The aims of this study were to examine both static functional connectivity (FC) and dynamic FC alterations in motor execution regions after stroke and to investigate whether the altered static or dynamic FC was associated with the clinical behaviors in stroke patients. Seventy-six stroke patients and 55 healthy controls (HC) were recruited. Static FC and dynamic FC maps were computed based on the seeds of six core regions in motor execution network. Correlation analyses were performed between static or dynamic FC and clinical behavioral scores in stroke patients. Compared with the HC, the stroke patients had significantly higher static FC between the seeds and the precentral or postcentral gyrus, frontal gyrus, inferior parietal lobule, thalamus and insula, and lower static FC between the seeds and the cerebellum and middle temporal gyrus. There were significant differences in dynamic FC between the seeds and precuneus, calcarine gyrus, insula, inferior parietal lobule, precentral gyrus, and middle temporal, frontal or occipital gyrus between the stroke patients and HC. Furthermore, a significant negative correlation was found between the Fugl-Meyer assessment scores and dynamic FC of the ipsilesional primary motor cortex and contralesional precentral gyrus in patients. The current study shows that the patterns of both static FC and dynamic FC changed after stroke, and correlation between motor function and temporal variability in the FC of the precentral gyrus was significant in stroke patients. Our findings indicate that dynamic FC might be a potential indicator for evaluating motor function after stroke.
Endocannabinoid (eCB) signaling mediates depolarization-induced suppression of excitation (DSE) and inhibition (DSI), two prominent forms of retrograde synaptic depression. N-Arachidonoylethanolamine (AEA) and 2-arachidonoylglycerol (2-AG), two known eCBs, are degraded by fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL), respectively. Selective blockade of FAAH and MAGL is critical for determining the roles of the eCBs in DSE/DSI and understanding how their action is regulated. 4-Nitrophenyl 4-(dibenzo[d][1,3]dioxol-5-yl(hydroxy)methyl)piperidine-1-carboxylate (JZL184) is a recently developed, highly selective, and potent MAGL inhibitor that increases 2-AG but not AEA concentrations in mouse brain. Here, we report that JZL184 prolongs DSE in Purkinje neurons in cerebellar slices and DSI in CA1 pyramidal neurons in hippocampal slices. The effect of JZL184 on DSE/DSI is mimicked by the nonselective MAGL inhibitor methyl arachidonyl fluorophosphonate. In contrast, neither the selective FAAH inhibitor cyclohexylcarbamic acid 3'-carbomoylbiphenyl-3-yl ester (URB597) nor FAAH knockout has a significant effect on DSE/DSI. JZL184 produces greater enhancement of DSE/DSI in mouse neurons than that in rat neurons. The latter finding is consistent with biochemical studies showing that JZL184 is more potent in inhibiting mouse MAGL than rat MAGL. These results indicate that the degradation of 2-AG by MAGL is the rate-limiting step that determines the time course of DSE/DSI and that JZL184 is a useful tool for the study of 2-AG-mediated signaling.