title: The 40-Hz auditory steady-state response: a selective biomarker for cortical NMDA function.
abstract: When subjected to a phasic input, sensory cortical neurons display a remarkable ability to entrain faithfully to the driving stimuli. The entrainment to rhythmic sound stimuli is often referred to as the auditory steady-state response (ASSR) and can be captured using noninvasive techniques, such as scalp-recorded electroencephalography (EEG). An ASSR to a driving frequency of approximately 40 Hz is particularly interesting in that it shows, in relative terms, maximal power, synchrony, and synaptic activity. Moreover, the 40-Hz ASSR has been consistently found to be abnormal in schizophrenia patients across multiple studies. The nature of the reported abnormality has been less consistent; while most studies report a deficit in entrainment, several studies have reported increased signal power, particularly when there are concurrent positive symptoms, such as auditory hallucinations. However, the neuropharmacological basis for the 40-Hz ASSR, as well as its dysfunction in schizophrenia, has been unclear until recently. On the basis of several recent reports, it is argued that the 40-Hz ASSR represents a specific marker for cortical NMDA transmission. If confirmed, the 40-Hz ASSR may be a simple and easy-to-access pharmacodynamic biomarker for testing the integrity of cortical NMDA neurotransmission that is robustly translational across species.
authors: Genetically Defined Diseases, Bristol-Myers Squibb Co, Wallingford, Connecticut.
authors: Digavalli V
authors: DV
authors: Sivarao
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism / Q000503:physiopathology; D004569:Electroencephalography; D005072:Evoked Potentials, Auditory; D006212:Hallucinations / Q000378:metabolism / Q000503:physiopathology; D006801:Humans; D016202:N-Methylaspartate / Q000378:metabolism*; D012559:Schizophrenia / Q000378:metabolism / Q000503:physiopathology; D009435:Synaptic Transmission
chemical_list: D015415:Biomarkers; D016202:N-Methylaspartate
keywords: 40-Hz ASSR; EEG; NMDA; biomarker; schizophrenia