Abstract
Both macaques and humans are capable of flexibly deploying their attention over time to track the temporal probabilities of a relevant stimulus (Coull & Nobre, 1998; Ghose & Maunsell, 2002; Janssen & Shadlen, 2005; Nobre, Correa & Coull, 2007; Rohenkohl et al., 2012). Although behavioral results in humans suggest that feature-based attention can be deployed with high temporal precision, fMRI studies have not been able to track the modulation of feature tuning in subsecond detail (Bueti et al., 2010; Warren, Yacoub & Ghose, 2014). In the present study, we use scalp electroencephalography to estimate orientation tuning functions over time while subjects monitored a flickering stimulus (30 Hz) for a brief orientation change target. Similar to previous studies, the probability of the target varied over time. Subjects reported the direction of the orientation change on trials where the change was present (50% of the time) and withheld a response on the remaining trials. We trained an orientation encoding model using the power and phase of the steady-state visual evoked potential (SSVEP) on change-absent trials (Garcia, Srinivasan & Serences, 2013). This technique exploits the spatial distribution of the SSVEP response across all electrodes to estimate orientation sensitivity changes over time, and was used to reconstruct orientation selective response profiles for the remaining half of the trials which contained a target. These orientation selective response profiles peaked just before the anticipated target time, revealing feature-selective temporal attention effects in human cortex.
Meeting abstract presented at VSS 2016