EFFECTS OF FAST ADAPTATION WITH COMPLEX MOTION
Striate and extrastriate neurons present short-term synaptic depression and facilitation in response to brief-transient stimulations. Recent psychophysical studies have shown some empirical relationships between these short-term forms of neural plasticity and of psychophysical behavior. It has been shown that depending on the adaptation duration it is possible to induce two opposite perceptual outcomes: rapid visual motion priming (rVMP) (adapting for tens of ms), and rapid motion aftereffect (rMAE) (adapting for hundreds of ms). In the present study we stimulated MT and MST neurons via the presentation of contracting and expanding circular gratings in order to assess whether rapid effects exist at these higher levels of motion processing. Results revealed strong rMAEs, perceptual sensitization (PS), which is a long lasting facilitation but not rVMP. Our results are considered to reflect the competition between coexistent forms of short- and long-term synaptic depression and facilitation implemented at different visual cortical circuitries.