Publications by authors named "Vincenzo Romei"

54 Publications

The temporal sensitivity to the tactile-induced double flash illusion mediates the impact of beta oscillations on schizotypal personality traits.

Conscious Cogn 2021 Apr 11;91:103121. Epub 2021 Apr 11.

Centre for Studies and Research in Cognitive Neuroscience, Universita' di Bologna, Cesena, Italy.

The coherent experience of the self and the world depends on the ability to integrate vs. segregate sensory information. Optimal temporal integration between the senses is mediated by oscillatory properties of neural activity. Previous research showed reduced temporal sensitivity to multisensory events in schizotypy, a personality trait linked to schizophrenia. Here we used the tactile-induced Double-Flash-Illusion (tDFI) to investigate the tactile-to-visual temporal sensitivity in schizotypy, as indexed by the temporal window of illusion (TWI) and its neural underpinnings. We measured EEG oscillations within the beta band, recently shown to correlate with the tDFI. We found individuals with higher schizotypal traits to have wider TWI and slower beta waves accounting for the temporal window within which they perceive the illusion. Our results indicate reduced tactile-to-visual temporal sensitivity to mediate the effect of slowed oscillatory beta activity on schizotypal personality traits. We conclude that slowed oscillatory patterns might constitute an early marker for psychosis proneness.
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http://dx.doi.org/10.1016/j.concog.2021.103121DOI Listing
April 2021

Fearful faces modulate spatial processing in peripersonal space: An ERP study.

Neuropsychologia 2021 Mar 17;156:107827. Epub 2021 Mar 17.

Centro studi e ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Alma Mater Studiorum - Università di Bologna, Campus di Cesena, 47521, Cesena, Italy.

Peripersonal space (PPS) represents the region of space surrounding the body. A pivotal function of PPS is to coordinate defensive responses to threat. We have previously shown that a centrally-presented, looming fearful face, signalling a potential threat in one's surroundings, modulates spatial processing by promoting a redirection of sensory resources away from the face towards the periphery, where the threat may be expected - but only when the face is presented in near, rather than far space. Here, we use electrophysiological measures to investigate the neural mechanism underlying this effect. Participants made simple responses to tactile stimuli delivered on the cheeks, while watching task-irrelevant neutral or fearful avatar faces, looming towards them either in near or far space. Simultaneously with the tactile stimulation, a ball with a checkerboard pattern (probe) appeared to the left or right of the avatar face. Crucially, this probe could either be close to the avatar face, and thus more central in the participant's vision, or further away from the avatar face, and thus more peripheral in the participant's vision. Electroencephalography was continuously recorded. Behavioural results confirmed that in near space only, and for fearful relative to neutral faces, tactile processing was facilitated by the peripheral compared to the central probe. This behavioural effect was accompanied by a reduction of the N1 mean amplitude elicited by the peripheral probe for fearful relative to neutral faces. Moreover, the faster the participants responded to tactile stimuli with the peripheral probe, relative to the central, the smaller was their N1. Together these results, suggest that fearful faces intruding into PPS may increase expectation of a visual event occurring in the periphery. This fear-induced effect would enhance the defensive function of PPS when it is most needed, i.e., when the source of threat is nearby, but its location remains unknown.
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http://dx.doi.org/10.1016/j.neuropsychologia.2021.107827DOI Listing
March 2021

Exposure to first-person shooter videogames is associated with multisensory temporal precision and migraine incidence.

Cortex 2021 Jan 2;134:223-238. Epub 2020 Nov 2.

Center for Studies and Research in Cognitive Neuroscience, University of Bologna, 47521, Cesena, Italy; Department of Psychology, University of Bologna, 40127, Bologna, Italy. Electronic address:

Adaptive interactions with the environment require optimal integration and segregation of sensory information. Yet, temporal misalignments in the presentation of visual and auditory stimuli may generate illusory phenomena such as the sound-induced flash illusion, in which a single flash paired with multiple auditory stimuli induces the perception of multiple illusory flashes. This phenomenon has been shown to be robust and resistant to feedback training. According to a Bayesian account, this is due to a statistically optimal combination of the signals operated by the nervous system. From this perspective, individual susceptibility to the illusion might be moulded through prolonged experience. For example, repeated exposure to the illusion and prolonged training sessions partially impact on the reported illusion. Therefore, extensive and immersive audio-visual experience, such as first-person shooter videogames, should sharpen individual capacity to correctly integrate multisensory information over time, leading to more veridical perception. We tested this hypothesis by comparing the temporal profile of the sound-induced illusion in a group of expert first-person shooter gamers and a non-players group. In line with the hypotheses, gamers experience significantly narrower windows of illusion (~87 ms) relative to non-players (~105 ms), leading to higher veridical reports in gamers (~68%) relative to non-players (~59%). Moreover, according to recent literature, we tested whether audio-visual intensive training in gamers could be related to the incidence of migraine, and found that its severity may be directly proportioned to the time spent on videogames. Overall, these results suggest that continued training within audio-visual environments such as first-person shooter videogames improves temporal discrimination and sensory integration. This finding may pave the way for future therapeutic strategies based on self-administered multisensory training. On the other hand, the impact of intensive training on visual-related stress disorders, such as migraine incidence, should be taken into account as a risk factor during therapeutic planning.
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http://dx.doi.org/10.1016/j.cortex.2020.10.009DOI Listing
January 2021

Driving associative plasticity in premotor-motor connections through a novel paired associative stimulation based on long-latency cortico-cortical interactions.

Brain Stimul 2020 Sep - Oct;13(5):1461-1463. Epub 2020 Aug 11.

Centro Studi e Ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Campus di Cesena, Alma Mater Studiorum, Università di Bologna, 47521, Cesena, Italy; Centro de Investigación en Neuropsicología y Neurociencias Cognitivas, Universidad Católica Del Maule, Talca, 3460000, Chile. Electronic address:

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http://dx.doi.org/10.1016/j.brs.2020.08.003DOI Listing
August 2020

Individual differences in sensory integration predict differences in time perception and individual levels of schizotypy.

