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14 result(s) for "Strappini Francesca"
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Self-supervised Natural Image Reconstruction and Large-scale Semantic Classification from Brain Activity
Reconstructing natural images and decoding their semantic category from fMRI brain recordings is challenging. Acquiring sufficient pairs of images and their corresponding fMRI responses, which span the huge space of natural images, is prohibitive. We present a novel self-supervised approach that goes well beyond the scarce paired data, for achieving both: (i) state-of-the art fMRI-to-image reconstruction, and (ii) first-ever large-scale semantic classification from fMRI responses. By imposing cycle consistency between a pair of deep neural networks (from image-to-fMRI & from fMRI-to-image), we train our image reconstruction network on a large number of “unpaired” natural images (images without fMRI recordings) from many novel semantic categories. This enables to adapt our reconstruction network to a very rich semantic coverage without requiring any explicit semantic supervision. Specifically, we find that combining our self-supervised training with high-level perceptual losses, gives rise to new reconstruction & classification capabilities. In particular, this perceptual training enables to classify well fMRIs of never-before-seen semantic classes, without requiring any class labels during training. This gives rise to: (i) Unprecedented image-reconstruction from fMRI of never-before-seen images (evaluated by image metrics and human testing), and (ii) Large-scale semantic classification of categories that were never-before-seen during network training. Such large-scale (1000-way) semantic classification from fMRI recordings has never been demonstrated before. Finally, we provide evidence for the biological consistency of our learned model.
Optic flow selectivity in the macaque parieto-occipital sulcus
In humans, several neuroimaging studies have demonstrated that passive viewing of optic flow stimuli activates higher-level motion areas, like V6 and the cingulate sulcus visual area (CSv). In macaque, there are few studies on the sensitivity of V6 and CSv to egomotion compatible optic flow. The only fMRI study on this issue revealed selectivity to egomotion compatible optic flow in macaque CSv but not in V6 (Cotterau et al. Cereb Cortex 27(1):330–343, 2017, but see Fan et al. J Neurosci. 35:16303–16314, 2015). Yet, it is unknown whether monkey visual motion areas MT + and V6 display any distinctive fMRI functional profile relative to the optic flow stimulation, as it is the case for the homologous human areas (Pitzalis et al., Cereb Cortex 20(2):411–424, 2010). Here, we described the sensitivity of the monkey brain to two motion stimuli (radial rings and flow fields) originally used in humans to functionally map the motion middle temporal area MT + (Tootell et al. J Neurosci 15: 3215-3230, 1995a; Nature 375:139–141, 1995b) and the motion medial parietal area V6 (Pitzalis et al. 2010), respectively. In both animals, we found regions responding only to optic flow or radial rings stimulation, and regions responding to both stimuli. A region in the parieto-occipital sulcus (likely including V6) was one of the most highly selective area for coherently moving fields of dots, further demonstrating the power of this type of stimulation to activate V6 in both humans and monkeys. We did not find any evidence that putative macaque CSv responds to Flow Fields.
A Systematic Review on Social Cognition in ADHD: The Role of Language, Theory of Mind, and Executive Functions
Background: In this systematic review, conducted according to the PRISMA 2020 guidelines, we aimed to assess differences in the cognitive processes associated with social cognition—namely language, theory of mind (ToM), and executive functions (EFs)—between ADHD and control groups. Methods: The review included studies indexed in PubMed, Google Scholar, and PsycINFO up until May 2024. Eligible original peer-reviewed articles met the following criteria: they were written in English, included a clinical group with a current primary ADHD diagnosis, were empirical, included quantitative data, and utilized standardized and validated measures with adequate psychometric properties to assess social cognitive processes. Results and Discussion: A total of 1215 individuals with ADHD participated in the selected studies. Out of the 22 articles reviewed, 17 reported significant differences between ADHD and the controls across several cognitive processes related to language and EF rather than ToM. These processes included pragmatic skills, verbal and nonverbal communication, emotional prosody, interaction skills, sarcasm, paradoxical sarcasm recognition, ambiguous situations, emotion recognition, false belief, social problem solving, social behaviors, and gesture codification. We also discuss the limitations of the research and the implications of our findings. Systematic review registration: PROSPERO ID: CRD42023474681.
