Differential contribution of motor cortex and caudate nucleus to instrumental tongue-forelimb synchronization in rats: a functional ablation study.
The functional ablation technique was used to assess the role of motor cortex and caudate nucleus in a complex skilled movement. Rats were trained to synchronize tongue and forepaw movements in a drinking box equipped with a retractable spout which was automatically withdrawn after every lick but could be returned by pressing and releasing a lever placed 4 cm below the spout. The animals learned to perform short presses synchronized with the lick cycle in such a way as to allow continuous drinking. Neural circuits implementing these lick-associated instrumental movements were blocked by intracranial injection of 10 ng of tetrodotoxin. Bilateral blockade of the motor cortex interfered with lick-synchronized bar pressing, but did not significantly influence licking from a stationary spout. Both licking and bar-pressing were impaired by bilateral injection of tetrodotoxin into the lateral part of the caudate nucleus for the duration of the tetrodotoxin-induced inactivation of the target region. The instrumental tongue-forelimb synchronization recovered considerably later, i.e. after two to three days. Functional blockade of the medial part of the caudate nucleus caused only a partial impairment of lick-synchronized bar pressing lasting less than 7 h and did not significantly influence consummatory licking. It is concluded that the tongue-forepaw synchronization is disrupted by blockade of motor cortex or lateral caudate considerably longer than the performance of the isolated component movements.
Zhuravin
I A
IA
Institute of Physiology, Academy of Sciences, Prague, Czech Republic.
Brozek
G
G
Bures
J
J
D000818:Animals; D002421:Caudate Nucleus / Q000187:drug effects / Q000502:physiology*; D003216:Conditioning, Operant; D004327:Drinking Behavior / Q000502:physiology*; D005246:Feedback; D005552:Forelimb / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000187:drug effects / Q000502:physiology*; D011597:Psychomotor Performance; D051381:Rats; D013779:Tetrodotoxin / Q000633:toxicity; D014059:Tongue / Q000502:physiology*
D013779:Tetrodotoxin