Ceyda Sayalı, Ph.D.

As an undergraduate in Istanbul, Turkey, I studied Psychology and Philosophy. My interests in cognitive neuroscience started through my extracurricular collaboration with work with Prof. Resit Canbeyli, from Bogazici University. Through this collaboration, I conducted experiments on Wistar rats that examined the relation between behavioral despair and learning, in an effort to define the behavioral effects of depression. My experience with this research filled my curiosity about the neurocognitive mechanisms underlying depression in humans. Therefore, I aimed to develop my skills in cognitive psychology and apply for a PhD program in cognitive neuroscience in the USA. Upon the receipt of my baccalaureate degree, I accepted a job offer from Koc University, as Dr. Fuat Balcı and Dr. Ilke Oztekin’s first lab manager for a nascent computational psychology lab. There, I gained training in Matlab programming and started comfortably coding new experiments and analyzing data, while simultaneously overseeing the challenges of opening a new lab. I collaborated with undergraduate and graduate students in the lab, over the course of two years. I was responsible for conducting and overseeing numerous research projects for both Dr. Oztekin on working memory and Dr. Balcı on time perception. During this time, I independently tested the dopamine based internal clock hypothesis in interval timing, and the role of feedback on working memory.

At Brown, I primarily worked with Dr. David Badre. I aimed to receive a deeper cognitive understanding of what might lead to apathy, a distinguishing symptom of depression. I realized that depressed patients place less subjective value on the same outcomes that healthy people find appealing. This leads to a lack of motivation to pursue these devalued outcomes (e.g. apathy). However, a common mechanism that affects both healthy and depressed individuals was demand avoidance: everyday decisions, like deciding to diligently review your analysis versus skimming it over before manuscript submission, are influenced by estimates of the cost of cognitive effort. Therefore, in order to understand the mechanisms underlying the costs/benefits associated with cognitive control, I developed a novel experimental demand avoidance paradigm and tested the neural mechanisms using fMRI underlying the learning of effort costs, the decision to avoid effort as well as a behavioral paradigm that delineated the source of cognitive effort costs

My findings during my PhD at Brown University informed me that ‘cost of cognitive control’ hypothesis of cognitive effort cannot fully account for all effort decisions and that individual differences underlie the evaluation of the same effort costs. To reconcile these findings, I designed a novel paradigm in my first postdoc, where I primarily worked with Prof. Roshan Cools (at Donders Institute, the Netherlands).  In my research with her, I adopted both objective and subjective measures to explain the cost/value associated with cognitive effort as a function of individual differences in trait-level affective states. I showed that what is underlying the link between task engagement and effortful tasks might be dynamic range that these tasks yield for minimization of performance accuracy prediction errors based on individual’s own capacity for a task, or in other words, the individual’s potential for performance improvement at that task. Moreover, pupil size, as a proxy for noradrenergic arousal tracked these performance improvements, boosting task-engagement.

Moreover, during my postdoc at Donders Institute, I aimed at receiving pharmacological intervention training. To do so, I collaborated with Dr. Rick Helmich who is both a researcher and a neurologist at the Parkinson Centre Nijmegen, works on motor and cognitive problems in Parkinson’s Disease (PD) patients, using neuroimaging and physiological measures. In my collaboration with him, I assessed cognitive deficits in PD patients as a function of dopaminergic drug manipulation using fMRI and a double-blind, randomized, within-subject design. 

At the Center for Psychedelics and Consciousness Research, I primarily worked with Dr. Fred Barrett. In one project, using fMRI, we investigated the post-dose neurocognitive effects of psilocybin-assisted therapy on patients with concurrent major depressive disorder and alcohol use disorder in a randomized double-blind placebo-controlled within-subject design clinical trial. In another, using EEG, we tested the acute neurocognitive effects of psilocybin in healthy volunteers. We also asked methodological questions regarding the reproducibility of TMS evoked EEG signals.