Monday, April 23, 2007

Briefer on basal ganglia

Here is a description of the basel ganglia that Rafael sent to me. Actually, it's from Per Alm and published in the proceedings for the IFA conference in Dublin 2006.

The basal ganglia circuits are organized in a direct and an indirect pathway. These two pathways are assumed to work in synergy to modulate the activity of the frontal cortex: the indirect pathway providing a diffuse inhibition of cortical activity and the direct pathway providing focused activation of the desired action. Furthermore, the two pathways are dominated by different types of dopamine receptors, D1 vs. D2, resulting in differential effects of dopamine. The cueing functions of the basal ganglia to the SMA are dependent on a clear distinction between focal activation and the surround inhibition of the cortex, in other words, a good signal-to-noise ratio. Based on this model it is easy to imagine that the cueing of the basal ganglia can be distorted in different ways. Too weak focal activation of the direct pathway would result in deficient activation of the desired action, for example difficulties in initiating speech movements. On the other hand, impaired diffuse inhibition of the cortex, provided by the indirect pathway, could result in a combination of release of unintended movements and impaired release of the intended movement. These scenarios have clear parallels with the symptoms of stuttering. Basal ganglia motor disorders are characterized by motor initiation problems, involuntary movements, and deregulated muscular tension, often with co-contraction of antagonistic muscles.

3 comments:

manuel said...

Hi,
i found an interesting paper about this topic.

here is the link:

http://www.uth.tmc.edu/clinicalneuro/
institute/2006/Vargha-Khadem%20Readings/
Alm%202004.pdf

Anonymous said...

C'est vraiment très intéressant. J'ai traduit l'article de Per Alm en français, et j'ignorais qu'il y avait un rapport entre le bgt et cela.

Olivier LB

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