Monday, January 09, 2006

Is PDS research as exciting??

Here is another interesting talk on preliminary brain imaging results by Kell, Neumann, and Giraud: I know Katrin Neumann and I have spoken to Anne-Lise Giraud once. I googled Christian Kell, and he is most web-famous for scanning the cortex representation on the penis! See here. Apparently, the region is very small! (contrary to the commonly presented picture! See above) Dispelling the terribly dangerous myth created by sexist females that men are controlled by their... I am wondering whether Kell finds his research of PDS as exciting?! :-)

The researchers from Frankfurt claim that prosodic production tasks during fMRI reveal functional deficits in stutterers. Prosody can be defined as the patterns of stress, intonation and timing in a language. They say that both groups with or without PDS show similar performances, but have different brain activation. I am not sure what to think. From my personal experience, I seem to be far more fluent when I actively control the prosody of my speech. It feels a bit like singing, or chorus reading. So even if abnormal, the prosody neural network seems to help me to be more fluent. But of course, this might only be the case when I actively control my prosody and on automatic mode it becomes unstable? How does this fit with the dual premotor systems hypothesis Per Alm has been advocating: see here? Not sure how their results would fit in. I don't think they have published the findings yet. I guess they are in the review process.

Here is the abstract:
Persistent developmental stuttering can be interpreted as the result of impaired linguistic motor executive function. Previous studies revealed pathologies in somatomotor as well as language-related cortices of stutterers. Frontal opercular regions (Broca and its right-hemispheric homologue) appear differentially activated in stutterers when compared with healthy controls. Stutterers seem to compensate their defect spontaneously via an activation of the right frontal operculum, while after fluency-shaping therapy a more left-lateralized frontal activation can be observed. Based on these findings, we sought to preferentially activate either the left or the right frontal lobe. Prosody perception usually involves lateralized cortical networks depending on whether it emphasises linguistic or emotional features. We therefore hypothesized that a similar functional lateralization should be observed in frontal regions during speech production emphasizing different prosodic features. While production of linguistic prosody should predominantly activate left-hemispheric regions, emotional prosody should reveal a more right-hemispheric network. The production of linguistic prosody should therefore reveal in a very selective manner relative left-hemispheric deactivations in stutterers, while production of emotional prosody should tell us more about the functional meaning of right frontal overactivations in stutterers relative to controls. After confirming functional lateralization of spoken prosody in normal subjects we compared activations in stutterers and controls. Despite similar behavioural performances, we found a very circumscribed left frontal deactivation in stutterers in the linguistic prosodic task in BrocaÂ’s area. The emotional prosodic task activated larger fronto-temporal networks in stutterers, but no significant differences were found in the group analysis. Our results delineate a focal functional lesion in the stutterersÂ’ left language executive network, which may require compensation by BrocaÂ’s right homologue.

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