Modulations of use-dependent excitability changes of human motor cortex (M1) by practice condition

Effects of repetitive index finger abductions on excitability changes in the human primary motor cortex (Ml) are assumed to be dependent on practice conditions of the task. To address how different effects occur dependent on various practice conditions, motor evoked potentials (MEPs) elicited from the first dorsal interosseous (FDI) muscle were investigated. Practice effects on the index finger abduction were examined for changes in excitability of first dorsal interosseous muscle under three forearm position changes (neutral vs prone) and two muscle contraction modes (isometric vs isotonic). Analysis showed that after practice MEP amplitude increased in the prone position but not in the neutral position and MEP increases in the isotonic contraction were larger than those in the isometric mode. These results suggest that use-dependent excitability changes are largely dependent on practice conditions because the amount of afferent input depends on the practice conditions.     

The role of the primary motor cortex during skill acquisition on a two-degrees-of-freedom movement task

One can partially eliminate motor skills acquired through practice in the hours immediately following practice by applying repetitive transcranial stimulation (rTMS) over the primary motor cortex. The disruption of acquired levels of performance has been demonstrated on tasks that are ballistic in nature. The authors investigated whether motor recall on a discrete aiming task is degraded following a disruption of the primary motor cortex induced via rTMS. Participants (N = 16) maintained acquired performance levels and patterns of muscle activity following the application of rTMS, despite a reduction in corticospinal excitability. Disruption of the primary motor cortex during a consolidation period did not influence the retention of acquired skill in this type of discrete visuomotor task.     

Difference of motor overflow depending on the impaired or unimpaired hand in stroke patients

The aim of this study was to investigate the patterns of contralateral motor overflow (i.e. mirror movement) between the homologous body parts on the right and left side, in stroke patients during single-finger and multi-finger maximum force production tasks. Forty subjects, including stroke (n = 20) and normal subjects (n = 20), participated in this study. The stroke subjects maximally pressed force sensors with their fingers in a flexed position using a single (index, middle, ring, or little) or all fingers (all 4 fingers) using the impaired (IH) or unimpaired (UIH) hand, while the non-patient subjects used their right hands for the same tasks. The maximal voluntary forces in the ipsilateral and unintended pressing forces of each contralateral finger were recorded during the tasks. The magnitude of motor overflow to the contralateral side was calculated using the index of contralateral independence (CI). During the single finger tasks, the finger CI was significantly decreased in the UIH (91%) compared with that in the IH (99%) or normal hands (99%). Likewise, the multiple finger tasks showed that the CI was significantly lower in the UIH (84%) compared with that in the IH (96%) or normal hands (99%). However, the maximal forces were significantly lower in the IH relative to those in the UIH and normal hands. These data demonstrate that stroke patients have greater motor overflow from the UIH to the IH.     

Simultaneous behavioral and neural (cochlear nucleus) measurement during signal detection in the rabbit

Classical conditioning of the rabbit nictitating membrane (NM) response was adapted as a model system for simultaneous measurement of behavioral and neural responses in auditory signal detection. Animals were trained to a 36-dB spectral-level white-noise CS paired with a corneal airpuff US. The CS intensity was then reduced to threshold, using a modified staircase procedure, and responses on detect and nondetect trials were compared for the same stimulus intensities. At threshold, the behavioral NM response was dichotomous, being present on detect trials and completely absent on nondetect trials. In marked contrast, evoked neural unit activity to the CS recorded from the anteroventral cochlear nucleus was clearly present and identical on both detect and nondetect trials, suggesting that the detection “decision” is made more centrally than the cochlear nucleus.     

