Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 45
Filtrar
1.
Nat Rev Neurosci ; 24(5): 313-329, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36997716

RESUMO

Wilful movement requires neural control. Commonly, neural computations are thought to generate motor commands that bring the musculoskeletal system - that is, the plant - from its current physical state into a desired physical state. The current state can be estimated from past motor commands and from sensory information. Modelling movement on the basis of this concept of plant control strives to explain behaviour by identifying the computational principles for control signals that can reproduce the observed features of movements. From an alternative perspective, movements emerge in a dynamically coupled agent-environment system from the pursuit of subjective perceptual goals. Modelling movement on the basis of this concept of perceptual control aims to identify the controlled percepts and their coupling rules that can give rise to the observed characteristics of behaviour. In this Perspective, we discuss a broad spectrum of approaches to modelling human motor control and their notions of control signals, internal models, handling of sensory feedback delays and learning. We focus on the influence that the plant control and the perceptual control perspective may have on decisions when modelling empirical data, which may in turn shape our understanding of actions.


Assuntos
Aprendizagem , Movimento , Humanos
2.
Nervenarzt ; 92(8): 802-808, 2021 Aug.
Artigo em Alemão | MEDLINE | ID: mdl-33591414

RESUMO

BACKGROUND: Typical lacunar syndromes do not include aphasia but aphasia has been reported in rare atypical lacunar syndromes. OBJECTIVE: Description of the phenomenology and of affected fiber tracts. MATERIAL AND METHODS: Case series of three patients with lacunar stroke as evidenced by magnetic resonance imaging. Identification of affected fiber tracts via fiber tracking from coregistered lesion sites in brains of two healthy participants. RESULTS: The lacunar strokes that produced aphasia were located in the very lateral territory of perforating branches of the middle cerebral artery and extended along the external capsule into its most rostrodorsal aspect. Even though the cortex, thalamus and most parts of the basal ganglia were unaffected, patients exhibited a mild to moderate nonfluent aphasia with syntactic deficits. Fiber tracking revealed that in contrast to the nonaphasic control patient with a neighboring lacunar stroke, the aphasic patient strokes involved particularly fibers of the left arcuate fascicle as well as fibers of the frontostriatal and frontal aslant tracts. CONCLUSION: Left lateral lacunar stroke can cause clinically relevant aphasia through disruption of speech-relevant fiber tracts.


Assuntos
Afasia , Acidente Vascular Cerebral Lacunar , Acidente Vascular Cerebral , Substância Branca , Afasia/diagnóstico , Encéfalo , Humanos , Acidente Vascular Cerebral Lacunar/diagnóstico , Acidente Vascular Cerebral Lacunar/diagnóstico por imagem
3.
J Neurosci ; 39(33): 6498-6512, 2019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31196933

RESUMO

The way the human brain represents speech in memory is still unknown. An obvious characteristic of speech is its evolvement over time. During speech processing, neural oscillations are modulated by the temporal properties of the acoustic speech signal, but also acquired knowledge on the temporal structure of language influences speech perception-related brain activity. This suggests that speech could be represented in the temporal domain, a form of representation that the brain also uses to encode autobiographic memories. Empirical evidence for such a memory code is lacking. We investigated the nature of speech memory representations using direct cortical recordings in the left perisylvian cortex during delayed sentence reproduction in female and male patients undergoing awake tumor surgery. Our results reveal that the brain endogenously represents speech in the temporal domain. Temporal pattern similarity analyses revealed that the phase of frontotemporal low-frequency oscillations, primarily in the beta range, represents sentence identity in working memory. The positive relationship between beta power during working memory and task performance suggests that working memory representations benefit from increased phase separation.SIGNIFICANCE STATEMENT Memory is an endogenous source of information based on experience. While neural oscillations encode autobiographic memories in the temporal domain, little is known on their contribution to memory representations of human speech. Our electrocortical recordings in participants who maintain sentences in memory identify the phase of left frontotemporal beta oscillations as the most prominent information carrier of sentence identity. These observations provide evidence for a theoretical model on speech memory representations and explain why interfering with beta oscillations in the left inferior frontal cortex diminishes verbal working memory capacity. The lack of sentence identity coding at the syllabic rate suggests that sentences are represented in memory in a more abstract form compared with speech coding during speech perception and production.


