New brain stimulation and imaging techniques present new opportunities

Our current cognitive skills are a product of a painstakingly slow process of evolution; hence, as expected with evolution, further cognitive enhancements will likely take generations. However, rapidly growing amounts of information, expansion of the internet, and increasing demands of work have led us to ask more and more of our brains at an alarming rate. Recent advancements in cognitive monitoring and augmentation from the Tufts Human Computer Interaction (HCI) lab show promise in helping to combat this growing concern. The development of functional near-infrared spectroscopy (fNIRS) and transcranial direct current stimulation (tDCS) has opened new doors that could not only reduce the stress of work, but also enhance our cognition in real time.

fNIRS is a functional neuroimaging technique where changes in levels of oxygenated and deoxygenated hemoglobin in a region of the brain are detected using optical fibers emitting near-infrared light. This technique does not require the long setup time, highly restricted position and intolerance to movement that are characteristic of other neuroimaging devices. Therefore fNIRS can more easily be applied in a real world setting, opening the door for the creation of commercial applications of brain state monitoring during normal cognitive activity. By applying this technique to create a passive interface for detecting levels of stress or strain, the HCI lab was able to begin addressing the problem at hand.

A test subject participating in an fNIRS experiment at the Tufts HCI lab

Traditional machine interfaces, such as a mouse or a keyboard, require explicit input from a user in order to issue a command. In contrast, a device utilizing an implicit input paradigm monitors the actions or states of the user and administers commands accordingly, often adapting to a given user’s habits or baseline states to create a seamless, passive experience. For example, a mobile application may use location as an implicit input to improve the user’s experience by giving information in context to the user’s location. To expand on this idea, the lab created an experiment in which implicit input was derived from lab subjects’ prefrontal cortex activity using an fNIRS device attached to their forehead with a headband. Participants were instructed to play a simulation of air traffic control operation, a highly stressful job. As the number of planes under the participants’ control increased, levels of brain activity increased as well, indicating elevated mental stress. When stress rose above a certain level, the simulation adjusted the level of difficulty by reducing the traffic. This led to a 35 percent increase in the participants’ ability to land safely. Hence, by having a computer constantly monitor a user’s neural activity and adjusting the workload accordingly, the user can maintain an optimal working cognitive state to reduce the mental burden.

With fNIRS showing much promise, the Tufts HCI lab has recently embarked a new adventure to explore how we could augment cognitive behavior through a safe , painless, and non-invasive brain stimulation technique: transcranial direct current stimulation (tDCS). Our neurons are activated through electrical nerve impulses called action potentials, which will only propagate if the electrical membrane potential of the neurons crosses a certain threshold through a high expenditure of glucose. tDCS can generate a gentle “push” to decrease this threshold by sending constant, low intensity current through electrodes from the outside. This would mean that less energy from the user would be spent in doing the same activity. Dr. Allan Snyder, the director for the Centre for the Mind at the University of Sydney, performed an initial study of the efficacy of tDCS. He showed that with excitatory (anodal) stimulation to the right temporal anterior lobe and inhibitory (cathodal) stimulation to the left temporal anterior lobe using tDCS, 40% of participants were able to solve the nine-dot problem, a canonical test with a generally low success rate. Without the supplemental stimulation, only 20% of participants succeeded after many trials and errors. By targeting areas of the brain under stress with fNIRS and applying tDCS to relieve that stress, the lab hopes to be able to create a strategy for augmenting our cognitive abilities.

The next step in this investigation is to understand the effects of cognitive enhancement on the brain as a whole. There is a finite amount of resources available to the brain at any given time. Since any activity comes with a resource cost, and the total demand of all activity cannot exceed the resource pool, there must be compensation for resource reallocation. Therefore, for example, stimulation of activity in one area might lead to oxygen deprivation in another area. The HCI lab is looking to not only understand what the costs are, but also how those costs could be compensated. A possible strategy that has been proposed is to identify areas that could be inhibited in order to free up more resources in a safe manner. The potential of having an implicit interface between the fNIRS and tDSC no longer seems to be a far-fetched reality that could certainly help create a more efficient and less-stressful working environment. With the theories in place, pilot studies showing promise and a new study ready to begin, the Tufts HCI lab would like to send a cordial invite to those who would like to participate.

(If you are interested in participating in this HCI study, please email


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