Conscious Cogn 2020 09 20;84:102979. Epub 2020 Jul 20.

Centre for Brain Science, Department of Psychology, University of Essex, Colchester, Essex, UK.

To interact functionally with our environment, our perception must locate events in time, including discerning whether sensory events are simultaneous. The Temporal Binding Window (TBW; the time window within which two stimuli tend to be integrated into one event) has been shown to relate to individual differences in perception, including schizotypy, but the relationship with subjective estimates of duration is unclear. We compare individual TBWs with individual differences in the filled duration illusion, exploiting differences in perception between empty and filled durations (the latter typically being perceived as longer). Schizotypy has been related to both these measures and is included to explore a potential link between these tasks and enduring perceptual differences. Results suggest that individuals with a narrower TBW make longer estimates for empty durations and demonstrate less variability in both conditions. Exploratory analysis of schizotypy data suggests a relationship with the TBW but is inconclusive regarding time perception.
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http://dx.doi.org/10.1016/j.concog.2020.102979DOI Listing
September 2020

Spatial Frequency Tuning and Transfer of Perceptual Learning for Motion Coherence Reflects the Tuning Properties of Global Motion Processing.

Vision (Basel) 2019 Sep 2;3(3). Epub 2019 Sep 2.

Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.

Perceptual learning is typically highly specific to the stimuli and task used during training. However, recently, it has been shown that training on global motion can transfer to untrained tasks, reflecting the generalising properties of mechanisms at this level of processing. We investigated (i) if feedback was required for learning in a motion coherence task, (ii) the transfer across the spatial frequency of training on a global motion coherence task and (iii) the transfer of this training to a measure of contrast sensitivity. For our first experiment, two groups, with and without feedback, trained for ten days on a broadband motion coherence task. Results indicated that feedback was a requirement for robust learning. For the second experiment, training consisted of five days of direction discrimination using one of three motion coherence stimuli (where individual elements were comprised of either broadband Gaussian blobs or low- or high-frequency random-dot ), with trial-by-trial auditory feedback. A pre- and post-training assessment was conducted for each of the three types of global motion coherence conditions and high and low spatial frequency contrast sensitivity (both without feedback). Our training paradigm was successful at eliciting improvement in the trained tasks over the five days. Post-training assessments found evidence of transfer for the motion coherence task exclusively for the group trained on low spatial frequency elements. For the contrast sensitivity tasks, improved performance was observed for low- and high-frequency stimuli, following motion coherence training with broadband stimuli, and for low-frequency stimuli, following low-frequency training. Our findings are consistent with perceptual learning, which depends on the global stage of motion processing in higher cortical areas, which is broadly tuned for spatial frequency, with a preference for low frequencies.
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http://dx.doi.org/10.3390/vision3030044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6802806PMC
September 2019

Posterior brain lesions selectively alter alpha oscillatory activity and predict visual performance in hemianopic patients.

Cortex 2019 12 4;121:347-361. Epub 2019 Oct 4.

Centre for Studies and Research in Cognitive Neuroscience, University of Bologna, Cesena, Italy; Department of Psychology, University of Bologna, Bologna, Italy. Electronic address:

Alpha oscillatory frequency and amplitude have been linked to visual processing and to the excitability of the visual cortex at rest. Therefore, posterior brain lesions, which damage the neural circuits of the visual system might induce alterations in the alpha oscillatory activity. To investigate this hypothesis, EEG activity was recorded during eyes-closed resting state in patients with hemianopia with posterior brain lesions, patients without hemianopia with anterior brain lesions and age-matched healthy controls. Patients with posterior lesions revealed a selective slowdown of individual alpha frequency in both the intact and the lesioned hemisphere and a reduction of alpha amplitude in the lesioned hemisphere, resulting in an interhemispheric imbalanced oscillatory alpha activity, while no significant alterations in the alpha range were found in patients with anterior lesions. This suggests a crucial role of posterior cortices in coordinating alpha oscillations in the visual system. Moreover, right posterior lesions had a more severe reduction of individual alpha frequency and altering of the interhemispheric distribution of the alpha amplitude, in line with the notion of the prominence of the right posterior cortices in balancing the interhemispheric functioning. Crucially, the duration of the in individual alpha frequency and the interhemispheric imbalance in alpha amplitude were directly linked to visuo-spatial performance across all participants and to impaired visual detection abilities in hemianopics, therefore supporting a functional role of alpha oscillations in visual processing and suggesting that activity in this frequency range at rest represents a neurophysiological marker reliably reflecting the integrity and the functionality of the visual system in humans.
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http://dx.doi.org/10.1016/j.cortex.2019.09.008DOI Listing
December 2019

Individual Alpha Frequency Predicts Perceived Visuotactile Simultaneity.

J Cogn Neurosci 2020 01 3;32(1):1-11. Epub 2019 Sep 3.

University of Chieti-Pescara.

Temporal encoding is a key feature in multisensory processing that leads to the integration versus segregation of perceived events over time. Whether or not two events presented at different offsets are perceived as simultaneous varies widely across the general population. Such tolerance to temporal delays is known as the temporal binding window (TBW). It has been recently suggested that individual oscillatory alpha frequency (IAF) peak may represent the electrophysiological correlate of TBW, with IAF also showing a wide variability in the general population (8-12 Hz). In our work, we directly tested this hypothesis by measuring each individual's TBW during a visuotactile simultaneity judgment task while concurrently recording their electrophysiological activity. We found that the individual's TBW significantly correlated with their left parietal IAF, such that faster IAF accounted for narrower TBW. Furthermore, we found that higher prestimulus alpha power measured over the same left parietal regions accounted for more veridical responses of non-simultaneity, which may be explained either by accuracy in perceptual simultaneity or, alternatively, in line with recent proposals by a shift in response bias from more conservative (high alpha power) to more liberal (low alpha power). We propose that the length of an alpha cycle constrains the temporal resolution within which perceptual processes take place.
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http://dx.doi.org/10.1162/jocn_a_01464DOI Listing
January 2020

Oscillatory Properties of Functional Connections Between Sensory Areas Mediate Cross-Modal Illusory Perception.

