Localization of sensorimotor cortex in neurosurgery by recording of somatosensory evoked potentials

The current method of localizing somatosensory and motor cortex during neurosurgical removal of abnormal tissue is Penfield's method of cortical stimulation. While useful, this method has drawbacks, in particular the need to operate under local anesthesia. Another method of localization, described here, involves intra-operative recording of short-latency somatosensory evoked potentials to stimulation of the contralateral median nerve, from electrodes placed directly on central cortex. Proper localization involves identification of potentials which invert in polarity across the central sulcus, identification of other potentials which are largest in the medial portion of the hand area of somatosensory cortex and do not polarity invert, and determination of the region of maximal potential amplitude. This method of localization works equally well whether the patient is under local or general anesthesia, but it occasionally fails in patients with tumors abutting or invading the hand area of sensorimotor cortex.     

The effect of leucine enkephalin on the development of a convulsive afterdischarge in the sensorimotor cortex of rats]

The application of leucin-enkephalin solution (LEU) (2 micrograms/2 microliters) on stimulated region of sensomotor cortex did not influence threshold of direct and transcallosal cortex responses (DR and TCR). On coupling of repeated electrostimulation train (RET) (duration of impulse--0.1 ms; duration of train--10 s; frequency--10/s) with application of LEU (after every odd train) the changes of DR and TCR in course of even trains and latency of afterdischarge appearance were such as in control ones. Simultaneously LEU effectively depressed short posttetanic potentiation of DR and TCR and potentiation of amplitude and duration AD, evoked by RET. It is suggested that LEU released from neurons in the course of RET does not participate in initiation of seizure in sensomotor cortex. A possible role of LEU in sensomotor cortex is limitation of intensity and duration of seizures and prevention of status epilepticus.     

The effect of cervical sympathetic ganglia extirpation on the growth of rats during postnatal ontogenesis]

Bilateral extirpation of the superior cervical sympathetic ganglia carried out during the first month after the birth of ratlings caused a delay in growth by 40-60%. Section of pre-ganglionic sympathetic fibers and also sham operations failed to lead to any significant changes. Normal growth and skeletal development were disturbed in gangliectomized rats: the zone of growth of the proximal end of the tibia was much narrower in the operated animals than in the intact ones and there was a delay in the spread of secondary ossification centres.     

急性脊髓损伤后大鼠电刺激运动诱发电位的变化

目的：比较不同程度脊髓损伤（SCI）与运动诱发电位（MEP）变化之间的关系,探索MEP检查在SCI早期诊断及预后中的价值。方法：27只雄性SD大鼠以改良Allen‘s打击法致伤T8－T9脊髓,按打击冲量随机分为空白对照组（n=5),SCI A组（50gcf,n=8),SCI B组（70gcf,n=8)和SCI C组（100gcf,n=6),采用单极经皮层电刺激,分别于损伤前、伤后即刻、15min、30min、1h、3h和6h连续观察scMEP变化,并计算脊髓出血坏死区域占脊髓横截面积的比率。结果：对照组MEP无显著改变,SCI A组和SCI B组动物MEP早成份波幅立即减低或消失,以后有所恢复,晚成份波消失后未再出现。SCI C组动物除2只大鼠SCI后MEP仍有所恢复外,其余动物再未出现MEP波。脊髓损伤随打击冲量增大而增加,与伤后1h scMEP最大波幅呈显著相关（r=-0.821)。结论：SCI后scMEP的变化程度与打击冲量和脊髓病理损伤面积相关,提示scMEP可以作为一种脊髓功能检测的客观指标。     

Reorganization of human evoked potentials during automatization of motor reactions

Evoked electrocortical activity appearing during rhythmic stimulation and its correlation with the level of expectancy of the signal next in turn (expressed in values of reaction time), were studied in nine grown up subjects. Reorganization of auditory evoked potentials (EPs), mostly expressed during reactions preceding the stimulus or coinciding with it occurs at motor responses to rhythmical stimuli. The character of correlation between EPs and perception is satisfactorily explained by a cyclic model of the sensory information processing. Adaptive behaviour is provided by the cyclic processes promoting engrams formation and adequate pretuning to probable events.     

Thyroid gland activity and motor activity during dog ontogenesis]

The locomotor activity (LA) and the level of the protein-bound iodine (PBI) in the blood serum were investigated in 62 puppies at the age of 1--12 months. A parallel elevation of PBI and the LA was observed the first 4 months after birth. The second peak of the LA at the age of 7--9 months was not accompanied by any PBI rise. Inhibition of the thyroid function with mercasolyl increased the LA at the age of 1--3 months and decreased it at the age of 7 months. An increase of the LA one month after thyroidectomy was found at the age of 1 and 3.5 months. The activity of puppies operated on at the age of one month showed a sharp fall after 2--4 months. The data on various effect of thyroid hormones on puppies of different age pointed to the complex relation between the LA and the thyroid gland function.     

