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Setting up the speech production network: how oscillations contribute to lateralized information routing.

Gehrig J, Wibral M, Arnold C, Kell CA - Front Psychol (2012)

Bottom Line: This MEG study focuses on the spectro-temporal dynamics that contribute to the setup of this network.While a broadband low frequency effect was found for any task preparation in bilateral prefrontal cortices, preparation for overt speech production was specifically associated with left-lateralized alpha and beta suppression in temporal cortices and beta suppression in motor-related brain regions.Beta phase coupling in the entire speech production network was modulated by anticipation of overt reading.

View Article: PubMed Central - PubMed

Affiliation: Cognitive Neuroscience Group, Department of Neurology, Brain Imaging Center, Goethe University Frankfurt, Germany.

ABSTRACT
Speech production involves widely distributed brain regions. This MEG study focuses on the spectro-temporal dynamics that contribute to the setup of this network. In 21 participants performing a cue-target reading paradigm, we analyzed local oscillations during preparation for overt and covert reading in the time-frequency domain and localized sources using beamforming. Network dynamics were studied by comparing different dynamic causal models of beta phase coupling in and between hemispheres. While a broadband low frequency effect was found for any task preparation in bilateral prefrontal cortices, preparation for overt speech production was specifically associated with left-lateralized alpha and beta suppression in temporal cortices and beta suppression in motor-related brain regions. Beta phase coupling in the entire speech production network was modulated by anticipation of overt reading. We propose that the processes underlying the setup of the speech production network connect relevant brain regions by means of beta synchronization and prepare the network for left-lateralized information routing by suppression of inhibitory alpha and beta oscillations.

No MeSH data available.


Related in: MedlinePlus

Comparison of behavioral task set effects from 84 participants with the temporal evolution of oscillations in the actual study. Instruction delay between cue and target presentation varied between 330, 670, and 1000 ms. Reaction time was measured as speech onset for neutral (dark gray) and happy intonation (light gray) after target presentation. Error bars indicate standard error, *significance at p < 0.05 corrected. Note that the set up of the speech production network coincides with occurrence of alpha and beta suppression.
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Figure 9: Comparison of behavioral task set effects from 84 participants with the temporal evolution of oscillations in the actual study. Instruction delay between cue and target presentation varied between 330, 670, and 1000 ms. Reaction time was measured as speech onset for neutral (dark gray) and happy intonation (light gray) after target presentation. Error bars indicate standard error, *significance at p < 0.05 corrected. Note that the set up of the speech production network coincides with occurrence of alpha and beta suppression.

Mentions: The effects specifically related to speech preparation were preceded by condition-independent preparatory effects. An early posterior alpha and beta suppression which likely originated from parietal sources was accompanied by a prefrontal increase in low frequencies ranging from 2 to 15 Hz. Importantly, this low frequency effect was not modulated by specific task content and was thus observed during task preparation both for overt and for covert reading. Given that there is considerable debate on what broad band effects signify, the mechanisms behind such an effect have to be studied in more detail. Such fronto-parietal activity – although unlikely oscillatory in nature – could reflect the executive control of implementing a “task set” (Dosenbach et al., 2006; Sakai and Passingham, 2006). Given that this activity did not differ between conditions, the tasks seem to have required similar amounts of executive control. The observed time courses of this activity suggest that the first 350 ms after cue presentation are used to decode the instruction and to generate the appropriate rules for behavioral control. Changes specific to the set up of the speech production network (sensorimotor alpha and beta suppression) were only detected after 350 ms. This indicates that it takes at least this time to set up this large scale network. To test this claim, we performed an additional behavioral study under the assumption that short instruction delays of less than 350 ms do not allow a proper setup of the speech production network resulting in increased reaction times measured as speech onset after target presentation. Indeed, shortening instruction delays to 330 ms increased reaction time in overt reading tasks (Figure 9). This suggests that this duration does not allow for a proper setup of the speech production network, extending network setup well into the execution phase which in turn delays speech onset. We thus believe that sensorimotor alpha and beta suppression is essential to set up the speech production network.


