"Ricercatore" TD(a) in Physiological Sciences, University of Pisa
- 2010-2013: Doctoral School of Psychology (curriculum cognitive science), University of Florence, Italy. Advisors: David C Burr, M Concetta Morrone.
- 2006-2008: MA Cognitive Neuroscience, 110/110 cum laude, Department of Psychology, Libera Università Vita-Salute San Raffaele, Milano, Italy.
- 2003-2006: BA Philosophy, 110/110 cum laude, Department of Philosophy, Libera Università Vita-Salute San Raffaele, Milano, Italy.
Current research and interests
- Binocular Rilvalry
- Plasticity of the visual system
- Multi-sensory perception
- Bistable perception
Deroy, O., Faivre, N., Lunghi, C., Spence, C., Aller, M. & Noppeney, U. (2016). The Complex Interplay Between Multisensory Integration and Perceptual Awareness, Multisensory Research. PDF
The integration of information has been considered a hallmark of human consciousness, as it requires information being globally available via widespread neural interactions. Yet the complex interdependencies between multisensory integration and perceptual awareness, or consciousness, remain to be defined. While perceptual awareness has traditionally been studied in a single sense, in recent years we have witnessed a surge of interest in the role of multisensory integration in perceptual awareness. Based on a recent IMRF symposium on multisensory awareness, this review discusses three key questions from conceptual, methodological and experimental perspectives: (1) What do we study when we study multisensory awareness? (2) What is the relationship between multisensory integration and perceptual awareness? (3) Which experimental approaches are most promising to characterize multisensory awareness? We hope that this review paper will provoke lively discussions, novel experiments, and conceptual considerations to advance our understanding of the multifaceted interplay between multisensory integration and consciousness.
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.
Lo Verde, L., Morrone, M. C. & Lunghi, C. (2016). Early Cross-modal Plasticity in Adults, J Cogn Neurosci, 1-10. PDF
It is known that, after a prolonged period of visual deprivation, the adult visual cortex can be recruited for nonvisual processing, reflecting cross-modal plasticity. Here, we investigated whether cross-modal plasticity can occur at short timescales in the typical adult brain by comparing the interaction between vision and touch during binocular rivalry before and after a brief period of monocular deprivation, which strongly alters ocular balance favoring the deprived eye. While viewing dichoptically two gratings of orthogonal orientation, participants were asked to actively explore a haptic grating congruent in orientation to one of the two rivalrous stimuli. We repeated this procedure before and after 150 min of monocular deprivation. We first confirmed that haptic stimulation interacted with vision during rivalry promoting dominance of the congruent visuo-haptic stimulus and that monocular deprivation increased the deprived eye and decreased the nondeprived eye dominance. Interestingly, after deprivation, we found that the effect of touch did not change for the nondeprived eye, whereas it disappeared for the deprived eye, which was potentiated after deprivation. The absence of visuo-haptic interaction for the deprived eye lasted for over 1 hr and was not attributable to a masking induced by the stronger response of the deprived eye as confirmed by a control experiment. Taken together, our results demonstrate that the adult human visual cortex retains a high degree of cross-modal plasticity, which can occur even at very short timescales.
Han, S., Lunghi, C. & Alais, D. (2016). The temporal frequency tuning of continuous flash suppression reveals peak suppression at very low frequencies, Sci Rep, (6), 35723. PDF
Continuous flash suppression (CFS) is a psychophysical technique where a rapidly changing Mondrian pattern viewed by one eye suppresses the target in the other eye for several seconds. Despite the widespread use of CFS to study unconscious visual processes, the temporal tuning of CFS suppression is currently unknown. In the present study we used spatiotemporally filtered dynamic noise as masking stimuli to probe the temporal characteristics of CFS. Surprisingly, we find that suppression in CFS peaks very prominently at approximately 1 Hz, well below the rates typically used in CFS studies (10 Hz or more). As well as a strong bias to low temporal frequencies, CFS suppression is greater for high spatial frequencies and increases with increasing masker contrast, indicating involvement of parvocellular/ventral mechanisms in the suppression process. These results are reminiscent of binocular rivalry, and unifies two phenomenon previously thought to require different explanations.
