Distribution of multi-unit pitch responses recorded intracranially from human auditory cortex

The perception of pitch requires the abstraction of stimulus properties related to the spectrotemporal structure of sound. Previous studies utilizing both animal electrophysiology and human imaging have indicated the presence of a center for pitch representation in the auditory cortex. Recent data from our own group - examining local field potentials (LFPs) in humans - indicate more widely distributed pitch-associated responses within the auditory cortex (Gander et al., 2019). To probe this with greater spatial resolution, we examined multi-unit activity related to three different auditory stimuli, in seven epilepsy patients who were implanted with high-impedance electrodes in auditory cortex for the clinical purpose of localizing seizures. The stimuli were regular-interval noise (RIN) with a pitch strength that is related to the temporal regularity, and pitch value determined by repetition rate, and harmonic complexes with missing fundamentals. We demonstrated increases in spiking activity in 69 of 104 (66%) responsive multi-unit activity in auditory cortex due to pitch-associated stimuli. Importantly, these responses were distributed across the entire extent of Heschl's gyrus (HG), in both primary and non-primary areas, rather than isolated to a specific region, and this finding was evident regardless of the stimulus presented. These findings are the first multi-unit pitch responses recorded from humans, and align with a recent study in macaques (Kikuchi et al., 2019) demonstrating that both local field potential and unit responses to pitch-inducing stimuli are distributed throughout auditory cortex.

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Long-term recording performance and biocompatibility of chronically implanted cylindrically-shaped, polymer-based neural interfaces

Biomedical Engineering / Biomedizinische Technik ◽

10.1515/bmt-2017-0154 ◽

2018 ◽

Vol 63 (3) ◽

pp. 301-315 ◽

Cited By ~ 7

Author(s):

Richárd Fiáth ◽

Katharina T. Hofer ◽

Vivien Csikós ◽

Domonkos Horváth ◽

Tibor Nánási ◽

...

Keyword(s):

Spatial Resolution ◽

Local Field ◽

Unit Activity ◽

Single Unit ◽

Local Field Potentials ◽

Field Potential ◽

Tissue Reaction ◽

Field Potentials ◽

Depth Electrodes

Abstract Stereo-electroencephalography depth electrodes, regularly implanted into drug-resistant patients with focal epilepsy to localize the epileptic focus, have a low channel count (6–12 macro- or microelectrodes), limited spatial resolution (0.5–1 cm) and large contact area of the recording sites (~mm2). Thus, they are not suited for high-density local field potential and multiunit recordings. In this paper, we evaluated the long-term electrophysiological recording performance and histocompatibility of a neural interface consisting of 32 microelectrodes providing a physical shape similar to clinical devices. The cylindrically-shaped depth probes made of polyimide (PI) were chronically implanted for 13 weeks into the brain of rats, while cortical or thalamic activity (local field potentials, single-unit and multi-unit activity) was recorded regularly to monitor the temporal change of several features of the electrophysiological performance. To examine the tissue reaction around the probe, neuron-selective and astroglia-selective immunostaining methods were applied. Stable single-unit and multi-unit activity were recorded for several weeks with the implanted depth probes and a weak or moderate tissue reaction was found around the probe track. Our data on biocompatibility presented here and in vivo experiments in non-human primates provide a strong indication that this type of neural probe can be applied in stereo-electroencephalography recordings of up to 2 weeks in humans targeting the localization of epileptic foci providing an increased spatial resolution and the ability to monitor local field potentials and neuronal spiking activity.

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Increased neural correlations in primate auditory cortex during slow-wave sleep

Journal of Neurophysiology ◽

10.1152/jn.00695.2012 ◽

2013 ◽

Vol 109 (11) ◽

pp. 2732-2738 ◽

Cited By ~ 10

Author(s):

Elias B. Issa ◽

Xiaoqin Wang

Keyword(s):

Auditory Cortex ◽

Spontaneous Activity ◽

Slow Wave ◽

Local Field ◽

Local Field Potential ◽

Slow Wave Sleep ◽

Field Potential ◽

Sensory Stimulation ◽

Acoustic Stimulation ◽

Functional Connections

During sleep, changes in brain rhythms and neuromodulator levels in cortex modify the properties of individual neurons and the network as a whole. In principle, network-level interactions during sleep can be studied by observing covariation in spontaneous activity between neurons. Spontaneous activity, however, reflects only a portion of the effective functional connectivity that is activated by external and internal inputs (e.g., sensory stimulation, motor behavior, and mental activity), and it has been shown that neural responses are less correlated during external sensory stimulation than during spontaneous activity. Here, we took advantage of the unique property that the auditory cortex continues to respond to sounds during sleep and used external acoustic stimuli to activate cortical networks for studying neural interactions during sleep. We found that during slow-wave sleep (SWS), local (neuron-neuron) correlations are not reduced by acoustic stimulation remaining higher than in wakefulness and rapid eye movement sleep and remaining similar to spontaneous activity correlations. This high level of correlations during SWS complements previous work finding elevated global (local field potential-local field potential) correlations during sleep. Contrary to the prediction that slow oscillations in SWS would increase neural correlations during spontaneous activity, we found little change in neural correlations outside of periods of acoustic stimulation. Rather, these findings suggest that functional connections recruited in sound processing are modified during SWS and that slow rhythms, which in general are suppressed by sensory stimulation, are not the sole mechanism leading to elevated network correlations during sleep.

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Component analysis reveals sharp tuning of the local field potential in the guinea pig auditory cortex

Journal of Neurophysiology ◽

10.1152/jn.00040.2012 ◽

2013 ◽

Vol 109 (1) ◽

pp. 261-272 ◽

Cited By ~ 16

Author(s):

Alain de Cheveigné ◽

Jean-Marc Edeline ◽

Quentin Gaucher ◽

Boris Gourévitch

Keyword(s):

Auditory Cortex ◽

Local Field ◽

Receptive Fields ◽

Field Potential ◽

Component Analysis ◽

Electrode Arrays ◽

Linear Combinations ◽

Spectrotemporal Receptive Fields ◽

Analysis Technique ◽

Channel Electrode

Local field potentials (LFPs) recorded in the auditory cortex of mammals are known to reveal weakly selective and often multimodal spectrotemporal receptive fields in contrast to spiking activity. This may in part reflect the wider “listening sphere” of LFPs relative to spikes due to the greater current spread at low than high frequencies. We recorded LFPs and spikes from auditory cortex of guinea pigs using 16-channel electrode arrays. LFPs were processed by a component analysis technique that produces optimally tuned linear combinations of electrode signals. Linear combinations of LFPs were found to have sharply tuned responses, closer to spike-related tuning. The existence of a sharply tuned component implies that a cortical neuron (or group of neurons) capable of forming a linear combination of its inputs has access to that information. Linear combinations of signals from electrode arrays reveal information latent in the subspace spanned by multichannel LFP recordings and are justified by the fact that the observations themselves are linear combinations of neural sources.

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