New Research published in Neuroimage!
Castaldi, E., Aagten-Murphy, D., Tosetti, M., Burr, D. & Morrone, M. C. (2016). Effects of adaptation on numerosity decoding in the human brain, Neuroimage, (143), 364-377. PDF
Psychophysical studies have shown that numerosity is a sensory attribute susceptible to adaptation. Neuroimaging studies have reported that, at least for relatively low numbers, numerosity can be accurately discriminated in the intra-parietal sulcus. Here we developed a novel rapid adaptation paradigm where adapting and test stimuli are separated by pauses sufficient to dissociate their BOLD activity. We used multivariate pattern recognition to classify brain activity evoked by non-symbolic numbers over a wide range (20-80), both before and after psychophysical adaptation to the highest numerosity. Adaptation caused underestimation of all lower numerosities, and decreased slightly the average BOLD responses in V1 and IPS. Using support vector machine, we showed that the BOLD response of IPS, but not in V1, classified numerosity well, both when tested before and after adaptation. However, there was no transfer from training pre-adaptation responses to testing post-adaptation, and vice versa, indicating that adaptation changes the neuronal representation of the numerosity. Interestingly, decoding was more accurate after adaptation, and the amount of improvement correlated with the amount of perceptual underestimation of numerosity across subjects. These results suggest that numerosity adaptation acts directly on IPS, rather than indirectly via other low-level stimulus parameters analysis, and that adaptation improves the capacity to discriminate numerosity.
Professor Adriana Fiorentini: 1/11/1926 – 29/2/2016
Nicoletta Berardi, Concetta Morrone, Donatella Spinelli - Perception - in press
Adriana Fiorentini was for many decades a pillar of the CNR Institute for Neurophysiology (then Neuroscience). On the 29th February 2016 she passed away peacefully in her sleep, with a smile. A whole generation of vision scientists remembers her with love and respect. Her wisdom, intelligence, dedication to science, enthusiasm for research and love of knowledge set an example to us all. She was a role model of respect, generosity, patience, collaboration and true humility: discrete and reserved, always there for her students and colleagues. Born and schooled in Milan, she graduated in Physics in 1948 at the University of Florence, studying optics under Professor Giuliano Toraldo di Francia at the National Institute of Optics in Arcetri.
During her studies she noticed a strange contrast phenomenon, which she correctly interpreted as the visual illusion known as “Mach Bands”: this observation was fundamental in shifting her research interests towards visual perception. In her early post-graduate years at Arcetri (1948-1968), Adriana published many innovative studies on physiological optics and perception, which are cited to this day. To mention just two: the seminal demonstration of human receptive fields (or “perceptive fields”) defined by antagonistic center‐surround interactions; and her first (but not last) Nature paper (with Donald MacKay of Keele), demonstrating a neural (VEP) correlate of a perceptual phenomenon ...[PDF]
Lunghi, C., Morrone, M. C., Secci, J. & Caputo, R. (2016). Binocular Rivalry Measured 2 Hours After Occlusion Therapy Predicts the Recovery Rate of the Amblyopic Eye in Anisometropic Children, Invest Ophthalmol Vis Sci, 4 (57), 1537-1546. PDF
Adriana Fiorentini (1/11/1926 - 29/2/2016)
Adriana Fiorentini passed away peacefully in her sleep last Monday. Adriana was an inspirational pillar of the Pisa Vision Laboratory and leading international visual scientist for over half a century. She was well loved by all her colleagues and students who had the privilege to work with and learn from her. We will miss her.
Shi, Z. & Burr, D. (2016). Predictive coding of multisensory timing, Current Opinion in Behavioral Sciences, (8), 200-206. PDF
The sense of time is foundational for perception and action, yet it frequently departs significantly from physical time. In the paper we review recent progress on temporal contextual effects, multisensory temporal integration, temporal recalibration, and related computational models. We suggest that subjective time arises from minimizing prediction errors and adaptive recalibration, which can be unified in the framework of predictive coding, a framework rooted in Helmholtz's ‘perception as inference’.
New Research published in Current Biology
Congratulations to Claudia who managed to publish yet another original research paper on Current Biology!
Lunghi, C. & Sale, A. (2015). A cycling lane for brain rewiring, Curr Biol, 23 (25), R1122-R1123. PDF
Brain plasticity, defined as the capability of cerebral neurons to change in response to experience, is fundamental for behavioral adaptability, learning, memory, functional development, and neural repair. The visual cortex is a widely used model for studying neuroplasticity and the underlying mechanisms. Plasticity is maximal in early development, within the so-called critical period, while its levels abruptly decline in adulthood . Recent studies, however, have revealed a significant residual plastic potential of the adult visual cortex by showing that, in adult humans, short-term monocular deprivation alters ocular dominance by homeostatically boosting responses to the deprived eye [2-4]. In animal models, a reopening of critical period plasticity in the adult primary visual cortex has been obtained by a variety of environmental manipulations, such as dark exposure, or environmental enrichment, together with its critical component of enhanced physical exercise [5-8]. Among these non-invasive procedures, physical exercise emerges as particularly interesting for its potential of application to clinics, though there has been a lack of experimental evidence available that physical exercise actually promotes visual plasticity in humans. Here we report that short-term homeostatic plasticity of the adult human visual cortex induced by transient monocular deprivation is potently boosted by moderate levels of voluntary physical activity. These findings could have a bearing in orienting future research in the field of physical activity application to clinical research.
- Short-term monocular deprivation alters early components of visual evoked potentials
- New Research published - September 2015
- The oblique effect is both allocentric and egocentric
- Strong Motion Deficits in Dyslexia Associated with DCDC2 Gene Alteration
- A low-cost and versatile system for projecting wide-field visual stimuli within fMRI scanners
- Short-Term Monocular Deprivation Alters GABA in the Adult Human Visual Cortex
- Children with autism spectrum disorder show reduced adaptation to number
- ass. Sante Malatesta
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