Spatio-Temporal Brain Mapping of Motion-Onset VEPs Combined with fMRI and Retinotopic Maps
Neuroimaging studies have identified several motion-sensitive visual areas in the human brain, but the time course of their activation cannot be measured with these techniques. In the present study, we combined electrophysiological and neuroimaging methods (including retinotopic brain mapping) to determine the spatio-temporal profile of motion-onset visual evoked potentials for slow and fast motion stimuli and to localize its neural generators. We found that cortical activity initiates in the primary visual area (V1) for slow stimuli, peaking 100 ms after the onset of motion. Subsequently, activity in the mid-temporal motion-sensitive areas, MT+, peaked at 120 ms, followed by peaks in activity in the more dorsal area, V3A, at 160 ms and the lateral occipital complex at 180 ms. Approximately 250 ms after stimulus onset, activity fast motion stimuli was predominant in area V6 along the parieto-occipital sulcus. Finally, at 350 ms (100 ms after the motion offset) brain activity was visible again in area V1. For fast motion stimuli, the spatio-temporal brain pattern was similar, except that the first activity was detected at 70 ms in area MT+. Comparing functional magnetic resonance data for slow vs. fast motion, we found signs of slow-fast motion stimulus topography along the posterior brain in at least three cortical regions (MT+, V3A and LOR).
A Comparative Study on Line Bisection and Landmark Task Performance Using a Hybrid Online Setting
Bisection tasks are commonly used to assess biases and asymmetries in visuospatial attention in both patients and neurologically intact individuals. In these tasks, participants are usually asked to identify the midpoint and manually bisect a horizontal line. Typically, healthy individuals tend to show an attention processing advantage for the left visual field, known as “pseudoneglect.” Here, performance at two computerized versions of the task was compared to assess pseudoneglect in neurologically intact individuals. Specifically, we used a hybrid online setting in which subjects (n = 35) performed the online tasks under the video guidance of the experimenter. We measured attentional biases in the line bisection and landmark tasks. We found pseudoneglect in both tasks, although the bias was larger in the line bisection task. Overall, these findings show that hybrid online tasks may provide a valid setting to assess attentional biases and suggest their feasibility in the clinical setting.
A Systematic Review on the Interaction between Emotion and Pseudoneglect
Background: A large body of research has shown brain asymmetries in spatial attention. Specifically, there is an attention-processing advantage for the left visual field in healthy, right-handed subjects, known as “pseudoneglect.” Several studies have revealed that emotions modulate this basic spatial phenomenon, but the direction of the effect is still unclear. Here we systematically review empirical evidence on the behavioral effects of emotion on pseudoneglect. Methods: We searched through Pubmed, Scopus, PsycINFO, and PsychArticles. Original peer-reviewed articles published until February 2021 were included if they (1) were written in English; (2) were conducted on adults; (3) included at least one task to measure pseudoneglect, and (4) included at least one task with emotional stimuli or employed a measure of emotional state/trait, as they relate to pseudoneglect. Results: Fifteen studies were included, and 784 healthy participants took part in all studies reviewed. Discussion: The results show some evidence of emotion modulation of pseudoneglect, but evidence on the direction of the effect is mixed. We discuss the role of methodological factors that could account for the available findings and the implications for emotion asymmetry hypotheses such as the right-hemisphere hypothesis, the valence-specific hypothesis, as well as neural and arousal frameworks of attention–emotion interactions.
