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。     

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.     

Cortical connections of the anterior (F5a) subdivision of the macaque ventral premotor area F5

We traced the cortical connections of the anterior sector (F5a) of the macaque ventral premotor (PMv) area F5 and compared them with those of the adjacent F5 sectors, F5c and F5p. F5a displays a very dense “intrinsic” connectivity with F5c and F5p, premotor connections limited to F4 and F6/pre-SMA, relatively robust prefrontal connections with areas 46v and 12, and dense connections with rostral opercular frontal areas. Outside the frontal cortex, connections of F5a are dense with the SII region, relatively robust with inferior parietal areas PFG and AIP, weak with the inferior parietal area PF, and moderate with area 24. The comparison with data from injections in F5c and F5p showed that F5a, though sharing some common parietal connections with the other F5 sectors, displays several characterizing features providing robust evidence for its connectional distinctiveness. The present study provides evidence for a general organization of the PMv similar to that of the medial and dorsal premotor cortex, with F5a representing a pre-PMv area. Specifically, the present data suggest that F5a is a privileged site of integration, in the PMv, of parietal sensory-motor signals with higher-order information originating from prefrontal, rostral frontal opercular areas, and F6/pre-SMA. The results of this integration can be then broadcasted to the adjacent F5 sectors for the generation and control of hand actions and cognitive motor functions.     

大鼠体感皮层后爪代表区的微电极测定

利用微电极测绘技术对Wistar大鼠大脑皮层体感一区进行电生理研究,测定了后爪代表区的面积、与相邻代表区的关系。证明后爪代表区内部存在分域关系,但由于后爪皮层代表区神经元的感受野较大,分域是粗略的。     

Spatial and Temporal Characteristics of Set-Related Inhibitory and Excitatory Inputs from the Dorsal Premotor Cortex to the Ipsilateral Motor Cortex Assessed by Dual-Coil Transcranial Magnetic Stimulation

The capacity to produce movements only at appropriate times is fundamental in successful behavior and requires a fine interplay between motor inhibition and facilitation. Evidence in humans indicates that the dorsal premotor cortex (PMCd) is involved in such preparatory and inhibitory processes, but how PMCd modulates motor output in humans is still unclear. We investigated this issue in healthy human volunteers, using a variant of the dual-coil transcranial magnetic stimulation (TMS) technique that allows testing the short-latency effects of conditioning TMS to the left PMCd on test TMS applied to the ipsilateral orofacial primary motor cortex (M1). Participants performed a delayed cued simple reaction time task. They were asked to produce a lip movement cued by an imperative GO-signal presented after a predictable SET-period, during which TMS was applied at different intervals. Results showed that the area of motor evoked potentials (MEPs) to test TMS was modulated by conditioning TMS. A transient inhibition cortico-bulbar excitability by PMCd stimulation was observed around the middle of the SET-period. Conversely, a ramping excitatory effect of PMCd stimulation appeared towards the end of the SET-period, as the time of the predicted GO-signal approached. The time-course of PMCd–M1 activity scaled to the varying SET-period duration. Our data indicate that inhibition and excitation of motor output during a delayed reaction time task are two distinct neural phenomena. They both originate in PMCd and are conveyed via cortico–cortical connections to the ipsilateral M1, where they are integrated to produce harmonic fluctuations of motor output.     

Monoclonal antibody (F5) to human prostate antigen

Hybridoma culture F5 has been developed which secretes monoclonal antibody (McAb) directed to an epitope of a prostatic glycoprotein of Mr 34 kD (Prostate Antigen, PA). Tissue levels of PA have been evaluated using a competitive-binding enzyme-immunoassay based upon the inhibition of McAb binding activity to purified antigen. Results indicated the specific occurrence of high antigen concentrations in extracts prepared from prostatic tissues. The antigenicity of epitope F5 is resistant to tissue fixation and embedding protocols, and has been demonstrated upon immunoperoxidase staining procedures. Immunoperoxidase data strongly indicate that McAb F5 possesses a singular specificity towards prostatic epithelial cells. Other tissues, whether normal or cancerous, fail to express this determinant. Specimens examined included epithelial and nonepithelial tissues along with a panel of carcinomas and sarcomas. The antibody was able to detect tumor cells at extra-prostatic sites and represents a powerful probe for the detection and differential diagnosis of metastatic cancer of the prostate.     

The Counting Function and Its Representation in the Parietal Cortex in Humans and Animals

Current data provide evidence that the ability to assess numbers is present not only in adult humans, but also in animals and children of preverbal age. Studies of behavior in infants and animals have demonstrated that the perception of number, the discrimination of quantities, and elementary addition and subtraction appear during onto- and phylogenesis before the appearance of speech. Number perception in humans and animals has common features: the greater the difference between numbers, the easier they are to discriminate; for a given difference between numbers, increases in size lead to increased difficulty in discrimination. Clinical data on counting impairments in patients and functional tomography studies of number operations in healthy subjects have shown that the key structures involved in number perception in humans are located in the parietal cortex. As demonstrated by experiments on monkeys and dogs, recognition of number in these species is also associated with the parietal area of the cortex. The similarity of the morphofunctional bases of “counting behavior” in humans and animals suggests that counting can be regarded as a functional mechanism of adaptive behavior which formed during evolution.