significantly lower than that associated with monotherapy in patients comedicated with valproate plus phenytoin (22.0 mL/h per kilogram) but not in patients comedicated with valproate plus carbamazepine (33.3 mL/h per kilogram). No other AEDs affected lamotrigine CL. CONCLUSION: Phenytoin increases lamotrigine CL by approximately 125%, carbamazepine increases lamotrigine CL by approximately 30% to 50%, and valproate decreases lamotrigine CL by approximately 60%. No newer AED, with the possible exception of oxcarbazepine, has a major impact on lamotrigine CL.
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Anticonvulsivantes/farmacologia , Antidepressivos/sangue , Epilepsia/sangue , Taxa de Depuração Metabólica/efeitos dos fármacos , Triazinas/sangue , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anticonvulsivantes/uso terapêutico , Antidepressivos/farmacocinética , Peso Corporal , Criança , Quimioterapia Combinada , Epilepsia/tratamento farmacológico , Feminino , Humanos , Lamotrigina , Masculino , Pessoa de Meia-Idade , Triazinas/farmacocinéticaRESUMO
A test sequence of alternating low-frequency (A) and high-frequency (B) tones in a repeating ". . . ABAB . . ." pattern is more likely to be heard as 2 segregated streams of tones when it is preceded by an isofrequency inducer sequence whose frequency matches either the A- or B-tone frequency (e.g., ". . . BBBB . . .") of the test, a phenomenon referred to as stream biasing. Low-level processes such as stimulus-selective adaptation of frequency-tuned neurons within early auditory processing stages have been thought by some to mediate stream biasing; however, the current study tested for the involvement of higher level processes. Inducers whose frequency matched neither the A- nor B-tone frequency (e.g., ". . . CCCC . . .") sometimes facilitated stream biasing. Stream biasing was also sensitive to complex features of the inducer sequence, namely whether the rhythmic pattern of the inducer matched the rhythm of the ABAB test. Stream biasing occurred even when an 8-s silent interval separated the inducer and test sequences, a time span longer than previously recognized (Beauvois & Meddis, 1997). These results suggest the involvement of persistent activation of high-level representations that affect perception.
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Estimulação Acústica/métodos , Percepção Auditiva/fisiologia , Memória/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto JovemRESUMO
BACKGROUND: Well-documented auditory processing deficits such as impaired frequency discrimination and reduced suppression of auditory brain responses in schizophrenia (SZ) may contribute to abnormal auditory functioning in everyday life. Lateral suppression of non-stimulated neurons by stimulated neurons has not been extensively assessed in SZ and likely plays an important role in precise encoding of sounds. Therefore, this study evaluated whether lateral suppression of activity in auditory cortex is impaired in SZ. METHODS: SZ participants and control participants watched a silent movie with subtitles while listening to trials composed of a 0.5s control stimulus (CS), a 3s filtered masking noise (FN), and a 0.5s test stimulus (TS). The CS and TS were identical on each trial and had energy corresponding to the high energy (recurrent suppression) or low energy (lateral suppression) portions of the FN. Event-related potentials were recorded and suppression was measured as the amplitude change between CS and TS. RESULTS: Peak amplitudes of the auditory P2 component (160-260ms) showed reduced lateral but not recurrent suppression in SZ participants. CONCLUSIONS: Reduced lateral suppression in SZ participants may lead to overlap of neuronal populations representing different auditory stimuli. Such imprecise neural representations may contribute to the difficulties SZ participants have in discriminating complex stimuli in everyday life.
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Córtex Auditivo/fisiopatologia , Percepção Auditiva/fisiologia , Transtornos Psicóticos/fisiopatologia , Esquizofrenia/fisiopatologia , Estimulação Acústica , Adulto , Eletroencefalografia , Potenciais Evocados Auditivos/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Percepção de Movimento/fisiologia , Estimulação Luminosa , Filtro Sensorial/fisiologia , Gravação em VídeoRESUMO
This study determined whether facilitation of auditory stream segregation could occur when facilitating context tones are accompanied by other sounds. Facilitation was measured as the likelihood of a repeated context tone that could match the low (A) or high (B) frequency of a repeating ABA test to increase the likelihood of hearing the test as segregated. We observed this type of facilitation when matching tones were alone, or with simultaneous bandpass noises or continuous speech, neither of which masked the tones. However, participants showed no streaming facilitation when a harmonic complex masked the context tones. Mistuning or desynchronizing the context tone relative to the rest of the complex did not facilitate streaming, despite the fact that the context tone was accessible to awareness and attention. Even presenting the context tone in a separate ear from the rest of the harmonic complex did not facilitate streaming, ruling out peripheral interference. Presenting the test as mistuned or desynchronized tones relative to complex tones eliminated the possibility that timbre changes from context to test interfered with facilitation resulting from the context. These results demonstrate the fragility of streaming facilitation and show that awareness of and attention to the context tones are not sufficient to overcome interference.
