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The neurobiology of cortical music representations
Music is undeniable one of humanity’s defining traits, as it has been documented since the earliest days of mankind, is present in all knowcultures and perceivable by all humans nearly alike. Intrigued by its omnipresence, researchers of all disciplines started the investigation of music’s mystic...
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| Format: | Dissertation |
| Sprache: | Englisch |
| Veröffentlicht: |
Philipps-Universität Marburg
2020
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| Online Zugang: | PDF-Volltext |
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| Zusammenfassung: | Music is undeniable one of humanity’s defining traits, as it has been documented since the earliest
days of mankind, is present in all knowcultures and perceivable by all humans nearly alike.
Intrigued by its omnipresence, researchers of all disciplines started the investigation of music’s
mystical relationship and tremendous significance to humankind already several hundred
years ago. Since comparably recently, the immense advancement of neuroscientific methods
also enabled the examination of cognitive processes related to the processing of music. Within
this neuroscience ofmusic, the vast majority of research work focused on how music, as an auditory
stimulus, reaches the brain and howit is initially processed, aswell as on the tremendous
effects it has on and can evoke through the human brain. However, intermediate steps, that is
how the human brain achieves a transformation of incoming signals to a seemingly specialized
and abstract representation of music have received less attention. Aiming to address this gap,
the here presented thesis targeted these transformations, their possibly underlying processes
and how both could potentially be explained through computational models. To this end, four
projects were conducted. The first two comprised the creation and implementation of two
open source toolboxes to first, tackle problems inherent to auditory neuroscience, thus also affecting
neuroscientific music research and second, provide the basis for further advancements
through standardization and automation. More precisely, this entailed deteriorated hearing
thresholds and abilities in MRI settings and the aggravated localization and parcellation of the
human auditory cortex as the core structure involved in auditory processing. The third project
focused on the human’s brain apparent tuning to music by investigating functional and organizational
principles of the auditory cortex and network with regard to the processing of different
auditory categories of comparable social importance, more precisely if the perception of music
evokes a is distinct and specialized pattern. In order to provide an in depth characterization
of the respective patterns, both the segregation and integration of auditory cortex regions was
examined. In the fourth and final project, a highly multimodal approach that included fMRI,
EEG, behavior and models of varying complexity was utilized to evaluate how the aforementioned
music representations are generated along the cortical hierarchy of auditory processing
and how they are influenced by bottom-up and top-down processes. The results of project 1
and 2 demonstrated the necessity for the further advancement of MRI settings and definition
of working models of the auditory cortex, as hearing thresholds and abilities seem to vary as
a function of the used data acquisition protocol and the localization and parcellation of the
human auditory cortex diverges drastically based on the approach it is based one. Project 3
revealed that the human brain apparently is indeed tuned for music by means of a specialized
representation, as it evoked a bilateral network with a right hemispheric weight that was not
observed for the other included categories. The result of this specialized and hierarchical recruitment
of anterior and posterior auditory cortex regions was an abstract music component
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that is situated in anterior regions of the superior temporal gyrus and preferably encodes music,
regardless of sung or instrumental. The outcomes of project 4 indicated that even though
the entire auditory cortex, again with a right hemispheric weight, is involved in the complex
processing of music in particular, anterior regions yielded an abstract representation that varied
excessively over time and could not sufficiently explained by any of the tested models. The
specialized and abstract properties of this representation was furthermore underlined by the
predictive ability of the tested models, as models that were either based on high level features
such as behavioral representations and concepts or complex acoustic features always outperformed
models based on single or simpler acoustic features. Additionally, factors know to influence
auditory and thus music processing, like musical training apparently did not alter the
observed representations. Together, the results of the projects suggest that the specialized and
stable cortical representation of music is the outcome of sophisticated transformations of incoming
sound signals along the cortical hierarchy of auditory processing that generate a music
component in anterior regions of the superior temporal gyrus by means of top-down processes
that interact with acoustic features, guiding their processing. |
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| Umfang: | 279 Seiten |
| DOI: | 10.17192/z2020.0001 |