Objective: Examine Parkinson’s disease (PD) related changes in the speech production network (SPN) and its reaction to emotional distraction.

Background: PD can cause speech alterations [1] and emotional processing impairments [2]. Using a picture naming task with an affective priming component, we compared the SPN of PD patients to that of healthy controls (HC) and characterized differences in susceptibility to emotional distraction.

Method: We used 3T fMRI data of a picture naming task to determine whole-brain functional networks [3] of 14 PD patients (aged 59.6 ± 10.1, 5 f/9 m) and 23 HC (aged 64.1 ± 6.5, 12 f/ 11 m) in a neutral and an affective condition (neutral vs. disgusted facial prime). We assessed five network metrics (network density, mean nodal degree, nodal strength, clustering coefficient and global efficiency) and did a qualitative hub analysis. Hubs were defined as having a nodal degree or nodal strength at least 1 SD above the mean. Using the hubs’ participation coefficient (pc), we classified them as connector hubs (pc within top 10% of hubs; facilitating intermodular communication) or provincial hubs (all others; facilitating intramodular communication). We assessed statistical differences in metrics with permutation t-tests (20.000 randomizations, p<0.05).

Results: In the neutral condition, the PD SPN differed from the HC SPN in terms of mean nodal degree (HC: 0.489±0.229; PD: 0.244±0.127; p<0.05), mean nodal strength (HC: 0.072±0.036; PD: 0.035±0.018; p<0.05) and mean clustering coefficient (HC: 0.117±0.022; PD: 0.096±0.024; p<0.05). In PD, affective priming led to an increase in mean nodal degree (neutral: 0.244±0.127; affective: 0.324±0.165; p<0.05) and in mean nodal strength (neutral: 0.035±0.018; affective: 0.044±0.023; p<0.05). In HC, only the mean clustering coefficient (neutral: 0.117±0.022; affective: 0.121±0.019; p<0.05) was affected. HC had nine connector hubs in the neutral, but none in the affective condition. Patients had no connector hubs in either condition. The number of provincial hubs increased in HC in the affective condition (31 vs. 38), but remained stable for patients (45 vs. 44).

Conclusion: We showed that the PD SPN differs from that of HC and is affected differently by emotional distraction. As intermodular communication was already strongly diminished in PD in neutral speech processing, affective priming had a less detrimental effect on communication patterns than in HC.

References: [1] Ho, A. K., Iansek, R., Marigliani, C., Bradshaw, J. L., & Gates, S. (1998). Speech impairment in a large sample of patients with Parkinson’s disease. Behavioural neurology, 11(3), 131–137. [2] Enrici, I., Adenzato, M., Ardito, R. B., Mitkova, A., Cavallo, M., Zibetti, M., Lopiano, L., & Castelli, L. (2015). Emotion processing in Parkinson’s disease: a three-level study on recognition, representation, and regulation. PloS one, 10(6), e0131470. [3] Bullmore, E., & Sporns, O. (2009). Complex brain networks: graph theoretical analysis of structural and functional systems. Nature reviews neuroscience, 10(3), 186-198.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/the-influence-of-affective-priming-on-the-speech-production-network-in-parkinsons-disease/