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Transcranial magnetic stimulation (TMS) is a noninvasive brain stimulation method that modulates brain activity by inducing electric fields in the brain. Real-time, state-dependent stimulation with TMS has shown that neural oscillation phase modulates corticospinal excitability. However, such motor evoked potentials (MEPs) only indirectly reflect motor cortex activation and are unavailable at other brain regions of interest. The direct and secondary cortical effects of phase-dependent brain stimulation remain an open question. In this study, we recorded the cortical responses during single-pulse TMS using electroencephalography (EEG) concurrently with the MEP measurements in 20 healthy human volunteers (11 female). TMS was delivered at peak, rising, trough, and falling phases of mu (8–13 Hz) and beta (14–30 Hz) oscillations in the motor cortex. The cortical responses were quantified through TMS evoked potential components N15, P50, and N100 as peak-to-peak amplitudes (P50-N15 and P50-N100). We further analyzed whether the prestimulus frequency band power was predictive of the cortical responses. We demonstrated that phase-specific targeting modulates cortical responses. The phase relationship between cortical responses was different for early and late responses. In addition, pre-TMS mu oscillatory power and phase significantly predicted both early and late cortical EEG responses in mu-specific targeting, indicating the independent causal effects of phase and power. However, only pre-TMS beta power significantly predicted the early and late TEP components during beta-specific targeting. Further analyses indicated distinct roles of mu and beta power on cortical responses. These findings provide insight to mechanistic understanding of neural oscillation states in cortical and corticospinal activation in humans.
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Causal Relationships and Programming Outcomes: A Transcranial Magnetic Stimulation Experiment
Understanding the relationship between cognition and programming outcomes is important: it can inform interventions that help novices become experts faster. Neuroimaging techniques can measure brain activity, but prior studies of programming report only correlations. We present the first causal neurological investigation of the cognition of programming by using Transcranial Magnetic Stimulation (TMS). TMS permits temporary and noninvasive disruption of specific brain regions. By disrupting brain regions and then measuring programming outcomes, we discover whether a true causal relationship exists. To the best of our knowledge, this is the first use of TMS to study software engineering. Where multiple previous studies reported correlations, we find no direct causal relationships between implicated brain regions and programming. Using a protocol that follows TMS best practices and mitigates for biases, we replicate psychology findings that TMS affects spatial tasks. We then find that neurostimulation can affect programming outcomes. Multi-level regression analysis shows that TMS stimulation of different regions significantly accounts for 2.2% of the variance in task completion time. Our results have implications for interventions in education and training as well as research into causal cognitive relationships.
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- Award ID(s):
- 2211749
- PAR ID:
- 10637818
- Publisher / Repository:
- ACM
- Date Published:
- ISBN:
- 9798400702174
- Page Range / eLocation ID:
- 1 to 13
- Format(s):
- Medium: X
- Location:
- Lisbon Portugal
- Sponsoring Org:
- National Science Foundation
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In this paper we propose a novel neurostimulation protocol that provides an intervention-based assessment to distinguish the contributions of different motor control networks in the cortico-spinal system. Specifically, we use a combination of non-invasive brain stimulation and neuromuscular stimulation to probe neuromuscular system behavior with targeted impulse-response system identification. In this protocol, we use an in-house developed human-machine interface (HMI) for an isotonic wrist movement task, where the user controls a cursor on-screen. During the task, we generate unique motor evoked potentials based on triggered cortical or spinal level perturbations. Externally applied brain-level perturbations are triggered through TMS to cause wrist flexion/extension during the volitional task. The resultant contraction output and related reflex responses are measured by the HMI. These movements also include neuromodulation in the excitability of the brain-muscle pathway via transcranial direct current stimulation. Colloquially, spinal-level perturbations are triggered through skin-surface neuromuscular stimulation of the wrist muscles. The resultant brain-muscle and spinal-muscle pathways perturbed by the TMS and NMES, respectively, demonstrate temporal and spatial differences as manifested through the human-machine interface. This then provides a template to measure the specific neural outcomes of the movement tasks, and in decoding differences in the contribution of cortical- (long-latency) and spinal-level (short-latency) motor control. This protocol is part of the development of a diagnostic tool that can be used to better understand how interaction between cortical and spinal motor centers changes with learning, or injury such as that experienced following stroke.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1145/3597503.3639096