Assuntos
Encéfalo/fisiologia , Memória de Curto Prazo/fisiologia , Percepção da Fala/fisiologia , Fala/fisiologia , Adulto , Eletrocorticografia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Adulto Jovem
4.
Hum Brain Mapp ; 38(1): 493-508, 2017 01.
Artigo em Inglês | MEDLINE | ID: mdl-27622923

RESUMO

Phonetic detail and lateralization of inner speech during covert sentence reading as well as overt reading in 32 right-handed healthy participants undergoing 3T fMRI were investigated. The number of voiceless and voiced consonants in the processed sentences was systematically varied. Participants listened to sentences, read them covertly, silently mouthed them while reading, and read them overtly. Condition comparisons allowed for the study of effects of externally versus self-generated auditory input and of somatosensory feedback related to or independent of voicing. In every condition, increased voicing modulated bilateral voice-selective regions in the superior temporal sulcus without any lateralization. The enhanced temporal modulation and/or higher spectral frequencies of sentences rich in voiceless consonants induced left-lateralized activation of phonological regions in the posterior temporal lobe, regardless of condition. These results provide evidence that inner speech during reading codes detail as fine as consonant voicing. Our findings suggest that the fronto-temporal internal loops underlying inner speech target different temporal regions. These regions differ in their sensitivity to inner or overt acoustic speech features. More slowly varying acoustic parameters are represented more anteriorly and bilaterally in the temporal lobe while quickly changing acoustic features are processed in more posterior left temporal cortices. Furthermore, processing of external auditory feedback during overt sentence reading was sensitive to consonant voicing only in the left superior temporal cortex. Voicing did not modulate left-lateralized processing of somatosensory feedback during articulation or bilateral motor processing. This suggests voicing is primarily monitored in the auditory rather than in the somatosensory feedback channel. Hum Brain Mapp 38:493-508, 2017. © 2016 Wiley Periodicals, Inc.


Assuntos
Encéfalo/fisiologia , Retroalimentação Fisiológica/fisiologia , Lateralidade Funcional/fisiologia , Fonética , Leitura , Percepção da Fala/fisiologia , Estimulação Acústica , Adulto , Encéfalo/diagnóstico por imagem , Mapeamento Encefálico , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Oxigênio/sangue , Estimulação Física , Semântica , Adulto Jovem
5.
Epilepsy Behav ; 76: 7-12, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28917498

RESUMO

Despite the availability of more than 15 new "antiepileptic drugs", the proportion of patients with pharmacoresistant epilepsy has remained constant at about 20-30%. Furthermore, no disease-modifying treatments shown to prevent the development of epilepsy following an initial precipitating brain injury or to reverse established epilepsy have been identified to date. This is likely in part due to the polyetiologic nature of epilepsy, which in turn requires personalized medicine approaches. Recent advances in imaging, pathology, genetics, and epigenetics have led to new pathophysiological concepts and the identification of monogenic causes of epilepsy. In the context of these advances, the First International Symposium on Personalized Translational Epilepsy Research (1st ISymPTER) was held in Frankfurt on September 8, 2016, to discuss novel approaches and future perspectives for personalized translational research. These included new developments and ideas in a range of experimental and clinical areas such as deep phenotyping, quantitative brain imaging, EEG/MEG-based analysis of network dysfunction, tissue-based translational studies, innate immunity mechanisms, microRNA as treatment targets, functional characterization of genetic variants in human cell models and rodent organotypic slice cultures, personalized treatment approaches for monogenic epilepsies, blood-brain barrier dysfunction, therapeutic focal tissue modification, computational modeling for target and biomarker identification, and cost analysis in (monogenic) disease and its treatment. This report on the meeting proceedings is aimed at stimulating much needed investments of time and resources in personalized translational epilepsy research. This Part II includes the experimental and translational approaches and a discussion of the future perspectives, while the diagnostic methods, EEG network analysis, biomarkers, and personalized treatment approaches were addressed in Part I [1].