The human middle temporal cortex responds to both active leg movements and egomotion-compatible visual motion
The human middle-temporal region MT+ is highly specialized in processing visual motion. However, recent studies have shown that this region is modulated by extraretinal signals, suggesting a possible involvement in processing motion information also from non-visual modalities. Here, we used functional MRI data to investigate the influence of retinal and extraretinal signals on MT+ in a large sample of subjects. Moreover, we used resting-state functional MRI to assess how the subdivisions of MT+ (i.e., MST, FST, MT, and V4t) are functionally connected. We first compared responses in MST, FST, MT, and V4t to coherent vs. random visual motion. We found that only MST and FST were positively activated by coherent motion. Furthermore, regional analyses revealed that MST and FST were positively activated by leg, but not arm, movements, while MT and V4t were deactivated by arm, but not leg, movements. Taken together, regional analyses revealed a visuomotor role for the anterior areas MST and FST and a pure visual role for the anterior areas MT and V4t. These findings were mirrored by the pattern of functional connections between these areas and the rest of the brain. Visual and visuomotor regions showed distinct patterns of functional connectivity, with the latter preferentially connected with the somatosensory and motor areas representing leg and foot. Overall, these findings reveal a functional sensitivity for coherent visual motion and lower-limb movements in MST and FST, suggesting their possible involvement in integrating sensory and motor information to perform locomotion.
Perceptual integration and attention in human extrastriate cortex
Visual crowding is a perceptual phenomenon with far-reaching implications in both perceptual (e.g., object recognition and reading) and clinical (e.g., developmental dyslexia and visual agnosia) domains. Here, we combined event-related fMRI measurements and wide-field brain mapping methods to investigate whether the BOLD response evoked by visual crowding is modulated by different attentional conditions. Participants underwent two sessions of psychophysical training outside the scanner, and then fMRI BOLD activity was measured simultaneously in early visual areas (including the visual word form area, VWFA), while they viewed strongly-crowded and weakly-crowded Gabor patches in attended and unattended conditions. We found that crowding increased BOLD activity in a network of areas including V1, V2, V3A, V4/V8, and VWFA. In V4/V8 and VWFA we found an increased activity related to attention. The effect of crowding in V1 was recorded only when attention was fully devoted to the target location. Our results provide evidence that some area beyond V1 might be the likely candidate for the site of crowding, thus supporting the view of visual crowding as a mid-level visual phenomenon.
Psychopathic Traits, Externalizing Problems, and Prosocial Behavior: The Role of Social Dominance Orientation
Psychopathic traits in community and referred youths are strongly associated with severe externalizing problems and low prosocial behavior. However, less is known about the mechanisms that may link youth psychopathy and these outcomes. Social dominance orientation (SDO), defined as the general individual orientation toward unequal and dominant/subordinate relationships, might represent a valuable construct to explore to better understand the association between psychopathic traits, externalizing problems, and prosocial behavior. Based on this, the current study aimed to investigate the relationship between psychopathic traits, SDO, externalizing problems, and prosocial behavior in a community sample (N = 92, 45.57% females, mean age = 12.53, and SD = 0.60) and in a clinical (N = 29, 9% female, mean age = 12.57, and SD = 0.57) samples of adolescents with Oppositional Defiant Disorder or Conduct Disorder. Results showed that SDO mediated the relationship between psychopathic traits and externalizing problems and between psychopathic traits and prosocial behavior only in the clinical sample. These findings can provide valuable information on psychopathic trait correlates in youths with aggressive behavior disorders; treatment implications are discussed.
Eye position modulates retinotopic responses in early visual areas: a bias for the straight-ahead direction
Even though the eyes constantly change position, the location of a stimulus can be accurately represented by a population of neurons with retinotopic receptive fields modulated by eye position gain fields. Recent electrophysiological studies, however, indicate that eye position gain fields may serve an additional function since they have a non-uniform spatial distribution that increases the neural response to stimuli in the straight-ahead direction. We used functional magnetic resonance imaging and a wide-field stimulus display to determine whether gaze modulations in early human visual cortex enhance the blood-oxygenation-level dependent (BOLD) response to stimuli that are straight-ahead. Subjects viewed rotating polar angle wedge stimuli centered straight-ahead or vertically displaced by ±20° eccentricity. Gaze position did not affect the topography of polar phase-angle maps, confirming that coding was retinotopic, but did affect the amplitude of the BOLD response, consistent with a gain field. In agreement with recent electrophysiological studies, BOLD responses in V1 and V2 to a wedge stimulus at a fixed retinal locus decreased when the wedge location in head-centered coordinates was farther from the straight-ahead direction. We conclude that stimulus-evoked BOLD signals are modulated by a systematic, non-uniform distribution of eye-position gain fields.