Aggressive behavior induced by electrical stimulation in the midbrain central gray of male rats

Electrical stimulation via electrodes implanted in the lateral hypothalamus may induce intraspecific aggressive behavior. Small electrolytic lesions placed via these electrodes resulted in a five– to tenfold increase in the current threshold for aggression. Degenerating fibers were stained by means of the Fink-Heimer method and could be followed caudally to the dorsal midbrain central gray and to the mammillary bodies. A few axons could be traced rostrally to the medial septum. Aggression could be induced from 10 of 112 electrodes implanted in the central gray; the other electrodes elicited either locomotion, vocalization, jump, or “alarm-like reactions.” The morphology of the induced aggression was similar to the morphology of the hypothalamically induced aggression, though it was often accompanied with motor disturbances and was less intense. Hypothalamic stimulation was combined with simultaneous central gray stimulation in rats with electrodes both in the hypothalamus and in the central gray. Hypothalamic thresholds for aggression could be lowered by this stimulation of the central gray, even when no aggressive responses were observed during central gray stimulation alone. This suggests that, although aggression is not manifest, electrical stimulation may activate neural tissue involved in aggressive behavior. It is concluded that in rats central gray and hypothalamus are part of the same neural network mediating intraspecific aggression.     

工作记忆刷新及其训练效应——经颅直流电刺激的作用

工作记忆刷新是执行功能的重要成分之一。以往研究结合n-back任务和经颅直流电刺激（transcranial direct current stimulation ,tDCS）技术探究刷新能力,发现tDCS技术能够一定程度上增强刷新训练效果并引起大脑神经元相关活动的变化,其增强效果能够维持一定的时间,且能够迁移到其他认知任务之中。但tDCS的干预效果在各项研究中存在一定的差异性。其作用效果会受到训练任务与训练方式、电流强度、电极布局和训练时间间隔等因素的影响。未来研究可以探索tDCS结合刷新训练的最佳刺激参数,以获得最优化的干预效果。     

Aggressive reactions of ducklings to a nonliving target object

This study asked whether ducklings' forceful pecks at a nonliving target object could be validly identified as aggressive. Previously isolated ducklings were exposed to a small cylindrical object that could serve as a target for aggressive pecks and as an object for attachment. After initially attempting to flee from the target, they vigorously pecked at it and also showed signs of the formation of a social (imprinting) attachment. In all important respects this pattern of behavior was identical to the pattern of escape, aggressive pecks, and attachment seen when a previously isolated duckling first encounters a conspecific. Social housing, a manipulation which attenuates aggression against live targets in ducklings and other species, reduced pecking at the nonliving target object. Early aversive stimulation, which enhances aggression against live targets, increased pecking at the object. These findings support the use of nonliving targets in the study of aggression in ducklings.     

Fetal behavioral responses to the touch of the mother’s abdomen: A Frame-by-frame analysis

The aim of the present study was to examine whether fetuses respond to the touching of the mother’s abdomen, and if they do, whether they differentiate based on familiarity and the source of the touch, utilizing 3D real-time (4D) sonography.Behavioral responses of 28 fetuses (20th to 33rd week of gestation; N = 15 in the 2nd and N = 13 in the 3rd trimester) were frame-by-frame coded using a coding system comprising 20 codes and were analyzed in four conditions, during the touch of the (1) mother, (2) the father, (3) the stranger and in a (4) no-touch, control condition.Fetuses showed differential responses to the touch, in particular in the duration of their reaching out to touch the uterus wall in the four conditions, and self-touch, dependent on the gestational age of the fetus. Fetuses in the 3rd trimester touched the uterus wall significantly longer than fetuses in the 2nd trimester did, when the mother touched compared to the control condition. At the same time, fetuses in the 3rd trimester also touched themselves less during the mother’s touch, compared when the stranger touched and also compared to the control condition.This differential response of the older fetuses might be due to the maturation of the central nervous system, and may indicate the emergence of a proprioceptive self-awareness by the 3rd trimester.     

