Support for the existence of a neural network in the brain dedicated to processing music can be found in the observation of remarkable preservation or selective loss of musical perception or production in cases with a brain damage. To illustrate the modularity of the brain musical system, several casereports of patients with focal brain lesions that involve selective musical deficits or preservation are presented. All the cases were quantitatively tested with our own standardized test battery already validated in the normal population. The first case exhibited a selective deficit of melodic abilities in the production mode (singing songs), however, with preserved temporal analysis (rhythm and metre), lyrics and prosody, all due to a lesion of the right temporal lobe of the non-dominant hemisphere. In the second case, a selective deficit of melodic perception of interval and rhythm (known as local analytical mechanisms) with preserved contour and metre was recorded. The lesion was unexpectedly localised in the fronto-parietal lobe of the right (non-dominant) hemisphere of a non-musician. The third case, with a fronto-temporal lesion of the left (dominant) hemisphere, demonstrated relative preservation of lyrics (together with intact intonation) as opposed to severely disturbed spontaneous speech in a patient with global aphasia. The opposite dissociation was documented in the fourth case suffering from a similar focal temporo-insular lesion of the left (dominant) hemisphere with chronic anomic aphasia and fluent spontaneous speech, but a severe deficit in producing previously-known lyrics. Various patterns of amusia have been discussed within the framework of current theories and modular concepts on the function and structure of the musical brain system.

        Key words: amusia, musical brain network, aphasia