Numerous research groups are now using analysis of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) results and relaying back information about regional activity in their brains to participants in the scanner in “real time”. In this study, we explored the feasibility of self-regulation of frontal cortical activation using real time fMRI (rtfMRI) neurofeedback in nicotine-dependent cigarette smokers during exposure to smoking cues. Ten cigarette smokers were shown smoking-related visual cues in a 3 Tesla MRI scanner to induce their nicotine craving. Participants were instructed to modify their craving using rtfMRI feedback with two different approaches. In a “reduce craving” paradigm, participants were instructed to “reduce” their craving, and decrease the anterior cingulate cortex (ACC) activity. In a separate “increase resistance” paradigm, participants were asked to increase their resistance to craving and to increase middle prefrontal cortex (mPFC) activity. We found that participants were able to significantly reduce the BOLD signal in the ACC during the “reduce craving” task (p=0.028). There was a significant correlation between decreased ACC activation and reduced craving ratings during the “reduce craving” session (p=0.011). In contrast, there was no modulation of the BOLD signal in mPFC during the “increase resistance” session. These preliminary results suggest that some smokers may be able to use neurofeedback via rtfMRI to voluntarily regulate ACC activation and temporarily reduce smoking cue-induced craving. Further research is needed to determine the optimal parameters of neurofeedback rtfMRI, and whether it might eventually become a therapeutic tool for nicotine dependence.
Background
tDCS appears to have modulatory effects on the excitability of cortical brain tissue. Though tDCS as presently applied causes no apparent harm to brain structure or function, a number of uncomfortable sensations can occur beneath the electrodes during stimulation, including tingling, pain, itching, and burning sensations. Therefore, we investigated the effect of topically applied Eutectic Mixture of Local Anesthetics (EMLA) on tDCS-related discomfort.
Methods
Nine healthy adults received both anodal and cathodal 2.0 mA tDCS for 5 minutes over the prefrontal cortex with the skin pretreated for 20 minutes with either EMLA or placebo cream. Participants rated procedural discomfort 6 times across 8 dimensions of sensation.
Results
On average, the mean sensation ratings for EMLA-associated tDCS stimulation were significantly lower than placebo-associated stimulation for every cutaneous sensation evaluated. Cathodal stimulation was associated with higher ratings of “sharpness” and intolerability than anodal stimulation.
Conclusions
Topical EMLA may reduce tDCS-related discomfort.
Background-Repetitive Transcranial Magnetic Stimulation (rTMS) is a novel, non-invasive method of stimulating selected regions of the brain that has both research applications and potential clinical utility, particularly for depression. In order to conduct high-quality clinical studies of rTMS, it is necessary to have a convincing placebo (or sham) treatment. Prefrontal rTMS causes cutaneous discomfort and muscle twitching; therefore, an optimal control condition, i.e., sham condition, would mimic the cutaneous sensation and muscular discomfort of rTMS without stimulating the brain. Ideally, the quality and intensity of the sham condition would feel identical to the quality and intensity of the rTMS condition except that the sham would have no effect on cortical activity. We designed and built a focal electrical stimulation system as a sham rTMS condition. While this electrical sham system is superior to methods employed in previous studies, little is known about how the new electrical sham system compares to active rTMS in terms of the level of discomfort and type of sensation it produces.
Background-Treatment-resistant depression presents a serious challenge to both patients and clinicians. The anterior and midlateral prefrontal cortices play complementary roles in integrating emotional and cognitive experiences and in modulating subcortical regions. Both regions offer a distinct opportunity for targeted antidepressant treatments. We chose to pilot the safety and therapeutic benefits of chronic and intermittent epidural prefrontal cortical stimulation (EpCS) in patients with treatment-resistant depression.
Meditation involves attentional regulation and may lead to increased activity in brain regions associated with attention such as dorsal lateral prefrontal cortex (DLPFC) and anterior cingulate cortex (ACC). Using functional magnetic resonance imaging, we examined whether DLPFC and ACC were activated during meditation. Subjects who meditate were recruited and scanned on a 3.0 Tesla scanner. Subjects meditated for four sessions of 12 min and performed four sessions of a 6 min control task. Individual and group t-maps were generated of overall meditation response versus control response and late meditation response versus early meditation response for each subject and time courses were plotted. For the overall group (n = 13), and using an overall brain analysis, there were no statistically significant regional activations of interest using conservative thresholds. A region of interest analysis of the entire group time courses of DLPFC and ACC were statistically more active throughout meditation in comparison to the control task. Moreover, dividing the cohort into short (n = 8) and long-term (n = 5) practitioners (>10 years) revealed that the time courses of long-term practitioners had significantly more consistent and sustained activation in the DLPFC and the ACC during meditation versus control in comparison to short-term practitioners. The regional brain activations in the more practised subjects may correlate with better sustained attention and attentional error monitoring. In summary, brain regions associated with attention vary over the time of a meditation session and may differ between long- and short-term meditation practitioners.
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