scholarly journals Synchronization in Monkey Motor Cortex During a Precision Grip Task. I. Task-Dependent Modulation in Single-Unit Synchrony

2001 ◽  
Vol 85 (2) ◽  
pp. 869-885 ◽  
Author(s):  
S. N. Baker ◽  
R. Spinks ◽  
A. Jackson ◽  
R. N. Lemon
Keyword(s):  
Motor Cortex ◽  
Firing Rate ◽  
Cross Correlation ◽  
Primary Motor Cortex ◽  
Precision Grip ◽  
Average Width ◽  
Population Synchrony ◽  
Hold Period ◽  
The Cross ◽  
The Impact

Neural synchronization in the cortex, and its potential role in information coding, has attracted much recent attention. In this study, we have recorded long spike trains (mean, 33,000 spikes) simultaneously from multiple single neurons in the primary motor cortex (M1) of two conscious macaque monkeys performing a precision grip task. The task required the monkey to use its index finger and thumb to move two spring-loaded levers into a target, hold them there for 1 s, and release for a food reward. Synchrony was analyzed using a time-resolved cross-correlation method, normalized using an estimate of the instantaneous firing rate of the cell. This was shown to be more reliable than methods using trial-averaged firing rate. A total of 375 neurons was recorded from the M1 hand area; 235 were identified as pyramidal tract neurons. Synchrony was weak [mean k′ = 1.05 ± 0.04 (SD)] but widespread among pairs of M1 neurons (218/1359 pairs with above-chance synchrony), including output neurons. Synchrony usually took the form of a broad central peak [average width, 18.7 ± 8.7 (SD) ms]. There were marked changes during different phases of the task. As a population, synchrony was greatest during the steady hold period in striking contrast to the averaged cell firing rate, which was maximal when the animal was moving the levers into target. However, the modulation of synchrony during task performance showed considerable variation across individual cell pairs. Two types of synchrony were identified: oscillatory (with periodic side lobes in the cross-correlation) and nonoscillatory. Their relative contributions were quantified by filtering the cross-correlations to exclude either frequencies from 18 to 37 Hz or all higher and lower frequencies. At the peak of population synchrony during the hold period, about half (51.7% in one monkey, 56.2% in the other) of the synchronization was within this oscillatory bandwidth. This study provides strong support for assemblies of neurons being synchronized during specific phases of a complex task with potentially important consequences for both information processing within M1 and for the impact of M1 commands on target motoneurons.

Abstract 170: Impact of Eloquent Motor Cortex-Tissue Reperfusion Beyond the Traditional TICI Scoring After Thrombectomy

Stroke ◽  
2020 ◽  
Vol 51 (Suppl_1) ◽  
Author(s):  
Radoslav I Raychev ◽  
Jeffrey Saver ◽  
Scott Brown ◽  
Gary Duckwiler ◽  
Reza Jahan ◽  
...  
Keyword(s):  
Multivariate Analysis ◽  
Motor Cortex ◽  
Primary Motor Cortex ◽  
Multivariable Analysis ◽  
Functional Independence ◽  
Digital Subtraction ◽  
Anterior Circulation ◽  
Endovascular Thrombectomy ◽  
Stroke Disability ◽  
The Impact