J Neurosci 2019 07 20;39(29):5711-5718. Epub 2019 May 20.

Centre for Brain Science, Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, United Kingdom,

The presentation of simple auditory stimuli can significantly impact visual processing and even induce visual illusions, such as the auditory-induced double flash illusion (DFI). These cross-modal processes have been shown to be driven by occipital oscillatory activity within the alpha band. Whether this phenomenon is network specific or can be generalized to other sensory interactions remains unknown. The aim of the current study was to test whether cross-modal interactions between somatosensory-to-visual areas leading to the same (but tactile-induced) DFI share similar properties with the auditory DFI. We hypothesized that if the effects are mediated by the oscillatory properties of early visual areas per se, then the two versions of the illusion should be subtended by the same neurophysiological mechanism (i.e., the speed of the alpha frequency). Alternatively, if the oscillatory activity in visual areas predicting this phenomenon is dependent on the specific neural network involved, then it should reflect network-specific oscillatory properties. In line with the latter, results recorded in humans (both sexes) show a network-specific oscillatory profile linking the auditory DFI to occipital alpha oscillations, replicating previous findings, and tactile DFI to occipital beta oscillations, a rhythm typical of somatosensory processes. These frequency-specific effects are observed for visual (but not auditory or somatosensory) areas and account for auditory-visual connectivity in the alpha band and somatosensory-visual connectivity in the beta band. We conclude that task-dependent visual oscillations reflect network-specific oscillatory properties favoring optimal directional neural communication timing for sensory binding. We investigated the oscillatory correlates of the auditory- and tactile-induced double flash illusion (DFI), a phenomenon where two interleaved beeps (taps) set within 100 ms apart and paired with one visual flash induce the sensation of a second illusory flash. Results confirm previous evidence that the speed of individual occipital alpha oscillations predict the temporal window of the auditory-induced illusion. Importantly, they provide novel evidence that the tactile-induced DFI is instead mediated by the speed of individual occipital beta oscillations. These task-dependent occipital oscillations are shown to be mediated by the oscillatory properties of the neural network engaged in the task to favor optimal temporal integration between the senses.
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http://dx.doi.org/10.1523/JNEUROSCI.3184-18.2019DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6636074PMC
July 2019

Slow Theta tACS of the Right Parietal Cortex Enhances Contralateral Visual Working Memory Capacity.

Brain Topogr 2019 05 29;32(3):477-481. Epub 2019 Jan 29.

Department of Psychology, Ludwig-Maximilians-Universität München, Leopoldstr. 13, 80802, Munich, Germany.

Recent research suggests alteration of visual working memory capacity by modulation of parietal theta frequency via transcranial alternating current stimulation (tACS). However, it remains to be clarified whether this effect is partly driven by co-stimulation of prefrontal cortex and subcortical structures. It was hypothesized that focal tACS over the parietal lobe without additional prefrontal or subcortical stimulation should lead to similar effects as reported in the literature. Healthy, young participants were tested on a visual working memory paradigm while receiving either focal parietal tACS at 4 Hz, at 7 Hz or sham stimulation. Focal right posterior 4 Hz tACS led to increased working memory capacity strictly for the visual hemifield contralateral to stimulation. Exclusive stimulation of posterior cortex by 4 Hz tACS replicates effects recently reported in literature, confirming that stimulation of the prefrontal cortex or subcortical structures are not a primary driver of these observations.
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http://dx.doi.org/10.1007/s10548-019-00702-2DOI Listing
May 2019

Prefrontal transcranial alternating current stimulation improves motor sequence reproduction.

Behav Brain Res 2019 04 19;361:39-49. Epub 2018 Dec 19.

Centre for Brain Science, Department of Psychology, University of Essex, CO4 3SQ, United Kingdom; Dipartimento di Psicologia and Centro Studi e Ricerche in Neuroscienze Cognitive, Campus di Cesena, Universitá di Bologna, 47521 Cesena, Italy.

Cortical activity in frontal, parietal, and motor regions during sequence observation correlates with performance on sequence reproduction. Increased cortical activity observed during observation has therefore been suggested to represent increased learning. Causal relationships have been demonstrated between M1 and motor sequence reproduction and between parietal cortex and bimanual learning. However, similar effects have not been reported for frontal regions despite a number of reports implicating its involvement in encoding of motor sequences. Investigating causal relations between cortical activity and reproduction of motor sequences in parietal, frontal and primary motor regions can disentangle whether specific regions during simple observation can be selectively ascribed to encoding or reproduction or both. We designed a sensorimotor paradigm that included a strong motor sequence component, and tested the impact of individually adjusted transcranial alternating current stimulation (IAF-tACS) to prefrontal, parietal, and primary motor regions on electroencephalographic motor rhythms (alpha and beta bandwidths) during motor sequence observation and the ability to reproduce the observed sequences. Independently of the stimulated region, IAF-tACS led to a reduction in suppression in the lower beta-range relative to sham. Prefrontal IAF-tACS however, led to significant improvement in motor sequence reproduction, pinpointing the crucial role of prefrontal regions in motor sequence reproduction.
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http://dx.doi.org/10.1016/j.bbr.2018.12.035DOI Listing
April 2019

Higher proneness to multisensory illusions is driven by reduced temporal sensitivity in people with high schizotypal traits.

Conscious Cogn 2018 10 19;65:263-270. Epub 2018 Sep 19.

