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 Spontaneous electrical low-frequency oscillations: a possible role in Hydra and all living systems

2021 ◽  
Vol 376 (1820) ◽  
pp. 20190763 ◽  
Author(s):  
Alison Hanson
Keyword(s):  
Potential Role ◽  
Low Frequency ◽  
Model Systems ◽  
Living Systems ◽  
Neural Oscillations ◽  
Low Frequency Oscillations ◽  
Basal Metazoan ◽  
Life On Earth ◽  
Diversity Of Life

As one of the first model systems in biology, the basal metazoan Hydra has been revealing fundamental features of living systems since it was first discovered by Antonie van Leeuwenhoek in the early eighteenth century. While it has become well-established within cell and developmental biology, this tiny freshwater polyp is only now being re-introduced to modern neuroscience where it has already produced a curious finding: the presence of low-frequency spontaneous neural oscillations at the same frequency as those found in the default mode network in the human brain. Surprisingly, increasing evidence suggests such spontaneous electrical low-frequency oscillations (SELFOs) are found across the wide diversity of life on Earth, from bacteria to humans. This paper reviews the evidence for SELFOs in diverse phyla, beginning with the importance of their discovery in Hydra , and hypothesizes a potential role as electrical organism organizers, which supports a growing literature on the role of bioelectricity as a ‘template’ for developmental memory in organism regeneration. This article is part of the theme issue ‘Basal cognition: conceptual tools and the view from the single cell’.

scholarly journals Dissociable oscillatory networks support gain and loss processing in human orbitofrontal cortex

2021 ◽  
Author(s):  
Ignacio Saez ◽  
Jack Lin ◽  
Edward Chang ◽  
Josef Parvizi ◽  
Robert T. Knight ◽  
...  
Keyword(s):  
Neural Activity ◽  
Orbitofrontal Cortex ◽  
Low Frequency ◽  
Brain Regions ◽  
Reward Processing ◽  
Neural Oscillations ◽  
Beta Band ◽  
Neuronal Ensembles ◽  
Gain And Loss

AbstractHuman neuroimaging and animal studies have linked neural activity in orbitofrontal cortex (OFC) to valuation of positive and negative outcomes. Additional evidence shows that neural oscillations, representing the coordinated activity of neuronal ensembles, support information processing in both animal and human prefrontal regions. However, the role of OFC neural oscillations in reward-processing in humans remains unknown, partly due to the difficulty of recording oscillatory neural activity from deep brain regions. Here, we examined the role of OFC neural oscillations (<30Hz) in reward processing by combining intracranial OFC recordings with a gambling task in which patients made economic decisions under uncertainty. Our results show that power in different oscillatory bands are associated with distinct components of reward evaluation. Specifically, we observed a double dissociation, with a selective theta band oscillation increase in response to monetary gains and a beta band increase in response to losses. These effects were interleaved across OFC in overlapping networks and were accompanied by increases in oscillatory coherence between OFC electrode sites in theta and beta band during gain and loss processing, respectively. These results provide evidence that gain and loss processing in human OFC are supported by distinct low-frequency oscillations in networks, and provide evidence that participating neuronal ensembles are organized functionally through oscillatory coherence, rather than local anatomical segregation.

scholarly journals Contribution of low-frequency climatic–oceanic oscillations to streamflow variability in small, coastal rivers of the Sierra Nevada de Santa Marta (Colombia)

2019 ◽  
Vol 23 (5) ◽  
pp. 2379-2400 ◽  
Author(s):  
Juan Camilo Restrepo ◽  
Aldemar Higgins ◽  
Jaime Escobar ◽  
Silvio Ospino ◽  
Natalia Hoyos
Keyword(s):  
Energy Spectrum ◽  
Sierra Nevada ◽  
Large Scale ◽  
Low Frequency ◽  
Maximum Power ◽  
Simultaneous Occurrence ◽  
Atmospheric Processes ◽  
Low Frequency Oscillations ◽  
Streamflow Variability

