It is increasingly recognised that we can orient attention flexibly in the temporal domain to anticipate relevant events occurring at predicted moments. This ability is highly adaptive in our dealings with the environment since temporal regularities are common and relevant events often occur in rhythmic streams. The mechanisms by which temporal expectations can change neural processing, however, remain largely uncharted. There is still considerable debate about whether and how temporal information is explicitly coded in the brain and, consequently, about what network(s) may provide sources of predictive temporal signals to modulate perceptual mechanisms. Equally, or even more, mysterious is how temporal information can come to bias perceptual mechanisms in the apparent absence of any receptive-field properties for coding timing. In order to characterise the psychological and neural mechanisms by which temporal expectations come to optimize behaviour, we have developed a series of novel paradigms that manipulate temporal expectations about visual target items using predictive cues or rhythms. We have shown consistent benefits of temporal expectation to response speed, and have documented enhancement of contrast sensitivity in psychophysically demanding tasks. Studies using hemodynamic and electrophysiological methods to image human brain activity have started to reveal the neural mechanisms involved in biasing information processing by temporal expectations. Our results show strong interactions between predictive signals about the anticipated timing and spatial location of relevant target events, and suggest that modulation of oscillatory activity may play an important role in carrying temporal regularities or associations to organise neural excitability around critical moments.
Kia NOBRE, Oxford Centre for Human Brain Activity and Brain & Cognition Laboratory, University of Oxford, United Kingdom