Syanah C. Wynn

Introduction
I am a cognitive neuroscientist, which means that I measure and/or manipulate brain activity of people while they perform tasks on a computer in the lab. To perform these tasks, participants need to use specific cognitive functions, like memory and decision making. In this way I can investigate the brain activity involved in these functions. My work focuses on the brain processes involved in memory-related decision-making and optimal learning. For instance, what determines the confidence we have in our memories: Why are some memories strong and vivid, while others are weak and vague? But also, how do we inhibit irrelevant processes and adapt after making mistakes to optimize our learning? The main method I use to measure brain activity related to memory confidence and other cognitive functions is called electroencephalography (EEG). In an EEG measurement, a cap with small electrodes is placed on the head of participants and through these electrodes, brain signals are recorded. For the manipulation of brain activity I use harmless brain stimulation methods, which work in various ways. For instance, some non-invasive brain stimulation (NIBS) methods work by using a very small electrical currents to slightly increase or decrease brain activity.
On this website you can find my publications in scientific journals and a news section where I keep you informed about ongoing projects and various updates.

Background
After a bachelor’s in Psychology at Leiden University and a research master’s in Cognitive Neuropsychology at VU Amsterdam, I started my PhD in 2015 at the Donders Institute. With Dennis Schutter, Sander Daselaar, Marc Hendriks, and Roy Kessels, I did research on the role of the parietal cortex in memory confidence, using EEG, transcranial magnetic stimulation (TMS) and transcranial alternating current stimulation (tACS) (Dissertation). During my time at the Donders Institute, I also collaborated on projects that focused on attention, decision making, and movement, using EEG, TMS and transcranial direct current stimulation (tDCS). Thereafter, I worked as a postdoctoral research associate at Bowdoin College with Erika Nyhus. My work there focused on the role of specific oscillations in brain networks underlying memory retrieval, utilizing EEG and tACS. Then I moved to Ole Jensen’s Neural Oscillations group at the University of Birmingham, examining how the brain accomplishes rapid object recognition. Currently, I work at the Johannes Gutenberg University Medical Center in Mainz, where I work on my DFG-funded research on the role of the parietal cortex in memory-related decision-making.

News

Jan 16, 2025	New paper in Imaging Neuroscience!
Jun 01, 2024	New preprint on bioRxiv!
May 10, 2024	New paper! Timing of semantic representations of pictures and words

Selected publications

Utilizing tACS to enhance memory confidence and EEG to predict individual differences in brain stimulation efficacy

Syanah C Wynn, Tom R. Marshall, and Erika Nyhus

Imaging Neuroscience, 2025

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The information transfer necessary for successful memory retrieval is believed to be mediated by theta and gamma oscillations. These oscillations have been linked to memory processes in electrophysiological studies, which were correlational in nature. In the current study, we used transcranial alternating current stimulation (tACS) to externally modulate brain oscillations to examine its direct effects on memory performance. Participants received sham, theta (4 Hz), and gamma (50 Hz) tACS over frontoparietal regions while retrieving information in a source memory paradigm. Linear regression models were used to investigate the direct effects of oscillatory noninvasive brain stimulation (NIBS) on memory accuracy and confidence. Our results indicate that both theta and gamma tACS altered memory confidence. Specifically, theta tACS seemed to lower the threshold for confidence in retrieved information, while gamma tACS appeared to alter the memory confidence bias. Furthermore, the individual differences in tACS effects could be predicted from electroencephalogram (EEG) measures recorded prior to stimulation, suggesting that EEG could be a useful tool for predicting individual variability in the efficacy of NIBS.
The role of theta and gamma oscillations in item memory, source memory, and memory confidence

Syanah C Wynn, Christopher D Townsend, and Erika Nyhus

Psychophysiology, 2024

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Theta and gamma oscillations have been linked to episodic memory processes in various studies. Both oscillations seem to be vital for processes guided by the medial temporal lobe, such as the retrieval of information from memory. While theta oscillations increase with successful memory, it is unclear what the unique contribution of theta is to various subcomponents of memory. On the other hand, memory-related gamma oscillations have been mainly reported in the hippocampus, leaving the role of neocortical gamma in memory underexplored. In this study, we investigated how unique variability in memory accuracy and memory confidence contributes to fluctuations in theta and gamma power. To this end, we recorded EEG from 54 participants while they performed a source memory task. From this task we obtained their item memory accuracy, source memory accuracy, item memory confidence, and source memory confidence. These behavioral measures were put in a trial-by-trial linear mixed effects model to uncover their unique contribution to the oscillatory power in frontal and parietal regions. Our results are in line with the involvement of theta oscillations in both memory accuracy and confidence, but seem to indicate a main role for theta oscillations in memory-related confidence. In addition, we found that gamma oscillations play various roles in memory processing, dependent on brain region.