PhD Project 4
Basal ganglia thalamocortical mechanisms of cognitive control in speaking
(last update 2019-06-27)
Mounting evidence suggests that cognitive control is essential for speaking. Three important cognitive control functions are updating, inhibiting, and shifting, which seem to depend on BGTC circuitry. However, little is known about how the BGTC circuitry contributes to speaking. The aim of the proposed project is to examine whether BGTC contributions to cognitive control in speaking are (1) domain-general, (2) reflected in functional and structural connectivity, (3) affected by dopaminergic genetic variation, and (4) affected by Parkinson’s disease. Results are expected to advance theory and to have important clinical implications.
The relationship was investigated between cognitive and motor control by assessing whether updating, inhibiting and shifting abilities were influenced by response modality by comparing vocal and manual responses. Behavioural findings indicate that updating abilities are influenced by response modality; whereas, inhibiting and shifting abilities are not. These findings were reduplicated in a second fMRI study that investigated whether activation related to any of the cognitive abilities was influenced by response modality in vocal and manual neural networks. Finally, in a third study, it was assessed whether cognitive abilities in relation to response modality was further influenced by impulsivity.
Neuroimaging findings indicate that all three cognitive abilities were grounded in the vocal network, and contrary to the behavioural findings, neural activity associated with updating abilities was not influenced by response modality; whereas, neural activity associated with both shifting and inhibiting abilities was. It is postulated that shifting and inhibiting abilities interact with response modality in the vocal network at the time of selecting or executing a motor response, absolving conflict between competing responses. This conflict remains otherwise present for updating abilities as indicated by the interaction observed behaviourally. Finally, the subjective findings revealed that activation observed in the vocal network was associated with attentional impulsivity; whereas, the manual network was associated with non-planning and motor impulsivity.
All three studies suggest that cognitive and motor control are indeed closely related, and that the vocal network plays a crucial role in cognitive abilities. These results help to shape the relation between cognitive control and language network.
Behavioural findings, where it was measured whether response modality, comparing vocal and manual responses, influenced updating, inhibiting and shifting abilities were published.
Using the same stimuli/task-design the neural networks recruited during vocal and manual response modalities were investigated using fMRI; Lastly, a third study using the same behavioural task investigated whether any of the impulsivity measures (i.e. attention, motor and/or non-planning) was related to the influence of response modality on cognitive control abilities, and whether this was observed in either vocal or manual networks.
This project approaches the unresolved question of domain-specificity of language in a novel and unique way.
It is collaboration between two centres, two labs, and combines multiple empirical techniques, addressing the debate on whether cognitive control is supramodal to motor control or whether it is more modality-specific, running in parallel with motor control.