[Show abstract][Hide abstract] ABSTRACT: We investigated whether transcranial direct current stimulation (TDCS), an electrode-based noninvasive brain stimulation technology, could enhance learning in a training task designed to teach individuals to identify threats in a synthetic aperture radar (SAR) image. To isolate the impact of TDCS alone, we investigated whether subjects could distinguish between “real” (2.0 mA; 30 minutes) and “sham” or placebo (2.0 mA; 30 seconds) stimulation. The training task was divided into two identical but separate blocks (four training modules per block) — each followed by a performance test. A sensation questionnaire that asked subjects to rate sensations of itchiness, pain, heat and discomfort on an 11-point Likert scale preceded each of the four training modules (S1-S4). Half of the subjects received real and sham stimulation during the first and second blocks respectively while the other half received vice versa. At the end of the entire learning task, we asked subjects to identify which of the blocks they thought they received real stimulation. Of the 17 healthy study participants analyzed (mean age 28.1 ± 5.9, 13 male) 65% and 35% could correctly and incorrectly identify the real stimulation condition respectively. Additionally, ANOVA analysis revealed that the average reported sensation levels in the real condition was statistically greater than those in the sham condition (F1,16 = 7.36, p = 0.0161) and that these values decreased more rapidly with time on the task in the sham condition (Real: S1 = 1.53, S2 = 1.09, S3 = 0.88, S4 = 0.83; Sham: S1 = 1.46, S2 = 0.19, S3 = 0.19, S4 = 0.10) . These results suggest that the sham stimulation condition is not as ideal as originally thought and that a new stimulation paradigm is necessary as an effective control. A two-sample t-test, however showed nearly significantly greater (p=0.0679) target search improvement in individuals who received real compared to sham stimulation following the first block of training. Subjects at this stage were not yet aware of what type of stimulation they received. Therefore, at least some of the learning enhancement can be attributed to tDCS-effects independent of psychological/sensation factors. Such findings suggest that brain stimulation can effectively be used to enhance learning, however, psychological/sensation factors should be taken into account when interpreting sham stimulation conditions.
Society for Neuroscience Annual Meeting, Washiongton D.C.; 11/2011
[Show abstract][Hide abstract] ABSTRACT: Transcranial direct current stimulation (tDCS) is a noninvasive brain stimulation method being investigated by the Air Force for its possible application in improving cognitive performance. tDCS applies a small electrical current (≤ 2 mA) through the scalp to modulate cortical excitability in targeted areas. Due to the current demand for imagery analysts (Chief Scientist Air Force, 2010), this study focuses on decreasing time required to them analysts using a synthetic aperture radar (SAR) task. All 18 subjects (mean age 28.06, SD 5.88, 13 male) received both active and sham stimulation of the F10 area (according to the 10-20 EEG system) in two separate, but identical, sessions of the SAR task. Half of the subjects received active stimulation in the first session, while the other half received active stimulation in the second session. Background information, including information on gaming experience and education, was collected from all subjects. Recent research shows that action video game players (VGP; 4 days per week, minimum 1 hr per day for previous 6 months) have a variety of improved visual skills compared to non-VGPs (Green & Bavelier, 2003). We also tested to see whether the level of education had an impact on learning performance. ANOVA’s were performed using the ratio of correct answers to false positives (T+/F+) and false negative (F-) count as dependent variables. Analyses were run for session 1, session 2, and the change from session 1 to session 2. Factors included (separated analyses) were whether the subject identified themselves as a gamer (yes or no), and the educational level of the subject (high school, at least some college, Masters or more). These results indicate that VGPs do not perform better in this imagery analysis task than non-VGPs. We also see no significant effect for education in this experiment. Therefore, experience does not seem to affect performance, and we instead suggest that variability in performance is due to other factors.
Society for Neuroscience Annual Meeting, Washington DC; 11/2011
[Show abstract][Hide abstract] ABSTRACT: This paper proposes a shift in the way researchers currently view and use transcranial brain stimulation technologies. From a neuroscience perspective, the standard application of both transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) has been mainly to explore the function of various brain regions. These tools allow for noninvasive and painless modulation of cortical tissue. In the course of studying the function of an area, many studies often report enhanced performance of a task during or following the stimulation. However, little follow-up research is typically done to further explore these effects. Approaching this growing pool of cognitive neuroscience literature with a neuroergonomics mindset (i.e., studying the brain at work), the possibilities of using these stimulation techniques for more than simply investigating the function of cortical areas become evident. In this paper, we discuss how cognitive neuroscience brain stimulation studies may complement neuroergonomics research on human performance optimization. And, through this discussion, we hope to shift the mindset of viewing transcranial stimulation techniques as solely investigatory basic science tools or possible clinical therapeutic devices to viewing transcranial stimulation techniques as interventional tools to be incorporated in applied science research and systems for the augmentation and enhancement of human operator performance.
[Show abstract][Hide abstract] ABSTRACT: With an exponential rise in the demand for intelligence, surveillance, and reconnaissance missions, the Air Force has found it difficult to train enough qualified image analysts to evaluate the plethora of images and video collected during these missions. Clark, et al (2011) recently provided evidence that a form of non-invasive brain stimulation known as transcranial direct current stimulation (TDCS) can accelerate learning of threat detection. Using a similar approach, we evaluated the effect of TDCS on learning performance in a task designed to train individuals to correctly identify enemy ground targets within static Synthetic Aperture Radar (SAR) images. This is arguably the most difficult portion of the image analyst training curriculum. Eighteen participants (age = 28.29 + 5.97 yrs., 13 males) performed this training task under two tDCS conditions: active (30 min at 2 mA) and sham (30 sec at 2 mA). Prior to training, participants completed a SAR image test to establish baseline performance. They then completed two identical training sessions, each of which included four training blocks and a test. Half of the participants (group 1) received anodal TDCS over the right F10 area (according to the 10-20 EEG system) during the first session and sham stimulation during the second. The other half of the participants (group 2) received the stimulation conditions in the opposite order. Performance on the task was measured using accuracy, defined as the ratio of correctly identified targets (true positives) to incorrectly identified targets (false positives). The results of the paired t-tests revealed significant difference in accuracy between the participant groups (p=0.05). Participants receiving active TDCS in the first session exhibited a mean accuracy of 6.51 + 1.52 while participants receiving sham TDCS in the first session produced a mean accuracy of 3.16 + 0.56. There were no statically significant differences in performance between the two groups in the second session. This indicates active stimulation in the second session caused participants of group 2 to “catch up” with the group 1 in terms of performance. Hence, the results provide evidence that TDCS can effectively be used to enhance learning of threats within a SAR image analysis task.
Society for Neuroscience Annual Meeting, Washionton DC; 11/2010