Medial prefrontal cortex involvement in aesthetic appreciation of paintings: a tDCS study.

Among the brain regions involved in the aesthetic evaluation of paintings, the prefrontal cortex seems to play a pivotal role. In particular, consistent neuroimaging evidence indicates that activity in the dorsolateral prefrontal cortex (mainly in the left hemisphere) and in medial and orbital sectors of the prefrontal cortex is linked to viewing aesthetically pleasing images. In this study, we focused on the contribution of the medial prefrontal cortex (mPFC) in mediating aesthetic decisions about paintings. We found that enhancing excitability in this region via anodal tDCS led participants to judge paintings as more beautiful. Although significant, the effects were moderate, possibly due to the neutral affective value of the artworks we used, suggesting that activity in mPFC may be critically dependent on the affective impact of the paintings.

TMS over the superior temporal sulcus affects expressivity evaluation of portraits.

When viewing a portrait, we are often captured by its expressivity, even if the emotion depicted is not immediately identifiable. If the neural mechanisms underlying emotion processing of real faces have been largely clarified, we still know little about the neural basis of evaluation of (emotional) expressivity in portraits. In this study, we aimed at assessing-by means of transcranial magnetic stimulation (TMS)-whether the right superior temporal sulcus (STS) and the right somatosensory cortex (SC), that are important in discriminating facial emotion expressions, are also causally involved in the evaluation of expressivity of portraits. We found that interfering via TMS with activity in (the face region of) right STS significantly reduced the extent to which portraits (but not other paintings depicting human figures with faces only in the background) were perceived as expressive, without, though, affecting their liking. In turn, interfering with activity of the right SC had no impact on evaluating either expressivity or liking of either paintings' category. Our findings suggest that evaluation of emotional cues in artworks recruit (at least partially) the same neural mechanisms involved in processing genuine biological others. Moreover, they shed light on the neural basis of liking decisions in art by art-naïve people, supporting the view that aesthetic appreciation relies on a multitude of factors beyond emotional evaluation.

Hemispheric asymmetry of liking for representational and abstract paintings.

Although the neural correlates of the appreciation of aesthetic qualities have been the target of much research in the past decade, few experiments have explored the hemispheric asymmetries in underlying processes. In this study, we used a divided visual field paradigm to test for hemispheric asymmetries in men and women's preference for abstract and representational artworks. Both male and female participants liked representational paintings more when presented in the right visual field, whereas preference for abstract paintings was unaffected by presentation hemifield. We hypothesize that this result reflects a facilitation of the sort of visual processes relevant to laypeople's liking for art-specifically, local processing of highly informative object features-when artworks are presented in the right visual field, given the left hemisphere's advantage in processing such features.

The dorsomedial prefrontal cortex mediates the interaction between moral and aesthetic valuation: a TMS study on the beauty-is-good stereotype.

Attractive individuals are perceived as possessing more positive personal traits than unattractive individuals. This reliance on aesthetic features to infer moral character suggests a close link between aesthetic and moral valuation. Here we aimed to investigate the neural underpinnings of the interaction between aesthetic and moral valuation by combining transcranial magnetic stimulation (TMS) with a priming paradigm designed to assess the Beauty-is-Good stereotype. Participants evaluated the trustworthiness of a series of faces (targets), each of which was preceded by an adjective describing desirable, undesirable, or neutral aesthetic qualities (primes). TMS was applied between prime and target to interfere with activity in two regions known to be involved in aesthetic and moral valuation: the dorsomedial prefrontal cortex (dmPFC, a core region in social cognition) and the dorsolateral prefrontal cortex (dlPFC, critical in decision making). Our results showed that when TMS was applied over vertex (control) and over the dlPFC, participants judged faces as more trustworthy when preceded by positive than by negative aesthetic primes (as also shown in two behavioral experiments). However, when TMS was applied over the dmPFC, primes had no effect on trustworthiness judgments. A second Experiment corroborated this finding. Our results suggest that mPFC plays a causal role linking moral and aesthetic valuation.

A TMS study on the contribution of visual area V5 to the perception of implied motion in art and its appreciation.

Over the last decade, researchers have sought to understand the brain mechanisms involved in the appreciation of art. Previous studies reported an increased activity in sensory processing regions for artworks that participants find more appealing. Here we investigated the intriguing possibility that activity in cortical area V5-a region in the occipital cortex mediating physical and implied motion detection-is related not only to the generation of a sense of motion from visual cues used in artworks, but also to the appreciation of those artworks. Art-naïve participants viewed a series of paintings and quickly judged whether or not the paintings conveyed a sense of motion, and whether or not they liked them. Triple-pulse TMS applied over V5 while viewing the paintings significantly decreased the perceived sense of motion, and also significantly reduced liking of abstract (but not representational) paintings. Our data demonstrate that V5 is involved in extracting motion information even when the objects whose motion is implied are pictorial representations (as opposed to photographs or film frames), and even in the absence of any figurative content. Moreover, our study suggests that, in the case of untrained people, V5 activity plays a causal role in the appreciation of abstract but not of representational art.

