The role of a core set of regions in the hippocampus and superior temporal cortex for skilled exploration of complex sound scenes in which precise sound "templates" are encoded and consolidated into memory over time in an experience-dependent manner.

F1.small
Over a typical career piano tuners spend tens of thousands of hours exploring a specialized acoustic environment. Tuning requires accurate perception and adjustment of beats in two-note chords that serve as a navigational device to move between points in previously learned acoustic scenes. It is a two-stage process that depends on the following: first, selective listening to beats within frequency windows, and, second, the subsequent use of those beats to navigate through a complex soundscape. The neuroanatomical substrates underlying brain specialization for such fundamental organization of sound scenes are unknown. Here, we demonstrate that professional piano tuners are significantly better than controls matched for age and musical ability on a psychophysical task simulating active listening to beats within frequency windows that is based on amplitude modulation rate discrimination. Tuners show a categorical increase in gray matter volume in the right frontal operculum and right superior temporal lobe. Tuners also show a striking enhancement of gray matter volume in the anterior hippocampus, parahippocampal gyrus, and superior temporal gyrus, and an increase in white matter volume in the posterior hippocampus as a function of years of tuning experience. The relationship with gray matter volume is sensitive to years of tuning experience and starting age but not actual age or level of musicality. Our findings support a role for a core set of regions in the hippocampus and superior temporal cortex in skilled exploration of complex sound scenes in which precise sound "templates" are encoded and consolidated into memory over time in an experience-dependent manner.

 

We assessed brain specialization in a previously unstudied group of expert listeners who spend large amounts of time exploring a complex acoustic environment that requires accurate perception and adjustment. The subjects, piano tuners, perform an active listening and adjustment task every time a piano is tuned where they explore an acoustic scene according to a specific route. Piano tuning is a highly sophisticated skill: a single tuning session might take up to 2 h and a professional tuner may typically tune up to 20 pianos a week, so the highest levels of expertise follow thousands of hours of experience over a period of 20 to 30 years (Capleton, 2007). Thus, this group provides a unique opportunity to investigate neuroanatomical bases of skilled organization of sound scenes.

Piano tuning requires the practitioner to perform successive navigation between tuned and untuned notes in which the beat rate between notes is used as a form of “signpost.” Traditionally, tuning starts with tuning a single note to a standard tuning fork. A two-note chord is then played, comprising the tuned note and another note. The two notes contain multiple frequencies at the fundamental and higher harmonics, and certain harmonics in the two notes occur close to each other and produce beats fluctuations in the envelope of the combined harmonics at a rate equal to their frequency difference (Fig. 1A). The piano tuner is required to detect a particular beat rate corresponding to the interval between the two notes played, and match that to a specific value. A further interval is then tuned based on the most recently tuned note and another note, and this process is repeated iteratively (Fig. 2A). The beat rate and the frequency region in which the beat is to be detected vary for different intervals but are fixed for any given interval with beat rates that are typically less than 20 Hz (Table 1). Country:Italy

Posted in Uncategorized and tagged