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

Abstract

The aim of the study is to investigate morphofunctional circuits underlying musical hallucinations (MH) in a 72-years old female that underwent a simultaneous 18fluoredeoxyglucose positron emission tomography (PET) and advanced magnetic resonance (MR) exam. This represents a particular case of MH occurred in an healthy subject, not displaying neurological or psychopathological disorders, and studied simultaneously with a multimodal approach. For the resting-state fMRI analysis a seed to seed approach was chosen. For the task-based fMRI, 4 different auditory stimuli were presented. Imaging findings were compared with data obtained by ten healthy controls matched for age and sex. Neuropsychological evaluation and questionnaires investigating depression and anxiety were also administered. PET findings showed hypermetabolism of: superior temporal gyri, anterior cingulate, left orbital frontal, and medial temporal cortices. Structural MRI did not show macroscopical lesions except for gliotic spots along the uncinate fascicle pathways with an increased cortical thickness for the right orbitofrontal cortex (p = 0.003). DTI showed increased fractional anisotropy values in the left uncinate fascicle, when compared to controls (p = 0.04). Resting-state fMRI showed increased functional connectivity between the left inferior frontal gyrus and the left temporal fusiform cortex (p = 0.01). Task-based fMRI confirmed PET findings showing an increased activation of the superior temporal gyrus in all the auditory tasks except for the monotone stimulus, with a significant activation of the left orbital frontal cortex only during the song in foreign language, object of MH. Results on cognitive test did not show cognitive impairment, excepting for the performance on Frontal Assessment Battery where the patient fails in the cognitive domains of conceptualization, sensitive to interference, and inhibitory control. The subject did not show depressive or anxiety symptoms. Summarizing, multimodal imaging analyses in the MH case showed a microstructural alteration of the left uncinate fascicle paralleled by an increased metabolism and functional connectivity of cortical regions that receive left uncinate projections (orbital frontal cortex, and medial temporal cortex). This alteration of fronto-hyppocampal circuits could be responsible of retrieval of known songs even in the absence of real stimuli.

Tasked-Based Functional Brain Connectivity in Multisensory Control of Wrist Movement After Stroke

“…The activation patterns seen in the neurologically intact control group revealed that wrist movement during single and multisensory search tasks elicits activation patterns mainly in the contralateral sensorimotor, and the bilateral premotor and somatosensory association cortices (Figure 2). As expected, the visual feedback task produced additional activation in the occipital lobe (44–46), while the auditory feedback produced activation in the temporal and superior occipital gyrus (47–49). Interestingly, the combined audiovisual condition in young adults also recruited areas in the dorsolateral prefrontal cortex and the bilateral posterior parietal cortex.…”

Gliosis and Neurodegenerative Diseases: The Role of PET and MR Imaging

“…Indeed, this innovative clinical diagnostic scanner allows to combine the functional specificity of PET radiotracers (e.g., targeting metabolism, hypoxia, inflammation, specific ligands, or receptors) to both high-resolution and multiparametric information derived by MR in a single imaging acquisition session (Herzog et al, 2010;Aiello et al, 2019). This simultaneity of findings achievable by PET/MR, if useful for reciprocal technical adjustments regarding temporal and spatial cross-modal alignment/synchronization, opens still debated insights about its clinical value in neurological patients, possibly incompliant and highly variable from a clinical point of view (Zaidi and Guerra, 2011;Cavaliere et al, 2018b).…”

“…However, stand-alone PET imaging is still limited by low spatial resolution, that obliges it to be co-registered to an higher resolution imaging techniques, such as CT and MR. Compared to CT, MRI provides different quantitative information (e.g., water and metabolites diffusion, metabolites concentrations, regional perfusion, and activation), simply modifying sequences' parameters, representing the gold standard for soft tissue and brain study and providing complementary information compared to PET imaging (Cavaliere et al, 2018b;Marchitelli et al, 2018). Moreover, the higher contrast resolution provided by MR can be more suitable for the segmentation of regions of reference useful to normalize PET signal in order to extract quantitative uptake parameters.…”

“…While, similarly to PET/CT scanners, findings derived by MRI and PET can be sequentially achieved in two different times, for highly dynamic systems like the brain this temporal gap could bias intermodality comparison. Indeed, sequential approach supposes that no significant modifications have occurred in the underlying state of the subject between two imaging sessionsa statement that could be ineffective both in physiological terms (e.g., changes in cognitive states or alertness) and in pathological conditions (e.g., psychiatric or neurological disorders) or as a result of medical interventions through psychological counseling, drugs or electrical/magnetic brain stimulations Cavaliere et al, 2018b). For these reasons, hybrid PET/MR scanners allow to overcome these limitations by simultaneously acquiring morphological, functional, molecular or metabolic information derived by both MRI and PET in a single shot.…”

Simultaneous EEG-fMRI for Functional Neurological Assessment

“…Since from its development, fMRI technique has been applied to characterize brain functional connectivity in several physiological conditions (26, 27) and many diseases, including brain tumors (28), multiple sclerosis (29), Alzheimer's diseases (AD) (30, 31), epilepsy (32), but also psychiatric disorders (33, 34).…”