Assuntos
Biomarcadores , Encéfalo/patologia , Epilepsia/terapia , Medicina de Precisão , Pesquisa Translacional Biomédica , Anticonvulsivantes/uso terapêutico , Barreira Hematoencefálica , Lesões Encefálicas/patologia , Epigenômica , Epilepsia/diagnóstico , Epilepsia/genética , Variação Genética , Humanos , Pesquisa Translacional Biomédica/tendências
6.
Epilepsy Behav ; 76: 13-18, 2017 11.
Artigo em Inglês | MEDLINE | ID: mdl-28917501

RESUMO

Despite the availability of more than 15 new "antiepileptic drugs", the proportion of patients with pharmacoresistant epilepsy has remained constant at about 20-30%. Furthermore, no disease-modifying treatments shown to prevent the development of epilepsy following an initial precipitating brain injury or to reverse established epilepsy have been identified to date. This is likely in part due to the polyetiologic nature of epilepsy, which in turn requires personalized medicine approaches. Recent advances in imaging, pathology, genetics and epigenetics have led to new pathophysiological concepts and the identification of monogenic causes of epilepsy. In the context of these advances, the First International Symposium on Personalized Translational Epilepsy Research (1st ISymPTER) was held in Frankfurt on September 8, 2016, to discuss novel approaches and future perspectives for personalized translational research. These included new developments and ideas in a range of experimental and clinical areas such as deep phenotyping, quantitative brain imaging, EEG/MEG-based analysis of network dysfunction, tissue-based translational studies, innate immunity mechanisms, microRNA as treatment targets, functional characterization of genetic variants in human cell models and rodent organotypic slice cultures, personalized treatment approaches for monogenic epilepsies, blood-brain barrier dysfunction, therapeutic focal tissue modification, computational modeling for target and biomarker identification, and cost analysis in (monogenic) disease and its treatment. This report on the meeting proceedings is aimed at stimulating much needed investments of time and resources in personalized translational epilepsy research. Part I includes the clinical phenotyping and diagnostic methods, EEG network-analysis, biomarkers, and personalized treatment approaches. In Part II, experimental and translational approaches will be discussed (Bauer et al., 2017) [1].


Assuntos
Anticonvulsivantes/uso terapêutico , Epilepsia/tratamento farmacológico , Epilepsia/genética , Medicina de Precisão , Barreira Hematoencefálica , Encéfalo/patologia , Lesões Encefálicas/patologia , Epigenômica , Marcadores Genéticos/genética , Variação Genética , Humanos , Medicina de Precisão/tendências , Pesquisa Translacional Biomédica , Resultado do Tratamento
7.
Cereb Cortex ; 26(4): 1539-1557, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-25596589

RESUMO

Choosing and implementing the rules for contextually adequate behavior depends on frontostriatal interactions. Observations in Parkinson's disease and pharmacological manipulations of dopamine transmission suggest that these corticobasal loops are modulated by dopamine. To determine, therefore, the physiological contributions of dopamine to task-rule-related processing, we performed a cue-target fMRI reading paradigm in 71 healthy participants and investigated the effects of COMT Val158Met, DAT1 VNTR 9/10, and DRD2/ANKK1 polymorphisms. The DRD2/ANKK1 polymorphism did not affect results. Intermediate prefrontal dopamine concentrations in COMT Val158Met heterozygotes facilitated preparatory interactions between the mesial prefrontal cortex and the left striatum during preparation for overt reading. To our knowledge, this is the first report of an inverted U-shaped curve modulation of cognition-related brain activity by prefrontal dopamine levels. In contrast, a linear effect of COMT Val158Met and DAT1 VNTR 9/10 polymorphisms on preparatory activity in the left inferior frontal gyrus pointed to a negative interaction between tonic lateral prefrontal and phasic subcortical dopamine. The COMT Val158Met polymorphism affected also feedforward and feedback processing in the sensorimotor speech system. Our results suggest that dopamine modulates corticobasal interactions on both the cortical and subcortical level but differently depending on the specific cognitive subprocesses involved.


