scholarly journals Auditory target detection activates frontal and parietal cortices: Evidence from high gamma power and low-frequency phase coherence in the subdural electrocorticogram

2008 ◽  
Vol 2 ◽  
Author(s):  
Knight Robert
Keyword(s):  
Target Detection ◽  
Low Frequency ◽  
Phase Coherence ◽  
Auditory Target ◽  
High Gamma ◽  
Gamma Power ◽  
Parietal Cortices ◽  
Frequency Phase

scholarly journals Including measures of high gamma power can improve the decoding of natural speech from EEG

2019 ◽  
Author(s):  
Shyanthony R. Synigal ◽  
Emily S. Teoh ◽  
Edmund C. Lalor
Keyword(s):  
Brain Imaging ◽  
Neural Activity ◽  
Speech Processing ◽  
Signal To Noise Ratio ◽  
Low Frequency ◽  
Natural Speech ◽  
Low Frequencies ◽  
High Gamma ◽  
Gamma Power ◽  
Speech Tracking

ABSTRACTThe human auditory system is adept at extracting information from speech in both single-speaker and multi-speaker situations. This involves neural processing at the rapid temporal scales seen in natural speech. Non-invasive brain imaging (electro-/magnetoencephalography [EEG/MEG]) signatures of such processing have shown that the phase of neural activity below 16 Hz tracks the dynamics of speech, whereas invasive brain imaging (electrocorticography [ECoG]) has shown that such rapid processing is even more strongly reflected in the power of neural activity at high frequencies (around 70-150 Hz; known as high gamma). The aim of this study was to determine if high gamma power in scalp recorded EEG carries useful stimulus-related information, despite its reputation for having a poor signal to noise ratio. Furthermore, we aimed to assess whether any such information might be complementary to that reflected in well-established low frequency EEG indices of speech processing. We used linear regression to investigate speech envelope and attention decoding in EEG at low frequencies, in high gamma power, and in both signals combined. While low frequency speech tracking was evident for almost all subjects as expected, high gamma power also showed robust speech tracking in a minority of subjects. This same pattern was true for attention decoding using a separate group of subjects who undertook a cocktail party attention experiment. For the subjects who showed speech tracking in high gamma power, the spatiotemporal characteristics of that high gamma tracking differed from that of low-frequency EEG. Furthermore, combining the two neural measures led to improved measures of speech tracking for several subjects. Overall, this indicates that high gamma power EEG can carry useful information regarding speech processing and attentional selection in some subjects and combining it with low frequency EEG can improve the mapping between natural speech and the resulting neural responses.

scholarly journals Untangling cortico-striatal connectivity and cross-frequency coupling in L-DOPA-induced dyskinesia

2015 ◽  
Author(s):  
Jovana Belic ◽  
Per Halje ◽  
Ulrike Richter ◽  
Per Petersson ◽  
Jeanette Hellgren Kotaleski
Keyword(s):  
Primary Motor Cortex ◽  
Effective Connectivity ◽  
Spectral Characteristics ◽  
Low Frequency ◽  
Frequency Range ◽  
Gamma Frequency ◽  
High Gamma ◽  
Freely Behaving ◽  
Beta Frequency ◽  
Cross Frequency Coupling

We simultaneously recorded local field potentials in the primary motor cortex and sensorimotor striatum in awake, freely behaving, 6-OHDA lesioned hemi-parkinsonian rats in order to study the features directly related to pathological states such as parkinsonian state and levodopa-induced dyskinesia. We analysed the spectral characteristics of the obtained signals and observed that during dyskinesia the most prominent feature was a relative power increase in the high gamma frequency range at around 80 Hz, while for the parkinsonian state it was in the beta frequency range. Here we show that during both pathological states effective connectivity in terms of Granger causality is bidirectional with an accent on the striatal influence on the cortex. In the case of dyskinesia, we also found a high increase in effective connectivity at 80 Hz. In order to further understand the 80- Hz phenomenon, we performed cross-frequency analysis and observed characteristic patterns in the case of dyskinesia but not in the case of the parkinsonian state or the control state. We noted a large decrease in the modulation of the amplitude at 80 Hz by the phase of low frequency oscillations (up to ~10 Hz) across both structures in the case of dyskinesia. This may suggest a lack of coupling between the low frequency activity of the recorded network and the group of neurons active at ~80 Hz.