Department of Psychology, University of Essex, Colchester CO4 3SQ, UK; Centro Studi e Ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Università di Bologna, 47521 Cesena, Italy. Electronic address:

A coherent sense of self, typically altered in schizophrenia, is accompanied by a coherent ability to integrate sensory information. According to the idea of a psychosis continuum, high schizotypal traits in the general population may be associated to higher proneness to multisensory illusions, akin to schizophrenia. We directly tested this hypothesis by means of the double-flash illusion in participants with low and high schizotypal scores. We confirmed the higher proneness to illusions in the high-schizotypal group. Crucially, such higher proneness was fully explained by a significantly reduced temporal sensitivity to integrate sensory information. We conclude that reduced temporal sensitivity accounts for enhanced proneness to illusions in people at higher risk and represents an early marker of psychosis.
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http://dx.doi.org/10.1016/j.concog.2018.09.006DOI Listing
October 2018

Strengthening functionally specific neural pathways with transcranial brain stimulation.

Curr Biol 2018 07;28(13):R735-R736

Centro studi e ricerche in Neuroscienze Cognitive, Dipartimento di Psicologia, Università di Bologna, 47521, Cesena, Italy; Centre for Brain Science, Department of Psychology, University of Essex, Colchester, CO4 3SQ, UK. Electronic address:

Cortico-cortical paired associative stimulation (ccPAS) is a recently established offline dual-coil transcranial magnetic stimulation (TMS) protocol [1-3] based on the Hebbian principle of associative plasticity and designed to transiently enhance synaptic efficiency in neural pathways linking two interconnected (targeted) brain regions [4,5]. Here, we present a new 'function-tuning ccPAS' paradigm in which, by pairing ccPAS with the presentation of a specific visual feature, for example a specific motion direction, we can selectively target and enhance the synaptic efficiency of functionally specific, but spatially overlapping, pathways. We report that ccPAS applied in a state-dependent manner and at a low intensity selectively enhanced detection of the specific motion direction primed during the combined visual-TMS manipulations. This paradigm significantly enhances the specificity of TMS-induced plasticity, by allowing the targeting of cortico-cortical pathways associated with specific functions.
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http://dx.doi.org/10.1016/j.cub.2018.05.083DOI Listing
July 2018

Alpha Oscillations Are Causally Linked to Inhibitory Abilities in Ageing.

J Neurosci 2018 05 3;38(18):4418-4429. Epub 2018 Apr 3.

Institute of Cognitive Neuroscience, University College London, London WC1N 3AR, United Kingdom,

Aging adults typically show reduced ability to ignore task-irrelevant information, an essential skill for optimal performance in many cognitive operations, including those requiring working memory (WM) resources. In a first experiment, young and elderly human participants of both genders performed an established WM paradigm probing inhibitory abilities by means of valid, invalid, and neutral retro-cues. Elderly participants showed an overall cost, especially in performing invalid trials, whereas younger participants' general performance was comparatively higher, as expected.Inhibitory abilities have been linked to alpha brain oscillations but it is yet unknown whether in aging these oscillations (also typically impoverished) and inhibitory abilities are causally linked. To probe this possible causal link in aging, we compared in a second experiment parietal alpha-transcranial alternating current stimulation (tACS) with either no stimulation (Sham) or with two control stimulation frequencies (theta- and gamma-tACS) in the elderly group while performing the same WM paradigm. Alpha- (but not theta- or gamma-) tACS selectively and significantly improved performance (now comparable to younger adults' performance in the first experiment), particularly for invalid cues where initially elderly showed the highest costs. Alpha oscillations are therefore causally linked to inhibitory abilities and frequency-tuned alpha-tACS interventions can selectively change these abilities in the elderly. Ignoring task-irrelevant information, an ability associated to rhythmic brain activity in the alpha frequency band, is fundamental for optimal performance. Indeed, impoverished inhibitory abilities contribute to age-related decline in cognitive functions like working memory (WM), the capacity to briefly hold information in mind. Whether in aging adults alpha oscillations and inhibitory abilities are linked is yet unknown. We experimentally manipulated frequency-tuned brain activity using transcranial alternating current stimulation (tACS), combined with a retro-cue paradigm assessing WM and inhibition. We found that alpha-tACS induced a significant improvement in target responses and misbinding errors, two indexes of inhibition. We concluded that in aging alpha oscillations are causally linked to inhibitory abilities, and that despite being impoverished, these abilities are still malleable.
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http://dx.doi.org/10.1523/JNEUROSCI.1285-17.2018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6596011PMC
May 2018

The speed of parietal theta frequency drives visuospatial working memory capacity.

PLoS Biol 2018 03 14;16(3):e2005348. Epub 2018 Mar 14.

Centre for Brain Science, Department of Psychology, University of Essex, Colchester, United Kingdom.

The speed of theta brain oscillatory activity is thought to play a key role in determining working memory (WM) capacity. Individual differences in the length of a theta cycle (ranging between 4 and 7 Hz) might determine how many gamma cycles (>30 Hz) can be nested into a theta wave. Gamma cycles are thought to represent single memory items; therefore, this interplay could determine individual memory capacity. We directly tested this hypothesis by means of parietal transcranial alternating current stimulation (tACS) set at slower (4 Hz) and faster (7 Hz) theta frequencies during a visuospatial WM paradigm. Accordingly, we found that 4-Hz tACS enhanced WM capacity, while 7-Hz tACS reduced WM capacity. Notably, these effects were found only for items presented to the hemifield contralateral to the stimulation site. This provides causal evidence for a frequency-dependent and spatially specific organization of WM storage, supporting the theta-gamma phase coupling theory of WM capacity.
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http://dx.doi.org/10.1371/journal.pbio.2005348DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5868840PMC
March 2018

Typical Lateral Interactions, but Increased Contrast Sensitivity, in Migraine-With-Aura.

Vision (Basel) 2018 Feb 9;2(1). Epub 2018 Feb 9.

Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK.

