Dynamic modulation of the processing of unpredicted technical errors by the posterior cingulate and the default mode network

The pervasive use of information technologies (IT) has tremendously benefited our daily lives. However, unpredicted technical breakdowns and errors can lead to the experience of stress, which has been termed technostress. It remains poorly understood how people dynamically respond to unpredicted system runtime errors occurring while interacting with the IT systems on a behavioral and neuronal level. To elucidate the mechanisms underlying such processes, we conducted a functional magnetic resonance imaging (fMRI) study in which 15 young adults solved arithmetic problems of three difficulty levels (easy, medium and hard) while two types of system runtime errors (problem errors and feedback errors) occurred in an unexpected manner. The problem error condition consisted of apparently defective displays of the arithmetic problem and the feedback error condition involved erroneous feedback. We found that the problem errors positively influenced participants’ problem-solving performance at the high difficulty level (i.e., hard tasks) at the initial stage of the session, while feedback errors disturbed their performance. These dynamic behavioral changes are mainly associated with brain activation changes in the posterior cingulate and the default mode network, including the posterior cingulate cortex, the mPFC, the retrosplenial cortex and the parahippocampal gyrus. Our study illustrates the regulatory role of the posterior cingulate in coping with unpredicted errors as well as with dynamic changes in the environment

Preservation and plasticity in the neural basis of numerical thinking in blindness

Numerical reasoning pervades modern human culture and depends on a fronto-parietal network, a key node of which is the intraparietal sulcus (IPS). In this dissertation I investigate how visual experience shapes the cognitive and neural basis of numerical thinking by studying numerical cognition in congenitally blind individuals. In Chapter 2, I ask how the cognitive basis of numerical thinking is shaped by visual experience. I test whether the precision of approximate number representations develops normally in the absence of vision and test whether the relationship between numerical approximation and math abilities is preserved in congenital blindness. In Chapter 3, I ask how the neural basis of symbolic number reasoning is modified by visual experience by studying neural responses to symbolic math in congenitally blind individuals. This initial investigation revealed that the fronto-parietal number system is preserved in blindness but that some “visual” cortices are recruited for symbolic number processing in blindness. The following chapters unpack these two patterns preservation and plasticity. In Chapter 4, I use resting-state data to ask whether functional connectivity with higher-cognitive networks is a potential mechanism by which “visual” cortices are reorganized in blindness. In Chapter 5, I work with individuals who became blind as adults to determine whether visual cortex plasticity for numerical functions is possible in the adult cortex or whether it is restricted to sensitive periods in development. In Chapter 6, I investigated whether the IPS and newly identified number-responsive “visual” area of congenitally blind individuals possess population codes that distinguish between different quantities. I find that the behavioral signatures of numerical reasoning are indistinguishable across congenitally blind and sighted groups and that the fronto-parietal number network, in particular the IPS, is preserved in the absence of vision. A dorsal occipital region showed the same functional profile as the IPS number system in congenitally blind individuals. Number-related plasticity was restricted to a sensitive period in development as it was not observed in adult-onset blind individuals. Furthermore, in congenital blindness, sub-specialization of the “visual” cortex for math and language processing followed the functional connectivity patterns of “visual” cortex