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  • 1
    Online Resource
    Online Resource
    Laminar Profile and Physiology of the α Rhythm in Primary Visual, Auditory, and Somatosensory Regions of Neocortex
    Society for Neuroscience ; 2015
    In:  The Journal of Neuroscience Vol. 35, No. 42 ( 2015-10-21), p. 14341-14352
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 35, No. 42 ( 2015-10-21), p. 14341-14352
    Abstract: The functional significance of the α rhythm is widely debated. It has been proposed that α reflects sensory inhibition and/or a temporal sampling or “parsing” mechanism. There is also continuing disagreement over the more fundamental questions of which cortical layers generate α rhythms and whether the generation of α is equivalent across sensory systems. To address these latter questions, we analyzed laminar profiles of local field potentials (LFPs) and concomitant multiunit activity (MUA) from macaque V1, S1, and A1 during both spontaneous activity and sensory stimulation. Current source density (CSD) analysis of laminar LFP profiles revealed α current generators in the supragranular, granular, and infragranular layers. MUA phase-locked to local current source/sink configurations confirmed that α rhythms index local neuronal excitability fluctuations. CSD-defined α generators were strongest in the supragranular layers, whereas LFP α power was greatest in the infragranular layers, consistent with some of the previous reports. The discrepancy between LFP and CSD findings appears to be attributable to contamination of the infragranular LFP signal by activity that is volume-conducted from the stronger supragranular α generators. The presence of α generators across cortical depth in V1, S1, and A1 suggests the involvement of α in feedforward as well as feedback processes and is consistent with the view that α rhythms, perhaps in addition to a role in sensory inhibition, may parse sensory input streams in a way that facilitates communication across cortical areas. SIGNIFICANCE STATEMENT The α rhythm is thought to reflect sensory inhibition and/or a temporal parsing mechanism. Here, we address two outstanding issues: (1) whether α is a general mechanism across sensory systems and (2) which cortical layers generate α oscillations. Using intracranial recordings from macaque V1, S1, and A1, we show α band activity with a similar spectral and laminar profile in each of these sensory areas. Furthermore, α generators were present in each of the cortical layers, with a strong source in superficial layers. We argue that previous findings, locating α generators exclusively in the deeper layers, were biased because of use of less locally specific local field potential measurements. The laminar distribution of α band activity appears more complex than generally assumed.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.0600-15.2015
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2015
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 2
    Online Resource
    Online Resource
    Tuning of the Human Neocortex to the Temporal Dynamics of Attended Events
    Society for Neuroscience ; 2011
    In:  The Journal of Neuroscience Vol. 31, No. 9 ( 2011-03-02), p. 3176-3185
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 31, No. 9 ( 2011-03-02), p. 3176-3185
    Abstract: Previous studies raise the hypothesis that attentional bias in the phase of neocortical excitability fluctuations (oscillations) represents a fundamental mechanism for tuning the brain to the temporal dynamics of task-relevant event patterns. To evaluate this hypothesis, we recorded intracranial electrocortical activity in human epilepsy patients while they performed an audiovisual stream selection task. Consistent with our hypothesis, (1) attentional modulation of oscillatory entrainment operates in a distinct network of areas including auditory, visual, posterior parietal, inferior motor, inferior frontal and superior midline frontal cortex, (2) the degree of oscillatory entrainment depends on the predictability of the stimulus stream, and (3) the attentional phase shift of entrained oscillation cooccurs with classical attentional effects observed on phase-locked evoked activity in sensory-specific areas but seems to operate on entrained low-frequency oscillations that cannot be explained by sensory activity evoked at the rate of stimulation. Thus, attentional entrainment appears to tune a network of brain areas to the temporal dynamics of behaviorally relevant event streams, contributing to its perceptual and behavioral selection.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.4518-10.2011
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2011
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 3
    Online Resource
    Online Resource
    Layer Specific Sharpening of Frequency Tuning by Selective Attention in Primary Auditory Cortex
    Society for Neuroscience ; 2014
    In:  The Journal of Neuroscience Vol. 34, No. 49 ( 2014-12-03), p. 16496-16508
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 34, No. 49 ( 2014-12-03), p. 16496-16508
