scholarly journals High‐gamma power changes after cognitive intervention: preliminary results from twenty‐one senior adult subjects

2016 ◽  
Vol 6 (3) ◽  
Author(s):  
Yoritaka Akimoto ◽  
Takayuki Nozawa ◽  
Akitake Kanno ◽  
Toshimune Kambara ◽  
Mizuki Ihara ◽  
...  
Keyword(s):  
Cognitive Intervention ◽  
Preliminary Results ◽  
High Gamma ◽  
Gamma Power ◽  
Senior Adult

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 Autobiographical Memory and Social Identity in Autism: Preliminary Results of Social Positioning and Cognitive Intervention

2021 ◽  
Vol 12 ◽  
Author(s):  
Prany Wantzen ◽  
Amélie Boursette ◽  
Elodie Zante ◽  
Jeanne Mioche ◽  
Francis Eustache ◽  
...  
Keyword(s):  
Social Identity ◽  
Autobiographical Memory ◽  
Cognitive Intervention ◽  
Autism Spectrum ◽  
Typically Developing ◽  
Autobiographical Narratives ◽  
Preliminary Results ◽  
Social Positioning ◽  
The Social ◽  
Adolescents With Asd

Autobiographical memory (AM) is closely linked to the self-concept, and fulfills directive, identity, social, and adaptive functions. Individuals with autism spectrum disorder (ASD) are now known to have atypical AM, which may be closely associated with social communication difficulties. This may result in qualitatively different autobiographical narratives, notably regarding social identity. In the present study, we sought to investigate this concept and develop a cognitive intervention targeting individuals with ASD. First, 13 adolescents with ASD and 13 typically developing adolescents underwent an AM interview featuring an original coding system designed to analyze the social self. We observed that the narratives produced by the ASD group focused more on the family than on extended social spheres, compared with those of the comparison group. Moreover, participants with ASD did not include themselves in the social groups they mentioned, and produced more references to others, compared with typically developing participants. Second, we designed a cognitive intervention program consisting of individual and group sessions that targeted AM. We conducted a pilot study among three adolescents with ASD aged 12, 16, and 17 years. Preliminary results showed that the program increased extra-family narrative references by the two youngest adolescents, who produced more social integration markers. Our study of autobiographical narratives yielded interesting findings about social positioning in ASD and showed how AM can be targeted in rehabilitation programs as a vector of social interaction.

scholarly journals Stratification of behavioral response to transcranial current stimulation by resting-state electrophysiology

2020 ◽  
Author(s):  
Atalanti A. Mastakouri
Keyword(s):  
Resting State ◽  
Behavioral Response ◽  
Prediction Method ◽  
Neurophysiological Mechanism ◽  
Reaching Task ◽  
State Activity ◽  
High Gamma ◽  
Spatial Configurations ◽  
Gamma Power ◽  
Transcranial Alternating Current Stimulation

Transcranial alternating current stimulation (tACS) enables the non-invasive stimulation of brain areas in desired frequencies, intensities and spatial configurations. These attributes have raised tACS to a widely used tool in cognitive neuroscience and a promising treatment in the field of motor rehabilitation. Nevertheless, considerable heterogeneity of its behavioral effects has been reported across individuals. We present a machine learning pipeline for predicting the behavioral response to 70 Hz contralateral motor cortex-tACS from Electroencephalographic resting-state activity preceding the stimulation. Specifically, we show in a cross-over study design that high-gamma (90--160 Hz) resting-state activity predicts arm-speed response to the stimulation in a concurrent reaching task. Moreover, we show in a prospective stimulation study that the behavioural effect size of stimulation significantly increases after the stratification of subjects with our prediction method. Finally, we discuss a plausible neurophysiological mechanism that links high resting-state gamma power in motor areas to stimulation response. As such, we provide a method that can distinguish responders from non-responders to tACS, prior to the stimulation treatment. This contribution could eventually bring us a step closer towards translating tACS into a safe and effective clinical treatment tool.

scholarly journals Comparison of tuning properties of gamma and high-gamma power in local field potential (LFP) versus electrocorticogram (ECoG) in visual cortex