Individuals with migraine show differences in visual perception compared to control groups. It has been suggested that differences in lateral interactions between neurons might account for some of these differences. This study seeks to further establish the strength and spatial extent of excitatory and inhibitory interactions in migraine-with-aura using a classic lateral masking task. Observers indicated which of two intervals contained a centrally presented, vertical Gabor target of varying contrast. In separate blocks of trials, the target was presented alone or was flanked by two additional collinear, high contrast Gabors. Flanker distances varied between 1 and 12 wavelengths of the Gabor stimuli. Overall, contrast thresholds for the migraine group were lower than those in the control group. There was no difference in the degree of lateral interaction in the migraine group. These results are consistent with the previous work showing enhanced contrast sensitivity in migraine-with-aura for small, rapidly presented targets, and they suggest that impaired performance in global perceptual tasks in migraine may be attributed to difficulties in segmenting relevant from irrelevant features, rather than altered local mechanisms.
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http://dx.doi.org/10.3390/vision2010007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6836116PMC
February 2018

Long-latency interhemispheric interactions between motor-related areas and the primary motor cortex: a dual site TMS study.

Sci Rep 2017 11 2;7(1):14936. Epub 2017 Nov 2.

IRCCS Fondazione Santa Lucia, 00179, Rome, Italy.

The primary motor cortex (M1) is highly influenced by premotor/motor areas both within and across hemispheres. Dual site transcranial magnetic stimulation (dsTMS) has revealed interhemispheric interactions mainly at early latencies. Here, we used dsTMS to systematically investigate long-latency causal interactions between right-hemisphere motor areas and the left M1 (lM1). We stimulated lM1 using a suprathreshold test stimulus (TS) to elicit motor-evoked potentials (MEPs) in the right hand. Either a suprathreshold or a subthreshold conditioning stimulus (CS) was applied over the right M1 (rM1), the right ventral premotor cortex (rPMv), the right dorsal premotor cortex (rPMd) or the supplementary motor area (SMA) prior to the TS at various CS-TS inter-stimulus intervals (ISIs: 40-150 ms). The CS strongly affected lM1 excitability depending on ISI, CS site and intensity. Inhibitory effects were observed independently of CS intensity when conditioning PMv, rM1 and SMA at a 40-ms ISI, with larger effects after PMv conditioning. Inhibition was observed with suprathreshold PMv and rM1 conditioning at a 150-ms ISI, while site-specific, intensity-dependent facilitation was detected at an 80-ms ISI. Thus, long-latency interhemispheric interactions, likely reflecting indirect cortico-cortical/cortico-subcortical pathways, cannot be reduced to nonspecific activation across motor structures. Instead, they reflect intensity-dependent, connection- and time-specific mechanisms.
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http://dx.doi.org/10.1038/s41598-017-13708-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5668244PMC
November 2017

Transcranial alternating current stimulation to the inferior parietal lobe decreases mu suppression to egocentric, but not allocentric hand movements.

Neuroscience 2017 03 3;344:124-132. Epub 2017 Jan 3.

Centre for Brain Science, Department of Psychology, University of Essex, CO4 3SQ, United Kingdom.

Egocentric vs. allocentric perspective during observation of hand movements has been related to self-other differentiation such that movements observed from an egocentric viewpoint have been considered as self-related while movements observed from an allocentric viewpoint have been considered as belonging to someone else. Correlational studies have generally found that egocentric perspective induces greater neurophysiological responses and larger behavioral effects compared to an allocentric perspective. However, recent studies question previous findings by reporting greater (μ) suppression and greater transcranial magnetic stimulation (TMS)-induced motor-evoked potentials (MEPs) during observation of allocentric compared to egocentric movements. Furthermore, self-other differentiation has been generally related to activity within the inferior parietal lobe (IPL), but direct evidence for a causal and functional role of IPL in self-other differentiation is lacking. The current study was therefore designed to investigate the influence that IPL exerts on self-other differentiation. To this aim, we measured the impact of individually adjusted alpha-tuned transcranial alternating current stimulation (tACS) applied over IPL on μ-suppression during hands movement observation from an egocentric and allocentric perspective. Electroencephalography (EEG) was recorded during movement observation before and immediately after tACS. Results demonstrated that tACS decreased μ-reactivity over sensorimotor (but not visual) regions for egocentric (but not allocentric) movement observation providing direct evidence for a causal involvement of IPL in the observation of self- but not other-related hand movement.
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http://dx.doi.org/10.1016/j.neuroscience.2016.12.045DOI Listing
March 2017

Long-latency modulation of motor cortex excitability by ipsilateral posterior inferior frontal gyrus and pre-supplementary motor area.

Sci Rep 2016 12 8;6:38396. Epub 2016 Dec 8.

Dipartimento di Psicologia and Centro studi e ricerche in Neuroscienze Cognitive, Campus di Cesena, Università di Bologna 47521 Cesena, Italy.

The primary motor cortex (M1) is strongly influenced by several frontal regions. Dual-site transcranial magnetic stimulation (dsTMS) has highlighted the timing of early (<40 ms) prefrontal/premotor influences over M1. Here we used dsTMS to investigate, for the first time, longer-latency causal interactions of the posterior inferior frontal gyrus (pIFG) and pre-supplementary motor area (pre-SMA) with M1 at rest. A suprathreshold test stimulus (TS) was applied over M1 producing a motor-evoked potential (MEP) in the relaxed hand. Either a subthreshold or a suprathreshold conditioning stimulus (CS) was administered over ipsilateral pIFG/pre-SMA sites before the TS at different CS-TS inter-stimulus intervals (ISIs: 40-150 ms). Independently of intensity, CS over pIFG and pre-SMA (but not over a control site) inhibited MEPs at an ISI of 40 ms. The CS over pIFG produced a second peak of inhibition at an ISI of 150 ms. Additionally, facilitatory modulations were found at an ISI of 60 ms, with supra- but not subthreshold CS intensities. These findings suggest differential modulatory roles of pIFG and pre-SMA in M1 excitability. In particular, the pIFG -but not the pre-SMA- exerts intensity-dependent modulatory influences over M1 within the explored time window of 40-150 ms, evidencing fine-tuned control of M1 output.
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http://dx.doi.org/10.1038/srep38396DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5144072PMC
December 2016

Information-Based Approaches of Noninvasive Transcranial Brain Stimulation.