Assuntos
Encéfalo/fisiologia , Catecol O-Metiltransferase/genética , Cognição/fisiologia , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Dopamina/metabolismo , Polimorfismo de Nucleotídeo Único , Leitura , Fala , Adulto , Orientação de Axônios/genética , Orientação de Axônios/fisiologia , Encéfalo/metabolismo , Mapeamento Encefálico , Genótipo , Humanos , Imageamento por Ressonância Magnética , Masculino , Repetições Minissatélites , Proteínas Serina-Treonina Quinases/genética , Receptores de Dopamina D2/genética , Adulto Jovem
8.
J Neurosci ; 35(4): 1411-22, 2015 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-25632119

RESUMO

Models propose an auditory-motor mapping via a left-hemispheric dorsal speech-processing stream, yet its detailed contributions to speech perception and production are unclear. Using fMRI-navigated repetitive transcranial magnetic stimulation (rTMS), we virtually lesioned left dorsal stream components in healthy human subjects and probed the consequences on speech-related facilitation of articulatory motor cortex (M1) excitability, as indexed by increases in motor-evoked potential (MEP) amplitude of a lip muscle, and on speech processing performance in phonological tests. Speech-related MEP facilitation was disrupted by rTMS of the posterior superior temporal sulcus (pSTS), the sylvian parieto-temporal region (SPT), and by double-knock-out but not individual lesioning of pars opercularis of the inferior frontal gyrus (pIFG) and the dorsal premotor cortex (dPMC), and not by rTMS of the ventral speech-processing stream or an occipital control site. RTMS of the dorsal stream but not of the ventral stream or the occipital control site caused deficits specifically in the processing of fast transients of the acoustic speech signal. Performance of syllable and pseudoword repetition correlated with speech-related MEP facilitation, and this relation was abolished with rTMS of pSTS, SPT, and pIFG. Findings provide direct evidence that auditory-motor mapping in the left dorsal stream causes reliable and specific speech-related MEP facilitation in left articulatory M1. The left dorsal stream targets the articulatory M1 through pSTS and SPT constituting essential posterior input regions and parallel via frontal pathways through pIFG and dPMC. Finally, engagement of the left dorsal stream is necessary for processing of fast transients in the auditory signal.


Assuntos
Vias Auditivas/fisiologia , Córtex Cerebral/fisiologia , Lateralidade Funcional , Fonética , Fala/fisiologia , Adulto , Vias Auditivas/irrigação sanguínea , Mapeamento Encefálico , Córtex Cerebral/irrigação sanguínea , Potencial Evocado Motor/fisiologia , Feminino , Humanos , Processamento de Imagem Assistida por Computador , Lábio/inervação , Masculino , Modelos Neurológicos , Músculo Esquelético/fisiologia , Oxigênio/sangue , Estimulação Luminosa , Tempo de Reação , Percepção da Fala , Adulto Jovem
9.
Neuroimage ; 139: 211-217, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-27329809

RESUMO

Previous studies have shown that the effect of temporal predictability of presented stimuli on attention allocation is enhanced by auditory-motor synchronization (AMS). The present P300 event-related potential study (N=20) investigated whether this enhancement depends on the process of actively synchronizing one's motor output with the acoustic input or whether a passive state of auditory-motor synchrony elicits the same effect. Participants silently counted frequency deviants in sequences of pure tones either during a physically inactive control condition or while pedaling on a cycling ergometer. Tones were presented either at fixed or variable intervals. In addition to the pedaling conditions with fixed or variable stimulation, there was a third condition in which stimuli were adaptively presented in sync with the participants' spontaneous pedaling. We replicated the P300 enhancement for fixed versus variable stimulation and the amplification of this effect by AMS. Synchronization performance correlated positively with P300 amplitude in the fixed stimulation condition. Most interestingly, P300 amplitude was significantly reduced for the passive synchronization condition by adaptive stimulus presentation as compared to the fixed stimulation condition. For the first time we thus provide evidence that it is not the passive state of (even perfect) auditory-motor synchrony that facilitates attention allocation during AMS but rather the active process of synchronizing one's movements with external stimuli.


