The critical role of the inferior frontal cortex in establishing a prediction model for generating subsequent mismatch negativity (MMN): A TMS-EEG study

BackgroundThe prediction violation account of automatic or pre-attentive change detection assumed that the inferior frontal cortex (IFC) is involved in establishing a prediction model for detecting unexpected changes. Evidence supporting the IFC’s contribution to prediction model is mainly based on the Mismatch Negativity (MMN) to deviants violating predictions that are established based on the frequently presented standard events. However, deviant detection involves processes, such as events comparison, other than prediction model establishment.ObjectiveThe current study investigated the critical role of the IFC in establishing a prediction model during standards processing for subsequent deviant detection.MethodsTranscranial Magnetic Stimulation (TMS) was applied at the IFC to disrupt the processing of the initial 2 or 5 standards of a 3-, 6-, or 9-standard train, while the MMN responses to pitch deviant presented after the standard trains were recorded and compared.ResultsAn abolishment of MMN was only observed when TMS was delivered to the IFC at the initial 2 standards of the 3-standard train, but not at the initial 5 standards, or when TMS at the vertex or TMS sound recording was applied. The MMNs were also preserved when IFC TMS, vertex TMS, or TMS sound recording was applied at the initial 2 or 5 standards of longer trains.ConclusionThe IFC plays a critical role in processing the initial standards of a short standard train for subsequent deviant detection. This result is consistent with the prediction violation account that the IFC is important for establishing the prediction model.     

Biophysical foundations underlying TMS: Setting the stage for an effective use of neurostimulation in the cognitive neurosciences

Transcranial Magnetic Stimulation (TMS) induces electrical currents in the brain to stimulate neural tissue. This article reviews our present understanding of TMS methodology, focusing on its biophysical foundations. We concentrate on how the laws of electromagnetic induction apply to TMS; addressing issues such as the location, area (i.e., focality), depth, and mechanism of TMS. We also present a review of the present limitations and future potential of the technique.     

Efficacy and safety of transcranial magnetic stimulation in the acute treatment of major depression: a multisite randomized controlled trial.

BACKGROUND: We tested whether transcranial magnetic stimulation (TMS) over the left dorsolateral prefrontal cortex (DLPFC) is effective and safe in the acute treatment of major depression. METHODS: In a double-blind, multisite study, 301 medication-free patients with major depression who had not benefited from prior treatment were randomized to active (n = 155) or sham TMS (n = 146) conditions. Sessions were conducted five times per week with TMS at 10 pulses/sec, 120% of motor threshold, 3000 pulses/session, for 4-6 weeks. Primary outcome was the symptom score change as assessed at week 4 with the Montgomery-Asberg Depression Rating Scale (MADRS). Secondary outcomes included changes on the 17- and 24-item Hamilton Depression Rating Scale (HAMD) and response and remission rates with the MADRS and HAMD. RESULTS: Active TMS was significantly superior to sham TMS on the MADRS at week 4 (with a post hoc correction for inequality in symptom severity between groups at baseline), as well as on the HAMD17 and HAMD24 scales at weeks 4 and 6. Response rates were significantly higher with active TMS on all three scales at weeks 4 and 6. Remission rates were approximately twofold higher with active TMS at week 6 and significant on the MADRS and HAMD24 scales (but not the HAMD17 scale). Active TMS was well tolerated with a low dropout rate for adverse events (4.5%) that were generally mild and limited to transient scalp discomfort or pain. CONCLUSIONS: Transcranial magnetic stimulation was effective in treating major depression with minimal side effects reported. It offers clinicians a novel alternative for the treatment of this disorder.     

Reversible reorganisation of the motor cortical representation of the hand in cervical dystonia.

Previous work has suggested that there may be a widespread disturbance of motor control mechanisms in patients with cervical dystonia. In the present study, we used transcranial magnetic stimulation to investigate the topography of the corticomotor projection to the abductor pollicis brevis (APB) muscle in 10 subjects with idiopathic torticollis. Threshold-adjusted stimuli were delivered at multiple scalp sites during a low-level voluntary contraction of the APB, and maps were generated of motor evoked potential amplitude versus scalp site. The cortical maps for the APB on the side opposite to the direction of head rotation were displaced laterally or posteriorly in all subjects and reverted to a more normal position after botulinum toxin injection of the cervical muscles in 5 subjects. The findings point to a reversible reorganisation of the corticomotor representation of the hand on the same side as the sternocleidomastoid (SCM) muscle that is involved in producing the dystonia. These results provide further evidence for the involvement of cortical centres and for a more widespread abnormality of motor control mechanisms in focal dystonia. The findings also support the notion that head turning is chiefly mediated by the hemisphere ipsilateral to the direction of the head rotation by means of a corticomotor projection to the contralateral SCM.     

Further evidence for excitability changes in human primary motor cortex during ipsilateral voluntary contractions

The present study aimed to further investigate whether the intracortical neural circuits within the primary motor cortex (M1) are modulated during ipsilateral voluntary finger movements. Single- and paired-pulse (interstimulus intervals, ISIs; 3 ms and 12 ms) transcranial magnetic stimulations of the left M1 were applied to elicit motor evoked potential (MEP) in the right first dorsal interosseous (Rt-FDI) muscle during voluntary contractions (10% and 30% maximum voluntary contraction) of the left FDI (Lt-FDI) muscle. F-waves of Rt-FDI muscle were recorded under these left index-finger conditions for ensuring that the excitability changes occur at the supraspinal level. MEPs were also recorded during motor imagery of the left index-finger abduction instead of overt movement. The results showed that, in single-pulse transcranial magnetic stimulation (TMS) paradigm, MEPs in Rt-FDI muscle were markedly enhanced during voluntary contractions of Lt-FDI muscle compared with the complete resting state. In paired-pulse TMS paradigm, the short intracortical inhibition was significantly reduced in proportion to increments of the ipsilateral muscle contraction, whereas the intracortical facilitation had no change. F-wave of Rt-FDI muscle was unchanged under these conditions, while MEP in Rt-FDI muscle was also enhanced during motor imagery of the left index-finger abduction. Based on the present results, it is suggested that the intracortical inhibitory neural circuits may be modulated in the transition from rest to activity of the ipsilateral homonymous muscle. The excitability changes in M1 might be induced by overflows of voluntary drive given to the ipsilateral limb, probably via the transcallosal pathway.     