2019 ◽  
Author(s):  
Agrita Dubey ◽  
Supratim Ray
Keyword(s):  
Visual Cortex ◽  
Local Field ◽  
Local Field Potential ◽  
Field Potential ◽  
Gamma Oscillations ◽  
Orientation Contrast ◽  
High Gamma ◽  
Gamma Power ◽  
Electrocorticogram Ecog ◽  
Local Field Potential Lfp

AbstractElectrocorticogram (ECoG), obtained from macroelectrodes placed on the cortex, is typically used in drug-resistant epilepsy patients, and is increasingly being used to study cognition in humans. These studies often use power in gamma (30-70 Hz) or high-gamma (>80 Hz) ranges to make inferences about neural processing. However, while the stimulus tuning properties of gamma/high-gamma power have been well characterized in local field potential (LFP; obtained from microelectrodes), analogous characterization has not been done for ECoG. Using a hybrid array containing both micro and ECoG electrodes implanted in the primary visual cortex of two female macaques, we compared the stimulus tuning preferences of gamma/high-gamma power in LFP versus ECoG and found them to be surprisingly similar. High-gamma power, thought to index the average firing rate around the electrode, was highest for the smallest stimulus (0.3° radius), and decreased with increasing size in both LFP and ECoG, suggesting local origins of both signals. Further, gamma oscillations were similarly tuned in LFP and ECoG to stimulus orientation, contrast and spatial frequency. This tuning was significantly weaker in electroencephalogram (EEG), suggesting that ECoG is more like LFP than EEG. Overall, our results validate the use of ECoG in clinical and basic cognitive research.

scholarly journals High-gamma activity in the human hippocampus during inter-trial rest periods of a virtual navigation task

2018 ◽  
Author(s):  
Yi Pu ◽  
Brian R. Cornwell ◽  
Douglas Cheyne ◽  
Blake W. Johnson
Keyword(s):  
Gamma Oscillations ◽  
Gamma Activity ◽  
Training Set ◽  
Virtual Navigation ◽  
Navigation Task ◽  
Theta Power ◽  
Rest Periods ◽  
Synthetic Aperture Magnetometry ◽  
High Gamma ◽  
Gamma Power

AbstractIn rodents, hippocampal cell assemblies formed during learning of a navigation task are observed to re-emerge during resting (offline) periods, accompanied by high-frequency oscillations (HFOs). This phenomenon is believed to reflect mechanisms for strengthening newly-formed memory traces. Using magnetoencephalography recordings and a beamforming source location algorithm (synthetic aperture magnetometry), we investigated high-gamma (80 – 140 Hz) oscillations in the hippocampal region in 18 human participants during inter-trial rest periods in a virtual navigation task. We found right hippocampal gamma oscillations mirrored the pattern of theta power in the same region during navigation, varying as a function of environmental novelty. Gamma power during inter-trial rest periods was positively correlated with theta power during navigation in the first training set when the environment was new and predicted faster learning in the subsequent training set two where the environment became familiar. These findings provide evidence for human hippocampal reactivation accompanied by high-gamma activities immediately after learning and establish a link between hippocampal high-gamma activities and memory consolidation.

scholarly journals Spatial-Temporal Functional Mapping Combined With Cortico-Cortical Evoked Potentials in Predicting Cortical Stimulation Results

2021 ◽  
Vol 15 ◽  
Author(s):  
Yujing Wang ◽  
Mark A. Hays ◽  
Christopher Coogan ◽  
Joon Y. Kang ◽  
Adeen Flinker ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Effective Connectivity ◽  
Single Pulse ◽  
Functional Mapping ◽  
Invasive Monitoring ◽  
Cortical Evoked Potentials ◽  
High Gamma ◽  
Gamma Power ◽  
Mapping Techniques ◽  
The One