Assuntos
Atenção/fisiologia , Percepção Auditiva/fisiologia , Córtex Cerebral/fisiologia , Atividade Motora , Desempenho Psicomotor , Estimulação Acústica , Adulto , Potenciais Evocados P300 , Feminino , Humanos , Masculino , Tempo de Reação , Fatores de Tempo , Adulto Jovem
10.
J Neurosci ; 33(4): 1640-50, 2013 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-23345236

RESUMO

Although advances have been made regarding how the brain perceives emotional prosody, the neural bases involved in the generation of affective prosody remain unclear and debated. Two models have been forged on the basis of clinical observations: a first model proposes that the right hemisphere sustains production and comprehension of emotional prosody, while a second model proposes that emotional prosody relies heavily on basal ganglia. Here, we tested their predictions in two functional magnetic resonance imaging experiments that used a cue-target paradigm, which allows distinguishing affective from sensorimotor aspects of emotional prosody generation. Both experiments show that when participants prepare for emotional prosody, bilateral ventral striatum is specifically activated and connected to temporal poles and anterior insula, regions in which lesions frequently cause dysprosody. The bilateral dorsal striatum is more sensitive to cognitive and motor aspects of emotional prosody preparation and production and is more strongly connected to the sensorimotor speech network compared with the ventral striatum. Right lateralization during increased prosodic processing is confined to the posterior superior temporal sulcus, a region previously associated with perception of emotional prosody. Our data thus provide physiological evidence supporting both models and suggest that bilateral basal ganglia are involved in modulating motor behavior as a function of affective state. Right lateralization of cortical regions mobilized for prosody control could point to efficient processing of slowly changing acoustic speech parameters in the ventral stream and thus identify sensorimotor processing as an important factor contributing to right lateralization of prosody.


Assuntos
Mapeamento Encefálico , Encéfalo/fisiologia , Emoções/fisiologia , Lateralidade Funcional/fisiologia , Percepção da Fala/fisiologia , Adulto , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino
11.
Pain ; 164(5): 1067-1077, 2023 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-36251980

RESUMO

ABSTRACT: Complex regional pain syndrome (CRPS) is characterized by inflammation and a failure of multimodal signal integration in the central nervous system (CNS). Central nervous system reorganization might account for sensory deficits, pain, and motor symptoms in CRPS, but it is not clear how motor control is affected by CNS mechanisms. The present study characterized the motor performance and related cortical activity of 16 CRPS patients and 16 control participants during the planning of visually guided unimanual grips, in patients with either the unaffected left or the affected right hand, and investigated resting-state sensorimotor coupling in MRI. Patients started isometric movements further in advance of the "go" cue and earlier than control participants. Even when accounting for this different timing, results showed side-independent overactivation in planning-related sensorimotor regions in CRPS during manual grips and increased functional coupling between those regions at rest. Fear of movement or individual pain scores contributed only marginally to the observed effects. The study suggests that changes in planning-related sensorimotor CNS regions may explain difficulties with force exertion and motor control in CRPS.Perspective : Functional changes in motor planning-related brain regions might indicate that feedback-enhanced functional motor training may be effective for CRPS rehabilitation.


Assuntos
Síndromes da Dor Regional Complexa , Humanos , Síndromes da Dor Regional Complexa/diagnóstico por imagem , Movimento/fisiologia , Encéfalo/diagnóstico por imagem , Dor , Medo
12.
Soc Cogn Affect Neurosci ; 18(1)2023 07 14.
Artigo em Inglês | MEDLINE | ID: mdl-37384576

RESUMO

Many socio-affective behaviors, such as speech, are modulated by oxytocin. While oxytocin modulates speech perception, it is not known whether it also affects speech production. Here, we investigated effects of oxytocin administration and interactions with the functional rs53576 oxytocin receptor (OXTR) polymorphism on produced speech and its underlying brain activity. During functional magnetic resonance imaging, 52 healthy male participants read sentences out loud with either neutral or happy intonation, a covert reading condition served as a common baseline. Participants were studied once under the influence of intranasal oxytocin and in another session under placebo. Oxytocin administration increased the second formant of produced vowels. This acoustic feature has previously been associated with speech valence; however, the acoustic differences were not perceptually distinguishable in our experimental setting. When preparing to speak, oxytocin enhanced brain activity in sensorimotor cortices and regions of both dorsal and right ventral speech processing streams, as well as subcortical and cortical limbic and executive control regions. In some of these regions, the rs53576 OXTR polymorphism modulated oxytocin administration-related brain activity. Oxytocin also gated cortical-basal ganglia circuits involved in the generation of happy prosody. Our findings suggest that several neural processes underlying speech production are modulated by oxytocin, including control of not only affective intonation but also sensorimotor aspects during emotionally neutral speech.