Lunghi, C. & Alais, D. (2015). Congruent tactile stimulation reduces the strength of visual suppression during binocular rivalry,Sci. Rep., (5), PDF
Presenting different images to each eye triggers ‘binocular rivalry’ in which one image is visible and the other suppressed, with the visible image alternating every second or so. We previously showed that binocular rivalry between cross-oriented gratings is altered when the fingertip explores a grooved stimulus aligned with one of the rivaling gratings: the matching visual grating's dominance duration was lengthened and its suppression duration shortened. In a more robust test, we here measure visual contrast sensitivity during rivalry dominance and suppression, with and without exploration of the grooved surface, to determine if rivalry suppression strength is modulated by touch. We find that a visual grating undergoes 45% less suppression when observers touch an aligned grating, compared to a cross-oriented one. Touching an aligned grating also improved visual detection thresholds for the ‘invisible’ suppressed grating by 2.4?dB, relative to a vision-only condition. These results show that congruent haptic stimulation prevents a visual stimulus from becoming deeply suppressed in binocular rivalry. Moreover, because congruent touch acted on the phenomenally invisible grating, this visuo-haptic interaction must precede awareness and likely occurs early in visual processing.
Lunghi, C., Emir, U. E., Morrone, M. C. & Bridge, H. (2015). Short-Term Monocular Deprivation Alters GABA in the Adult Human Visual Cortex,Curr Biol, 11 (25), 1496-1501. PDF
Neuroplasticity is a fundamental property of the nervous system that is maximal early in life, within the critical period [1-3]. Resting GABAergic inhibition is necessary to trigger ocular dominance plasticity and to modulate the onset and offset of the critical period [4, 5]. GABAergic inhibition also plays a crucial role in neuroplasticity of adult animals: the balance between excitation and inhibition in the primary visual cortex (V1), measured at rest, modulates the susceptibility of ocular dominance to deprivation [6-10]. In adult humans, short-term monocular deprivation strongly modifies ocular balance, unexpectedly boosting the deprived eye, reflecting homeostatic plasticity [11, 12]. There is no direct evidence, however, to support resting GABAergic inhibition in homeostatic plasticity induced by visual deprivation. Here, we tested the hypothesis that GABAergic inhibition, measured at rest, is reduced by deprivation, as demonstrated by animal studies. GABA concentration in V1 of adult humans was measured using ultra-high-field 7T magnetic resonance spectroscopy before and after short-term monocular deprivation. After monocular deprivation, resting GABA concentration decreased in V1 but was unaltered in a control parietal area. Importantly, across participants, the decrease in GABA strongly correlated with the deprived eye perceptual boost measured by binocular rivalry. Furthermore, after deprivation, GABA concentration measured during monocular stimulation correlated with the deprived eye dominance. We suggest that reduction in resting GABAergic inhibition triggers homeostatic plasticity in adult human V1 after a brief period of abnormal visual experience. These results are potentially useful for developing new therapeutic strategies that could exploit the intrinsic residual plasticity of the adult human visual cortex.
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.
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.
Lunghi, C., Morrone, M. C. & Alais, D. (2014). Auditory and tactile signals combine to influence vision during binocular rivalry,J Neurosci, 3 (34), 784-792. PDF
Resolution of perceptual ambiguity is one function of cross-modal interactions. Here we investigate whether auditory and tactile stimuli can influence binocular rivalry generated by interocular temporal conflict in human subjects. Using dichoptic visual stimuli modulating at different temporal frequencies, we added modulating sounds or vibrations congruent with one or the other visual temporal frequency. Auditory and tactile stimulation both interacted with binocular rivalry by promoting dominance of the congruent visual stimulus. This effect depended on the cross-modal modulation strength and was absent when modulation depth declined to 33%. However, when auditory and tactile stimuli that were too weak on their own to bias binocular rivalry were combined, their influence over vision was very strong, suggesting the auditory and tactile temporal signals combined to influence vision. Similarly, interleaving discrete pulses of auditory and tactile stimuli also promoted dominance of the visual stimulus congruent with the supramodal frequency. When auditory and tactile stimuli were presented at maximum strength, but in antiphase, they had no influence over vision for low temporal frequencies, a null effect again suggesting audio-tactile combination. We also found that the cross-modal interaction was frequency-sensitive at low temporal frequencies, when information about temporal phase alignment can be perceptually tracked. These results show that auditory and tactile temporal processing is functionally linked, suggesting a common neural substrate for the two sensory modalities and that at low temporal frequencies visual activity can be synchronized by a congruent cross-modal signal in a frequency-selective way, suggesting the existence of a supramodal temporal binding mechanism.