Trends Neurosci 2016 11 30;39(11):782-795. Epub 2016 Sep 30.

Department of Psychology, Faculty of Science and Technology, University of Westminster, London, UK. Electronic address:

Progress in cognitive neuroscience relies on methodological developments to increase the specificity of knowledge obtained regarding brain function. For example, in functional neuroimaging the current trend is to study the type of information carried by brain regions rather than simply compare activation levels induced by task manipulations. In this context noninvasive transcranial brain stimulation (NTBS) in the study of cognitive functions may appear coarse and old fashioned in its conventional uses. However, in their multitude of parameters, and by coupling them with behavioral manipulations, NTBS protocols can reach the specificity of imaging techniques. Here we review the different paradigms that have aimed to accomplish this in both basic science and clinical settings and follow the general philosophy of information-based approaches.
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http://dx.doi.org/10.1016/j.tins.2016.09.001DOI Listing
November 2016

Empowering Reentrant Projections from V5 to V1 Boosts Sensitivity to Motion.

Curr Biol 2016 08 11;26(16):2155-60. Epub 2016 Aug 11.

Department of Psychology and Center for Studies and Research in Cognitive Neuroscience, University of Bologna, Cesena Campus, Viale Europa 980, 47521 Cesena, Italy; IRCCS Fondazione Santa Lucia, Via Ardeatina 306, 00179 Rome, Italy. Electronic address:

Evidence from macaques [1] and humans [2, 3] has shown that back projections from extrastriate areas to the primary visual area (V1) determine whether visual awareness will arise. For example, reentrant projections from the visual motion area (V5) to V1 are considered to be critical for awareness of motion [2, 3]. If these projections are also instrumental to functional processing of moving stimuli [4-8], then increasing synaptic efficacy in V5-V1 connections should induce functionally relevant short-term plastic changes, resulting in enhanced perception of visual motion. Using transcranial magnetic stimulation (TMS), we applied a novel cortico-cortical paired associative stimulation (ccPAS) protocol to transiently enhance visual motion sensitivity and demonstrate both the functional relevance of V5-V1 reentrant projections to motion perception and their plasticity. Specifically, we found that ccPAS aimed at strengthening reentrant connectivity from V5 to V1 (but not in the opposite direction) enhanced the human ability to perceive coherent visual motion. This perceptual enhancement followed the temporal profile of Hebbian plasticity [9-18] and was observed only when an optimal timing of 20 ms between TMS pulses [2, 3, 5, 6] was used, not when TMS pulses were delivered synchronously. Thus, plastic change is critically dependent on both the direction and timing of connectivity; if either of these requirements was not met, perceptual enhancement did not take place. We therefore provide novel causal evidence that V5-V1 back projections, instrumental to motion perception, are functionally malleable. These findings have implications for theoretical models of visual awareness and for the rehabilitation of visual deficits.
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http://dx.doi.org/10.1016/j.cub.2016.06.009DOI Listing
August 2016

Multisensory signalling enhances pupil dilation.

Sci Rep 2016 05 18;6:26188. Epub 2016 May 18.

Centre for Brain Science, Department of Psychology, University of Essex, Colchester, CO4 3SQ, UK.

Detecting and integrating information across the senses is an advantageous mechanism to efficiently respond to the environment. In this study, a simple auditory-visual detection task was employed to test whether pupil dilation, generally associated with successful target detection, could be used as a reliable measure for studying multisensory integration processing in humans. We recorded reaction times and pupil dilation in response to a series of visual and auditory stimuli, which were presented either alone or in combination. The results indicated faster reaction times and larger pupil diameter to the presentation of combined auditory and visual stimuli than the same stimuli when presented in isolation. Moreover, the responses to the multisensory condition exceeded the linear summation of the responses obtained in each unimodal condition. Importantly, faster reaction times corresponded to larger pupil dilation, suggesting that also the latter can be a reliable measure of multisensory processes. This study will serve as a foundation for the investigation of auditory-visual integration in populations where simple reaction times cannot be collected, such as developmental and clinical populations.
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http://dx.doi.org/10.1038/srep26188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4870616PMC
May 2016

The COGs (context, object, and goals) in multisensory processing.

Exp Brain Res 2016 May 1;234(5):1307-23. Epub 2016 Mar 1.

The Laboratory for Investigative Neurophysiology (The LINE), Neuropsychology and Neurorehabilitation Service and Department of Radiology, Centre Hospitalier Universitaire Vaudois (CHUV), University Hospital Center and University of Lausanne, BH7.081, rue du Bugnon 46, 1011, Lausanne, Switzerland.

Our understanding of how perception operates in real-world environments has been substantially advanced by studying both multisensory processes and "top-down" control processes influencing sensory processing via activity from higher-order brain areas, such as attention, memory, and expectations. As the two topics have been traditionally studied separately, the mechanisms orchestrating real-world multisensory processing remain unclear. Past work has revealed that the observer's goals gate the influence of many multisensory processes on brain and behavioural responses, whereas some other multisensory processes might occur independently of these goals. Consequently, other forms of top-down control beyond goal dependence are necessary to explain the full range of multisensory effects currently reported at the brain and the cognitive level. These forms of control include sensitivity to stimulus context as well as the detection of matches (or lack thereof) between a multisensory stimulus and categorical attributes of naturalistic objects (e.g. tools, animals). In this review we discuss and integrate the existing findings that demonstrate the importance of such goal-, object- and context-based top-down control over multisensory processing. We then put forward a few principles emerging from this literature review with respect to the mechanisms underlying multisensory processing and discuss their possible broader implications.
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http://dx.doi.org/10.1007/s00221-016-4590-zDOI Listing
May 2016

Causal evidence that intrinsic beta-frequency is relevant for enhanced signal propagation in the motor system as shown through rhythmic TMS.