Abstract. This study evaluated the influence of low-frequency oscillations, that are linked to large-scale oceanographic–atmospheric processes, on streamflow variability in small tropical coastal mountain rivers of the Sierra Nevada de Santa Marta, Colombia. We used data from six rivers that had > 32 years of complete, continuous monthly streamflow records. This investigation employed spectral analyses to (1) explore temporal characteristics of streamflow variability, (2) estimate the net contribution to the energy spectrum of low-frequency oscillations to streamflow anomalies, and (3) analyze the linkages between streamflow anomalies and large-scale, low-frequency oceanographic–atmospheric processes. Wavelet analyses indicate that the 8–12-year component exhibited a quasi-stationary state, with a peak of maximum power between 1985 and 2005. These oscillations were nearly in phase in all rivers. Maximum power peaks occurred for the Palomino and Rancheria rivers in 1985 and 1995, respectively. The wavelet spectrum highlights a change in river variability patterns between 1995 and 2015, characterized by a shift towards the low-frequency oscillations' domain (8–12 years). The net contribution of these oscillations to the energy spectrum was as high as 51 %, a value much larger than previously thought for rivers in northwestern South America. The simultaneous occurrence of hydrologic oscillations, as well as the increase in the amplitude of the 8–12-year band, defined periods of extremely anomalous wet seasons during 1989–1990, 1998–2002 and 2010–2011, reflecting the role of low-frequency oscillations in modulating streamflow variability in these rivers. Cross-wavelet transform and wavelet coherence revealed high common powers and significant coherences in low-frequency bands (>96 months) between streamflow anomalies and Atlantic Meridional Oscillation (AMO), Pacific Decadal Oscillation (PDO) and the Tropical North Atlantic Index (TNA). These results show the role of large-scale, low-frequency oceanographic–climate processes in modulating the long-term hydrological variability of these rivers.

Very-low-frequency oscillations in heart rate and blood pressure in periodic breathing: role of the cardiovascular limb of the hypoxic chemoreflex

2000 ◽  
Vol 99 (2) ◽  
pp. 125 ◽  
Author(s):  
Darrel P. FRANCIS ◽  
L. Ceri DAVIES ◽  
Keith WILLSON ◽  
Piotr PONIKOWSKI ◽  
Andrew J.S. COATS ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Low Frequency ◽  
Periodic Breathing ◽  
Very Low Frequency ◽  
Low Frequency Oscillations

scholarly journals Implicit temporal predictability biases slow oscillatory phase in auditory cortex and enhances pitch discrimination sensitivity

2018 ◽  
Author(s):  
Sophie K. Herbst ◽  
Jonas Obleser
Keyword(s):  
Target Tone ◽  
Pitch Discrimination ◽  
Neural Oscillations ◽  
Phase Reset ◽  
Standard Tone ◽  
Input Structure ◽  
Oscillatory Phase ◽  
Temporal Predictability ◽  
Delta Oscillations

AbstractCan human listeners use strictly implicit temporal contingencies in auditory input to form temporal predictions, and if so, how are these predictions represented endogenously? To assess this question, we implicitly manipulated foreperiods in an auditory pitch discrimination task. Unbeknownst to participants, the pitch of the standard tone could either be deterministically predictive of the onset of the target tone, or convey no predictive information. Both conditions were presented interleaved in one stream, and separated by variable inter-stimulus intervals such that there was no dominant stimulus rhythm throughout. Even though participants were unaware of the implicit temporal contingencies, pitch discrimination sensitivity (i.e. the slope of the psychometric function) increased when the onset of the target tone was predictable in time (N = 49). Concurrently recorded EEG data (N = 24) revealed that standard tones which initiated temporal predictions evoked a more negative N1 component than non-predictive standards, and were followed by an increase in delta power during the foreperiod. Furthermore, the phase angle of delta oscillations (1–3Hz) evoked by the standard tone predicted pitch discrimination sensitivity at the target tone (1.75 s later on average), which suggests that temporal predictions can be initiated by an optimized delta phase reset. In sum, we show that auditory perception benefits from implicit temporal contingencies, and provide evidence for a role of slow neural oscillations in the endogenous representation of temporal predictions, in absence of exogenously driven entrainment to rhythmic input.Significance StatementTemporal contingencies are ubiquitous in sensory environments, especially in the auditory domain, and have been shown to facilitate perception and action. Yet, how these contingencies in exogenous inputs are transformed into an endogenous representation of temporal predictions is not known. Here, we implicitly induced temporal predictability in the absence of a rhythmic input structure, that is without exogenously driven entrainment of neural oscillations. Our results show that even implicit and non-rhythmic temporal predictions are extracted and used by human observers, underlining the role of timing in sensory processing. Furthermore, our EEG results point towards an instrumental role of delta oscillations in initiating temporal predictions by an optimized phase reset in response to a temporally predictive cue.

