Python-生成模拟原始脑电数据 / 四六文摘

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在实验中有时需要原始脑电数据来进行模拟实验，但又限于实验条件的不足，需要构造模拟的原始脑电数据。

本示例通过多次重复所需的源激活来生成原始数据。

案例介绍

# 导入工具包import numpy as npimport matplotlib.pyplot as plt

import mnefrom mne import find_events, Epochs, compute_covariance, make_ad_hoc_covfrom mne.datasets import samplefrom mne.simulation import (simulate_sparse_stc, simulate_raw, add_noise, add_ecg, add_eog)%matplotlib auto

data_path = sample.data_path()raw_fname = data_path + '/MEG/sample/sample_audvis_raw.fif'fwd_fname = data_path + '/MEG/sample/sample_audvis-meg-eeg-oct-6-fwd.fif'

# 加载真实数据作为模板raw = mne.io.read_raw_fif(raw_fname)raw.set_eeg_reference(projection=True)

生成偶极子时间序列

# 设置偶极子的数量n_dipoles = 4# 每个epoch或者event的时间窗口长度epoch_duration = 2.#谐波数n = 0 # 随机状态（可复制）rng = np.random.RandomState(0)

def data_fun(times): """产生时间交错的正弦波，谐波为10Hz""" global n n_samp = len(times) window = np.zeros(n_samp) start, stop = [int(ii * float(n_samp) / (2 * n_dipoles)) for ii in (2 * n, 2 * n + 1)] window[start:stop] = 1. n += 1 data = 25e-9 * np.sin(2. * np.pi * 10. * n * times) data *= window return data

times = raw.times[:int(raw.info['sfreq'] * epoch_duration)]fwd = mne.read_forward_solution(fwd_fname)src = fwd['src']stc = simulate_sparse_stc(src, n_dipoles=n_dipoles, times=times, data_fun=data_fun, random_state=rng)# look at our source datafig, ax = plt.subplots(1)ax.plot(times, 1e9 * stc.data.T)ax.set(ylabel='Amplitude (nAm)', xlabel='Time (sec)')mne.viz.utils.plt_show()

得到模拟原始数据并绘制

"""模拟原始数据"""raw_sim = simulate_raw(raw.info, [stc] * 10, forward=fwd, cov=None, verbose=True)cov = make_ad_hoc_cov(raw_sim.info)add_noise(raw_sim, cov, iir_filter=[0.2, -0.2, 0.04], random_state=rng)add_ecg(raw_sim, random_state=rng)add_eog(raw_sim, random_state=rng)raw_sim.plot()plt.show()

绘制诱发数据

"""绘制诱发数据"""events = find_events(raw_sim) # only 1 pos, so event number == 1epochs = Epochs(raw_sim, events, 1, tmin=-0.2, tmax=epoch_duration)cov = compute_covariance(epochs, tmax=0., method='empirical', verbose='error') # quick calcevoked = epochs.average()evoked.plot_white(cov, time_unit='s')plt.show()