Assuntos
Ocitocina , Fala , Humanos , Masculino , Ocitocina/farmacologia , Imageamento por Ressonância Magnética , Receptores de Ocitocina/genética , Idioma , Método Duplo-Cego , Administração Intranasal , Encéfalo/fisiologia
13.
Cereb Cortex ; 21(4): 932-7, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20833698

RESUMO

Speech production is a left-lateralized brain function, which could arise from a left dominance either in speech executive or sensory processes or both. Using functional magnetic resonance imaging in healthy subjects, we show that sensory cortices already lateralize when speaking is intended, while the frontal cortex only lateralizes when speech is acted out. The sequence of lateralization, first temporal then frontal lateralization, suggests that the functional lateralization of the auditory cortex could drive hemispheric specialization for speech production.


Assuntos
Mapeamento Encefálico , Lateralidade Funcional/fisiologia , Córtex Somatossensorial/fisiologia , Fala/fisiologia , Adulto , Feminino , Humanos , Interpretação de Imagem Assistida por Computador , Imageamento por Ressonância Magnética , Masculino , Adulto Jovem
14.
Front Oncol ; 12: 815733, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35463387

RESUMO

Objectives: Gliomas are often diagnosed due to epileptic seizures as well as neurocognitive deficits. First treatment choice for patients with gliomas in speech-related areas is awake surgery, which aims at maximizing tumor resection while preserving or improving patient's neurological status. The present study aimed at evaluating neurocognitive functioning and occurrence of epileptic seizures in patients suffering from gliomas located in language-related areas before and after awake surgery as well as during their follow up course of disease. Materials and Methods: In this prospective study we included patients who underwent awake surgery for glioma in the inferior frontal gyrus, superior temporal gyrus, or anterior temporal lobe. Preoperatively, as well as in the short-term (median 4.1 months, IQR 2.1-6.0) and long-term (median 18.3 months, IQR 12.3-36.6) postoperative course, neurocognitive functioning, neurologic status, the occurrence of epileptic seizures and number of antiepileptic drugs were recorded. Results: Between 09/2012 and 09/2019, a total of 27 glioma patients, aged 36.1 ± 11.8 years, were included. Tumor resection was complete in 15, subtotal in 6 and partial in 6 patients, respectively. While preoperatively impairment in at least one neurocognitive domain was found in 37.0% of patients, postoperatively, in the short-term, 36.4% of patients presented a significant deterioration in word fluency (p=0.009) and 34.8% of patients in executive functions (p=0.049). Over the long-term, scores improved to preoperative baseline levels. The number of patients with mood disturbances significantly declined from 66.7% to 34.8% after surgery (p=0.03). Regarding seizures, these were present in 18 (66.7%) patients prior to surgery. Postoperatively, 22 (81.5%) patients were treated with antiepileptic drugs with all patients presenting seizure-freedom. Conclusions: In patients suffering from gliomas in eloquent areas, the combination of awake surgery, regular neurocognitive assessment - considering individual patients´ functional outcome and rehabilitation needs - and the individual adjustment of antiepileptic therapy results in excellent patient outcome in the long-term course.

15.
Proc Natl Acad Sci U S A ; 105(31): 10984-9, 2008 Aug 05.
Artigo em Inglês | MEDLINE | ID: mdl-18664576

RESUMO

Neural variability in responding to identical repeated stimuli has been related to trial-by-trial fluctuations in ongoing activity, yet the neural and perceptual consequences of these fluctuations remain poorly understood. Using functional neuroimaging, we recorded brain activity in subjects who reported perceptual decisions on an ambiguous figure, Rubin's vase-faces picture, which was briefly presented at variable intervals of > or = 20 s. Prestimulus activity in the fusiform face area, a cortical region preferentially responding to faces, was higher when subjects subsequently perceived faces instead of the vase. This finding suggests that endogenous variations in prestimulus neuronal activity biased subsequent perceptual inference. Furnishing evidence that evoked sensory responses, we then went on to show that the pre- and poststimulus activity interact in a nonlinear way and the ensuing perceptual decisions depend upon the prestimulus context in which they occur.


