Do excitability and arousal extend persistence in iconic memory?

Basic data for this project

Description

Our perceptual experience is not solely determined by the physical properties of sensory stimuli, but also by internal brain states at the time of stimulus presentation. Two key physiological dimensions of such states are neuronal excitability and arousal, which fluctuate spontaneously from moment to moment and modulate sensory processing. Numerous studies using near-threshold stimuli have shown that these fluctuations strongly influence whether a stimulus is detected. However, it remains unclear whether excitability and arousal also impact the temporal persistence of stimulus representations — that is, how long visual information remains available after stimulus offset. This project investigates whether and how spontaneous fluctuations in excitability and arousal modulate the persistence of iconic memory, a high-capacity but rapidly decaying form of visual storage that retains detailed sensory information for several hundred milliseconds. The central hypothesis is that higher excitability and arousal prolong the availability of visual information — either by amplifying the initial neural response or by slowing its decay. To test this, we combine high-temporal-resolution EEG recordings and pupillometry with well-established paradigms that allow precise measurement of temporal persistence. We focus on two complementary EEG markers of excitability: (1) alpha-band oscillations (8–12 Hz), which inversely track cortical excitability, and (2) aperiodic spectral parameters (specifically the slope and offset of the 1/f-like background activity), which reflect the excitation–inhibition balance independently of rhythmic oscillations. Across a series of experiments, we will examine: • whether higher pre-stimulus excitability and arousal (reflected in lower alpha power, flatter spectral slope, and larger pupil size) are associated with enhanced informational persistence, • whether these effects also modulate the amplitude and duration of early visual-evoked EEG components, such as the C1, • whether excitability influences visible persistence, the brief perceptual impression of a stimulus after offset, • and whether spatial attention, both spontaneous and cue-driven, interacts with lateralized excitability fluctuations to shape iconic memory performance. By shifting the focus from threshold detection to the temporal dynamics of sensory persistence, this project aims to clarify how internal brain states shape early visual representations. These findings will advance our understanding of how excitability and arousal influence perception beyond detection, offering new insight into the mechanisms underlying moment-to-moment variability in visual experience.