EEG patterns from acute to chronic stroke phases in focal cerebral ischemic rats: correlations with functional recovery

Abstract

Monitoring the neural activities from the ischemic penumbra provides critical information on neurological recovery after stroke. The purpose of this study is to evaluate the temporal alterations of neural activities using electroencephalography (EEG) from the acute phase to the chronic phase, and to compare EEG with the degree of post-stroke motor function recovery in a rat model of focal ischemic stroke. Male Sprague-Dawley rats were subjected to 90 min transient middle cerebral artery occlusion surgery followed by reperfusion for seven days (n = 58). The EEG signals were recorded at the pre-stroke phase (0 h), acute phase (3, 6 h), subacute phase (12, 24, 48, 72 h) and chronic phase (96, 120, 144, 168 h) (n = 8). This study analyzed post-stroke seizures and polymorphic delta activities (PDAs) and calculated quantitative EEG parameters such as the alpha-to-delta ratio (ADR). The ADR represented the ratio between alpha power and delta power, which indicated how fast the EEG activities were. Forelimb and hindlimb motor functions were measured by De Ryck's test and the beam walking test, respectively. In the acute phase, delta power increased fourfold with the occurrence of PDAs, and the histological staining showed that the infarct was limited to the striatum and secondary sensory cortex. In the subacute phase, the alpha power reduced to 50% of the baseline, and the infarct progressed to the forelimb cortical region. ADRs reduced from 0.23 ± 0.09 to 0.04 ± 0.01 at 3 h in the acute phase and gradually recovered to 0.22 ± 0.08 at 168 h in the chronic phase. In the comparison of correlations between the EEG parameters and the limb motor function from the acute phase to the chronic phase, ADRs were found to have the highest correlation coefficients with the beam walking test (r = 0.9524, p < 0.05) and De Ryck's test (r = 0.8077, p < 0.05). This study measured EEG activities after focal cerebral ischemia and showed that functional recovery was closely correlated with the neural activities in the penumbra. Longitudinal EEG monitoring at different phases after a stroke can provide information on the neural activities, which are well correlated with the motor function recovery.

Baclofen facilitates sleep, neuroplasticity, and recovery after stroke in rats

“…Furthermore, Bac led to a recovery of the power in the higher frequencies (above 8 Hz). Noteworthy, recent observations in rats, linked motor function recovery with EEG frequencies >7 Hz 41,43. SWA during NREM sleep has been associated with neuroplasticity processes9,17–19 and therefore could be proposed to play a role in the promotion of endogenous restorative mechanisms and functional improvement during stroke recovery.…”

Rescue of cortical neurovascular functions during the hyperacute phase of ischemia by peripheral sensory stimulation

“…Because delta (0.1-4 Hz) and alpha (8-12 Hz) frequency bands have been reported to be strong indicators for both injury and recovery after ischemia (Zhang et al, 2013), these two frequency bands were used to estimate inter-hemispheric coherence in our study. Specifically, the changes in inter-hemispheric coherence in the bilateral S1FL regions (Ch3-Ch4) were used to evaluate the effects of peripheral sensory stimulation treatment before and after PTI induction (Figs.…”

Improving neurovascular outcomes with bilateral forepaw stimulation in a rat photothrombotic ischemic stroke model

“…[38][39][40] A multivariate autoregressive model (MVAR) was adapted to carry out these analyses. 41 XðtÞ ¼ ½x 1 ðtÞ; x 2 ðtÞ; : : : ; x n ðtÞ T denoted the multichannel ECoG data vector, and x n ðtÞ denoted the n'th channel of ECoG signal (i.e., n ¼ 6, in this study).…”