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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.

Adriana and Lamberto

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]

New Research published in Investigative Ophthalmology & Visual Science!

Congratulation to Claudia and Concetta who just published a new paper on Investigative Ophthalmology & Visual Science!

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


PURPOSE. Recent studies on adults have shown that short-term monocular deprivation boosts the deprived eye signal in binocular rivalry, reflecting homeostatic plasticity. Here we investigate whether homeostatic plasticity is present also during occlusion therapy for moderate amblyopia. METHODS. Binocular rivalry and visual acuity (using Snellen charts for children) were measured in 10 children (mean age 6.2 ± 1 years) with moderate anisometropic amblyopia before the beginning of treatment and at four intervals during occlusion therapy (2 hours, 1, 2, and 5 months). Visual stimuli were orthogonal gratings presented dichoptically through ferromagnetic goggles and children reported verbally visual rivalrous perception. Bangerter filters were applied on the spectacle lens over the best eye for occlusion therapy. RESULTS. Two hours of occlusion therapy increased the nonamblyopic eye predominance over the amblyopic eye compared with pretreatment measurements, consistent with the results in adults. The boost of the nonamblyopic eye was still present after 1 month of treatment, steadily decreasing afterward to reach pretreatment levels after 2 months of continuous occlusion. Across subjects, the increase in nonamblyopic eye predominance observed after 2 hours of occlusion correlated (rho = -0.65, P = 0.04) with the visual acuity improvement of the amblyopic eye measured after 2 months of treatment. CONCLUSIONS. Homeostatic plasticity operates during occlusion therapy for moderate amblyopia and the increase in nonamblyopic eye dominance observed at the beginning of treatment correlates with the amblyopic eye recovery rate. These results suggest that binocular rivalry might be used to monitor visual cortical plasticity during occlusion therapy, although further investigations on larger clinical populations are needed to validate the predictive power of the technique.



2016Lunghi_IOVS_preview

New Research published in Scientific Reports and Cognition!

Double achievement for Michele and David! Congratulations to Roberto and Marco, too!

Fornaciai, M., Arrighi, R. & Burr, D. C. (2016). Adaptation-Induced Compression of Event Time Occurs Only for Translational Motion, Scientific Reports, (6), 23341. PDF

Adaptation to fast motion reduces the perceived duration of stimuli displayed at the same location as the adapting stimuli. Here we show that the adaptation-induced compression of time is specific for translational motion. Adaptation to complex motion, either circular or radial, did not affect perceived duration of subsequently viewed stimuli. Adaptation with multiple patches of translating motion caused compression of duration only when the motion of all patches was in the same direction. These results show that adaptation-induced compression of event-time occurs only for uni-directional translational motion, ruling out the possibility that the neural mechanisms of the adaptation occur at early levels of visual processing.


2016Fornaciai1




Fornaciai, M., Cicchini, G. M. & Burr, D. C. (2016). Adaptation to number operates on perceived rather than physical numerosity, Cognition, (151), 63-67. PDF

Humans share with many animals a number sense, the ability to estimate rapidly the approximate number of items in a scene. Recent work has shown that like many other perceptual attributes, numerosity is susceptible to adaptation. It is not clear, however, whether adaptation works directly on mechanisms selective to numerosity, or via related mechanisms, such as those tuned to texture density. To disentangle this issue we measured adaptation of numerosity of 10 pairs of connected dots, as connecting dots makes them appear to be less numerous than unconnected dots. Adaptation to a 20-dot pattern (same number of dots as the test) caused robust reduction in apparent numerosity of the connected-dot pattern, but not of the unconnected dot-pattern. This suggests that adaptation to numerosity, at least for relatively sparse dot-pattern, occurs at neural levels encoding perceived numerosity, rather than at lower levels responding to the number of elements in the scene.

2016Fornaciai2

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.

Adriana

New Research published in Current Opinion in Behavioral Sciences

Congratulations to David who published a new paper on Current Opinion in Behavioral Sciences!

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’.


2016BurrPredictivecodingMultisensoryTiming

New Research published in Scientific Reports

Congratulations to Marco and David who published a new paper on Scientific Reports!


Turi, M., Karaminis, T., Pellicano, E. & Burr, D. (2016). No rapid audiovisual recalibration in adults on the autism spectrum, Scientific Reports, (6), 21756. PDF

Autism spectrum disorders (ASD) are characterized by difficulties in social cognition, but are also associated with atypicalities in sensory and perceptual processing. Several groups have reported that autistic individuals show reduced integration of socially relevant audiovisual signals, which may contribute to the higher-order social and cognitive difficulties observed in autism. Here we use a newly devised technique to study instantaneous adaptation to audiovisual asynchrony in autism. Autistic and typical participants were presented with sequences of brief visual and auditory stimuli, varying in asynchrony over a wide range, from 512?ms auditory-lead to 512?ms auditory-lag, and judged whether they seemed to be synchronous. Typical adults showed strong adaptation effects, with trials proceeded by an auditory-lead needing more auditory-lead to seem simultaneous, and vice versa. However, autistic observers showed little or no adaptation, although their simultaneity curves were as narrow as the typical adults. This result supports recent Bayesian models that predict reduced adaptation effects in autism. As rapid audiovisual recalibration may be fundamental for the optimisation of speech comprehension, recalibration problems could render language processing more difficult in autistic individuals, hindering social communication.


2016Turi_ScientificReports

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 [1]. 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.


The ratio between the mean phase duration of the deprived and that of the non-deprived eye plotted as a function of time from removal of the eye-patch. From Lunghi & Sale, 2015.

New Research published in Journal of Physiology

Congratulations to Claudia and Maria Concetta, whose work has been published on Journal of Physiology and is the issue's cover article!


Lunghi, C., Berchicci, M., Morrone, M. C. & Di Russo, F. (2015). Short-term monocular deprivation alters early components of visual evoked potentials, J Physiol, 19 (593), 4361-4372. PDF

Very little is known about plasticity in the adult visual cortex. In recent years psychophysical studies have shown that short-term monocular deprivation alters visual perception in adult humans. Specifically, after 150 min of monocular deprivation the deprived eye strongly dominates the dynamics of binocular rivalry, reflecting homeostatic plasticity. Here we investigate the neural mechanisms underlying this form of short-term visual cortical plasticity by measuring visual evoked potentials (VEPs) on the scalp of adult humans during monocular stimulation before and after 150 min of monocular deprivation. We found that monocular deprivation had opposite effects on the amplitude of the earliest component of the VEP (C1) for the deprived and non-deprived eye stimulation. C1 amplitude increased (+66%) for the deprived eye, while it decreased (-29%) for the non-deprived eye. Source localization analysis confirmed that the C1 originates in the primary visual cortex. We further report that following monocular deprivation, the amplitude of the peak of the evoked alpha spectrum increased on average by 23% for the deprived eye and decreased on average by 10% for the non-deprived eye, indicating a change in cortical excitability. These results indicate that a brief period of monocular deprivation alters interocular balance in the primary visual cortex of adult humans by both boosting the activity of the deprived eye and reducing the activity of the non-deprived eye. This indicates a high level of residual homeostatic plasticity in the adult human primary visual cortex, probably mediated by a change in cortical excitability.


Cover image for Journal of Physiology Volume 593, Issue 19

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