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Atenção/fisiologia , Percepção Auditiva/fisiologia , Conscientização/fisiologia , Adolescente , Adulto , Feminino , Humanos , Masculino , Mascaramento Perceptivo/fisiologia , Som , Percepção da Fala/fisiologia , Adulto JovemRESUMO
An important question is the extent to which declines in memory over time are due to passive loss or active interference from other stimuli. The purpose of the present study was to determine the extent to which implicit memory effects in the perceptual organization of sound sequences are subject to loss and interference. Toward this aim, we took advantage of two recently discovered context effects in the perceptual judgments of sound patterns, one that depends on stimulus features of previous sounds and one that depends on the previous perceptual organization of these sounds. The experiments measured how listeners' perceptual organization of a tone sequence (test) was influenced by the frequency separation, or the perceptual organization, of the two preceding sequences (context1 and context2). The results demonstrated clear evidence for loss of context effects over time but little evidence for interference. However, they also revealed that context effects can be surprisingly persistent. The robust effects of loss, followed by persistence, were similar for the two types of context effects. We discuss whether the same auditory memories might contain information about basic stimulus features of sounds (i.e., frequency separation), as well as the perceptual organization of these sounds.
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Percepção Auditiva/fisiologia , Julgamento/fisiologia , Memória de Curto Prazo/fisiologia , Reconhecimento Fisiológico de Modelo/fisiologia , Estimulação Acústica/métodos , Adolescente , Adulto , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Mascaramento Perceptivo/fisiologia , Psicoacústica , Adulto JovemRESUMO
BACKGROUND: Pediatric traumatic brain injury accounts for approximately 37,000 hospitalizations and 2,685 deaths in the United State annually. The 2003 guidelines consolidated and summarized the body of literature on this subject. Among the material covered was the role of surgical management of elevated intracranial pressure. Here we review the guideline recommendations, recent literature on the topic, and important recent results in the adult population. METHODS: A Medline literature review was performed to identify studies published since 2000 addressing decompressive craniectomy in the pediatric and adult populations. Important articles included in the 2003 guidelines were also reviewed. All references were reviewed to identify additional relevant studies. RESULTS: There is little new data that addresses the key issues for investigation proposed in the 2003 pediatric guidelines. The only randomized trial in the pediatric population remains a 2001 study, which demonstrated a benefit of decompressive craniectomy. One recent randomized trial in adults demonstrated no benefit of the procedure and an additional randomized trial in adults is underway. No pediatric randomized trial is planned. Smaller, non-randomized series appear to support the practice. CONCLUSION: Based on the only randomized trial in children and the abundance of smaller studies, it is our belief that decompressive craniectomy does provide a benefit in terms of the management of intracranial hypertension and overall outcome in children.
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Lesões Encefálicas/cirurgia , Craniectomia Descompressiva/métodos , Criança , Humanos , Resultado do TratamentoRESUMO
OBJECT: While some low-grade pediatric gliomas may be cured with resection, many patients harbor tumors that cannot be completely resected safely, are difficult to access via an open surgical approach, or recur. Gamma Knife surgery may be beneficial in the treatment of these tumors. METHODS: The authors reviewed a consecutive series of 24 pediatric patients treated at the authors' institution between 1989 and 2011. All patients harbored tumors that were either surgically inaccessible or had evidence of residual or recurrent growth after resection. Progression-free survival was evaluated and correlated with clinical variables. Additional outcomes evaluated were clinical outcome, imaging response, and overall survival. RESULTS: Between 1989 and 2011, 13 male and 11 female patients (median age 11 years, range 4-18 years) with gliomas were treated. Tumor pathology was pilocytic astrocytoma (WHO Grade I) in 15 patients (63%), WHO Grade II in 4 (17%), and WHO Grade III in 1 (4%). The tumor pathology was not confirmed in 4 patients (17%). The mean tumor volume at the time of treatment was 2.4 cm(3). Lesions were treated with a median maximum dose of 36 Gy, median of 3 isocenters, and median marginal dose of 15 Gy. The median duration of imaging follow-up was 74 months, and the median duration of clinical follow-up was 144 months. The tumors responded with a median decrease in volume of 71%. At last follow up, a decrease in tumor size of at least 50% was demonstrated in 18 patients (75%) and complete tumor resolution was achieved in 5 (21%). Progression-free survival at last follow-up was achieved in 20 patients (83%). Progression was documented in 4 patients (17%), with 3 patients requiring repeat resection and 1 patient dying. The initial tumor volume was significantly greater in patients with disease progression (mean volume 4.25 vs 2.0 cm(3), p < 0.001). Age, tumor pathology, tumor location, previous radiation, Karnofsky Performance Scale score, symptom duration, and target dosage did not differ significantly between the 2 groups. CONCLUSIONS: Gamma Knife surgery can provide good clinical control of residual or recurrent gliomas in pediatric patients. Worse outcomes in the present series were associated with larger tumor volumes at the time of treatment.
