Therapy mediated speech motor processing investigated by MRI,. fMRI and ... India). Objective: To observe the impact of rehabilitation on motor proc- essing and real-time ... MR scanner (Avanto, Siemens, Germany) using head coil and visual.
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Fig. 1 (171). 172 Therapy mediated speech motor processing investigated by MRI, fMRI and spectrogram S. Gudwani, M. Behari, M. Saxena, S.S. Kumaran (New Delhi, India) Objective: To observe the impact of rehabilitation on motor processing and real-time articulatory movements during speech production. Background: In Parkinson’s disease (PD) speech perceptual features are due to reduced articulatory displacements and improper coordination of muscle groups for consonant production. These skilled motor programs for articulatory and respiratory movements are controlled by cerebral cortex and basal ganglia that deteriorate
gradually with progressive degeneration. The training can induce plasticity in motor areas that supports the production and refinement of skilled movement sequences. These changes are studied by using behavioral assessments and functional magnetic resonance imaging (fMRI). Methods: The pilot study included six PD subjects and were clinically scored according to UPDRS-III, Hoehn and Yahr stages and Frenchay’s dysarthria Scale in ‘on-state’. Imaging was done in 1.5T MR scanner (Avanto, Siemens, Germany) using head coil and visual stimuli was presented using MR compatible binocular goggles (Nordic Neuro Lab, Norway) that was read aloud by the subject. The single shot echo-planar imaging (EPI) sequence was used to observe the cortical BOLD (blood oxygen level dependent) activity. The
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spatio-temporal real-time dynamics of articulation was done by 2Dsingle slice ‘trufi’ sequence in sagittal view of vocal tract. Spectrogram analysis was done on Wavesurfer and praat softwares. All the investigations were done at recruitment (baseline) and after rehabilitation of 24 weeks (follow-up). Results: The results showed that there was improved post-therapy precision in the articulatory movement parameters: tongue tip distance, contact location, precision of contact, distance of groove, grooving, velic aperture (for nasality), opening of epiglottis & elevation of larynx (voicing). These articulatory-precisions correlated with the spectrogram analysis done post-therapy. The BOLD activity is explained in terms of the effort made during articulatory and respiratory movements. Conclusions: Post rehabilitation improvement is observed in speech motor processing, communicability and functionality.
173 Initial human PET studies with [18F]PR04.MZ for quantification of striatal and extrastriatal dopamine transporters V. Kramer, C. Juri, P. Chana, R. Pruzzo, M. Piel, A. Amaral, M. Avila, F. R€ osch, H. Amaral (Santiago, Chile) Objective: To report initial human PET studies with [18F]PR04.MZ a high affine and selective dopamine transporter (DAT) ligand for quantification of striatal and extra striatal DATs. Background: The DAT is considered to be a valuable target for preclinical detection of neurodegenerative diseases and its availability correlates with striatal dopamine concentration and clinical severity of Parkinson’s disease. Methods: Three Healthy male subjects (mean age 47 years) underwent a dynamic PET scan (Siemens mCT) for a duration of 2 h after bolus injection of 165 6 15 MBq (mean 6 SD) [18F]PR04.MZ. Data analysis using noninvasive Simplified Reference Tissue Model (SRTM) method and Cerebellum as reference was performed for estimation of binding potential in different brain regions. Results: Highest tracer uptake was observed in putamen and caudate nucleus after 25 minutes followed by slow washout. The tissueto-cerebellum ratio in putamen, caudate nucleus and midbrain region reached a maximum of about 23.5, 21.5 and 5 after 75, 70 and 45 minutes, respectively and remained nearly constant till end of scan. Binding Potential determined using SRTM method were 16 6 0.3, 14 6 1.5 and 2.6 6 0.3 (mean 6 SD) respectively. Main excretion pathways were urinary and gastrointestinal elimination as determined by whole-body scan after 2 h and bone uptake of 18F-fluoride as main metabolite was observed.
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Conclusions: [18F]PR04.MZ showed a relatively fast kinetic and very high specific uptake in DAT rich regions in the human brain and seems to be a promising tool for striatal an extra striatal DAT quantification. Although it has been shown that noninvasive SRTM may be applied for data analysis this still has to be proved by comparison with invasive methods and is part of current studies.
174 Neural correlates of levodopa-responsive vs. levodopa-resistant freezing of gait in Parkinson’s disease: A PET study A. Maillet, S. Thobois, V. Fraix, P. Derost, B.R. Bloem, P. Krack, S. Chabarde`s, P. Pollak, B. Deb^ u (Grenoble, France) Objective: To explore the effects of levodopa and PPN stimulation on the cerebral networks activated during motor imagery of gait in patients with levodopa-responsive (L1) or levodopa-resistant (L-) freezing of gait (FoG). Background: Recent imaging studies have shed some light on the neural correlates of gait control in parkinsonian patients with and without gait impairment. However, the influence of dopaminergic treatments or that of pedonculopontine nucleus (PPN) stimulation on these networks remains unclear. Methods: Eight L1FoG patients, three L-FoG patients and eight controls were included. All participants performed a motor imagery of gait and a control tasks during H2015-PET acquisitions. The L1FoG patients were tested both OFF and ON medication, and the L-FoG patients OFF and ON PPN stimulation. Results: Contrasting motor imagery of gait – control tasks revealed activations within the sensorimotor areas, basal ganglia (BG), and cerebellum in controls. In L1FoG patients OFF medication, we observed activations within superior parietal lobule (SPL) and pontine nuclei. Levodopa administration restored activations in the BG loop while reducing the SPL and Pontine nuclei activations. L-FoG patients OFF PPN stimulation showed activation within the SPL. PPN stimulation restored activations within the BG, cerebellum, and brainstem, and reduced activation of the SPL. Conclusions: Our PET data suggest that L1FoG may reflect the worsened expression of PD akinesia. SPL activations could reflect a compensatory loop that is recruited, together with the pontine nuclei, when patients are OFF treatment. L-FoG seems to involve dysfunction of both the BG and cerebellum loops, which are restored under PPN stimulation. The compensatory SPL loop may become less efficient with disease progression, leading to L-FOG.