Lunghi, C. & Alais, D. (2013). Touch Interacts with Vision during Binocular Rivalry with a Tight Orientation Tuning,PLoS One, 3 (8), e58754. PDF
Multisensory integration is a common feature of the mammalian brain that allows it to deal more efficiently with the ambiguity of sensory input by combining complementary signals from several sensory sources. Growing evidence suggests that multisensory interactions can occur as early as primary sensory cortices. Here we present incompatible visual signals (orthogonal gratings) to each eye to create visual competition between monocular inputs in primary visual cortex where binocular combination would normally take place. The incompatibility prevents binocular fusion and triggers an ambiguous perceptual response in which the two images are perceived one at a time in an irregular alternation. One key function of multisensory integration is to minimize perceptual ambiguity by exploiting cross-sensory congruence. We show that a haptic signal matching one of the visual alternatives helps disambiguate visual perception during binocular rivalry by both prolonging the dominance period of the congruent visual stimulus and by shortening its suppression period. Importantly, this interaction is strictly tuned for orientation, with a mismatch as small as 7.5 degrees between visual and haptic orientations sufficient to annul the interaction. These results indicate important conclusions: first, that vision and touch interact at early levels of visual processing where interocular conflicts are first detected and orientation tunings are narrow, and second, that haptic input can influence visual signals outside of visual awareness, bringing a stimulus made invisible by binocular rivalry suppression back to awareness sooner than would occur without congruent haptic input.
Lunghi, C., Burr, D. C. & Morrone, M. C. (2013). Long-term effects of monocular deprivation revealed with binocular rivalry gratings modulated in luminance and in color,J Vis, 6 (13), PDF
During development, within a specific temporal window called the critical period, the mammalian visual cortex is highly plastic and literally shaped by visual experience; to what extent this extraordinary plasticity is retained in the adult brain is still a debated issue. We tested the residual plastic potential of the adult visual cortex for both achromatic and chromatic vision by measuring binocular rivalry in adult humans following 150 minutes of monocular patching. Paradoxically, monocular deprivation resulted in lengthening of the mean phase duration of both luminance-modulated and equiluminant stimuli for the deprived eye and complementary shortening of nondeprived phase durations, suggesting an initial homeostatic compensation for the lack of information following monocular deprivation. When equiluminant gratings were tested, the effect was measurable for at least 180 minutes after reexposure to binocular vision, compared with 90 minutes for achromatic gratings. Our results suggest that chromatic vision shows a high degree of plasticity, retaining the effect for a duration (180 minutes) longer than that of the deprivation period (150 minutes) and twice as long as that found with achromatic gratings. The results are in line with evidence showing a higher vulnerability of the P pathway to the effects of visual deprivation during development and a slower development of chromatic vision in humans.
Lunghi, C. & Morrone, M. C. (2013). Early interaction between vision and touch during binocular rivalry,Multisens Res, 3 (26), 291-306. PDF
Multisensory integration is known to occur at high neural levels, but there is also growing evidence that cross-modal signals can be integrated at the first stages of sensory processing. We investigated whether touch specifically affected vision during binocular rivalry, a particular type of visual bistability that engages neural competition in early visual cortices. We found that tactile signals interact with visual signals outside of awareness, when the visual stimulus congruent with the tactile one is perceptually suppressed during binocular rivalry and when the interaction is strictly tuned for matched visuo-tactile spatial frequencies. We also found that voluntary action does not play a leading role in mediating the effect, since the interaction was observed also when tactile stimulation was passively delivered to the finger. However, simultaneous presentation of visual and tactile stimuli is necessary to elicit the interaction, and an asynchronous priming touch stimulus is not affecting the onset of rivalry. These results point to a very early cross-modal interaction site, probably V1. By showing that spatial proximity between visual and tactile stimuli is a necessary condition for the interaction, we also suggest that the two sensory spatial maps are aligned according to retinotopic coordinates, corroborating the hypothesis of a very early interaction between visual and tactile signals during binocular rivalry.
