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1.
J Neurosci ; 44(24)2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38670804

RESUMO

The 40 Hz auditory steady-state response (ASSR), an oscillatory brain response to periodically modulated auditory stimuli, is a promising, noninvasive physiological biomarker for schizophrenia and related neuropsychiatric disorders. The 40 Hz ASSR might be amplified by synaptic interactions in cortical circuits, which are, in turn, disturbed in neuropsychiatric disorders. Here, we tested whether the 40 Hz ASSR in the human auditory cortex depends on two key synaptic components of neuronal interactions within cortical circuits: excitation via N-methyl-aspartate glutamate (NMDA) receptors and inhibition via gamma-amino-butyric acid (GABA) receptors. We combined magnetoencephalography (MEG) recordings with placebo-controlled, low-dose pharmacological interventions in the same healthy human participants (13 males, 7 females). All participants exhibited a robust 40 Hz ASSR in auditory cortices, especially in the right hemisphere, under a placebo. The GABAA receptor-agonist lorazepam increased the amplitude of the 40 Hz ASSR, while no effect was detectable under the NMDA blocker memantine. Our findings indicate that the 40 Hz ASSR in the auditory cortex involves synaptic (and likely intracortical) inhibition via the GABAA receptor, thus highlighting its utility as a mechanistic signature of cortical circuit dysfunctions involving GABAergic inhibition.


Assuntos
Córtex Auditivo , Potenciais Evocados Auditivos , Neurônios GABAérgicos , Magnetoencefalografia , Humanos , Córtex Auditivo/efeitos dos fármacos , Córtex Auditivo/fisiologia , Masculino , Feminino , Adulto , Potenciais Evocados Auditivos/efeitos dos fármacos , Potenciais Evocados Auditivos/fisiologia , Neurônios GABAérgicos/fisiologia , Neurônios GABAérgicos/efeitos dos fármacos , Adulto Jovem , Inibição Neural/fisiologia , Inibição Neural/efeitos dos fármacos , Estimulação Acústica
2.
Neuroreport ; 14(9): 1239-42, 2003 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-12824767

RESUMO

How do we detect changes in our visual environment? By continuously comparing visual inputs to templates of experiences in the immediate past? Or by determining their rareness, how infrequently a visual event occurred previously? Recent results from event-related potentials have been interpreted in favour of the first hypothesis, as in the case of the auditory mismatch negativity. Here we demonstrate that rareness, rather than mismatch with a template, underlies visual change detection. Such rareness is detected through a dedicated mechanism in human visual cortex about 100 ms after the rare event occurs, reflected in the rareness-related negativity (RRN).


Assuntos
Estimulação Luminosa/métodos , Córtex Visual/fisiologia , Percepção Visual/fisiologia , Adolescente , Adulto , Potenciais Evocados Visuais/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
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