Background: Targeted eloquence-based tissue reperfusion within the primary motor cortex may have differential effect on disability as compared to the traditional volume-based (TICI) reperfusion after endovascular thrombectomy (EVT) in setting of acute ischemic stroke (AIS). Methods: We explored the impact of eloquent reperfusion (ER) within primary motor cortex (PMC) on clinical outcome (mRS) in AIS patients undergoing EVT. ER was defined as presence of flow on final digital subtraction angiography (DSA) within four main cortical branches, supplying the PMC (MCA - precentral, central, anterior parietal; ACA- pericallosal) and graded as absent (0), partial (1), and complete (2). Prospectively collected data from two centers were analyzed. Multivariable analysis was conducted to assess the impact of ER on 90-day disability (mRS) among patients with anterior circulation occlusion who achieved partial reperfusion (TICI 2 a and b). Results: Among the 125 patients who met study criteria, median age was 73, median NIHSS was 16, median ASPECTS was 7, 48% (60/125) were female, and 36.8% achieved functional independence (mRS 0-2) at 90 days. ER distribution was: Absent (0) in 19/125 (15.2%); Partial (1) in 52/125 (41.6%), and Complete (2) in 54/125 (43.2%). TICI 2b was achieved in 102/125 (81.6%) and ER was substantially higher in those patients (p<0.001). In multivariate analysis, in addition to age and sICH, ER had a profound independent impact on 90-day disability (OR 6.10, p=0.001 for ER 1 vs 0; and OR 9.87, p<0.001 for ER 2 vs 0). In contrast, extent of total partial reperfusion (TICI 2b vs 2a) was not related to 90-day disability. Conclusions: Our findings support that eloquent PMC-tissue reperfusion is a major determinant of functional outcome, more impactful than volume-based degree of partial reperfusion. More aggressive, PMC-targeted revascularization among patients with non-eloquent partial reperfusion may further improve post-stroke disability after EVT.

Analyzing the Impact of COVID-19 on the Cross-Correlations between Financial Search Engine Data and Movie Box Office

2020 ◽  
pp. 2150021
Author(s):  
Renyu Wang ◽  
Yujie Xie ◽  
Hong Chen ◽  
Guozhu Jia
Keyword(s):  
Financial Market ◽  
Cross Correlation ◽  
Multifractal Spectrum ◽  
Movie Industry ◽  
Box Office ◽  
Cross Correlation Analysis ◽  
Cross Correlations ◽  
The Cross ◽  
Google Search ◽  
The Impact

This paper explores the COVID-19 influences on the cross-correlation between the movie market and the financial market. The nonlinear cross-correlations between movie box office data and Google search volumes of financial terms such as Dow Jones Industrial Average (DJIA), NASDAQ and PMI are investigated based on multifractal detrended cross-correlation analysis (MF-DCCA). The empirical results show there are nonlinear cross-correlations between movie market and financial market. Metrics such as Hurst exponents, singular exponents and multifractal spectrum demonstrate that the cross-correlation between movie market and financial market is persistent, and the cross-correlation in long term is more stable than that in short term. In the COVID-19 period, the multifractal features of cross-correlation become stronger implying that COVID-19 enhanced the complexity between the movie industry and the financial market. Furthermore, through the rolling window analysis, the Hurst exponent dynamic trends indicate that COVID-19 has a clear influence on the cross-correlation between movie market and financial market.

scholarly journals Expanding the parameter space of anodal transcranial direct current stimulation of the primary motor cortex

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Desmond Agboada ◽  
Mohsen Mosayebi Samani ◽  
Asif Jamil ◽  
Min-Fang Kuo ◽  
Michael A. Nitsche
Keyword(s):  
Motor Cortex ◽  
Parameter Space ◽  
Primary Motor Cortex ◽  
Cortical Excitability ◽  
Motor Evoked Potentials ◽  
Anodal Tdcs ◽  
Stimulation Parameters ◽  
Motor Cortex Excitability ◽  
The Impact ◽  
Motor Cortex Plasticity

AbstractSize and duration of the neuroplastic effects of tDCS depend on stimulation parameters, including stimulation duration and intensity of current. The impact of stimulation parameters on physiological effects is partially non-linear. To improve the utility of this intervention, it is critical to gather information about the impact of stimulation duration and intensity on neuroplasticity, while expanding the parameter space to improve efficacy. Anodal tDCS of 1–3 mA current intensity was applied for 15–30 minutes to study motor cortex plasticity. Sixteen healthy right-handed non-smoking volunteers participated in 10 sessions (intensity-duration pairs) of stimulation in a randomized cross-over design. Transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEP) were recorded as outcome measures of tDCS effects until next evening after tDCS. All active stimulation conditions enhanced motor cortex excitability within the first 2 hours after stimulation. We observed no significant differences between the three stimulation intensities and durations on cortical excitability. A trend for larger cortical excitability enhancements was however observed for higher current intensities (1 vs 3 mA). These results add information about intensified tDCS protocols and suggest that the impact of anodal tDCS on neuroplasticity is relatively robust with respect to gradual alterations of stimulation intensity, and duration.

