Motor preparation tracks decision boundary crossing in temporal decision-making

Abstract

Interval timing, the ability of animals to estimate the passage of time, is thought to involve diverse neural processes rather than a single central "clock" (Paton & Buonomano, 2018). Each of the different processes engaged in interval timing follows a different dynamic path, according to its specific function. For example, attention tracks anticipated events, such as offsets of intervals (Rohenkohl & Nobre, 2011), while motor processes control the timing of the behavioral output (De Lafuente et al., 2024). Hence, different processes provide complimentary perspectives on mechanisms of time perception. The temporal bisection task, where participants categorize intervals as "long" or "short", is thought to rely on the same mechanisms as other perceptual decisions (Balc & Simen, 2014). In line with this hypothesis, we previously described an EEG potential that tracks the formation of decision following the end of the timed interval (Ofir & Landau, 2022). Here, we track the dynamics of motor preparation to investigate the formation of decision within the timed interval. In contrast to typical perceptual decisions, where motor plans for all response alternatives are prepared simultaneously (Shadlen & Kiani, 2013), we find that different temporal decisions develop sequentially. While preparation for "long" responses was already underway before interval offset, no preparation was found for "short" responses. Furthermore, within intervals categorized as "long", motor preparation was stronger at interval offset for faster responses. Our findings shed light on the unique dynamics of temporal decisions and demonstrate the importance of considering neural activity in timing tasks from multiple perspectives.