大鼠压杆行为的运动皮层局部场电位研究

目的：提取与大鼠右前肢运动相关联的初级运动皮层场电位的信号特征,并探讨依据局部场电位（LFP）识别前肢运动行为的可行性。方法：4只SD大鼠通过训练习得压杆取水操作,然后在左右脑初级运动皮层M1区分别植入多通道束状微电极,术后恢复后进行大鼠压杆行为实验,以2 kHz/s速率记录深部脑电信号及压杆状态信号,同步记录行为过程的视频信号。以通道间的差分信号作为局部场电位信号,分析局部场电位信号的时域特征,进行聚类分析。以压杆状态信号和视频分析为判定依据,对聚类结果进行分析。结果：局部场电位信号在大鼠压杆动作时明显增强,不同通道的局部场电位信号幅值、波形有差异,表明与前肢运动相关联的M1区局部场电位信号有空间分布特征;依据阈值准则从局部场电位信号检测压杆行为的检出率为80%。结论：依据局部场电位信号特征对大鼠前肢运动进行检测具有可行性。     

Functional maturation of the cat visual cortex during prenatal ontogenesis]

Development of the perceiving function of the visual cortex was studied on the foeti of cats in the second stage of antenatal development with intact placental blood circulation. It has been found that functional maturing of the cortical end of the visual analyser starts at the beginning of the second half of antenatal life. At this period EPs to stimulation of the optic nerve are recorded throughout the dorsal cortex of the contralateral hemisphere. At first they appear as slow three-phase (positive-negative-positive) oscillations of a small amplitude. As the foetus develops, the EP amplitude increases, and the EP configuration in the striate zone of the cortex becomes complex. Two weaks before birth, a short-latency negative wave appears against the background of the primary positive oscillation. In the last week of antenatal development of the foeti and in the first few days of the kittens life, EPs are represented in the specific zone of the visual cortex (g. lateralis) as two negative oscillations, and in the so-called associative zone (the middle part of the suprasylvian gyrus) by one long-latency high-amplitude negative oscillation which corresponds by latency to the second negative EP component in the striate cortex.     

Effect of beta-phenylethylamine on evoked potentials of the neostriatum of rats]

The effect of intraperitoneal (70 mg/kg) and local (39 ug) administration of beta-phenylethylamine (beta-PEA) on evoked potentials (EP) in the caudate nucleus upon stimulation of substantia nigra zona compacta (SNC) and frontal cortex in rats has been studied. beta-PEA, glutamate and haloperidol were injected into the caudate nucleus by means of a system consisting of a pushpull cannule and an electrode for simultaneous registration of EP. Specificity in the effect of the drugs on EP in response to stimulation of the cortex and substantia nigra was revealed. The intraperitoneal injection of beta-PEA induced, comparatively to the application, more rapid and potent decrease in the amplitude of the component (N2-P2) as a result of the substantia nigra stimulation and slightly influenced the EP amplitude in stimulation of the frontal cortex. It was established using haloperidol that the component (N2-P2) of EP in response to the substantia nigra stimulation is of dopaminergic neuron function in the nigro-neostrital system of the rat brain.     

The effect of opioid neuropeptides on the cholino- and adrenoreactivity of the sensorimotor cortex cells in rats

The effect of two neuropeptides, dalargine and betaendorphine, on cholino- and adrenoreactivity of sensorimotor cortex cells has been studied in immobilized rats in acute experiments. Subcutaneous administration of the peptides led to redistribution of cells according to the type of their reaction and to changes in intensity of neuronal reactions to the applied neurotransmitters. The observed changes in chemoreactive properties of cortical neurons under the influence of the neuropeptides may play a certain part in the processes of learning and memory.     

The effect of acute alcohol administration on auditory evoked potentials in altricial nestlings during the development of natural behavior]

Acute ethanol influence on field L auditory evoked potentials (AEP) was studied in 4-8-days-old altricial nestlings of pied flycatcher. Nestlings were presented with tone pips related with the realization of natural behaviour (2.0 and 5.0 kHz) and bearing no meaning for the behaviour of the young of the age under study (3.0 kHz). Ethanol ingestion was found to reduce the maturity index (MI) of AEP in response to "behavioural" but not to control frequencies; this effect was first observed at day 5, when nestlings eyes opened and defence behaviour appeared, while previously formed feeding behaviour was significantly modified. During the next 2 days alcohol had a greater effect upon the AEP in response to 2.0 kHz tone pips, related with feeding behaviour of increasing complexity than upon the AEP in response to 5.0 kHz, related with the defence behaviour that remained relatively constant. The previous data concerning the effect of alcohol on unit activity are used to support the view that MI increase during the early postembryonic ontogeny is due to the involvement of neurons with newly formed behavioural specializations into the subserving of new behavioural patterns while the decrease of MI under alcohol is due to the depression of activity in these neurons.