Modulation of itch and pain signals processing in ventrobasal thalamus by thalamic reticular nucleus.

Thalamic reticular nucleus (TRN) is known to be crucial for dynamically modulating sensory processing. Recently, the functional role of TRN in itch and pain sensation processing has drawn much attention. We found that ventrobasal thalamus (VB) neurons exhibited scratching behavior-related and nociceptive behavior-related neuronal activity changes, and most of VB neurons responsive to pruritic stimulus were also activated by nociceptive stimulus. Inhibition of VB could relieve itch-induced scratching behaviors and pathological pain without affecting basal nociceptive thresholds, and activation of VB could facilitate scratching behaviors. Tracing and electrophysiology recording results showed that VB mainly received inhibitory inputs from ventral TRN. Furthermore, optogenetic activation of TRN-VB projections suppressed scratching behaviors, and ablation of TRN enhanced scratching behaviors. In addition, activation of TRN-VB projections relieved the pathological pain without affecting basal nociceptive thresholds. Thus, our study indicates that TRN modulates itch and pain signals processing via TRN-VB inhibitory projections.

Resting-state abnormalities in functional connectivity of the default mode network in autism spectrum disorder: a meta-analysis.

Increasing evidence has shown that the resting state brain connectivity of default mode network (DMN) which are important for social cognition are disrupted in autism spectrum disorder (ASD). However, previous neuroimaging studies did not present consistent results. Therefore, we performed a meta-analysis of resting-state functional connectivity (rsFC) studies of DMN in the individuals with ASD and healthy controls (HCs) to provide a new perspective for investigating the pathophysiology of ASD. We carried out a search using the terms: ("ASD" OR "Autism") AND ("resting state" OR "rest") AND ("DMN" OR "default mode network") in PubMed, Web of Science and Embase to identify the researches published before January 2020. Ten resting state datasets including 203 patients and 208 HCs were included. Anisotropic Effect Size version of Signed Differential Mapping (AES-SDM) method was applied to identify group differences. In comparison with the HCs, the patients with ASD showed increased connectivity in cerebellum, right middle temporal gyrus, superior occipital gyrus, right supramarginal gyrus, supplementary motor area and putamen. Decreased connectivity was discovered in some nodes of DMN, such as medial prefrontal cortex, precuneus and angular gyrus. These results may help us to further clarify the neurobiological mechanisms in patients with ASD.

[Effect of electroacupuncture on morphine-conditioned place preference and activation of glutamatergic neurons in the ventromedial prefrontal cortex in rats].

OBJECTIVE: To observe the effect of electroacupuncture (EA) at "Zusanli"(ST36) and "Sanyinjiao"(SP6) on conditioned place preference (CPP) and activation of glutamatergic neurons in the ventromedial prefrontal cortex (VMPFC) of morphine-addiction rats, so as to explore its mechanisms underlying detoxification. METHODS: Thirty male SD rats were randomly and equally divided into control, model and EA groups. The rats with acquisition of morphine-induced CPP received intraperitoneal injection of morphine (10 mg/kg) in the morphine-paired chamber, once daily for 3 consecutive days, and those of the control group received intraperitoneal injection of the same dose of normal saline in saline-paired chamber. Thirty minutes before CPP acquisition training, EA (2 Hz/100 Hz, 0.5 to 1.0 mA) was applied to ST36 and SP6 for 20 min every day. The double-labeled neurons of Fos/vesicular glutamate transporter 2 (VGLUT2) in the VMPFC were detected by using fluorescent immunohistochemistry. The discharges of the VMPFC neurons were recorded by using a multi-channel microarray electrophysiological system, followed by performing a z-score standardized processing. The ratio of firing rate frequency of rats in the morphine-paired chamber/saline-paired chamber was calculated, and further statistical analysis was conducted on the data based on the standardized z-scores. The neuronal firing characteristic of glutamatergic neuron is low frequency and wide wave. RESULTS: Compared with the control group, the score of morphine-induced CPP and numbers of Fos, VGLUT2-positive and Fos-VGLUT2 double-labeled positive cells were significantly increased in the model group (P<0.01，P<0.05). After EA and in comparison with the model group, the morphine CPP score and numbers of Fos, VGLUT2-positive and Fos-VGLUT2 double-labeled cells were significantly reduced in the EA group (P<0.01，P<0.05). The ratio of firing rate of the VMPFC neurons in the preference chamber and the percentage of inhibitory neurons as well as the z-score were considerably lower in the EA group than in the model group (P<0.001). CONCLUSION: EA can suppress morphine-induced seeking behavior in rats, which may be related to its inhibitory effect on glutamatergic neurons in the VMPFC.

[Brain regions responding to acupuncture stimulation of Zusanli (ST36) in healthy subjects analyzed on the basis of spontaneous brain activity].

OBJECTIVE: To determine the attributes of responses of the higher nerve center to acupuncture stimulation of Zusanli (ST36) on the basis of spontaneous brain activity, so as to explore the synchronization level of different brain rejoins after acupuncture. METHODS: All studies using fMRI to investigate the effect of acupuncture stimulation of ST36 and/or other acupoints on the human brain (at least 10 healthy subjects or patients in one group) published in journals from January of 1995 to January of 2018 were searched from databases of CNKI and PubMed by using keywords of acupuncture, electroacupuncture, and resting-state functional magnetic resonance images (rs-fMRI) or regional homogeneity (ReHo). Brain functional image data of acupuncture stimulation of ST36 and/or other acupoints were collected and analyzed with anisotropic effect size-signed differential mapping (AES-SDM) software (Meta-analysis), and those of acupuncture of simple ST36 analyzed as a subgroup. RESULTS: A total of 229 papers in Chinese and 109 in English were collected. According to our inclusive and exclusive standards, 11 papers containing 235 subjects were brought into analysis at last. Meta-analysis of brain image data of acupuncture at ST36 and/or other acupoints (comparison between pre- and post-acupuncture) revealed that the same brain regions (generality) which showed a significant increase in ReHo, are the right and left anterior cingulated gyrus, right caudate, left superior frontal gyrus, right middle frontal gyrus, and the right paracentral lobe, and those which showed a marked decrease of ReHo are the left mid-inferior occipital gyrus, left and right precentral and postcentral gyrus. The brain regions responding to acupuncture at ST36 only (specificity) are the right inferior parietal lobe, left middle inferior gyrus, right posterior lobe of cerebellum, and the left angular gyrus which displayed an increase of ReHo, and the right middle superior frontal gyrus which showed a decrease in ReHo. CONCLUSION: After acupuncturing at ST36, the relative generality and specificity of the central response in healthy subjects reflected as the location of the affected brain regions and the difference in the synchronization level of the corresponding spontaneous brain activities.