Building connectomes using diffusion MRI: why, how and but

Why has diffusion MRI become a principal modality for mapping connectomes in vivo? How do different image acquisition parameters, fiber tracking algorithms and other methodological choices affect connectome estimation? What are the main factors that dictate the success and failure of connectome reconstruction? These are some of the key questions that we aim to address in this review. We provide an overview of the key methods that can be used to estimate the nodes and edges of macroscale connectomes, and we discuss open problems and inherent limitations. We argue that diffusion MRI-based connectome mapping methods are still in their infancy and caution against blind application of deep white matter tractography due to the challenges inherent to connectome reconstruction. We review a number of studies that provide evidence of useful microstructural and network properties that can be extracted in various independent and biologically-relevant contexts. Finally, we highlight some of the key deficiencies of current macroscale connectome mapping methodologies and motivate future developments

Musica: Lingua Mundi

“The man that hath no music in himself, nor is not mov’d with concord of sweet sounds, is fit for treasons, stratagems, and spoils; the motions of his spirit are dull as night, and his affections dark as Erebus. Let not such man be trusted”: this is what one can read in Shakespeare’s play The Merchant of Venice. That music has always been an essential part of human life is beyond question and that man, at the origin of his existence, first sang before speaking is a view which most men hold. Music has been often associated with emotions and language, and most scholars and linguists agree that language stems from music, and that music is a primordial and archaic language used by primitive men to communicate and strengthen their relationships with their own culture and society. Quoting Rousseau one can read that : […]les prémiers discours furent les prémiéres chansons: les retours périodique et mesurés du rhytme, les infléxions melodieuses des accens firent naitre la poesie et la musique avec la langue, ou plustôt tout cela n’étoit que la langue même pour ces heureux climats et ces heureux tems où les seuls besoins pressans qui demandoient le concours d’autrui étoint ceux que le cœur faisoit naitre. Modern studies are trying to figure out why music influences human emotions as it does. Various researches empirically explain how music affects the human brain, mind and consciousness. Music is also said to have the capacity to blend and therefore to retain stable traces of cultural contact in a way that languages do only inefficiently; languages tend to undergo total replacement rather than blending after cultural contact, and thus tend to lose remnants of cultural interaction. And what about the relationship between modern languages and music? Is music still considered a language? And what relations does it maintain with verbal language? It is often considered as an imitation or expression of human emotions and believed to have a special relationship with man’s inner space rather than with rationality and concepts. Obviously, however, it must have some kind of link with language if one thinks that it has always been associated with it for centuries. Lacking the narrative and objectual structures to which one is accustomed in language, music frequently has an affinity with the amorphous, archaic and extremely powerful emotional materials of childhood. Another way of expressing the point is that music seems to elude our self-protective devices, our techniques of manipulation and control, in such a way that it seems to write directly into man’s inner soul. Why can people, affected by aphasia, sing or process music better than language? Why subjects affected by Parkinson, Tourette, Alzheimer diseases can sing or dance but cannot speak, walk or coordinate motorial functions? Why is language acquisition more flexible in children than in adults but this is not true with music which can always be acquired? Can one support the idea that music, as water, evoke man’s primordial forces and life? My intended work rises from these observations and intends to explain how music may be used pragmatically towards foreign language acquisition and, extensively, language processing and whether a critical or receptive period exists also for it. To tell the truth, cognitive psychology affirms that listeners unconsciously abstract and store structural information from the music they hear, thereby establishing longstanding mental representations that shape their subsequent musical perception. But what happens to the human brain when listening to music? How does music influence human perception? As Friedrich Nietzsche said “without music, life would be a mistake”, can we agree with him