The Impact of Wavelength Step on Radial Velocity Error

2012 ◽  
Vol 239-240 ◽  
pp. 794-797
Author(s):  
Fang Zuo ◽  
A Li Luo
Keyword(s):  
Radial Velocity ◽  
Measurement Method ◽  
Cross Correlation ◽  
Stellar Spectra ◽  
Velocity Error ◽  
Target Spectrum ◽  
Different Types ◽  
The Cross ◽  
The Impact ◽  
Internal Error

Radial velocity (RV) of a star caused by Doppler shift could be easily measured by cross-correlated it’s spectrum with a serial template. Generally, the RV error of a spectrum always is given by the widths of the cross-correlation function of the target spectrum and related template spectrum. RV error comes from many factors, causing from instruments, observation weather, etc.. In this paper, simulation with different types of stellar spectra, which has different temperature, is implemented. The results show that there is an internal error which is not generated by the calculation steps for a given resolution step, for example, 5km/s error exists in the cross-correlation based RV measurement method for resolution about R~2000. The simulation also proves that this error could not be avoided for any type of stars.

GPS Cross Correlation Mitigation Technique in Multipath Environment

2010 ◽  
Vol 439-440 ◽  
pp. 715-720
Author(s):  
Jun Yao Gao ◽  
Jing Shu Yang ◽  
Jia Zhao
Keyword(s):  
Interference Cancellation ◽  
Cross Correlation ◽  
Parallel Interference Cancellation ◽  
Multipath Environment ◽  
Simulation Results ◽  
The Cross ◽  
The Impact ◽  
Mitigation Technique

The paper investigates the cross correlation mitigation (CCM) technique in the multipath propagating environment. It analyses the impact of cross correlation firstly, then expounds the universal technique in CCM, at last presents an improved DPIC (Delayed Parallel Interference Cancellation) method based on MEDLL. The algorithm estimates the parameters of multipath by using MEDLL, reconstructs the strong signals IF utilizing these parameters, and mitigates the cross correlation with the aid of DPIC method. At last, simulation results prove the validity of this method.

Task-related changes in intracortical inhibition assessed with paired- and triple-pulse transcranial magnetic stimulation

2015 ◽  
Vol 113 (5) ◽  
pp. 1470-1479 ◽  
Author(s):  
George M. Opie ◽  
Michael C. Ridding ◽  
John G. Semmler
Keyword(s):  
Transcranial Magnetic Stimulation ◽  
Motor Cortex ◽  
Magnetic Stimulation ◽  
Muscle Activation ◽  
Primary Motor Cortex ◽  
Index Finger ◽  
Precision Grip ◽  
Intracortical Inhibition ◽  
Presynaptic Mechanisms ◽  
First Dorsal Interosseous Muscle

Recent research has demonstrated a task-related modulation of postsynaptic intracortical inhibition within primary motor cortex for tasks requiring isolated (abduction) or synergistic (precision grip) muscle activation. The current study sought to investigate task-related changes in pre- and postsynaptic intracortical inhibition in motor cortex. In 13 young adults (22.5 ± 3.5 yr), paired-pulse transcranial magnetic stimulation (TMS) was used to measure short (SICI)- and long-interval intracortical inhibition (LICI) (i.e., postsynaptic motor cortex inhibition) in first dorsal interosseous muscle, and triple-pulse TMS was used to investigate changes in SICI-LICI interactions (i.e., presynaptic motor cortex inhibition). These measurements were obtained at rest and during muscle activation involving isolated abduction of the index finger and during a precision grip using the index finger and thumb. SICI was reduced during abduction and precision grip compared with rest, with greater reductions during precision grip. The modulation of LICI during muscle activation depended on the interstimulus interval (ISI; 100 and 150 ms) but was not different between abduction and precision grip. For triple-pulse TMS, SICI was reduced in the presence of LICI at both ISIs in resting muscle (reflecting presynaptic motor cortex inhibition) but was only modulated at the 150-ms ISI during index finger abduction. Results suggest that synergistic contractions are accompanied by greater reductions in postsynaptic motor cortex inhibition than isolated contractions, but the contribution of presynaptic mechanisms to this disinhibition is limited. Furthermore, timing-dependent variations in LICI provide additional evidence that measurements using different ISIs may not represent activation of the same cortical process.

