Transcranial Magnetic Stimulation Elicits Coupled Neural and Hemodynamic Consequences

ArticleinScience 317(5846):1918-21 · October 2007with110 Reads
Impact Factor: 33.61 · DOI: 10.1126/science.1146426 · Source: PubMed
Abstract

Transcranial magnetic stimulation (TMS) is an increasingly common technique used to selectively modify neural processing. However, application of TMS is limited by uncertainty concerning its physiological effects. We applied TMS to the cat visual cortex and evaluated the neural and hemodynamic consequences. Short TMS pulse trains elicited initial activation (∼1 minute) and prolonged suppression (5 to 10 minutes) of neural responses. Furthermore, TMS disrupted the temporal structure of activity by altering phase relationships between neural signals. Despite the complexity of this response, neural changes were faithfully reflected in hemodynamic signals; quantitative coupling was present over a range of stimulation parameters. These results demonstrate long-lasting neural responses to TMS and support the use of hemodynamic-based neuroimaging to effectively monitor these changes over time.

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Available from: Brian N Pasley
    • "Stimulation intensity was also customized, on a site-and subject-specific basis, to account for variations in the distance between coil and cortical target location. Moreover, the single-pulse intervention, at a relatively modest intensity, ensures that only neuronal populations directly under the coil that are already activated by the task are effectively perturbed, whereas neighboring or uninvolved neuronal populations are more likely to remain functionally unaffected (Allen et al., 2007). The different methods used to localize the TMS targets for EBA (subject-specific fMRI) and IPS (average stereotaxic coordinates from earlier studies) could, however, have introduced a bias toward stronger detection power for EBA stimulation compared with IPS stimulation (Sack et al., 2009). "
    [Show abstract] [Hide abstract] ABSTRACT: How do object perception and action interact at a neural level? Here we test the hypothesis that perceptual features, processed by the ventral visuoperceptual stream, are used as priors by the dorsal visuomotor stream to specify goal-directed grasping actions. We present three main findings, which were obtained by combining time-resolved transcranial magnetic stimulation and kinematic tracking of grasp-and-rotate object manipulations, in a group of healthy human participants (N=22). First, the extrastriate body area (EBA), in the ventral stream, provides an initial structure to motor plans, based on current and desired states of a grasped object and of the grasping hand. Second, the contributions of EBA are earlier in time than those of a caudal intraparietal region known to specify the action plan. Third, the contributions of EBA are particularly important when desired and current object configurations differ, and multiple courses of actions are possible. These findings specify the temporal and functional characteristics for a mechanism that integrates perceptual processing with motor planning.
    Full-text · Article · Mar 2016
    • "Entretanto, esses mecanismos ainda não foram comprovados e ao contrário disso, existem estudos que mostram que uma mesma frequência pode causar diferentes efeitos quando aplicada em diferentes regiões cerebrais(Speer et al., 2003), ou ainda podem causar diferentes efeitos quando aplicada em uma mesma região em pessoas diferentes( " Study and Modulation of Human Cortical Excitability With Tra... " , [s.d.]). No estudo de Allen é sugerido que o processo que é induzido pela terapia de EMTr é mais complexo do que somente aumento e redução de atividade e se deve provavelmente a um processo de neuroplasticidade (Allen, Pasley, Duong, & Freeman, 2007), que pode ser entendido como o fortalecimento ou enfraquecimento de algumas ligações entre neurônios, o que pode alterar algumas características daquela rede neural. Além disso a explicação do mecanismo da melhora da depressão pelo jornalista não tem fundamentos científicos. "
    Preview · Article · Jan 2016
    • "In addition to providing novel insight into the mechanisms of arousal regulation by central thalamus , our study offers important insight into the cellular origins of the fMRI BOLD signal. While there is a growing body of evidence suggesting that negative BOLD signals reflect local decreases in neuronal activity (Shmuel et al., 2006; Pasley et al., 2007; Allen et al., 2007; Devor et al., 2007; Sotero and Trujillo-Barreto, 2007), the nature of this signal remains a subject of debate and holds significant potential for the interpretation of functional imaging studies (Schridde et al., 2008; Ekstrom, 2010). It has been shown that different sensory stimuli can evoke positive and negative BOLD signals in the same cortical area, which are linked to increases and decreases in neural activity, respectively (Shmuel et al., 2006). "
    [Show abstract] [Hide abstract] ABSTRACT: Central thalamus plays a critical role in forebrain arousal and organized behavior. However, network-level mechanisms that link its activity to brain state remain enigmatic. Here, we combined optogenetics, fMRI, electrophysiology, and video-EEG monitoring to characterize the central thalamus-driven global brain networks responsible for switching brain state. 40 and 100 Hz stimulations of central thalamus caused widespread activation of forebrain, including frontal cortex, sensorimotor cortex, and striatum, and transitioned the brain to a state of arousal in asleep rats. In contrast, 10 Hz stimulation evoked significantly less activation of forebrain, inhibition of sensory cortex, and behavioral arrest. To investigate possible mechanisms underlying the frequency-dependent cortical inhibition, we performed recordings in zona incerta, where 10, but not 40, Hz stimulation evoked spindle-like oscillations. Importantly, suppressing incertal activity during 10 Hz central thalamus stimulation reduced the evoked cortical inhibition. These findings identify key brain-wide dynamics underlying central thalamus arousal regulation.
    Full-text · Article · Dec 2015 · eLife Sciences
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