Sleep strongly affects synaptic strength, making it critical for cognition, especially learning and memory formation. Whether and how sleep deprivation modulates human brain physiology and cognition is poorly understood. Here we examined how overnight sleep deprivation vs overnight sufficient sleep affects (a) cortical excitability, measured by transcranial magnetic stimulation, (b) inducibility of long-term potentiation (LTP)- and long-term depression (LTD)-like plasticity via transcranial direct current stimulation (tDCS), and (c) learning, memory, and attention. We found that sleep deprivation increases cortical excitability due to enhanced glutamate-related cortical facilitation and decreases and/or reverses GABAergic cortical inhibition. Furthermore, tDCS-induced LTP-like plasticity (anodal) abolishes while the inhibitory LTD-like plasticity (cathodal) converts to excitatory LTP-like plasticity under sleep deprivation. This is associated with increased EEG theta oscillations due to sleep pressure. Motor learning, behavioral counterparts of plasticity, and working memory and attention, which rely on cortical excitability, are also impaired during sleep deprivation. Our study indicates that upscaled brain excitability and altered plasticity, due to sleep deprivation, are associated with impaired cognitive performance. Besides showing how brain physiology and cognition undergo changes (from neurophysiology to higher-order cognition) under sleep pressure, the findings have implications for variability and optimal application of noninvasive brain stimulation.

This talk will focus on our lab's extensive research on understanding and enhancing creative analogical reasoning. I will cover the development of the analogy finding matrix task, evidence for conscious augmentation of creative state during this task, and the real-world implications this ability has for college STEM education. I will also discuss recent research aimed at enhancing performance on this creative analogical reasoning task using both transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS).

Transcranial electrical stimulation (tES) techniques, including transcranial alternating and direct current stimulation (tACS and tDCS), are non-invasive brain stimulation technologies increasingly used for modulation of targeted neural and cognitive processes. Integration of tES with human functional magnetic resonance imaging (fMRI) provides a novel avenue in human brain mapping for investigating the neural mechanisms underlying tES. Advances in the field of tES-fMRI can be hampered by the methodological variability between studies that confounds comparability/replicability. To address the technical/methodological details and to propose a new framework for future research, the scientific international network of tES-fMRI (INTF) was founded with two main aims: • To foster scientific exchange between researchers for sharing ideas, exchanging experiences, and publishing consensus articles; • To implement the joint studies through a continuing dialogue with the institutes across the globe. The network organized three international scientific webinars, in which considerable heterogeneities of technical/methodological aspects in studies combining tES with fMRI were discussed along with strategies to help to bridge respective knowledge gaps, and distributes newsletters that are sent regularly to the network members from the Twitter and LinkedIn accounts.