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Neoplasias Encefálicas/cirurgia , Glioma/cirurgia , Recidiva Local de Neoplasia/cirurgia , Radiocirurgia , Adolescente , Neoplasias Encefálicas/patologia , Criança , Pré-Escolar , Fatores de Confusão Epidemiológicos , Intervalo Livre de Doença , Feminino , Seguimentos , Glioma/patologia , Humanos , Masculino , Prontuários Médicos , Radiocirurgia/efeitos adversos , Radiocirurgia/métodos , Reoperação , Projetos de Pesquisa , Estudos Retrospectivos , Fatores de Tempo , Resultado do Tratamento , Carga TumoralRESUMO
BACKGROUND: Auditory impairments in schizophrenia have been demonstrated previously, especially for tasks requiring precise encoding of frequency, although it is unclear the extent to which they have difficulty using pitch information and other cues to segregate sounds. We determined the extent to which those with schizophrenia have difficulty using pitch information and other auditory cues to segregate sounds that are presented sequentially. METHODS: Ten participants with schizophrenia and nine healthy/normal control participants completed a battery of tasks that tested for the ability to perform sequential auditory stream segregation using pitch, amplitude modulation, or inter-aural phase difference as cues to segregation. RESULTS: All three sequential segregation tasks showed reduced tendency for those with schizophrenia to perceive segregated sounds, compared to control participants. CONCLUSIONS: These findings extend prior research by demonstrating a general impairment on sequential sound segregation tasks in schizophrenia, and not just on tasks that require precise encoding of frequency. Together, the pattern of results provide evidence that auditory impairments in schizophrenia result from selective abnormalities in neural circuits that carry out specific computations necessary for stream segregation, as opposed to an impairment in processing specific cues.
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Transtornos da Percepção Auditiva/fisiopatologia , Esquizofrenia/fisiopatologia , Adulto , Sinais (Psicologia) , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Testes Neuropsicológicos , Percepção da Altura Sonora/fisiologia , Psicoacústica , Fatores de TempoRESUMO
Auditory perception and cognition entails both low-level and high-level processes, which are likely to interact with each other to create our rich conscious experience of soundscapes. Recent research that we review has revealed numerous influences of high-level factors, such as attention, intention, and prior experience, on conscious auditory perception. And recently, studies have shown that auditory scene analysis tasks can exhibit multistability in a manner very similar to ambiguous visual stimuli, presenting a unique opportunity to study neural correlates of auditory awareness and the extent to which mechanisms of perception are shared across sensory modalities. Research has also led to a growing number of techniques through which auditory perception can be manipulated and even completely suppressed. Such findings have important consequences for our understanding of the mechanisms of perception and also should allow scientists to precisely distinguish the influences of different higher-level influences.
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We used behavior and event-related potentials (ERPs) to examine auditory stream segregation in people with schizophrenia and control participants. During each trial, a context pattern was presented, consisting of low (A) and high (B) tones and silence (-) in a repeating ABA- pattern, with a frequency separation (Δf) of 3, 6, or 12 semitones. Next, a test ABA-pattern was presented that always had a 6-semitone Δf. Larger Δf during the context resulted in more perception of two streams and larger N1 and P2 ERPs, but less perception of two streams during the test pattern. These effects of Δf were smaller in schizophrenia. Individuals with schizophrenia also showed a reduced effect of prior perceptual judgments. Overall, the findings demonstrate that people with schizophrenia have abnormalities in segregating sounds. These abnormalities result from difficulties utilizing frequency cues in addition to reduced temporal context effects.