title: Layer specific sharpening of frequency tuning by selective attention in primary auditory cortex.
abstract: Recent electrophysiological and neuroimaging studies provide converging evidence that attending to sounds increases the response selectivity of neuronal ensembles even at the first cortical stage of auditory stimulus processing in primary auditory cortex (A1). This is achieved by enhancement of responses in the regions that process attended frequency content, and by suppression of responses in the surrounding regions. The goals of our study were to define the extent to which A1 neuronal ensembles are involved in this process, determine its effect on the frequency tuning of A1 neuronal ensembles, and examine the involvement of the different cortical layers. To accomplish these, we analyzed laminar profiles of synaptic activity and action potentials recorded in A1 of macaques performing a rhythmic intermodal selective attention task. We found that the frequency tuning of neuronal ensembles was sharpened due to both increased gain at the preferentially processed or best frequency and increased response suppression at all other frequencies when auditory stimuli were attended. Our results suggest that these effects are due to a frequency-specific counterphase entrainment of ongoing delta oscillations, which predictively orchestrates opposite sign excitability changes across all of A1. This results in a net suppressive effect due to the large proportion of neuronal ensembles that do not specifically process the attended frequency content. Furthermore, analysis of laminar activation profiles revealed that although attention-related suppressive effects predominate the responses of supragranular neuronal ensembles, response enhancement is dominant in the granular and infragranular layers, providing evidence for layer-specific cortical operations in attentive stimulus processing.
authors.affiliation: Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute, Orangeburg, New York 10962.
authors.forename: Monica Noelle
authors.initials: MN
authors.lastname: O'Connell
authors.affiliation: Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute, Orangeburg, New York 10962, Department of Neuroscience and Physiology, New York University School of Medicine, New York, New York 10016.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Barczak
authors.affiliation: Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute, Orangeburg, New York 10962, Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, New York 10032, and.
authors.forename: Charles E
authors.initials: CE
authors.lastname: Schroeder
authors.affiliation: Cognitive Neuroscience and Schizophrenia Program, Nathan Kline Institute, Orangeburg, New York 10962, Department of Neuroscience and Physiology, New York University School of Medicine, New York, New York 10016 plakatos@nki.rfmh.org.
authors.forename: Peter
authors.initials: P
authors.lastname: Lakatos
mesh_terms: D000161:Acoustic Stimulation; D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001288:Attention / Q000502:physiology*; D001303:Auditory Cortex / Q000502:physiology*; D058256:Brain Waves / Q000502:physiology; D003700:Delta Rhythm / Q000502:physiology; D005260:Female; D008253:Macaca mulatta; D009474:Neurons / Q000502:physiology; D011597:Psychomotor Performance / Q000502:physiology
keywords: auditory; current source density; entrainment; macaque; oscillations; selective attention