Fronto-Temporal Circuits in Musical Hallucinations: A PET-MR Case Study

Area of Science:

• Neuroscience
• Medical Imaging

Background:

• Musical hallucinations (MH) are complex auditory phenomena.
• Investigating the neural basis of MH in healthy individuals offers unique insights.
• Multimodal imaging is crucial for understanding intricate brain circuits.

Purpose of the Study:

• To investigate the morphofunctional brain circuits underlying musical hallucinations (MH).
• To examine a unique case of MH in a healthy subject using simultaneous PET and advanced MR imaging.
• To compare imaging findings with healthy controls and assess cognitive and emotional states.

Main Methods:

• Simultaneous 18-fluorodeoxyglucose positron emission tomography (PET) and magnetic resonance (MR) imaging.
• Resting-state and task-based functional MRI (fMRI), including seed-to-seed analysis.
• Diffusion tensor imaging (DTI) and neuropsychological evaluations.

Main Results:

• PET showed hypermetabolism in the superior temporal, anterior cingulate, orbitofrontal, and medial temporal cortices.
• Structural MRI revealed gliotic spots in the uncinate fascicle and increased right orbitofrontal cortical thickness.
• DTI indicated increased fractional anisotropy in the left uncinate fascicle; fMRI showed altered connectivity in fronto-temporal regions.

Conclusions:

• Multimodal imaging identified microstructural alterations in the left uncinate fascicle and increased metabolism/connectivity in associated cortical regions.
• Altered fronto-hippocampal circuits may explain the retrieval of familiar songs in the absence of real auditory stimuli.
• The findings contribute to understanding the neural underpinnings of musical hallucinations in healthy individuals.