Setting up the speech production network: how oscillations contribute to lateralized information routing.

Gehrig J, Wibral M, Arnold C, Kell CA - Front Psychol (2012)

Comparison of behavioral task set effects from 84 participants with the temporal evolution of oscillations in the actual study. Instruction delay between cue and target presentation varied between 330, 670, and 1000 ms. Reaction time was measured as speech onset for neutral (dark gray) and happy intonation (light gray) after target presentation. Error bars indicate standard error, *significance at p < 0.05 corrected. Note that the set up of the speech production network coincides with occurrence of alpha and beta suppression.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3368321&req=5

Figure 9: Comparison of behavioral task set effects from 84 participants with the temporal evolution of oscillations in the actual study. Instruction delay between cue and target presentation varied between 330, 670, and 1000 ms. Reaction time was measured as speech onset for neutral (dark gray) and happy intonation (light gray) after target presentation. Error bars indicate standard error, *significance at p < 0.05 corrected. Note that the set up of the speech production network coincides with occurrence of alpha and beta suppression.
Mentions: The effects specifically related to speech preparation were preceded by condition-independent preparatory effects. An early posterior alpha and beta suppression which likely originated from parietal sources was accompanied by a prefrontal increase in low frequencies ranging from 2 to 15 Hz. Importantly, this low frequency effect was not modulated by specific task content and was thus observed during task preparation both for overt and for covert reading. Given that there is considerable debate on what broad band effects signify, the mechanisms behind such an effect have to be studied in more detail. Such fronto-parietal activity – although unlikely oscillatory in nature – could reflect the executive control of implementing a “task set” (Dosenbach et al., 2006; Sakai and Passingham, 2006). Given that this activity did not differ between conditions, the tasks seem to have required similar amounts of executive control. The observed time courses of this activity suggest that the first 350 ms after cue presentation are used to decode the instruction and to generate the appropriate rules for behavioral control. Changes specific to the set up of the speech production network (sensorimotor alpha and beta suppression) were only detected after 350 ms. This indicates that it takes at least this time to set up this large scale network. To test this claim, we performed an additional behavioral study under the assumption that short instruction delays of less than 350 ms do not allow a proper setup of the speech production network resulting in increased reaction times measured as speech onset after target presentation. Indeed, shortening instruction delays to 330 ms increased reaction time in overt reading tasks (Figure 9). This suggests that this duration does not allow for a proper setup of the speech production network, extending network setup well into the execution phase which in turn delays speech onset. We thus believe that sensorimotor alpha and beta suppression is essential to set up the speech production network.

Bottom Line: This MEG study focuses on the spectro-temporal dynamics that contribute to the setup of this network.While a broadband low frequency effect was found for any task preparation in bilateral prefrontal cortices, preparation for overt speech production was specifically associated with left-lateralized alpha and beta suppression in temporal cortices and beta suppression in motor-related brain regions.Beta phase coupling in the entire speech production network was modulated by anticipation of overt reading.

View Article: PubMed Central - PubMed

Affiliation: Cognitive Neuroscience Group, Department of Neurology, Brain Imaging Center, Goethe University Frankfurt, Germany.

ABSTRACT
Speech production involves widely distributed brain regions. This MEG study focuses on the spectro-temporal dynamics that contribute to the setup of this network. In 21 participants performing a cue-target reading paradigm, we analyzed local oscillations during preparation for overt and covert reading in the time-frequency domain and localized sources using beamforming. Network dynamics were studied by comparing different dynamic causal models of beta phase coupling in and between hemispheres. While a broadband low frequency effect was found for any task preparation in bilateral prefrontal cortices, preparation for overt speech production was specifically associated with left-lateralized alpha and beta suppression in temporal cortices and beta suppression in motor-related brain regions. Beta phase coupling in the entire speech production network was modulated by anticipation of overt reading. We propose that the processes underlying the setup of the speech production network connect relevant brain regions by means of beta synchronization and prepare the network for left-lateralized information routing by suppression of inhibitory alpha and beta oscillations.

No MeSH data available.


Related in: MedlinePlus