Non-Invasive Human Brain to Brain Interface
In 2013, together with Dr. Rajesh Rao, Drs. Stocco and Prat have demonstrated the possibility of transferring simple information directly between two brains using non-invasive brain stimulation devices. This pilot study has been extensively covered by the media, and has led to a number of published research articles. Thanks to a generous grant from the W. M. Keck foundation, we re currently expanding the possibilities of direct brain-to-brain communication.
Speaking one language is, in itself, an amazing achievement. According to some estimates, however, almost half of the world population manages to be proficient in two or more different languages. Research shows that such mastering of multiple languages has profound effects an individual’s cognitive abilities, extending beyond social and communicative benefits. In fact, bilinguals outperform monolinguals in a variety of tasks that are cognitively demanding , such as those drawing on executive processes such as inhibitory control and working memory. In other words, speaking two languages seems to “train” the brain in a manner that has effects that generalize to non-language domains. Our current research at the CCDL is using “Dynamic Causal Modeling” of neuroimaging data, in combination with our existing understanding of the neural basis of individual differences in cognitive capabilities, to better understand the nature of the brain changes induced by bilingualism, and explain how this translates into a general cognitive benefit.
Cognitive Control and Language Production
Cognitive control or “the ability to behave in accord with rules, goals, or intentions, even when this runs counter to reflexive or otherwise highly compelling, competing responses” (Rougier et al., 2005, p. 7338) is an ability that is essential to humans in order to successfully perform daily tasks (like driving to the grocery store after work!). This ability is involved in many different aspects of our daily tasks including but not limited to problem-solving, switching from one task to another, decision-making, learning, and maintaining focus in the face of distraction. Cognitive control also appears to be associated with one’s ability to successfully produce language. However, the extent to which different aspects of cognitive control are related to language production remains unclear. At the CCDL, we are trying to further understand the causal relationship between various aspects of cognitive control and language production by using experimental manipulations during speech to determine whether specific aspects of cognitive control differentially impact language production in individuals with relative advantages and disadvantages in cognitive control.
Dynamic Right Hemisphere Recruitment for Language
Our ability to understand linguistic function and dysfunction is contingent upon an improved understanding of how language processes are distributed in the intact brain, and how resources are allocated as a function of the ever changing demands. This project,funded by the National Institute on Deafness and other Communication Disorders, applies TMS, fMRI, and concurrent TMS/fMRI investigations to explore a new hypothesis about the dynamic roles of the two cerebral hemispheres in normal language processes and implications for recovery of function following unilateral brain damage. Our hypothesis in brief is that the right hemisphere (RH) becomes engaged in a variety of linguistic tasks when the processing demands of the task outstrip the resources available in the dominant left hemisphere (LH) and some of the residual processing “spills over” into RH homologues (e.g., Just & Varma, 2007; Prat, Mason, & Just, 2011). Importantly, the spillover hypothesis predicts that RH involvement varies across tasks and individuals, as a function of the relation between cognitive and neural resources available to an individual and of the demands required to complete the task. Recovery from unilateral brain damage is likely to vary as a function of pre-injury lateralization; therefore our understanding of the factors related to individual differences in language lateralization is imperative. One goal of this project is to obtain knowledge about the causes and correlates of individual differences in language laterality. Another is to investigate system-level characteristics of the cortical network responsible for language processes, and how they relate to individual language lateralization and skill. A final goal is to investigate how the language network changes as a whole in response to impaired functioning in isolated regions. This information will further our understanding of how the two hemispheres cooperate during intact language processes, and ultimately improve our understanding of deficits associated with unilateral damage and how to enhance recovery.
Role and Function of the Basal Ganglia in Human Cognition
We are currently developing computational models that would help us explain how basal ganglia function explans and interacts with other facets of cognition, including language, learning, and decision-making.