Hypophonia in Parkinson's disease: neural correlates of voice treatment revealed by PET.
OBJECTIVE
To investigate the neural correlates of hypophonia in individuals with idiopathic PD (IPD) before and after voice treatment with the Lee Silverman Voice Treatment method (VT) using (15)O-H(2)O PET.


METHODS
Regional cerebral blood flow (rCBF) changes associated with overt speech-motor tasks relative to the resting state were measured in the IPD subjects before and after VT, and in a group of healthy control volunteers.


RESULTS
Behavioral measures of voice loudness significantly improved following treatment. Before VT, patients had strong speech-related activations in motor and premotor cortex (M1-mouth, supplementary motor cortex [SMA], and inferior lateral premotor cortex [ILPm]), which were significantly reduced post-VT. Similar to the post-treatment session, premotor activations were absent (SMA) or below statistical threshold (M1-mouth) in the healthy control group. In addition, following VT treatment, significant right-sided activations were present in anterior insular cortex, caudate head, putamen, and dorsolateral prefrontal cortex (DLPFC). Finally, the VT-induced neural changes were not present with transient experimenter-cued increases of loudness in VT-untreated patients.


CONCLUSIONS
Effective improvement of IPD hypophonia following voice treatment with VT was accompanied by a reduction of cortical motor-premotor activations, resembling the functional pattern observed in healthy volunteers and suggesting normalization, and additional recruitment of right anterior insula, caudate head, putamen, and DLPFC. This treatment-dependent functional reorganization suggests a shift from an abnormally effortful (premotor cortex) to a more automatic (basal ganglia, anterior insula) implementation of speech-motor actions.
Liotti
M
M
Research Imaging Center, Department of Medicine, University of Texas Health Science Center at San Antonio, TX, USA. mario.liotti@nottingham.ac.uk
Ramig
L O
LO
Vogel
D
D
New
P
P
Cook
C I
CI
Ingham
R J
RJ
Ingham
J C
JC
Fox
P T
PT
D000368:Aged; D001479:Basal Ganglia / Q000000981:diagnostic imaging / Q000503:physiopathology; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology; D010699:Phonation; D011932:Reading; D012016:Reference Values; D014055:Tomography, Emission-Computed; D016896:Treatment Outcome; D014705:Verbal Behavior; D014832:Voice Disorders / Q000150:complications / Q000175:diagnosis* / Q000534:rehabilitation*; D014834:Voice Training