    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.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.2055-14.2014
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2014
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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  • 4
    Online Resource
    Online Resource
    Detecting Spontaneous Neural Oscillation Events in Primate Auditory Cortex
    Society for Neuroscience ; 2022
    In:  eneuro Vol. 9, No. 4 ( 2022-07), p. ENEURO.0281-21.2022-
    Details
    In: eneuro, Society for Neuroscience, Vol. 9, No. 4 ( 2022-07), p. ENEURO.0281-21.2022-
    Abstract: Electrophysiological oscillations in the brain have been shown to occur as multicycle events, with onset and offset dependent on behavioral and cognitive state. To provide a baseline for state-related and task-related events, we quantified oscillation features in resting-state recordings. We developed an open-source wavelet-based tool to detect and characterize such oscillation events (OEvents) and exemplify the use of this tool in both simulations and two invasively-recorded electrophysiology datasets: one from human, and one from nonhuman primate (NHP) auditory system. After removing incidentally occurring event-related potentials (ERPs), we used OEvents to quantify oscillation features. We identified ∼2 million oscillation events, classified within traditional frequency bands: δ, θ, α, β, low γ, γ, and high γ. Oscillation events of 1–44 cycles could be identified in at least one frequency band 90% of the time in human and NHP recordings. Individual oscillation events were characterized by nonconstant frequency and amplitude. This result necessarily contrasts with prior studies which assumed frequency constancy, but is consistent with evidence from event-associated oscillations. We measured oscillation event duration, frequency span, and waveform shape. Oscillations tended to exhibit multiple cycles per event, verifiable by comparing filtered to unfiltered waveforms. In addition to the clear intraevent rhythmicity, there was also evidence of interevent rhythmicity within bands, demonstrated by finding that coefficient of variation of interval distributions and Fano factor (FF) measures differed significantly from a Poisson distribution assumption. Overall, our study provides an easy-to-use tool to study oscillation events at the single-trial level or in ongoing recordings, and demonstrates that rhythmic, multicycle oscillation events dominate auditory cortical dynamics.
    Type of Medium: Online Resource
    ISSN: 2373-2822
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    URL: Article
    DOI: 10.1523/ENEURO.0281-21.2022
    DOI: 10.1523/ENEURO.0281-21.2022.t8-1
    DOI: 10.1523/ENEURO.0281-21.2022.t8-2
    DOI: 10.1523/ENEURO.0281-21.2022.t9-1
    DOI: 10.1523/ENEURO.0281-21.2022.t9-2
    DOI: 10.1523/ENEURO.0281-21.2022.t9-3
    DOI: 10.1523/ENEURO.0281-21.2022.t9-4
    DOI: 10.1523/ENEURO.0281-21.2022.f9-1
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2022
    detail.hit.zdb_id: 2800598-3
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  • 5
    Online Resource
    Online Resource
    Phase Entrainment of Human Delta Oscillations Can Mediate the Effects of Expectation on Reaction Speed
    Society for Neuroscience ; 2010
    In:  The Journal of Neuroscience Vol. 30, No. 41 ( 2010-10-13), p. 13578-13585
    Details
    In: The Journal of Neuroscience, Society for Neuroscience, Vol. 30, No. 41 ( 2010-10-13), p. 13578-13585
    Abstract: The more we anticipate a response to a predictable stimulus, the faster we react. This empirical observation has been confirmed and quantified by many investigators suggesting that the processing of behaviorally relevant stimuli is facilitated by probability-based confidence of anticipation. However, the exact neural mechanisms underlying this phenomenon are largely unknown. Here we show that performance changes related to different levels of expectancy originate in dynamic modulation of delta oscillation phase. Our results obtained in rhythmic auditory target detection tasks indicated significant entrainment of the EEG delta rhythm to the onset of the target tones with increasing phase synchronization at higher levels of predictability. Reaction times correlated with the phase of the delta band oscillation at target onset. The fastest reactions occurred during the delta phase that most commonly coincided with the target event in the high expectancy conditions. These results suggest that low-frequency oscillations play a functional role in human anticipatory mechanisms, presumably by modulating synchronized rhythmic fluctuations in the excitability of large neuronal populations and by facilitating efficient task-related neuronal communication among brain areas responsible for sensory processing and response execution.
    Type of Medium: Online Resource
    ISSN: 0270-6474 , 1529-2401
    URL: Article
    DOI: 10.1523/JNEUROSCI.0703-10.2010
    Language: English
    Publisher: Society for Neuroscience
    Publication Date: 2010
    detail.hit.zdb_id: 1475274-8
    SSG: 12
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