Squeezing-enhanced fiber Mach-Zehnder interferometer for low-frequency phase measurement

2017 ◽  
Vol 110 (2) ◽  
pp. 021106 ◽  
Author(s):  
Fang Liu ◽  
Yaoyao Zhou ◽  
Juan Yu ◽  
Jiale Guo ◽  
Yang Wu ◽  
...  
Keyword(s):  
Phase Measurement ◽  
Low Frequency ◽  
Zehnder Interferometer ◽  
Frequency Phase ◽  
Mach Zehnder Interferometer

The Role of Low-frequency Neural Oscillations in Speech Processing: Revisiting Delta Entrainment

2019 ◽  
Vol 31 (8) ◽  
pp. 1205-1215 ◽  
Author(s):  
Victor J. Boucher ◽  
Annie C. Gilbert ◽  
Boutheina Jemel
Keyword(s):  
Speech Processing ◽  
Low Frequency ◽  
Phase Coherence ◽  
Theta Oscillations ◽  
Neural Oscillations ◽  
Acoustic Cues ◽  
Low Frequency Oscillations ◽  
Temporal Grouping ◽  
Delta Oscillations

Studies that use measures of cerebro-acoustic coherence have shown that theta oscillations (3–10 Hz) entrain to syllable-size modulations in the energy envelope of speech. This entrainment creates sensory windows in processing acoustic cues. Recent reports submit that delta oscillations (<3 Hz) can be entrained by nonsensory content units like phrases and serve to process meaning—though such views face fundamental problems. Other studies suggest that delta underlies a sensory chunking linked to the processing of sequential attributes of speech sounds. This chunking associated with the “focus of attention” is commonly manifested by the temporal grouping of items in sequence recall. Similar grouping in speech may entrain delta. We investigate this view by examining how low-frequency oscillations entrain to three types of stimuli (tones, nonsense syllables, and utterances) having similar timing, pitch, and energy contours. Entrainment was indexed by “intertrial phase coherence” in the EEGs of 18 listeners. The results show that theta oscillations at central sites entrain to syllable-size elements in speech and tones. However, delta oscillations at frontotemporal sites specifically entrain to temporal groups in both meaningful utterances and meaningless syllables, which indicates that delta may support but does not directly bear on a processing of content. The findings overall suggest that, although theta entrainment relates to a processing of acoustic attributes, delta entrainment links to a sensory chunking that relates to a processing of properties of articulated sounds. The results also show that measures of intertrial phase coherence can be better suited than cerebro-acoustic coherence in revealing delta entrainment.

scholarly journals Language prediction mechanisms in human auditory cortex

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
K. J. Forseth ◽  
G. Hickok ◽  
P. S. Rollo ◽  
N. Tandon
Keyword(s):  
Speech Perception ◽  
Auditory Cortex ◽  
Speech Production ◽  
Low Frequency ◽  
Spoken Language ◽  
Planum Temporale ◽  
Gamma Power ◽  
And Function ◽  
Predictive Mechanisms ◽  
Stimulation Of

Abstract Spoken language, both perception and production, is thought to be facilitated by an ensemble of predictive mechanisms. We obtain intracranial recordings in 37 patients using depth probes implanted along the anteroposterior extent of the supratemporal plane during rhythm listening, speech perception, and speech production. These reveal two predictive mechanisms in early auditory cortex with distinct anatomical and functional characteristics. The first, localized to bilateral Heschl’s gyri and indexed by low-frequency phase, predicts the timing of acoustic events. The second, localized to planum temporale only in language-dominant cortex and indexed by high-gamma power, shows a transient response to acoustic stimuli that is uniquely suppressed during speech production. Chronometric stimulation of Heschl’s gyrus selectively disrupts speech perception, while stimulation of planum temporale selectively disrupts speech production. This work illuminates the fundamental acoustic infrastructure—both architecture and function—for spoken language, grounding cognitive models of speech perception and production in human neurobiology.

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