Dissonant music engages early visual processing.

The neuroscientific examination of music processing in audio-visual contexts offers a valuable framework to assess how auditory information influences the emotional encoding of visual information. Using fMRI during naturalistic film viewing, we investigated the neural mechanisms underlying the effect of music on valence inferences during mental state attribution. Thirty-eight participants watched the same short-film accompanied by systematically controlled consonant or dissonant music. Subjects were instructed to think about the main character's intentions. The results revealed that increasing levels of dissonance led to more negatively valenced inferences, displaying the profound emotional impact of musical dissonance. Crucially, at the neuroscientific level and despite music being the sole manipulation, dissonance evoked the response of the primary visual cortex (V1). Functional/effective connectivity analysis showed a stronger coupling between the auditory ventral stream (AVS) and V1 in response to tonal dissonance and demonstrated the modulation of early visual processing via top-down feedback inputs from the AVS to V1. These V1 signal changes indicate the influence of high-level contextual representations associated with tonal dissonance on early visual cortices, serving to facilitate the emotional interpretation of visual information. Our results highlight the significance of employing systematically controlled music, which can isolate emotional valence from the arousal dimension, to elucidate the brain's sound-to-meaning interface and its distributive crossmodal effects on early visual encoding during naturalistic film viewing.

[Differential association between the regional metabolism of the prefrontal cortex and limbic structures, and the time of abstinence in substance dependent individuals]. / Asociación diferencial entre el metabolismo regional de la corteza prefrontal y las estructuras límbicas y el tiempo de abstinencia en individuos dependientes de sustancias.

Despite the existence of numerous neuroimaging studies demonstrating significant brain functional alterations in substance users, only a few studies have tried to analyze the association between the duration of abstinence and brain metabolism within substance users. The aim of this study was to examine the association between resting-state regional brain metabolism (measured with 18F-fluordeoxyglucose Positron Emission Tomography (FDGPET) and duration of drug abstinence in a sample of 49 abstinent polysubstance users. PET images were pre-processed and analyzed using SPM5 and SPSS 15. After image pre-processing, the level of glucose uptake in a pre-established set of regions of interest was extracted and bivariate correlations between this and the duration of abstinence of the participants were conducted. Results showed a negative correlation between duration of abstinence and the amygdale and the hippocampus bilaterally and a positive correlation between duration of abstinence and the left inferior frontal operculum. The associations found suggest different involvement of these structures in maintaining abstinence and emphasize the need to work on stress regulation, craving and behaviour control even after significant periods of abstinence.

Sensory cortical response to uncertainty and low salience during recognition of affective cues in musical intervals.

Previous neuroimaging studies have shown an increased sensory cortical response (i.e., heightened weight on sensory evidence) under higher levels of predictive uncertainty. The signal enhancement theory proposes that attention improves the quality of the stimulus representation, and therefore reduces uncertainty by increasing the gain of the sensory signal. The present study employed functional magnetic resonance imaging (fMRI) to investigate the neural correlates for ambiguous valence inferences signaled by auditory information within an emotion recognition paradigm. Participants categorized sound stimuli of three distinct levels of consonance/dissonance controlled by interval content. Separate behavioural and neuroscientific experiments were conducted. Behavioural results revealed that, compared with the consonance condition (perfect fourths, fifths and octaves) and the strong dissonance condition (minor/major seconds and tritones), the intermediate dissonance condition (minor thirds) was the most ambiguous, least salient and more cognitively demanding category (slowest reaction times). The neuroscientific findings were consistent with a heightened weight on sensory evidence whilst participants were evaluating intermediate dissonances, which was reflected in an increased neural response of the right Heschl's gyrus. The results support previous studies that have observed enhanced precision of sensory evidence whilst participants attempted to represent and respond to higher degrees of uncertainty, and converge with evidence showing preferential processing of complex spectral information in the right primary auditory cortex. These findings are discussed with respect to music-theoretical concepts and recent Bayesian models of perception, which have proposed that attention may heighten the weight of information coming from sensory channels to stimulate learning about unknown predictive relationships.

Neural mechanisms underlying valence inferences to sound: The role of the right angular gyrus.

We frequently infer others' intentions based on non-verbal auditory cues. Although the brain underpinnings of social cognition have been extensively studied, no empirical work has yet examined the impact of musical structure manipulation on the neural processing of emotional valence during mental state inferences. We used a novel sound-based theory-of-mind paradigm in which participants categorized stimuli of different sensory dissonance level in terms of positive/negative valence. Whilst consistent with previous studies which propose facilitated encoding of consonances, our results demonstrated that distinct levels of consonance/dissonance elicited differential influences on the right angular gyrus, an area implicated in mental state attribution and attention reorienting processes. Functional and effective connectivity analyses further showed that consonances modulated a specific inhibitory interaction from associative memory to mental state attribution substrates. Following evidence suggesting that individuals with autism may process social affective cues differently, we assessed the relationship between participants' task performance and self-reported autistic traits in clinically typical adults. Higher scores on the social cognition scales of the AQ were associated with deficits in recognising positive valence in consonant sound cues. These findings are discussed with respect to Bayesian perspectives on autistic perception, which highlight a functional failure to optimize precision in relation to prior beliefs.

Neural correlates of hot and cold executive functions in polysubstance addiction: association between neuropsychological performance and resting brain metabolism as measured by positron emission tomography.

The study of substance-abuse-related neuropsychological deficits and brain alterations may provide a better understanding of the neuroadaptations associated with addiction. In this study we investigated the association between performance on neuropsychological tests of cold and hot executive functions and regional brain metabolism. Measured with positron emission tomography (PET), in a sample of 49 substance-dependent individuals (SDI). Neuropsychological performance in the SDI group was compared to that of a non-drug-using control group of 30 participants, and associated with two sets of PET-derived dependent measures: one based on regions of interest (examining mean uptake in selected regions), and a second based on voxel uptake measures (using Statistical Parametric Mapping voxel-based whole-brain analyses). Behavioral analyses showed that SDI had poorer performance than controls across executive function and emotion processing measures. Regression models showed that SDI's performance in "cold" executive tests (i.e., updating, inhibition and flexibility) was associated with regional metabolism in the dorsolateral prefrontal cortex (DLPFC), mid-superior frontal gyrus, superior and inferior temporal gyrus and inferior parietal cortex, whereas performance in "hot" executive functions (i.e., self-regulation, decision-making and emotion perception) was associated with DLPFC, mid-superior frontal gyrus, anterior and mid-posterior cingulate, and temporal and fusiform gyrus. These results are discussed in terms of their relevance for the understanding of cognitive dysfunction and neuroadaptations linked to addiction.