Neurophysiologic markers of primary motor cortex for laryngeal muscles and premotor cortex in caudal opercular part of inferior frontal gyrus investigated in motor speech disorder: a navigated transcranial magnetic stimulation (TMS) study

Transcranial magnetic stimulation studies have so far reported the results of mapping the primary motor cortex (M1) for hand and tongue muscles in stuttering disorder. This study was designed to evaluate the feasibility of repetitive navigated transcranial magnetic stimulation (rTMS) for locating the M1 for laryngeal muscle and premotor cortical area in the caudal opercular part of inferior frontal gyrus, corresponding to Broca’s area in stuttering subjects by applying new methodology for mapping these motor speech areas. Sixteen stuttering and eleven control subjects underwent rTMS motor speech mapping using modified patterned rTMS. The subjects performed visual object naming task during rTMS applied to the (a) left M1 for laryngeal muscles for recording corticobulbar motor-evoked potentials (CoMEP) from cricothyroid muscle and (b) left premotor cortical area in the caudal opercular part of inferior frontal gyrus while recording long latency responses (LLR) from cricothyroid muscle. The latency of CoMEP in control subjects was 11.75 ± 2.07 ms and CoMEP amplitude was 294.47 ± 208.87 µV, and in stuttering subjects CoMEP latency was 12.13 ± 0.75 ms and 504.64 ± 487.93 µV CoMEP amplitude. The latency of LLR in control subjects was 52.8 ± 8.6 ms and 54.95 ± 4.86 in stuttering subjects. No significant differences were found in CoMEP latency, CoMEP amplitude, and LLR latency between stuttering and control-fluent speakers. These results indicate there are probably no differences in stuttering compared to controls in functional anatomy of the pathway used for transmission of information from premotor cortex to the M1 cortices for laryngeal muscle representation and from there via corticobulbar tract to laryngeal muscles.     

Effects of variation in the warning signal on reaction times of severe subnormals

Reaction times of normal and subnormal subjects were compared, when a warning stimulus varied in modality as well as in its temporal relation to the RT signal. When the warning stimulus was in a different modality from the RT signal, reaction times were shorter than when both were in the same modality. Mongols, in contrast to the other subjects, responded relatively faster to light than to sound.

The effect of varying the time interval between warning and signal was linearly related to response speed. The results are discussed in respect to the comparative alerting effects of temporal relations between stimuli and their different modalities.     

The effect of motor preparation on changes in h reflex amplitude during the response latency of a warned reaction time task

Monosynaptic Hoffman reflexes (H reflexes) were recorded from the soleus muscle during the response latency of a warned reaction time (RT) task that required plantarflexion of the foot. The task was done under four conditions of predictability of the response signal (RS), created by the factorial combination of foreperiod duration (1 and 4 s) and variability (fixed and variable). RT varied systematically with RS predictability and was facilitated in conditions that favored prediction of the RS. The response latency was divided into two successive phases by the onset of reflex augmentation: a premotor phase of constant reflex amplitude and a succeeding motor phase marked by progressively increasing reflex amplitude. Reflex augmentation during the motor phase was coupled more closely to the imminent movement than to the preceding signal to respond. The duration of the premotor phase was unaffected by RS predictability, but the duration of the motor phase (like RT) was shorter when the RS was more predictable. The maximum H reflex amplitude reached during the motor phase was greater when the RS was more predictable. The tonic level of H reflex amplitude during the premotor phase was greater in conditions that made prediction of the RS difficult. A second experiment showed that this difference was present throughout the foreperiod. These results suggest that conditions that favor prediction of the RS enhance motor preparation. changes in motor preparation (which affect RT) affect the processes underlying reflex amplitudes in the premotor phase and throughout the preceding foreperiod, in conditions that make prediction of the RS difficult, appear to reflect heightened general arousal.     

Degree of representation of the matching concept in pigeons (Columba livia)

In Experiment 1, 12 pigeons (Columba livia) were trained on a simultaneous matching-to-sample task with 2 stimuli and then tested with 2 novel stimuli. Half of the birds were trained with a fixed ratio schedule requirement of 1 (FR1) or 20 (FR20) pecks on the sample stimulus. None of the birds showed any evidence of concept-mediated transfer. In Experiment 2, 12 pigeons were trained with 3 stimuli and then tested with the same novel stimuli used in Experiment 1. Half of the birds in each group were trained with either an FR1 or FR20 requirement on the sample stimulus. Two of the FR20 birds showed high levels of transfer to the novel stimuli similar to that of monkeys in a previous study.     