Neuroimage 2016 Feb 14;126:120-30. Epub 2015 Nov 14.

Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, University College London, London, UK.

Correlative evidence provides support for the idea that brain oscillations underpin neural computations. Recent work using rhythmic stimulation techniques in humans provide causal evidence but the interactions of these external signals with intrinsic rhythmicity remain unclear. Here, we show that sensorimotor cortex follows externally applied rhythmic TMS (rTMS) stimulation in the beta-band but that the elicited responses are strongest at the intrinsic individual beta peak frequency. While these entrainment effects are of short duration, even subthreshold rTMS pulses propagate through the network and elicit significant cortico-spinal coupling, particularly when stimulated at the individual beta-frequency. Our results show that externally enforced rhythmicity interacts with intrinsic brain rhythms such that the individual peak frequency determines the effect of rTMS. The observed downstream spinal effect at the resonance frequency provides evidence for the causal role of brain rhythms for signal propagation.
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http://dx.doi.org/10.1016/j.neuroimage.2015.11.020DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4739512PMC
February 2016

The multisensory function of the human primary visual cortex.

Neuropsychologia 2016 Mar 11;83:161-169. Epub 2015 Aug 11.

The Laboratory for Investigative Neurophysiology (The LINE), Neuropsychology and Neurorehabilitation Service and Department of Radiology, University Hospital Center and University of Lausanne, Lausanne, Switzerland; Attention, Brain, and Cognitive Development Group, Department of Experimental Psychology, University of Oxford, United Kingdom. Electronic address:

It has been nearly 10 years since Ghazanfar and Schroeder (2006) proposed that the neocortex is essentially multisensory in nature. However, it is only recently that sufficient and hard evidence that supports this proposal has accrued. We review evidence that activity within the human primary visual cortex plays an active role in multisensory processes and directly impacts behavioural outcome. This evidence emerges from a full pallet of human brain imaging and brain mapping methods with which multisensory processes are quantitatively assessed by taking advantage of particular strengths of each technique as well as advances in signal analyses. Several general conclusions about multisensory processes in primary visual cortex of humans are supported relatively solidly. First, haemodynamic methods (fMRI/PET) show that there is both convergence and integration occurring within primary visual cortex. Second, primary visual cortex is involved in multisensory processes during early post-stimulus stages (as revealed by EEG/ERP/ERFs as well as TMS). Third, multisensory effects in primary visual cortex directly impact behaviour and perception, as revealed by correlational (EEG/ERPs/ERFs) as well as more causal measures (TMS/tACS). While the provocative claim of Ghazanfar and Schroeder (2006) that the whole of neocortex is multisensory in function has yet to be demonstrated, this can now be considered established in the case of the human primary visual cortex.
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http://dx.doi.org/10.1016/j.neuropsychologia.2015.08.011DOI Listing
March 2016

Individual differences in alpha frequency drive crossmodal illusory perception.

Curr Biol 2015 Jan 24;25(2):231-235. Epub 2014 Dec 24.

Centre for Brain Science, Department of Psychology, University of Essex, Wivenhoe Park, Colchester CO4 3SQ, UK. Electronic address:

Perception routinely integrates inputs from different senses. Stimulus temporal proximity critically determines whether or not these inputs are bound together. Despite the temporal window of integration being a widely accepted notion, its neurophysiological substrate remains unclear. Many types of common audio-visual interactions occur within a time window of ∼100 ms. For example, in the sound-induced double-flash illusion, when two beeps are presented within ∼100 ms together with one flash, a second illusory flash is often perceived. Due to their intrinsic rhythmic nature, brain oscillations are one candidate mechanism for gating the temporal window of integration. Interestingly, occipital alpha band oscillations cycle on average every ∼100 ms, with peak frequencies ranging between 8 and 14 Hz (i.e., 120-60 ms cycle). Moreover, presenting a brief tone can phase-reset such oscillations in visual cortex. Based on these observations, we hypothesized that the duration of each alpha cycle might provide the temporal unit to bind audio-visual events. Here, we first recorded EEG while participants performed the sound-induced double-flash illusion task and found positive correlation between individual alpha frequency (IAF) peak and the size of the temporal window of the illusion. Participants then performed the same task while receiving occipital transcranial alternating current stimulation (tACS), to modulate oscillatory activity either at their IAF or at off-peak alpha frequencies (IAF±2 Hz). Compared to IAF tACS, IAF-2 Hz and IAF+2 Hz tACS, respectively, enlarged and shrunk the temporal window of illusion, suggesting that alpha oscillations might represent the temporal unit of visual processing that cyclically gates perception and the neurophysiological substrate promoting audio-visual interactions.
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http://dx.doi.org/10.1016/j.cub.2014.11.034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4300399PMC
January 2015

Hearing brighter: changing in-depth visual perception through looming sounds.

Cognition 2014 Sep 22;132(3):312-23. Epub 2014 May 22.

