Network mechanisms of cognitive control: We study how brain networks interact to transmit, select, or inhibit information for flexible human behaviors.

Integration of control representations: We investigate the structure, dynamics, and interactions between task representations that facilitate cognitive control.

Methods: Our research utilizes a variety of methods, including fMRI, TMS, MEG, EEG, task-free (resting-state) and task-based connectivity analyses,cognitive and oculomotor paradigms, and studies of patients with focal cortical or subcortical lesions.

Cognitive control functions of the human thalamocortical system


The mammalian brain can be conceptualized as a thalamocortical system, yet the thalamus is often ignored in studies of brain network organization. One major focus of our research is to use advanced network neurosciecne techniques to investigate the thalamus's contribution to diverse network and cognitive functions.

  • Hwang, K., Bertolero M., Liu, W., D’Esposito, M. (2017). The human thalamus is an integrative hub for functional brain Networks. Journal of Neurosciene. 37(23), 5594-5607
  • Chen X., Sorenson, E., Hwang, K. (2023). Thalamocortical contributions to working memory processes during the n-back task. Neurobiology of Learning and Memory, 197(107701).
  • Hwang, K., Shine, J.M., Cole, M.W., Sorenson, E. (2022). Thalamocortical contributions to cognitive task activity. eLife, 11, e81282.
  • Shine, J.M., Lewis, L.D., Garrett, D., Hwang K. (2023). The impact of the human thalamus on brain-wide information processing. Nature Reviews Neuroscience, 24(7), 416-430
  • Effects of thalamic lesions


    The human thalamus is a difficult region to study because of its small size and deep location. To address this challenge, we are now conducting studies with a novel approach: combining multimodal neuroimaging (fMRI and EEG) and human lesions studies. The goal is to determine how the disruption of thalamocortical interactions after thalamic lesion affects cortical neural activity and behavior. We are now focusing on how the thalamus modulate cortical evoked responses, neural oscillations, and cortico-cortical functional connectivity for cognitive control.

  • Hwang, K., Bruss, J., Tranel, D., & Boes, A. D. (2020). Network localization of executive function deficits in patients with focal thalamic lesions. Journal of Cognitive Neuroscience, 32(12), 2303-2319.
  • Reber, J., Hwang, K., Bowren, M.A., Bruss, J., Tranel, D., Boes, A.D (2021). Cognitive impairment after focal brain damage is associated damages to structural, but not functional network hubs. Proceedings of the National Academy of Sciences 118.19 (2021).
  • Hwang, K., Shine, J.M., Bruss, J., Tranel, D., Boes, A.D. (2021). Neuropsychological evidence of multi-modal network hubs in the human thalamus. eLife. 2021;10:e69480
  • Structure and dynamics of task representations


    Task representations is a central component of cognitive control. However, several important properties of task representations are not well understood, including their structure and interactive dynamics. This is likely because it is difficult to directly observe these latent properties of mental representations using conventional behavioral and neuroimaging methods. We are conducting mulitmodal neuroimag, lesion, and behavioral modeling studies to discover the structure and dynamics of representations that facilitate cognitive control.

  • Cellier, D., Petersen, I.T., Hwang, K. (2022). Dynamics of hierarchical task representations. Journal of Neuroscience, 42(38), 7276-7284.
  • Leach, S.L., Hollis, J., Sorenson, E., Cellier, D., Hwang, K. (2022) Mapping representational integration for hierarchical cognitive control. Cognitive Neuroscience Society Meeting, San Francisco CA

  • Netowrk processes implementing cognitive control


    Could functional connectivity be modulated by "top-down biasing signals"? We are studying how cognitive control influences information exchange between task-related brain regions, and to identify brain regions interacting with dynamic functional connectivity patterns. We use TMS to causally map regions that provide "biasing signals" to enhance or inhibit functional connectivity for cognitive control.

  • Iyer, K.K., Hwang, K., Hearne, L. J., Muller, E., D’Esposito, M., Shine, J.M., Cocchi, L. (2022). Focal neural perturbations reshape the low-dimensional brain activity flow supporting task performance. Nature Communications.
  • Hwang, K., Shine, J.M., Cellier, D., D’Esposito, M. (2020). The human intraparietal sulcus modulates task-evoked functional connectivity. Cerebral Cortex. 30(3), 875-887.
  • Hwang, K., Shine, J. M., D’Esposito, M. (2019). Fronto-parietal activity interacts with task-evoked changes in functional connectivity. Cerebral Cortex. 29(2):802-813 Link to paper.
  • Cognitive flexibility and hierarchical cognitive control


    The cardinal characteristic of cognitive control is it is flexible and context dependent. We are not governed by the same set of rules in every situation. If so, how do we use circumstantial information to adjust our actions, specifically, adjust mappings between sensory and motor processes? We have developed a paradigm that requires human subjects to switch between action rules depending on a superordinate, circumstantial context. Parallel EEG and fMRI studies are now in progress.

  • Chen, X., Yeh, F-C., Hollis, J., Sorenson, E., Cellier, D., Hwang, K. (2022) Thalamic convergenze zones facilitate flexible cognitive control. Cognitive Neuroscience Society Meeting, San Francisco CA
  • Riddle, J., Vogelsang, D. A., Hwang, K., Cellier, D., & D'Esposito, M. (2020). Distinct oscillatory dynamics underlie different components of hierarchical cognitive control. Journal of Neuroscience, 40(25), 4945-4953.

  • Spectral neural dynamics and cognitive control


    How do brain networks flexibly process and communicate information? Possibly through oscillatory neural activities. Different brain rhythms are thought to reflect distinct biophysical and circuit-level processes, thus could be indices of distinct neurocognitive mechanisms. We study how oscillatory neural dynamics support cognitive control in adults and during development.

  • Cellier, D., Riddle, J., Petersen, I., & Hwang, K. (2021). The development of theta and alpha neural oscillations from ages 3 to 24 years. Developmental Cognitive Neuroscience, 100969.
  • Riddle, J., Hwang, K., Cellier, D., Dhanani, S., D’Esposito, M. (2019). Causal evidence for the role of neuronal oscillations in top-down and bottom-up attention. Journal of Cognitive Neuroscience.
  • Hwang, K., Ghuman A. S., Manoach, D. S., Jones, S. R., Luna, B. (2016). Frontal preparatory neural oscillations associated with cognitive control: A developmental study comparing young adults and adolescents. NeuroImage, 136:139-48.
  • Hwang, K., Ghuman A. S., Manoach, D. S., Jones, S .R., Luna, B. (2014). Cortical Neurodynamics of Inhibitory control. Journal of Neuroscience, 34(29):9551:9561.
  • Functional brain network architecture


    Historically, cognitive control and its neurodevelopment have been studied using univariate approaches to probe relevant brain regions in isolation. However, several brain maturational processes (e.g., myelination) affect the brain as a network from childhood through adolescence. Hence, how functional brain networks are organized across development has important implication to its information processing capacity. Right now we are focusing on network properties of the human thalamocortical system.

  • Marek, S.A., Hwang, K., Foran, W. W., Luna, B. (2015). The role of network organization and integration in the development of cognitive control. PLOS Biology, 13(12): e1002328. doi:10.1371/journal.pbio.1002328.
  • Hwang, K., Hallquist, M. N., Luna, B. (2013). The development of hub architecture in the human functional brain network. Cerebral Cortex, 23(10):2380-2393.
  • Hwang, K., Luna, B. (2012). The development of brain connectivity supporting prefrontal cortical functions. D.T. Stuss & R.T. Knight (Eds.) Principle of frontal lobe functions, 2nd Ed. New York: Oxford University Press.