Temporal Dissection of Stimulus-Driven and Task-Driven Processes during Perceptual Decision about 3D SFM Stimuli

A Miskiewicz (1) , S Buffat (2, 1) , J Lorenceau (1, 3) , A.-L Paradis (3, 4)

1 CRICM - Centre de Recherche de l'Institut du Cerveau et de la Moelle épinière
2 IRBA - Institut de Recherche Biomédicale des Armées [Brétigny-sur-Orge]
3 LENA - Laboratoire de neurosciences cognitives et d'imagerie cérébrale
4 IIN - Institut d'imagerie neurofonctionnelle

Analyzing the visual properties of a stimulus, such as its shape or its motion, involves a temporally con-strained cascade of processes including sensory integration, attentional selection and perceptual decision. In natural condi-tions, these processing stages may temporally overlap. In this study, we used a time constrained paradigm designed to segre-gate these stages, and recorded MEG activity to characterize their cortical correlates. The experimental sequence comprised a structure-from-motion (SFM) target flanked by pre and post masks, which limited the stimulus-driven processes in time. The MEG responses were recorded in three perceptual tasks bearing on the presence or absence of the target SFM stimulus, on its direction of motion or on its 3D shape. Subjects' responses were delayed to the end of the trials us-ing a random stimulus-response mapping. The analysis of the evoked magnetic fields reveals temporal-ly non-overlapping responses for stimulus-driven and task-related processes. Source reconstruction reveals that the occipital, dorsal and ventral stimulus-related areas follow different temporal pro-files, The response in IPS slowly rising after the beginning of the activity in the lateral occipital cortex and falling back to the baseline prior the delayed motor response, may reflect accumulating evidence on the presented stimulus leading to a motor response, in line with the results from single cell studies in monkey LIP [1].

Mots clés: visual motion; 3-D shape; perceptual decision; MEG; source reconstruction

Domaines: Neurosciences; Sciences cognitives

A Miskiewicz, S Buffat, J Lorenceau, A.-L Paradis. Temporal Dissection of Stimulus-Driven and Task-Driven Processes during Perceptual Decision about 3D SFM Stimuli. Supek, Susac. Biomag 2010, France. 28, Springer Verlag, pp.326 - 329, 2010, IFMBE Proceedings Series, 978-3-642-12196-8. ⟨10.1007/978-3-642-12197-5_76⟩. ⟨hal-01076912⟩