Abstract
The objects located straight-ahead of the body are preferentially processed by the visual system. They are more rapidly detected and evoke stronger BOLD responses in early visual areas than elements that are retinotopically identical but located at eccentric spatial positions. To characterize the dynamics of the underlying neural mechanisms, we recorded in 29 subjects the EEG responses to peripheral targets differing solely by their locations with respect to the body. Straight-ahead stimuli led to stronger responses than eccentric stimuli for several components whose latencies ranged between 70 and 350 ms after stimulus onset. The earliest effects were found at 70 ms for a component that originates from occipital areas, the contralateral P1. To determine whether the straight-ahead direction affects primary visual cortex responses, we performed an additional experiment (n = 29) specifically designed to generate two robust components, the C1 and C2, whose cortical origins are constrained within areas V1, V2 and V3. Our analyses confirmed all the results of the first experiment and also revealed that the C2 amplitude between 130 and 160 ms after stimulus onset was significantly stronger for straight-ahead stimuli. A frequency analysis of the pre-stimulus baseline revealed that gaze-driven alterations in the visual hemi-field containing the straight-ahead direction were associated with a decrease in alpha power in the contralateral hemisphere, suggesting the implication of specific neural modulations before stimulus onset. Altogether, our EEG data demonstrate that preferential responses to the straight-ahead direction can be detected in the visual cortex as early as about 70 ms after stimulus onset.
Highlights
The objects we are facing are endowed with a special behavioral status as they offer maximal affordance for manipulation and represent potential obstacles during locomotion
We wanted (1) to determine if there is a privileged cortical processing of the straight-ahead direction, as previously reported in publications based on single-cell recordings in macaque (Durand et al 2010) and neuroimaging data in human (Strappini et al 2015) and (2) to exploit the high temporal resolution of EEG to characterize the dynamics of the underlying neural mechanisms
The aim of this study was to characterize the dynamics of the privileged processing of the straight-ahead direction in human visual cortex
Summary
The objects we are facing are endowed with a special behavioral status as they offer maximal affordance for manipulation and represent potential obstacles during locomotion. Paying a special attention to these straight-ahead elements is desirable. Our gaze is directed straight-ahead, so that the important neuronal resources allocated to central vision process these elements efficiently. It can happen that an unexpected event in the surrounding space attracts attention and gaze direction and central vision toward an eccentric location. Elements located straightahead fall in the periphery of the retina for which vision is much less accurate. A compensatory mechanism that permits an enhanced processing of the straight-ahead direction in this case has been evidenced by single-cell recordings in the primary visual (V1) area of rhesus macaque monkeys (Durand et al 2010). Most V1 neurons with peripheral receptive fields (RF) exhibit an increased visual sensitivity as their RF is brought closer to the straight-ahead direction by
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