Assuntos
Encéfalo/metabolismo , Discriminação Psicológica/fisiologia , Face , Ilusões Ópticas/fisiologia , Reconhecimento Visual de Modelos/fisiologia , Adulto , Encéfalo/fisiologia , Potenciais Evocados Visuais , Feminino , Humanos , Imageamento por Ressonância Magnética , Estimulação Luminosa , Fatores de Tempo
16.
Proc Natl Acad Sci U S A ; 105(18): 6747-52, 2008 May 06.
Artigo em Inglês | MEDLINE | ID: mdl-18436648

RESUMO

Human face-to-face communication is essentially audiovisual. Typically, people talk to us face-to-face, providing concurrent auditory and visual input. Understanding someone is easier when there is visual input, because visual cues like mouth and tongue movements provide complementary information about speech content. Here, we hypothesized that, even in the absence of visual input, the brain optimizes both auditory-only speech and speaker recognition by harvesting speaker-specific predictions and constraints from distinct visual face-processing areas. To test this hypothesis, we performed behavioral and neuroimaging experiments in two groups: subjects with a face recognition deficit (prosopagnosia) and matched controls. The results show that observing a specific person talking for 2 min improves subsequent auditory-only speech and speaker recognition for this person. In both prosopagnosics and controls, behavioral improvement in auditory-only speech recognition was based on an area typically involved in face-movement processing. Improvement in speaker recognition was only present in controls and was based on an area involved in face-identity processing. These findings challenge current unisensory models of speech processing, because they show that, in auditory-only speech, the brain exploits previously encoded audiovisual correlations to optimize communication. We suggest that this optimization is based on speaker-specific audiovisual internal models, which are used to simulate a talking face.


Assuntos
Percepção Auditiva/fisiologia , Encéfalo/fisiologia , Comunicação , Simulação por Computador , Percepção da Fala/fisiologia , Adulto , Comportamento , Face , Feminino , Humanos , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade
17.
Clin Neurol Neurosurg ; 207: 106816, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34280675

RESUMO

OBJECTIVE: Patients with brain tumors frequently present neurocognitive deficits. Aiming at better understanding the impact of tumor localization on neurocognitive processes, we evaluated neurocognitive function prior to glioma surgery within one of four specific regions in the left speech-dominant hemisphere. METHODS: Between 04/2011 and 12/2019, 43 patients undergoing neurocognitive evaluation prior to awake surgery for gliomas (WHO grade I: 2; II: 6; III: 23; IV: 11) in the inferior frontal gyrus (IFG; n = 20), the anterior temporal lobe (ATL; n = 6), the posterior superior temporal region/supramarginal gyrus (pST/SMG; n = 7) or the posterior middle temporal gyrus (pMTG; n = 10) of the language dominant left hemisphere were prospectively included in the study. Cognitive performances were analyzed regarding an influence of patient characteristics and tumor localization. RESULTS: Severe impairment in at least one neurocognitive domain was found in 36 (83.7%) patients. Anxiety and depression were observed most frequently, followed by verbal memory impairments. Verbal memory was more strongly affected in patients with ATL or pST/SMG tumors compared to IFG tumors (p = 0.004 and p = 0.013, resp.). Overall, patients suffering from tumors in the ATL were most frequently and severely impaired. CONCLUSION: Patients suffering from gliomas involving different regions within the language dominant hemisphere frequently present impairments in neurocognitive domains also other than language. Considering individual functions at risk may help in better advising patients prior to treatment and in tailoring the individual therapeutic strategy to preserve patients' quality of life.


Assuntos
Neoplasias Encefálicas/patologia , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/patologia , Glioma/patologia , Adolescente , Adulto , Idoso , Neoplasias Encefálicas/complicações , Feminino , Lateralidade Funcional , Glioma/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Córtex Pré-Frontal/patologia , Lobo Temporal/patologia , Área de Wernicke/patologia , Adulto Jovem
18.
J Clin Med ; 10(5)2021 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-33801401