Modulator effect of socio-emotional variables on training in elaboration strategies in Compulsory Secondary Education (CSE): paraphrase and applications

The purpose of this work is to verify the modulation of motivation, self-concept, and causal attributions in the efficacy of a training program of strategies to elaborate information in the stage of Compulsory Secondary Education (CSE). We selected 328 students from CSE, 179 from second grade and 149 from fourth grade, and three measurement moments: pretest, posttest, and follow-up. The results indicate greater use of learning strategies by students with higher intrinsic motivation, in contrast to students with higher extrinsic motivation, who use learning strategies less frequently. With regard to self-concept, the results differ as a function of the course. In second grade, we found modulation of the variable Academic self-concept, whereas in fourth grade, such modulation is produced by General self-concept and Private self-concept. In general, there is a tendency towards more enduring significant improvements in students with medium and high self-concept, especially in their perception of the use of strategies or in complex tasks that involve relating the contents to be learned with experiences from their daily life. However, students with low self-concept significantly improve strategies associated with learning how to perform specific tasks.     

十五年来《周易》热(二)

第二篇 《周易》基本知识一、《易经》与《易传》 《周易》是古代一本用于占卜的书,它包括《易经》和《易传》两大部分。 《易经》有六十四卦,每卦有六爻。爻有两种,其中“-”叫做阴爻, “--”叫做阳爻。     

十五年来《周易》热(四)

第四篇 《周易》与传统文化 一、《周易》不是中国传统文化之源 《周易》热除了热衷于从那张易图中发现什么科学奥秘之外,就是不适当地抬高《周易》的历史地位,把《周易》说成是中国文化的源头,说成是中国古代最重要的书,甚至今天也是最重要的书。     

十五年来《周易》热(六)

第六篇 《周易》热似是而非的方法论 除了故意歪曲,把陈旧的算命术做“预测学”之外,《周易》之所以能够热闹十几年,也是由于一系列似是而非的方法论上的错误。使用者有意无意用这样的方法去证明自己的结论,相信这些结论的人也有意无意地同时也相信了这些人所使用的方法,高明一点的甚至自己照猫画虎,也成了所谓易学家。所以,这些方法,也是使人误入歧途的方法,必须加以清理。 这些方法概括起来,主要是五种。即把后起的当原有,把相似当源头,把神话当事实,把糟粕作精华。最后,就是宣扬无法证明的事实,以混淆人们的视听。下面我们逐一加以评说。     

Kicking the (barking) dog effect: the moderating role of target attributes on triggered displaced aggression

Sometimes aggression is displaced onto a target who is not totally innocent but emits a mildly irritating behavior called a triggering event. In three experiments, the authors examine stable personal attributes of targets that can impact such triggered displaced aggression (TDA). Lower levels of TDA were directed to targets whose attitudes were similar as compared to dissimilar to those of the actor (Experiment 1) and to targets who were ingroup as compared to out-group members (Experiment 2). Conceptually replicating the findings of Experiments 1 and 2, the manipulated valence of the target (viz., liked, neutral, and disliked) functioned in a similar manner, with positive valence serving a buffering function against a triggering action that followed an initial provocation (Experiment 3). The results from all three experiments are consistent with cognitive neoassociationist theory.     

十五年来《周易》热(三)

“科学易”解析 一、关于《河图》的秘密 各种易图之中,最重要的就是《河图》。“科学易”首先看重的也是《河图》。他们声称破解了几千年来无人知晓的《河图》之秘,认为其中有丰富的科学内容。     

十五年来《周易》热(一)

随着特异功能热的兴起,20世纪80年代,我国也兴起了一股“《周易》热”。一些特异功能大师,也都纷纷成为“易学大师”。并且互相或者自我标榜,称为什么“易侠”、“易仙”、“易圣”等等。学术性的《周易》研究,成为伪科学的一块重要领地。许多连繁体字都认不了几个的人们,纷纷成为“易学专家”,就像江湖术士一夜之间就成了所谓“气功大师”一样。而且直到现在,在清理特