Department of Psychology, Centre for Brain Science, University of Essex, Colchester, UK. Electronic address:

Rapidly approaching (looming) sounds are ecologically salient stimuli that are perceived as nearer than they are due to overestimation of their loudness change and underestimation of their distance (Neuhoff, 1998; Seifritz et al., 2002). Despite evidence for crossmodal influence by looming sounds onto visual areas (Romei, Murray, Cappe, & Thut, 2009, 2013; Tyll et al., 2013), it is unknown whether such sounds bias visual percepts in similar ways. Nearer objects appear to be larger and brighter than distant objects. If looming sounds impact visual processing, then visual stimuli paired with looming sounds should be perceived as brighter and larger, even when the visual stimuli do not provide motion cues, i.e. are static. In Experiment 1 we found that static visual objects paired with looming tones (but not static or receding tones) were perceived as larger and brighter than their actual physical properties, as if they appear closer to the observer. In a second experiment, we replicate and extend the findings of Experiment 1. Crucially, we did not find evidence of such bias by looming sounds when visual processing was disrupted via masking or when catch trials were presented, ruling out simple response bias. Finally, in a third experiment we found that looming tones do not bias visual stimulus characteristics that do not carry visual depth information such as shape, providing further evidence that they specifically impact in-depth visual processing. We conclude that looming sounds impact visual perception through a mechanism transferring in-depth sound motion information onto the relevant in-depth visual dimensions (such as size and luminance but not shape) in a crossmodal remapping of information for a genuine, evolutionary advantage in stimulus detection.
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http://dx.doi.org/10.1016/j.cognition.2014.04.011DOI Listing
September 2014

Crossmodal enhancement of visual orientation discrimination by looming sounds requires functional activation of primary visual areas: a case study.

Neuropsychologia 2014 Apr 15;56:350-8. Epub 2014 Feb 15.

CsrNC, Centro studi e ricerche in Neuroscienze Cognitive, Alma Mater Studiorum - Università di Bologna, Polo Scientifico-Didattico di Cesena, 47521 Cesena, Italy; Dipartimento di Psicologia, Alma Mater Studiorum - Università di Bologna, 40127 Bologna, Italy. Electronic address:

Approaching or looming sounds are salient, potentially threatening stimuli with particular impact on visual processing. The early crossmodal effects by looming sounds (Romei, Murray, Cappe, & Thut, 2009) and their selective impact on visual orientation discrimination (Leo, Romei, Freeman, Ladavas, & Driver, 2011) suggest that these multisensory interactions may take place already within low-level visual cortices. To investigate this hypothesis, we tested a patient (SDV) with bilateral occipital lesion and spared residual portions of V1/V2. Accordingly, SDV׳s visual perimetry revealed blindness of the central visual field with some residual peripheral vision. In two experiments we tested for the influence of looming vs. receding and stationary sounds on SDV׳s line orientation discrimination (orientation discrimination experiment) and visual detection abilities (detection experiment) in the preserved or blind portions of the visual field, corresponding to spared and lesioned areas of V1, respectively. In the visual orientation discrimination experiment we found that SDV visual orientation sensitivity significantly improved for visual targets paired with looming sounds but only for lines presented in the partially preserved visual field. In the visual detection experiment, where SDV was required to simply detect the same stimuli presented in the orientation discrimination experiment, a generalised sound-induced visual improvement both in the intact and in blind portion of the visual field was observed. These results provide direct evidence that early visual areas are critically involved in crossmodal modulation of visual orientation sensitivity by looming sounds. Thus, a lesion in V1 prevents the enhancement of visual orientation sensitivity. In contrast, the same lesion does not prevent the visual detection enhancement by a sound, probably due to alternative visual pathways (e.g. retino-colliculo-extrastriate) which are usually spared in these patients and able to mediate the crossmodal enhancement of basic visual abilities such as detection.
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http://dx.doi.org/10.1016/j.neuropsychologia.2014.02.008DOI Listing
April 2014

Disruption of dorsolateral prefrontal cortex decreases model-based in favor of model-free control in humans.

Neuron 2013 Nov 24;80(4):914-9. Epub 2013 Oct 24.

Wellcome Trust Centre for Neuroimaging, Institute of Neurology, UCL, 12 Queen Square, London WC1N 3BG, UK. Electronic address:

Human choice behavior often reflects a competition between inflexible computationally efficient control on the one hand and a slower more flexible system of control on the other. This distinction is well captured by model-free and model-based reinforcement learning algorithms. Here, studying human subjects, we show it is possible to shift the balance of control between these systems by disruption of right dorsolateral prefrontal cortex, such that participants manifest a dominance of the less optimal model-free control. In contrast, disruption of left dorsolateral prefrontal cortex impaired model-based performance only in those participants with low working memory capacity.
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http://dx.doi.org/10.1016/j.neuron.2013.08.009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893454PMC
November 2013

The contributions of sensory dominance and attentional bias to cross-modal enhancement of visual cortex excitability.

J Cogn Neurosci 2013 Jul 5;25(7):1122-35. Epub 2013 Feb 5.

University of Glasgow.

Approaching or looming sounds (L-sounds) have been shown to selectively increase visual cortex excitability [Romei, V., Murray, M. M., Cappe, C., & Thut, G. Preperceptual and stimulus-selective enhancement of low-level human visual cortex excitability by sounds. Current Biology, 19, 1799-1805, 2009]. These cross-modal effects start at an early, preperceptual stage of sound processing and persist with increasing sound duration. Here, we identified individual factors contributing to cross-modal effects on visual cortex excitability and studied the persistence of effects after sound offset. To this end, we probed the impact of different L-sound velocities on phosphene perception postsound as a function of individual auditory versus visual preference/dominance using single-pulse TMS over the occipital pole. We found that the boosting of phosphene perception by L-sounds continued for several tens of milliseconds after the end of the L-sound and was temporally sensitive to different L-sound profiles (velocities). In addition, we found that this depended on an individual's preferred sensory modality (auditory vs. visual) as determined through a divided attention task (attentional preference), but not on their simple threshold detection level per sensory modality. Whereas individuals with "visual preference" showed enhanced phosphene perception irrespective of L-sound velocity, those with "auditory preference" showed differential peaks in phosphene perception whose delays after sound-offset followed the different L-sound velocity profiles. These novel findings suggest that looming signals modulate visual cortex excitability beyond sound duration possibly to support prompt identification and reaction to potentially dangerous approaching objects. The observed interindividual differences favor the idea that unlike early effects this late L-sound impact on visual cortex excitability is influenced by cross-modal attentional mechanisms rather than low-level sensory processes.
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http://dx.doi.org/10.1162/jocn_a_00367DOI Listing
July 2013