Activation of the Human Premotor Cortex During Motor Preparation in Visuomotor Tasks

Functional brain mapping studies in humans suggest that both motor and premotor cortices interact during movement execution. The aim of this study was to investigate whether the premotor cortex also participates in motor planning. We measured movement-related cerebral fields (MRCFs) using magnetoencephalography from the left hemisphere of 12 healthy right-handed participants during two simple visuomotor tasks cued by two visual stimuli S1 and S2. Participants performed a unilateral task in which they always extended the right index finger after S2 presentation regardless of the color of S1 and a bilateral task in which they extended either the right or left index finger after S2 presentation according to the color of S1. Significantly higher MRCF activity was observed during the 500 ms S1 to S2 interval in the bilateral task than in the unilateral task. In the bilateral task trials, the latency of the peak MRCF during the S1 to S2 interval was 343.9 ± 73.5 ms after S1 presentation and that of the peak of movement-evoked field 1 was 33.4 ± 3.9 ms after movement onset in the bilateral task. Equivalent current dipoles at the peak MRCF were significantly medial (9.2 ± 12.1 mm) and anterior (19.8 ± 6.9 mm) to the reference location in the somatosensory cortex (area 3b) established by median nerve stimulation. This location corresponds to the dorsal premotor cortex. These findings suggest that activation of the premotor cortex observed during the interstimulus interval may represent a neurophysiological marker of response selection.     

Cartilage Metabolism is Modulated by Synovial Fluid Through Metalloproteinase Activity

Synovial fluid (SF) contains various cytokines that regulate chondrocyte metabolism and is dynamically associated with joint disease. The objective of this study was to investigate the effects of diluted normal SF on catabolic metabolism of articular cartilage under inflammatory conditions. For this purpose, SF was isolated from healthy bovine joints, diluted, and added to cartilage explant cultures stimulated with interleukin-1 (IL-1) for 12 days. The kinetic release of sulfated glycosaminoglycan (sGAG) and collagen, as well as nitric oxide and gelatinase matrix metalloproteinases were analyzed in the supernatant. Chondrocyte survival and matrix integrity in the explants were evaluated with Live/Dead and histological staining. Diluted synovial fluid treatment suppressed sGAG and collagen release, downregulated the production of nitric oxide and matrix metalloproteinases, reduced IL-1-induced chondrocyte death, and rescued matrix depletion. Our results demonstrate that normal SF can counteract inflammation-driven cartilage catabolism. This study reports on the protective function of healthy SF and the therapeutic potential of recapitulation of SF for cartilage repair.     

猴大脑内侧皮质运动区投射到运动前区的神经元的分布

目的定性和定量解析内侧皮质运动区投射到运动前区不同部位神经元的分布。方法采用多重标记法在同一只猴运动前区(PM)的三个不同部位即吻背侧部(PMdr)、尾背侧部(PMdc)及腹侧部(PMv)分别注入DY、FB、WGA-HRP三种不同的逆行标记物,对在内侧皮质运动区(MMC)逆行标记神经元的分布进行精确的定位和定量分析。结果投射到PMdr的神经元主要分布在前辅助运动区(prp-SMA)及前扣带回皮质运动区(CMAr);投射到PMdc的神经元,在MMC均有不同的分布,但在后扣带回皮质运动区(CMAc)被标记的神经元量明显多于其它部位;投射到PMv的神经元主要分布在辅助运动区(SMA)和CMAc,在CMAr也有少量标记神经元。结论SMA和CMAc主要投射到PMv,PMdr多接受pre-SMA和CMAr的投射。     

Neuronal Organization of the Ventral Anterior and Ventral Lateral Nuclei of the Human Thalamus

Neuroscience and Behavioral Physiology -     

Intercorrelation of the Activity of Close-Lying Neurons in the Cat Cerebral Cortex During Slow-Wave Sleep

Neuroscience and Behavioral Physiology - Cross-correlation analysis of baseline spike activity was performed for 184 pairs of close-lying neurons in the car cortex in the state of slow-wave sleep....     

The Effect of Nicotine on HPA Axis Activity in Females is Modulated by the FKBP5 Genotype

Tobacco smoking modulates activity in the hypothalamic‐pituitary‐adrenal (HPA) axis and is used to cope with stress, especially by females. The single nucleotide polymorphism (SNP) rs1360780, linked to FK506‐binding protein 51 (FKBP5), has been shown to affect HPA axis functioning, and has thus been suggested as a promising candidate for indicating vulnerability to stress‐related disorders. The aim of this study was to investigate the interaction between nicotine consumption and rs1360780 on cortisol plasma levels in females. A total of 296 female smokers (assessed by the Fagerström Test for Nicotine Dependence; FTND) were genotyped for the SNP rs1360780. We measured participants’ cortisol plasma concentration in blood plasma collected 3 h after standardized tobacco smoking exposure. In the 36 TT‐homozygotes, we found a significant negative correlation between the FTND sum score and cortisol plasma concentrations. Using linear regression analysis, we found that the FTND sum score accounted for 12.4% of the variance of cortisol plasma levels. This association was not detected in C‐allele carriers. Our results suggest that nicotine is an important confounder in the modulation of HPA axis activity by FKBP5. In light of these findings, future studies on FKBP5 should seek to include data on nicotine consumption as a covariate.     

High Gamma Oscillations of Sensorimotor Cortex During Unilateral Movement in the Developing Brain: a MEG Study

Recent studies in adults have found consistent contralateral high gamma activities in the sensorimotor cortex during unilateral finger movement. However, no study has reported on this same phenomenon in children. We hypothesized that contralateral high gamma activities also exist in children during unilateral finger movement. Sixty normal children (6–17 years old) were studied with a 275-channel MEG system combined with synthetic aperture magnetometry (SAM). Sixty participants displayed consistently contralateral event-related synchronization (C-ERS) within high gamma band (65–150 Hz) in the primary motor cortices (M1) of both hemispheres. Interestingly, nineteen younger children displayed ipsilateral event-related synchronization (I-ERS) within the high gamma band (65–150 Hz) just during their left finger movement. Both I-ERS and C-ERS were localized in M1. The incidence of I-ERS showed a significant decrease with age. Males had significantly higher odds of having ipsilateral activity compared to females. Noteworthy, high gamma C-ERS appeared consistently, while high gamma I-ERS changed with age. The asymmetrical patterns of neuromagnetic activities in the children’s brain might represent the maturational lateralization and/or specialization of motor function. In conclusion, the present results have demonstrated that contralateral high-gamma neuromagnetic activities are potential biomarkers for the accurate localization of the primary motor cortex in children. In addition, the interesting finding of the ipsilateral high-gamma neuromagnetic activities opens a new window for us to understand the developmental changes of the hemispherical functional lateralization in the motor system.