Florida State University

Accepting new graduate students.

Dr. Justin Riddle

Assistant Professor of Psychology and Neuroscience
PDB B425


The Riddle Lab is investigating the neural basis of cognitive control and psychiatric illness. We study how network-scale brain activity measured with EEG and functional MRI can be modulated by non-invasive brain stimulation techniques like transcranial magnetic stimulation (TMS) and transcranial alternating current stimulation (tACS). By gaining a causal understanding of the neural oscillations that underlie cognitive control, we hope to develop novel treatment paradigms to address the rising mental health crisis.
Current Research
Our research identified a novel control signal that is engaged when participants are engaged in goal-directed behavior and decision-making. Low-frequency oscillations in prefrontal cortex coupled to high-frequency activity in the motor cortex during decision-making when the individual is incorporated their goals into the decision process. This prefrontal delta to motor beta cross-frequency coupling was also discovered to be reduced in patients with elevated symptoms of anhedonia in major depressive disorder. Multiple randomized clinical trials are underway to understand the neural mechanisms underlying this signal and to apply stimulation designed to restore delta-beta coupling in patients. Low-frequency network activity in the prefrontal cortex is also being investigated in the context of control over working memory. Working memory is the ability to maintain information in the absence of information in the environment. This process underlies higher-order cognition, is disrupted in psychiatric illness, and treatments for psychiatric illness target the prefrontal regions responsible for directing working memory. Our research is investigating how low-frequency oscillations organize activity in the frontal-parietal network to support control over working memory. Furthermore, we are developing brain stimulation tools to probe the causal role of these control signals and to understand how the prefrontal cortex contributes to working memory.
Recent Publications
Riddle J; Alexander ML; Schiller CE; Rubinow DR; Frohlich F (2022). Reduction in left frontal alpha oscillations by transcranial alternating current stimulation in major depressive disorder is context-dependent in a randomized clinical trial. Biological Psychiatry: Cognitive Neuroscience and Neuroimaging, 7(3), 302-311.
Riddle J; Alexander ML; Schiller CE; Rubinow DR; Frohlich F (2022). Reward-based decision-making engages distinct modes of cross-frequency coupling. Cerebral Cortex, 32 (10), 2079-2094.
Riddle J; Frohlich F (2021). Targeting neural oscillations with transcranial alternating current stimulation. Brain Research, 147491.
Riddle J; McFerren, A; Frohlich F (2021). Causal role of cross-frequency coupling in distinct components of cognitive control. Progress in Neurobiology, 102033.
Riddle J; Scimeca J; Cellier D; Dhanani S; D’Esposito M (2020). Causal Evidence for a Role of Theta and Alpha Oscillations in the Control of Working Memory. Current Biology, 30(9), 1748-54.
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