Functional human brain mapping is commonly performed during invasive monitoring with intracranial electroencephalographic (iEEG) electrodes prior to resective surgery for drug­ resistant epilepsy. The current gold standard, electrocortical stimulation mapping (ESM), is time ­consuming, sometimes elicits pain, and often induces after discharges or seizures. Moreover, there is a risk of overestimating eloquent areas due to propagation of the effects of stimulation to a broader network of language cortex. Passive iEEG spatial-temporal functional mapping (STFM) has recently emerged as a potential alternative to ESM. However, investigators have observed less correspondence between STFM and ESM maps of language than between their maps of motor function. We hypothesized that incongruities between ESM and STFM of language function may arise due to propagation of the effects of ESM to cortical areas having strong effective connectivity with the site of stimulation. We evaluated five patients who underwent invasive monitoring for seizure localization, whose language areas were identified using ESM. All patients performed a battery of language tasks during passive iEEG recordings. To estimate the effective connectivity of stimulation sites with a broader network of task-activated cortical sites, we measured cortico-cortical evoked potentials (CCEPs) elicited across all recording sites by single-pulse electrical stimulation at sites where ESM was performed at other times. With the combination of high gamma power as well as CCEPs results, we trained a logistic regression model to predict ESM results at individual electrode pairs. The average accuracy of the classifier using both STFM and CCEPs results combined was 87.7%, significantly higher than the one using STFM alone (71.8%), indicating that the correspondence between STFM and ESM results is greater when effective connectivity between ESM stimulation sites and task-activated sites is taken into consideration. These findings, though based on a small number of subjects to date, provide preliminary support for the hypothesis that incongruities between ESM and STFM may arise in part from propagation of stimulation effects to a broader network of cortical language sites activated by language tasks, and suggest that more studies, with larger numbers of patients, are needed to understand the utility of both mapping techniques in clinical practice.

Forebrain Acetylcholine Modulates Isoflurane and Ketamine Anesthesia in Adult Mice

2021 ◽  
Vol 134 (4) ◽  
pp. 588-606 ◽  
Author(s):  
L. Stan Leung ◽  
Liangwei Chu ◽  
Marco A. M. Prado ◽  
Vania F. Prado
Keyword(s):  
Interaction Effect ◽  
Gamma Activity ◽  
Wild Type ◽  
Male Adult ◽  
Adult Mice ◽  
Loss Of Righting Reflex ◽  
High Gamma ◽  
Ketamine Anesthesia ◽  
Gamma Power ◽  
Righting Reflex

Background Cholinergic drugs are known to modulate general anesthesia, but anesthesia responses in acetylcholine-deficient mice have not been studied. It was hypothesized that mice with genetic deficiency of forebrain acetylcholine show increased anesthetic sensitivity to isoflurane and ketamine and decreased gamma-frequency brain activity. Methods Male adult mice with heterozygous knockdown of vesicular acetylcholine transporter in the brain or homozygous knockout of the transporter in the basal forebrain were compared with wild-type mice. Hippocampal and frontal cortical electrographic activity and righting reflex were studied in response to isoflurane and ketamine doses. Results The loss-of-righting-reflex dose for isoflurane was lower in knockout (mean ± SD, 0.76 ± 0.08%, n = 18, P = 0.005) but not knockdown (0.78 ± 0.07%, n = 24, P = 0.021), as compared to wild-type mice (0.83 ± 0.07%, n = 23), using a significance criterion of P = 0.017 for three planned comparisons. Loss-of-righting-reflex dose for ketamine was lower in knockout (144 ± 39 mg/kg, n = 14, P = 0.006) but not knockdown (162 ± 32 mg/kg, n = 20, P = 0.602) as compared to wild-type mice (168 ± 24 mg/kg, n = 21). Hippocampal high-gamma (63 to 100 Hz) power after isoflurane was significantly lower in knockout and knockdown mice compared to wild-type mice (isoflurane-dose and mouse-group interaction effect, F[8,56] = 2.87, P = 0.010; n = 5 to 6 mice per group). Hippocampal high-gamma power after ketamine was significantly lower in both knockout and knockdown mice when compared to wild-type mice (interaction effect F[2,13] = 6.06, P = 0.014). The change in frontal cortical gamma power with isoflurane or ketamine was not statistically different among knockout, knockdown, and wild-type mice. Conclusions These findings suggest that forebrain cholinergic neurons modulate behavioral sensitivity and hippocampal gamma activity during isoflurane and ketamine anesthesia. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

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