scholarly journals A silent disco: Persistent entrainment of low-frequency neural oscillations underlies beat-based, but not memory-based temporal expectations

2020 ◽  
Author(s):  
Fleur L. Bouwer ◽  
Johannes J. Fahrenfort ◽  
Samantha K. Millard ◽  
Heleen A. Slagter
Keyword(s):  
Neuronal Activity ◽  
Beat Frequency ◽  
Low Frequency ◽  
Neural Oscillations ◽  
Expected Time ◽  
Low Frequency Oscillations ◽  
Eeg Data ◽  
Predictable Pattern ◽  
Temporal Intervals ◽  
Multivariate Pattern

AbstractTemporal expectations (e.g., predicting “when”) facilitate sensory processing, and are suggested to rely on entrainment of low frequency neural oscillations to regular rhythmic input. However, temporal expectations can be formed not only in response to a regular beat, such as in music (“beat-based” expectations), but also based on a predictable pattern of temporal intervals of different durations (“memory-based” expectations). Here, we examined the neural mechanisms underlying beat-based and memory-based expectations, by assessing EEG activity and behavioral responses during silent periods following rhythmic auditory sequences that allowed for beat-based or memory-based expectations, or had random timing. In Experiment 1 (N = 32), participants rated how well probe tones at various time points fitted the previous rhythm. Beat-based expectations affected fitness ratings for at least two beat-cycles, while the effects of memory-based expectations subsided after the first expected time point in the silence window. In Experiment 2 (N = 27), using EEG, we found a CNV following the final tones of memory-based and random, but not beat-based sequences, suggesting that climbing neuronal activity may specifically reflect memory-based expectations. Moreover, we found enhanced power in the EEG signal at the beat frequency for beat-based sequences both during listening and the silence. For memory-based sequences, we found enhanced power at a frequency inherent to the memory-based pattern only during listening, but not during the silence, suggesting that ongoing entrainment of low frequency oscillations may be specific to beat-based expectations. Finally, using multivariate pattern decoding on the raw EEG data, we could classify above chance from the silence which type of sequence participants had heard before. Together, our results suggest that beat-based and memory-based expectations rely on entrainment and climbing neuronal activity, respectively.

Role of cardiac output in mediating arterial blood pressure oscillations

1996 ◽  
Vol 271 (3) ◽  
pp. R641-R646 ◽  
Author(s):  
D. S. O'Leary ◽  
D. J. Woodbury
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Low Frequency ◽  
Left Ventricular ◽  
Right Atrial ◽  
Total Power ◽  
Av Block ◽  
Arterial Blood ◽  
Low Frequency Oscillations

The objective of this study was to determine the role of cardiac output in mediating spontaneous fluctuations in mean arterial pressure (MAP) conscious dogs. Dogs were chronically instrumented to monitor MAP and cardiac output. Atrioventricular (AV) block was induced, and left ventricular and right atrial electrodes were implanted. After recovery, MAP was observed for 5 min under two conditions: 1) normal variation in heart rate and cardiac output via triggering the ventricular stimulator with each atrial depolarization (effectively reversing the AV block, AV-linked stimulation) and 2) computer control of ventricular rate to maintain cardiac output constant on a by-beat basis at the same level as observed during normal variations in heart rate and cardiac output. When cardiac output was held constant, large-amplitude, low-frequency oscillations in MAP were readily apparent. Spectral analysis by fast Fourier transform revealed that during constant cardiac output the power observed at low frequencies in the MAP spectrum represented 95.0 +/- 2.7% of the total power compared with 75.5 +/- 4.6% during normal variations in heart rate and cardiac output (P < 0.05). In addition, when cardiac output was held constant, the power observed at higher frequencies markedly decreased from 24.5 +/- 4.6% of total power during AV-linked stimulation to only 5.0 +/- 2.7% of total power during constant cardiac output (P < 0.05). We conclude that low-frequency oscillations in MAP are due to changes in peripheral resistance, whereas a significant amount of high-frequency changes in MAP stems from spontaneous changes in cardiac output.

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