基于遗传算法的经颅磁刺激线圈阵列设计与场分布计算

为解决经颅磁刺激的兴奋点定位问题提出了以圆环面聚焦线圈阵列实现电磁聚焦的方案。而后,使用经过改进的自适应遗传算法对注入阵列各单元线圈电流的大小和相位进行了优化,在目标区域内很好的实现了电磁聚焦。通过计算,显示了线圈阵列在优化后的电流组态下产生的磁场和电场在计算区域内的分布和二维等高线图,表明了该聚焦线圈阵列可在目标区域产生具有良好聚焦性能的电场和磁场分布,并具有可同时聚焦至多个目标的能力。     

高频重复经颅磁刺激联合认知行为治疗对脑卒中后焦虑和抑郁共病状态患者的影响

目的观察高频重复经颅磁刺激(rTMS)联合认知行为治疗对脑卒中后焦虑(PSA)、脑卒中后抑郁(PSD)共病状态患者的影响。 方法采用随机数字表法将160例脑卒中后焦虑抑郁状态患者分为对照组和观察组。两组患者均给予脑卒中常规治疗、抗抑郁药物治疗和认知行为治疗,对照组同时给予高频rTMS假刺激治疗,观察组则给予高频rTMS真刺激治疗。观察4周后2组患者抑郁症状、焦虑症状、睡眠质量、日常生活能力改善情况。 结果两组患者汉密尔顿抑郁量表(HAMD)评分、汉密尔顿焦虑量表(HAMA)评分、匹兹堡睡眠指数量表(PSQI)、改良Barthel指数(MBI)在治疗前差异无统计学意义(P均>0.05)。治疗4周后,对照组和观察组的HAMD评分、HAMA评分、PSQI较治疗前下降,差异有统计学意义(P均<0.05),其中观察组下降更为明显,与对照组相比,差异有统计学意义(P<0.05)。对照组和观察组MBI与治疗前相比,均有明显提高,差异有统计学意义(P<0.05),而观察组和对照组相比,观察组分数提高更显著,差异有统计学意义(P<0.05)。观察组治疗有效率为87.50%,高于对照组的71.25%。两组之间差异有统计学意义(Uc＝－3.45,P<0.001)。 结论高频rTMS治疗联合认知行为治疗和认知行为治疗均能有效改善PSA+PSD患者的焦虑抑郁症状、睡眠质量及日常生活能力,但高频rTMS治疗联合认知行为治疗的效果更加明显。     

消化道无线内窥镜便携式图像接收装置的硬件设计

消化道无线内窥镜便携式图像接收装置是在TMS320C6211DSP的基础上进行开发的。先对摄像胶囊发出的调制信号进行接收和解调，然后利用视频解码芯片SAA7114H的同步信号，经过时序逻辑变换，控制对断续视频信号的采集，并将其存储到CF卡中。此外．还利用高速DSP对图像信号进行预处理和压缩．可大大节约数据的存储空间和处理时间。     

Deacetylation of 4-(5-acetylamino-2-furyl)thiazole and formation of 1-(4-thiazolyl)-3-cyano-1-propanone by rat liver tissues

The reductive metabolism of the rat carcinogen 4-(5-nitro-2furyl)thiazole (NFT) to 1-4-thiazolyl)-3-cyano-1-propanone (TCP) is reported. Formation of TCP from NFT involved furan ring fission. This could have occurred through involvement of either aminofuran or N-hydroxylaminofuran as precursors. To examine if 4-(5-amino-2-furyl)thiazole is a precursor for TCP, a stable model compound, 4-(5-acetylamino-2-furyl)thiazole (AAFT), was prepared and subjected to enzymatic deacetylation, using rat liver tissue homogenates. AAFT was synthesized by catalytic hydrogenation of NFT with 5% palladium on activated carbon, followed by acetylation with acetic anhydride. AAFT, a white crystalline powder, melted at 168–170°, had an extinction coefficient of 17.9 mM^?1 cm^?1 at 293 nm in ethyl acetate, and exhibited spectroscopic and mass spectral characteristics consistent with the assigned structure. Incubation with rat liver 10,000 g supernatant preparations resulted in the biotransformation of AAFT as evidenced by a decrease in absorption at 290 nm. Incubation of ¹⁴C-labeled AAFT followed by extraction with chloroform-diethyl ether (1:1) resulted in the recovery of a major portion (56%) of the radioactivity in the organic phase when the label was at the 2-position of the thiazole ring, while the major amount (82%) of radioactivity was recovered in the aqueous phase when the 1-¹⁴C-acetyl group was labeled. The radioactivity from the aqueous phase was extractable into the organic phase following acidification to pH 1, an observation consistent with deacetylation. Furthermore, the deacetylation product exhibited a mass spectrum, and retention times in gas and high pressure liquid chromatography, similar to those of synthetic TCP. These data establish 4-(5-amino-2-furyl)thiazole, derived from AAFT by deacetylation, as a precursor for TCP.