Enhancing interactivity with transcranial direct current stimulation

Transcranial Direct Current Stimulation (tDCS) is a non-invasive type of neural stimulation known for modulation of cortical excitability leading to positive effects on working memory and attention. The availability of low-cost and consumer grade tDCS has democratized access to such devices allowing us to explore its applicability to HCI. We review the relevant literature and identify potential avenues for exploration within the context of enhancing interactivity and use of tDCS in the context of HCI

Noninvasive Brain Stimulation and Personal Identity: Ethical Considerations.

As noninvasive brain stimulation (NIBS) technology advances, these methods may become increasingly capable of influencing complex networks of mental functioning. We suggest that these might include cognitive and affective processes underlying personality and belief systems, which would raise important questions concerning personal identity and autonomy. We give particular attention to the relationship between personal identity and belief, emphasizing the importance of respecting users\u27 personal values. We posit that research participants and patients should be encouraged to take an active approach to considering the personal implications of altering their own cognition, particularly in cases of neurocognitive enhancement. We suggest that efforts to encourage careful consideration through the informed consent process would contribute usefully to studies and treatments that use NIBS

The Neuroenhancement of Healthy Individuals Using tDCS: Some Ethical, Legal and Societal Aspects

Over the past two decades there has been increasing scientific interest in Human Enhancement, that is, the possibilities of expanding and enhancing the capabilities of healthy individuals with direct technological interventions into the body. The (sub)field of neuroenhancement, which explores attempts to technologically increase attention, memory, perception, learning and other cognitive capabilities, as well as alter mood and emotions, has become especially prominent. Recently, transcranial Direct Current Stimulation (tDCS) has emerged as a possible method for enhancing cognitive abilities in healthy individuals. The article provides a short overview of the concept of neuroenhancement and of the cognitive enhancement effects that tDCS has demonstrated in the scientific literature. It further focuses on the (neuro)ethical, legal and societal implications of such a practice, and points out issues and questions that especially require further research and investigation, both from a neuroscientific and from a social sciences and humanities perspective. tDCS could become another addition to the increasing set of Human Enhancement Technologies, but it requires further rigorous studies and trials in order to properly assess its potential risks and benefits

Human Sensation of Transcranial Electric Stimulation.

Noninvasive transcranial electric stimulation is increasingly being used as an advantageous therapy alternative that may activate deep tissues while avoiding drug side-effects. However, not only is there limited evidence for activation of deep tissues by transcranial electric stimulation, its evoked human sensation is understudied and often dismissed as a placebo or secondary effect. By systematically characterizing the human sensation evoked by transcranial alternating-current stimulation, we observed not only stimulus frequency and electrode position dependencies specific for auditory and visual sensation but also a broader presence of somatic sensation ranging from touch and vibration to pain and pressure. We found generally monotonic input-output functions at suprathreshold levels, and often multiple types of sensation occurring simultaneously in response to the same electric stimulation. We further used a recording circuit embedded in a cochlear implant to directly and objectively measure the amount of transcranial electric stimulation reaching the auditory nerve, a deep intercranial target located in the densest bone of the skull. We found an optimal configuration using an ear canal electrode and low-frequency (<300 Hz) sinusoids that delivered maximally ~1% of the transcranial current to the auditory nerve, which was sufficient to produce sound sensation even in deafened ears. Our results suggest that frequency resonance due to neuronal intrinsic electric properties need to be explored for targeted deep brain stimulation and novel brain-computer interfaces

Efficacy of Transcranial Direct Current Stimulation Coupled with a Multidisciplinary Rehabilitation Program for the Treatment of Fibromyalgia

Pain control in fibromyalgia patients is limited no matter the therapeutic regimens used. Recent data have shown that daily sessions of anodal transcranial direct current stimulation (tDCS) over the primary motor cortex (M1) in patients with fibromyalgia (FM) are associated with reduction of pain perception

Effects of Transcranial Direct Current Stimulation on Episodic Memory Related to Emotional Visual Stimuli

The present study investigated emotional memory following bilateral transcranial electrical stimulation (direct current of 1 mA, for 20 minutes) over fronto-temporal cortical areas of healthy participants during the encoding of images that differed in affective arousal and valence. The main result was a significant interaction between the side of anodal stimulation and image emotional valence. Specifically, right anodal/left cathodal stimulation selectively facilitated the recall of pleasant images with respect to both unpleasant and neutral images whereas left anodal/right cathodal stimulation selectively facilitated the recall of unpleasant images with respect to both pleasant and neutral images. From a theoretical perspective, this double dissociation between the side of anodal stimulation and the advantage in the memory performance for a specific type of stimulus depending on its pleasantness supported the specific-valence hypothesis of emotional processes, which assumes a specialization of the right hemisphere in processing unpleasant stimuli and a specialization of the left hemisphere in processing pleasant stimuli. From a methodological point of view, first we found tDCS effects strictly dependent on the stimulus category, and second a pattern of results in line with an interfering and inhibitory account of anodal stimulation on memory performance. These findings need to be carefully considered in applied contexts, such as the rehabilitation of altered emotional processing or eye-witness memory, and deserve to be further investigated in order to understand their underlying mechanisms of action

Transcranial Direct Current Stimulation (tDCS) Improves Performance on Spelling and Word Detection Tasks

Deficits in written language involving spelling can have negative effects on a person’s education and occupation. Conventional spelling therapy is a time consuming and cost-prohibitive option, if even available, highlighting the need for improved methods for remediation. One possible way to address this need may be through the use of transcranial direct current stimulation (tDCS). This study sought to examine the effects of tDCS on performance during spelling, word detection, and facial recognition tasks. Active or sham tDCS was randomly assigned to typically functioning adults. The anode electrode was placed over Broca’s area (F7 in the 10/20 EEG system) and the cathode was positioned over the upper right arm. Outcome was assessed before, during, immediately after tDCS, and again 3-5 days after tDCS. Data was analyzed using analysis of variance (ANOVA) to examine if group differences existed. Significant differences were found between active and sham tDCS on both the spelling and word-search tests. There was no significant difference between active and sham tDCS on either of the facial recognition tasks

High-definition tDCS of the temporo-parietal cortex enhances access to newly learned words

Learning associations between words and their referents is crucial for language learning in the developing and adult brain and for language re-learning after neurological injury. Non-invasive transcranial direct current stimulation (tDCS) to the posterior temporo-parietal cortex has been suggested to enhance this process. However, previous studies employed standard tDCS set-ups that induce diffuse current flow in the brain, preventing the attribution of stimulation effects to the target region. This study employed high-definition tDCS (HD-tDCS) that allowed the current flow to be constrained to the temporo-parietal cortex, to clarify its role in novel word learning. In a sham-controlled, double-blind, between-subjects design, 50 healthy adults learned associations between legal non-words and unfamiliar object pictures. Participants were stratified by baseline learning ability on a short version of the learning paradigm and pairwise randomized to active (20 mins; N = 25) or sham (40 seconds; N = 25) HD-tDCS. Accuracy was comparable during the baseline and experimental phases in both HD-tDCS conditions. However, active HD-tDCS resulted in faster retrieval of correct word-picture pairs. Our findings corroborate the critical role of the temporo-parietal cortex in novel word learning, which has implications for current theories of language acquisition