Congenital prosopagnosia is associated with a genetic variation in the oxytocin receptor (OXTR) gene: An exploratory study.

Face-recognition deficits, referred to with the term prosopagnosia (i.e., face blindness), may manifest during development in the absence of any brain injury (from here the term congenital prosopagnosia, CP). It has been estimated that approximately 2.5% of the population is affected by face-processing deficits not depending on brain lesions, and varying a lot in severity. The genetic bases of this disorder are not known. In this study we tested for genetic association between single-nucleotide polymorphisms (SNPs) in the oxytocin receptor gene (OXTR) and CP in a restricted cohort of Italian participants. We found evidence of an association between the common genetic variants rs53576 and rs2254298 OXTR SNPs and prosopagnosia. This association was also found when including an additional group of German individuals classified as prosopagnosic in the analysis. Our preliminary data provide initial support for the involvement of genetic variants of OXTR in a relevant cognitive impairment, whose genetic bases are still largely unexplored.

The role of the occipital face area in holistic processing involved in face detection and discrimination: A tDCS study.

OBJECTIVE: The aim of this study was to examine the role of occipital face area (OFA) in mediating observers' tendency to perceive faces as "wholes" (holistic processing) both when detecting and discriminating faces. To investigate this issue, we modulated OFA activity using transcranial direct current stimulation (tDCS). METHOD: In Experiment 1, participants performed a face detection task (the Mooney faces task) and a face discrimination task (the Composite faces task), which both assess holistic face processing. In Experiment 2, participants were asked to detect both Mooney faces and Mooney objects, to test face selectivity of OFA. In each experimental session, the tasks were presented once before (pre) and once after (post) administration of 20 min of excitability increasing anodal tDCS (real) and sham stimulation over the putative OFA. RESULTS: Compared with sham stimulation, we found that real anodal tDCS interfered with both Mooney faces and objects detection, whereas it had no effect on holistic processing involved in face discrimination, as measured by the Composite faces task. CONCLUSIONS: Our results suggest that OFA is causally implicated in facial detection at least in degraded conditions (i.e., when the "face" signal needs to be extracted from a noisy background). In turn, our data do not implicate OFA in holistic processing in face discrimination. Finally, our data suggest a possible role of OFA in categorization of other nonface stimuli, a conclusion that must be taken with caution, as stimulation over OFA may affect object-selective adjacent regions.

Biases in spatial bisection induced by viewing male and female faces.

Research on visual attention triggered by face gender is still relatively sparse. In the present study, three experiments are reported in which male and female participants were required to estimate the midpoint of a line (i.e., the "line bisection task"): at each end of the line a face was presented. Depending on the experimental condition, faces could be of the same gender (i.e., two males or two females) or the opposite gender. Experiments 1 and 2 converged in showing that when a male face was presented at the right and a female face at the left endpoint of the line, a clear rightward bias emerged compared to the other experimental conditions, indicating that male faces captured attention more than female faces. Importantly, male faces used across Experiments 1 and 2 were rated as more threatening than female faces, suggesting that perceived level of threat may have been responsible for the observed bias toward the male face. Experiment 3 corroborated this hypothesis by finding an attentional bias toward the male face with high threat (angry) faces but not with low threat (smiling) faces.

Processing of featural and configural aspects of faces is lateralized in dorsolateral prefrontal cortex: a TMS study.

Facial recognition relies on distinct and parallel types of processing: featural processing focuses on the individual components of a face (e.g., the shape or the size of the eyes), whereas configural (or "relational") processing considers the spatial interrelationships among the single facial components (e.g., distance of the mouth from the nose). Previous neuroimaging evidence has suggested that featural and configural processes may rely on different brain circuits. By using rTMS, here we show for the first time a double dissociation in dorsolateral prefrontal cortex for different aspects of face processing: in particular, TMS over the left middle frontal gyrus (BA8) selectively disrupted featural processing, whereas TMS over the right inferior frontal gyrus (BA44) selectively interfered with configural processing of faces. By establishing a causal link between activation in left and right prefrontal areas and different modes of face processing, our data extend previous neuroimaging evidence and may have important implications in the study of face-processing deficits, such as those manifested in prosopagnosia and autistic spectrum disorders.