scholarly journals Noise-Correlation Is Modulated by Reward Expectation in the Primary Motor Cortex Bilaterally During Manual and Observational Tasks in Primates

2020 ◽  
Vol 14 ◽  
Author(s):  
Brittany Moore ◽  
Sheng Khang ◽  
Joseph Thachil Francis
Keyword(s):  
Motor Cortex ◽  
Firing Rate ◽  
Primary Motor Cortex ◽  
Action Observation ◽  
Noise Correlation ◽  
Information Channel ◽  
Qualitative Response ◽  
Computer Interfaces ◽  
Single Target ◽  
Target Center

Reward modulation is represented in the motor cortex (M1) and could be used to implement more accurate decoding models to improve brain-computer interfaces (BCIs; Zhao et al., 2018). Analyzing trial-to-trial noise-correlations between neural units in the presence of rewarding (R) and non-rewarding (NR) stimuli adds to our understanding of cortical network dynamics. We utilized Pearson’s correlation coefficient to measure shared variability between simultaneously recorded units (32–112) and found significantly higher noise-correlation and positive correlation between the populations’ signal- and noise-correlation during NR trials as compared to R trials. This pattern is evident in data from two non-human primates (NHPs) during single-target center out reaching tasks, both manual and action observation versions. We conducted a mean matched noise-correlation analysis to decouple known interactions between event-triggered firing rate changes and neural correlations. Isolated reward discriminatory units demonstrated stronger correlational changes than units unresponsive to reward firing rate modulation, however, the qualitative response was similar, indicating correlational changes within the network as a whole can serve as another information channel to be exploited by BCIs that track the underlying cortical state, such as reward expectation, or attentional modulation. Reward expectation and attention in return can be utilized with reinforcement learning (RL) towards autonomous BCI updating.

scholarly journals Adaptive seismic noise reduction using Wiener filter

2019 ◽  
Vol 8 (1) ◽  
pp. 12-20
Author(s):  
Sesar Prabu Dwi Sriyanto
Keyword(s):  
Seismic Noise ◽  
Cross Correlation ◽  
Seismic Station ◽  
Wiener Filter ◽  
Dominant Frequency ◽  
Observation System ◽  
Before And After ◽  
Filter Process ◽  
The Cross ◽  
The Impact

Seismic noise disrupts the earthquake observation system due to the frequency and amplitude of seismic noise similar to the earthquake signal. The filter process is one of the methods that can be used to reduce seismic noise. In this study, the Wiener filter algorithm was designed with the Decision-Directed method for Apriori SNR estimation. This filter was chosen because it is adaptive, so it can adjust to environmental conditions without requiring manual parameter settings. The data used are earthquake signals that occur in the Palu area, Central Sulawesi, which are recorded on PKA29 temporary seismic station from February 3 to April 28, 2015. After each signal data has been filtered, then it is evaluated by calculating SNR differences before and after filtering, the signal's dominant frequency, and the cross-correlation of the signal before and after filtering. As a result, the Wiener filter is able to reduce the noise content in earthquake signals according to noisy frequencies before earthquake signals. The impact is that SNR has increased with an average of 8.056 dB. In addition, this filter is also able to maintain the shape of earthquake signals. This is indicated by the normalization value of the cross-correlation between signals before and after the filter which ranges from 0.703 to 1.00.

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