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The coordination of behavior and physiology by the nervous system is complex, requiring the integration of inputs from the environment. Sensory neurons, as the detectors of external stimuli, have the important role of detecting and relaying this information to the rest of the nervous system. Proper formation, connectivity, and function of dendrites and cilia in sensory neurons are essential for the detection of stimuli. In this thesis, I use the power of invertebrate genetic systems to explore the development and function of these neuronal structures.In the first part of my thesis, I use the Drosophila melanogaster larval PNS to explore the role of three different genes in dendritic morphology and neuronal function. The dendritic arborization (DA) neurons are sensory neurons that elaborate complex and diverse dendritic morphologies beneath the epidermis. I find that Argonaute 1 (Ago1), an important part of the microRNA pathway, and Argonaute 2 (Ago2), an essential component RNAi pathway, do not have a role in dendrite patterning. However, Ago2 does regulate expression of pickpocket1 mRNA, a channel that regulates larval locomotion. Additionally, I find that mutations in the BTB-POZ domain transcription factor longitudinals lacking reduce dendrite elaboration.In the second half of my thesis, I use Caenorhabditis elegans as a model organism to examine the role of the Bardet-Biedl Syndrome genes, required for intraflagellar transport in cilia, in metabolic homeostasis. bbs mutant worms display increased lipid accumulation, as revealed by the lipophilic dye Nile Red. Surprisingly, in a comprehensive analysis of cilia mutants, mutations in only some intraflagellar transport components alter fat content, suggesting that generally interfering with cilia formation and signaling does not affect lipid levels. A series of epistasis experiments reveal that these IFT genes participate in the bb pathway to regulate intestinal lipid accumulation. Intriguingly, the heterotrimeric kinesin-II kap-1 functions downstream of bbs. I then use candidate gene approaches and RNAi screens to seek an understanding of how bbs genes regulate fat stores. Taken together, these studies provide insight into the formation and function of sensory neuronal processes.

Emotion-related areas of the brain, such as the medial frontal cortices, amygdala, and striatum, are activated during listening to sad or happy music as well as during listening to pleasurable music. Indeed, in music, like in other arts, sad and happy emotions might co-exist and be distinct from emotions of pleasure or enjoyment. Here we aimed at discerning the neural correlates of sadness or happiness in music as opposed those related to musical enjoyment. We further investigated whether musical expertise modulates the neural activity during affective listening of music. To these aims, 13 musicians and 16 non-musicians brought to the lab their most liked and disliked musical pieces with a happy and sad connotation. Based on a listening test, we selected the most representative 18 sec excerpts of the emotions of interest for each individual participant. Functional magnetic resonance imaging (fMRI) recordings were obtained while subjects listened to and rated the excerpts. The cortico-thalamo-striatal reward circuit and motor areas were more active during liked than disliked music, whereas only the auditory cortex and the right amygdala were more active for disliked over liked music. These results discern the brain structures responsible for the perception of sad and happy emotions in music from those related to musical enjoyment. We also obtained novel evidence for functional differences in the limbic system associated with musical expertise, by showing enhanced liking-related activity in fronto-insular and cingulate areas in musicians.

Music therapists use guided affect regulation in the treatment of mood disorders. However, self-directed uses of music in affect regulation are not fully understood. Some uses of music may have negative effects on mental health, as can non music regulation strategies, such as rumination. Psychological testing and functional magnetic resonance imaging (fMRI) were used explore music listening strategies in relation to mental health. Participants (n = 123) were assessed for depression, anxiety and Neuroticism, and uses of Music in Mood Regulation (MMR). Neural responses to music were measured in the medial prefrontal cortex (mPFC) in a subset of participants (n = 56). Discharge, using music to express negative emotions, related to increased anxiety and Neuroticism in all participants and particularly in males. Males high in Discharge showed decreased activity of mPFC during music listening compared with those using less Discharge. Females high in Diversion, using music to distract from negative emotions, showed more mPFC activity than females using less Diversion. These results suggest that the use of Discharge strategy can be associated with maladaptive patterns of emotional regulation, and may even have long-term negative effects on mental health. This finding has real-world applications in psychotherapy and particularly in clinical music therapy.

Music is often studied as a cognitive domain alongside language. The emotional aspects of music have also been shown to be important, but views on their nature diverge. For instance, the specific emotions that music induces and how they relate to emotional expression are still under debate. Here we propose a mental and neural chronometry of the aesthetic experience of music initiated and mediated by external and internal contexts such as intentionality, background mood, attention, and expertise. The initial stages necessary for an aesthetic experience of music are feature analysis, integration across modalities, and cognitive processing on the basis of long-term knowledge. These stages are common to individuals belonging to the same musical culture. The initial emotional reactions to music include the startle reflex, core "liking," and arousal. Subsequently, discrete emotions are perceived and induced. Presumably somatomotor processes synchronizing the body with the music also come into play here. The subsequent stages, in which cognitive, affective, and decisional processes intermingle, require controlled cross-modal neural processes to result in aesthetic emotions, aesthetic judgments, and conscious liking. These latter aesthetic stages often require attention, intentionality, and expertise for their full actualization.