Using Electrical Stimulation to Test the Causal Role of Aperiodic Activity in Working Memory

Poster Session B - Sunday, March 30, 2025, 8:00 – 10:00 am EDT, Back Bay Ballroom/Republic Ballroom

Quirine van Engen¹ (quvaneng@ucsd.edu), Gabriela Freedland¹, Justin Riddle^2,3, Bradley Voytek^1,4,5,6; ¹Department of Cognitive Science, University of California, San Diego, ²Department of Psychology, Florida State University, ³Program in Neuroscience, Florida State University, ⁴Halıcıoğlu Data Science Institute, University of California, San Diego, ⁵Neurosciences Graduate Program, University of California, San Diego, ⁶Kavli institute for Brain and Mind, University of California, San Diego

Working memory (WM) is a cognitive function that enables temporary storage and manipulation of information for tasks like reasoning and decision making. While research has focused on oscillatory activity in narrow frequency bands, most neuronal activity is asynchronous, manifesting as aperiodic activity. Aperiodic activity is characterized by a 1/f power law distribution, and its slope is speculated to reflect the E:I balance. Recent evidence suggests aperiodic activity dynamically changes with cognitive demands, including WM, but lacks causal evidence. To investigate this causal connection, we collected EEG data from participants (n = 36) completing two days of a visual delayed continuous report task with varying WM loads. We developed a novel non-invasive electrical stimulation paradigm that mimics aperiodic activity: transcranial Random Aperiodic Stimulation (tRAS). Day two included this paradigm targeting the fronto-parietal network with the goal to causally manipulate endogenous neural aperiodic activity to become steeper or flatter while they performed the task. From day 1, we replicate classic WM findings: worse performance on higher WM load conditions than lower loads. We hypothesize that steeper stimulation causes the slope of aperiodic activity to increase, and will be paired with an increase in WM performance. If our results support our hypothesis, this research is critical for aging, since aperiodic activity flattens with age, paralleling a cognitive decline. If we find evidence for a direct, causal connection between aperiodic activity and WM, we have opened the door to finding a way to slow mental aging and improve the longevity of their minds.

Topic Area: EXECUTIVE PROCESSES: Working memory