Decrease of prefrontal-posterior EEG coherence: loose control during social-emotional stimulation

In two experiments we aimed to investigate if individual differences in state-dependent decreases or increases of EEG coherence between prefrontal and posterior cortical regions may be indicative of a mechanism modulating the impact social-emotional information has on an individual. Two independent samples were exposed to an emotional stimulation paradigm in which the participants were invited to get involved and sympathize with the persons they were watching (study 1) or listening to (study 2), and who were expressing sadness or anxiety. The two studies yielded consistent results. Higher scores in trait absorption and in the propensity to ruminate were associated with decreased EEG beta coherence during the stimulation, whereas coherence increased in individuals low in absorption or rumination. Coherence changes did not predict to which degree the participants felt infected by the displayed emotions, but in individuals showing decreased prefrontal-posterior coupling during the stimulation, feelings of sadness and anxiety had a greater tendency to persist. The findings suggest that more loose prefrontal-posterior coupling may be related to loosening of control of the prefrontal cortex over incoming social-emotional information and, consequently, to deeper emotional involvement and absorption, whereas increased prefrontal-posterior coupling may be related to strong control, dampening of emotional experience, and not letting oneself become emotionally affected.     

Perceptual processing affects the reactivation of a sensory dimension during a categorization task

According to grounded theories of cognition, knowledge is grounded in its sensory-motor features. Therefore, perceptual and conceptual processing should be based on the same distributed system so that conceptual and perceptual processes should interact. The present study assesses whether gustatory stimulation (participants tasted a sweet or a nonsweet yoghurt) could influence performance on a categorization task that involves the reactivation of the same sensory dimension. The results indicate that participants were slower (Experiment 1) or faster (Experiment 2), respectively, at categorizing pictures as representing edible sweet stimuli when they either simultaneously or had previously tasted a sweet yoghurt as compared to a nonsweet yoghurt. These results confirm the significant overlap between perceptual and memory mechanisms and suggest the functional equivalence between perceptually present and perceptually absent (memory reactivated) dimensions.     

Noninvasive Brain Stimulation over the M1 Enhances Bimanual Force Control Ability: A Randomized Double-Blind Sham-Controlled Study

Well-coordinated bimanual force control is common in daily life. We investigated the effects of anodal transcranial direct current stimulation (tDCS) over the primary motor cortex on bimanual force control. Under a cross-over study, young adults (n = 19; female = 6, male = 13) completed three bimanual force control tasks at 5%, 25%, and 50% of bimanual maximum voluntary force (BMVF) before and after real or sham tDCS. Real tDCS enhanced accuracy at all BMVF, reduced variability at 5% BMVF, and increased coordination at 5% BMVF. Real tDCS improved force control at 5% and 25% BMVF, and especially increased bimanual coordination at 5% BMVF. These findings might have implications for establishing interventions for patients with hand force control deficits.     

Oriented sulphides induced by electric current in medium carbon steel

Oriented sulphides parallel to the electric current direction have been experimentally observed when a pulsed electric current is passed through medium carbon steels with MnS inclusions. Two different configurations of sulphides occur after the application of the electric current: namely, oriented elongated ellipsoidal particles and oriented chain-like particles composed of two or three small spherical sulphides. Theoretical analysis indicates that this phenomenon is associated with minimization of the electrical resistance of the material.     

Motor excitability during movement preparation in Tourette syndrome

Tourette syndrome (TS) is a neurodevelopmental disorder characterized by the occurrence of motor and vocal tics. TS has been linked to the impaired operation of cortical‐striatal‐thalamic‐cortical circuits that give rise to hyper‐excitability of cortical motor areas, which may be exacerbated by dysfunctional intra‐cortical inhibitory mechanisms. That said, many individuals gain control over their tics during adolescence and it has been suggested that this increased control arises as a result of the development of mechanisms that operate to suppress corticospinal excitability (CSE) ahead of volitional movements. Here we used single‐pulse transcranial magnetic stimulation (TMS) in conjunction with a manual Go/NoGo task to investigate alterations in CSE ahead of volitional movements in a group of adolescents with TS (N = 10). Our study demonstrated that CSE, as measured by TMS‐induced motor‐evoked potentials (MEPs), was significantly reduced in the TS group in the period immediately preceding a finger movement. More specifically, we show that individuals with TS, unlike their age‐matched controls, do not exhibit the predicted increase in mean MEP amplitude and decrease in MEP variability that immediately precede the execution of volitional movements in typically developing young adults. Finally, we report that the magnitude of the rise in MEP amplitude across the movement preparation period in TS is significantly negatively correlated with clinical measures of motor tic severity, suggesting that individuals with severe motor tics are least able to modulate motor cortical excitability.