29 research outputs found
Top-down effects on early visual processing in humans: a predictive coding framework
An increasing number of human electroencephalography (EEG) studies examining the earliest component of the visual evoked potential, the so-called C1, have cast doubts on the previously prevalent notion that this component is impermeable to top-down effects. This article reviews the original studies that (i) described the C1, (ii) linked it to primary visual cortex (V1) activity, and (iii) suggested that its electrophysiological characteristics are exclusively determined by low-level stimulus attributes, particularly the spatial position of the stimulus within the visual field. We then describe conflicting evidence from animal studies and human neuroimaging experiments and provide an overview of recent EEG and magnetoencephalography (MEG) work showing that initial V1 activity in humans may be strongly modulated by higher-level cognitive factors. Finally, we formulate a theoretical framework for understanding top-down effects on early visual processing in terms of predictive coding
Early retinotopic responses to violations of emotion-location associations may depend on conscious awareness
Modulation of the earliest visual evoked potential by attention: now you see it, now you don’t
Cognitive modulations of early visual cortex activity in humans
The experiments conducted for this thesis examined the earliest stages of processing in human visual cortex. Using electroencephalographic recordings, it was observed that the first component of the visual evoked potential, the so-called C1, is affected by learning and attention. This contrasts with earlier studies which overwhelmingly reported no effects of higher cognitive processes on early visual cortex activity. It is suggested that methodological improvements such as the adaptation of stimulus parameters to the physiological characteristics of lower visual areas partly explain the new findings. Together with other recent studies, these results show that previously prevalent notions of primary visual cortex (V1) as an inflexible module for the treatment of low-level stimulus characteristics may need to be revised. The idea that V1 can act as an adaptive and flexible processor, previously based on animal studies, is thus starting to gain support from the human literature
Early retinotopic responses to violations of emotion-location associations may depend on conscious awareness
Dissociating learning-induced changes in fMRI signal from structural modifications: a comment on Dorjee and Bowers (2012)
Effects of group affiliation on neural signatures of fairness norm violations in antisocial violent offenders
Attentional Filtering in Early Visual Cortex
EEG study investigating effects of attentional load on C1 based on individually pre-selected stimulus parameters; published as Herde, L., Schönauer-Firle, M., & Rauss, K. (2022). Retinotopically specific effects of attention on human early visual cortex activity. Journal of Experimental Psychology: Human Perception and Performance, 48(8), 856–870. https://doi.org/10.1037/xhp000102