van der Groen, O., van der Burg, E., Lunghi, C. & Alais, D. (2013). Touch influences visual perception with a tight orientation-tuning,PLoS One, 11 (8), e79558. PDF
Stimuli from different sensory modalities are thought to be processed initially in distinct unisensory brain areas prior to convergence in multisensory areas. However, signals in one modality can influence the processing of signals from other modalities and recent studies suggest this cross-modal influence may occur early on, even in 'unisensory' areas. Some recent psychophysical studies have shown specific cross-modal effects between touch and vision during binocular rivalry, but these cannot completely rule out a response bias. To test for genuine cross-modal integration of haptic and visual signals, we investigated whether congruent haptic input could influence visual contrast sensitivity compared to incongruent haptic input in three psychophysical experiments using a two-interval, two-alternative forced-choice method to eliminate response bias. The initial experiment demonstrated that contrast thresholds for a visual grating were lower when exploring a haptic grating that shared the same orientation compared to an orthogonal orientation. Two subsequent experiments mapped the orientation and spatial frequency tunings for the congruent haptic facilitation of vision, finding a clear orientation tuning effect but not a spatial frequency tuning. In addition to an increased contrast sensitivity for iso-oriented visual-haptic gratings, we found a significant loss of sensitivity for orthogonally oriented visual-haptic gratings. We conclude that the tactile influence on vision is a result of a tactile input to orientation-tuned visual areas.
Lunghi C, Burr DC, Morrone C. (2011). Brief periods of monocular deprivation disrupt ocular balance in human adult visual cortex, Curr Biol. 2011 Jul 26;21(14):R538-9. PDF
Neuroplasticity is a fundamental property of the developing mammalian visual system, with residual potential in adult human cortex . A short period of abnormal visual experience (such as occlusion of one eye) before closure of the critical period has dramatic and permanent neural consequences, reshaping visual cortical organization in favour of the non-deprived eye [2,3]. We used binocular rivalry  - a sensitive probe of neural competition - to demonstrate that adult human visual cortex retains a surprisingly high degree of neural plasticity, with important perceptual consequences. We report that 150 minutes of monocular deprivation strongly affects the dynamics of binocular rivalry, unexpectedly causing the deprived eye to prevail in conscious perception twice as much as the non-deprived eye, with significant effects for up to 90 minutes. Apparent contrast of stimuli presented to the deprived eye was also increased, suggesting that the deprivation acts by up-regulation of cortical gain-control mechanisms of the deprived eye. The results suggest that adult visual cortex retains a good deal of plasticity that could be important in reaction to sensory loss.
Lunghi, C., Binda, P. & Morrone, M. C. (2010). Touch disambiguates rivalrous perception at early stages of visual analysis,Curr Biol, 4 (20), R143-144. PDF
Binocular rivalry is a powerful tool to study human consciousness: two equally salient stimuli are imaged on the retinae, but at any given instant only one is consciously perceived, the other suppressed.The suppression takes place early, probably in V1. However, a trace of the suppressed signal has been detected along the dorsal visual pathway (BOLD responses) and demonstrated with psychophysical experiments. The suppressed image of a rotating sphere during rivalry is restored to consciousness when the observer actively controls the rotation and a similar effect on the suppressed signal has been shown for motion perception and reflexive eye movements (see Supplemental References). Here, we asked whether cross-modal sensory signals could selectively interact with rivalrous visual signals that are analyzed at a very early stage, probably V1. An auditory stimulus, when attended, can influence binocular rivalry, extending dominance times for a congruent visual stimulus. Tactile information can also disambiguate unstable visual motion and can fuse with vision to improve discrimination (e.g. slant). Our results indicate that a haptic oriented stimulus can disambiguate visual perception during binocular rivalry of gratings of orthogonal orientation, not only by prolonging dominance but also by curtailing suppression of the visual stimulus of matched orientation. The effect is selective for the spatial frequency of the stimuli, suggesting that haptic signals interact with early visual representations to enhance access to conscious perception.
- 06-11/05/2011: “VSS 2011” (Vision Science Society, Annual Meeting), Naples (Florida, US). Talk, title: “ Experience-dependent plasticity in adult human visual cortex revealed by binocular rivalry”. Link
- 08/22-26/2010: “ECVP 2010” (European Conference on Visual Perception), Lausanne (Switzerland). Talk, title: "The effect of transient monocular deprivation on binocular rivalry". Link;
- 08/24-28/2009: “ECVP 2009” (European Conference on Visual Perception), Regensburg (Germany). Poster Presentation. Link;