Perceptual learning beyond retinotopic reference frame

Abstract

Repetitive experience with the same visual stimulus and task can remarkably improve behavioral performance on the task. This wellknown perceptual-learning phenomenon is usually specific to the trained retinal-or visual-field location, which is taken as an indication of plastic changes in retinotopic visual areas. In previous studies of perceptual learning, however, a change in stimulus location on the retina is accompanied by positional changes of the stimulus in nonretinotopic frames of reference, such as relative to the head and other objects. It is unclear, therefore, whether the putative location specificity is exclusively retinotopic or if it could also depend on nonretinotopic representation of the stimulus, which is particularly important for multisensory and sensorimotor integration as well as for maintenance of stable visual percepts. Here, by manipulating subjects' gaze direction to control spatial and retinal locations of stimuli independently, we found that, when the stimulated retinal regions were held constant, the improvement with training in motion-direction discrimination of two successively displayed stimuli was restricted to the relative spatial position of the stimuli but independent of their absolute locations in head-and world-centered frame. These findings indicate location specificity of perceptual learning beyond retinotopic frame of reference, suggesting a pliable spatiotopic mechanism that can be specifically shaped by experience for better spatiotemporal integration of the learned stimuli.coordinate system | motion discrimination | retinotopic specificity | spatiotopic specificity | plasticity V isual information can be encoded not only in eye-centered (i.e., retinotopic) but also in nonretinotopic reference frames, such as the head-, world-, or object-centered coordinate systems. Psychophysical studies have revealed both retinotopic and spatiotopic processing mechanisms in some visual tasks (1-6). In a motion-detection task, for instance, two subthreshold stimuli can be temporally integrated when they appear at the same retinal location (retinotopic integration) or at different retinal locations but at the same spatial location (spatiotopic integration) when gaze shift is involved (1). Electrophysiological and functional MRI (fMRI) studies have shown that many cortical areas can represent visual stimuli in head-, body-, world-, or object-centered coordinates (7-13). In addition to multiple reference frames, dynamic remapping of retinotopic receptive fields (RFs) of neurons around the time of saccadic eye movement could also contribute to spatiotopic processing (14-16). Extraretinotopic processing is not only suited for multisensory integration and sensory-motor control (17, 18) but also related to some essential functions of the visual system, such as mediating spatiotopic temporal integration of visual stimuli and maintaining stable and continuous visual percepts across eye movements (19).Although nonretinotopic visual processing has been widely explored from different perspectives,...

A Lack of Anticipatory Remapping of Retinotopic Receptive Fields in the Middle Temporal Area

“…However, a recent fMRI study suggested that human MT has a spatiotopic processing component (d’Avossa et al, 2007) and psychophysical evidence from adaptation, perceptual learning and integration studies appear to support this (Melcher and Morrone, 2003; Melcher, 2005; Zhang and Li, 2010; but see Afraz and Cavanagh, 2009; Knapen et al, 2009; Morris et al, 2010). Recently, we conducted a psychophysical study on humans which used a short-term memory for motion task that appeared to corroborate the possibility of spatiotopic processing in area MT (Ong et al, 2009).…”

A Perceptual Learning Deficit in Chinese Developmental Dyslexia as Revealed by Visual Texture Discrimination Training

“…Gibson (1963, p. 29) defined perceptual learning as '[any] relatively permanent and consistent change in the perception of a stimulus array, following practice or experience with this array'. However, recent psychophysical studies have also suggested that perceptual improvements might be related to changes outside of the visual cortices (Zhang & Li, 2010;: Perceptual learning could be a result of refinement of processing in the decisionmaking and attentional systems. However, recent psychophysical studies have also suggested that perceptual improvements might be related to changes outside of the visual cortices (Zhang & Li, 2010;: Perceptual learning could be a result of refinement of processing in the decisionmaking and attentional systems.…”

“…The mainstream view suggests that cortical changes occurring in the early visual cortex, such as the primary visual cortex, (V1) underlie behavioural changes in visual perceptual learning (Karni & Sagi, 1991;Pourtois, Rauss, Vuilleumier, & Schwartz, 2008;Schoups, Vogels, Qian, & Orban, 2001;Schwartz et al, 2002;Walker, Stickgold, Jolesz, & Yoo, 2005;Yotsumoto et al, 2008). However, recent psychophysical studies have also suggested that perceptual improvements might be related to changes outside of the visual cortices (Zhang & Li, 2010;: Perceptual learning could be a result of refinement of processing in the decisionmaking and attentional systems. This idea is supported by neuroimaging studies showing that only the activity pattern in the anterior cingulate cortex tracks changes during perceptual learning (Kahnt, Grueschow, Speck, & Haynes, 2011).…”

Remapping of the line motion illusion across eye movements

“…How do we successfully perceive motion in allocentric/spatiotopic coordinates? There is recent psychophysical and fMRI evidence both for (Melcher and Morrone 2003;d'Avossa et al 2007;Ezzati et al 2008;Ong et al 2009;Fracasso et al 2010;Zhang and Li 2010) and against (Boi et al 2011;Wenderoth and Wiese 2008;Knapen et al 2009, Gardner et al 2008) spatiotopic motion processing. It is well accepted that coding visual stimuli in spatiotopic coordinates requires a more complex process than retinotopic coding, since spatial updating mechanisms must take into account the metrics of the upcoming saccade in order to integrate subsequent frames into a coherent percept (Prime et al 2011).…”