RESUMO

Local anesthetics are commonly administered by nuchal infiltration to provide a temporary interscalene brachial plexus block (ISB) in a surgical setting. Although less commonly reported, local anesthetics can induce central nervous system toxicity. In this case study, we present three patients with acute central nervous system toxicity induced by local anesthetics applied during ISB with emphasis on neurological symptoms, key neuroradiological findings and functional outcome. Medical history, clinical and imaging findings, and outcome of three patients with local anesthetic-induced toxic left hemisphere syndrome during left ISB were analyzed. All patients were admitted to our neurological intensive care unit between November 2016 and September 2019. All three patients presented in poor clinical condition with impaired consciousness and left hemisphere syndrome. Electroencephalography revealed slow wave activity in the affected hemisphere of all patients. Seizure activity with progression to status epilepticus was observed in one patient. In two out of three patients, cortical FLAIR hyperintensities and restricted diffusion in the territory of the left internal carotid artery were observed in magnetic resonance imaging. Assessment of neurological severity scores revealed spontaneous partial reversibility of neurological symptoms. Local anesthetic-induced CNS toxicity during ISB can lead to severe neurological impairment and anatomically variable cerebral lesions.

19.
J Neurosci ; 29(47): 14803-11, 2009 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-19940175

RESUMO

Gibbon's scalar expectancy theory assumes three processing stages in time estimation: a collating level in which event durations are automatically tracked, a counting level that reads out the time-tracking system, and a comparing level in which event durations are matched to abstract temporal references. Pöppel's theory, however, postulates a dual system for perception of durations below and above 2 s. By testing the neurophysiological plausibility of Gibbon's proposal using functional magnetic resonance imaging, we validate a three-staged model of time estimation and further show that the collating process is duplicated. Although the motor system automatically tracks durations below 2 s, mesial brain regions of the so-called "default mode network" keep track of longer events. Our results further support unique counting and comparing systems, involving prefrontal and parietal cortices in collators' readout, and the temporal cortex in contextual time estimation. These findings provide a coherent neuroanatomical framework for two theories of time perception.


Assuntos
Encéfalo/anatomia & histologia , Encéfalo/fisiologia , Modelos Neurológicos , Rede Nervosa/fisiologia , Percepção do Tempo/fisiologia , Adulto , Mapeamento Encefálico , Feminino , Lateralidade Funcional/fisiologia , Humanos , Imageamento por Ressonância Magnética , Masculino , Rede Nervosa/anatomia & histologia , Vias Neurais/anatomia & histologia , Vias Neurais/fisiologia , Testes Neuropsicológicos , Lobo Parietal/anatomia & histologia , Lobo Parietal/fisiologia , Córtex Pré-Frontal/anatomia & histologia , Córtex Pré-Frontal/fisiologia , Lobo Temporal/anatomia & histologia , Lobo Temporal/fisiologia , Fatores de Tempo , Adulto Jovem
20.
J Neurosci ; 29(43): 13445-53, 2009 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-19864557

RESUMO

Viewing our interlocutor facilitates speech perception, unlike for instance when we telephone. Several neural routes and mechanisms could account for this phenomenon. Using magnetoencephalography, we show that when seeing the interlocutor, latencies of auditory responses (M100) are the shorter the more predictable speech is from visual input, whether the auditory signal was congruent or not. Incongruence of auditory and visual input affected auditory responses approximately 20 ms after latency shortening was detected, indicating that initial content-dependent auditory facilitation by vision is followed by a feedback signal that reflects the error between expected and received auditory input (prediction error). We then used functional magnetic resonance imaging and confirmed that distinct routes of visual information to auditory processing underlie these two functional mechanisms. Functional connectivity between visual motion and auditory areas depended on the degree of visual predictability, whereas connectivity between the superior temporal sulcus and both auditory and visual motion areas was driven by audiovisual (AV) incongruence. These results establish two distinct mechanisms by which the brain uses potentially predictive visual information to improve auditory perception. A fast direct corticocortical pathway conveys visual motion parameters to auditory cortex, and a slower and indirect feedback pathway signals the error between visual prediction and auditory input.


Assuntos
Encéfalo/fisiologia , Percepção da Fala/fisiologia , Percepção Visual/fisiologia , Adulto , Encéfalo/irrigação sanguínea , Mapeamento Encefálico , Circulação Cerebrovascular , Retroalimentação Psicológica/fisiologia , Feminino , Humanos , Imageamento por Ressonância Magnética , Magnetoencefalografia , Masculino , Pessoa de Meia-Idade , Modelos Neurológicos , Percepção de Movimento/fisiologia , Vias Neurais/fisiologia , Psicoacústica , Fatores de Tempo , Adulto Jovem
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA