Mediodorsal thalamic evoked responses in the rat prefrontal cortex: influence of the mesocortical DA system.
The prefrontal cortex (PFC) receives a dopaminergic (DA) innervation from the ventral tegmental area (VTA) and is reciprocally connected with the mediodorsal thalamic nucleus (MD). The present study was performed in anaesthetized rats to determine the influence of the mesocortical DA system on excitatory responses evoked in the PFC by stimulation of MD: (1) short latency (< 4 ms) responses resulting from activation of the MD-PFC pathway; (2) long latency responses (> 10 ms) resulting from activation of recurrent collaterals of PFC neurons projecting to MD. Local DA application and VTA stimulation did not affect short latency responses but blocked long latency responses. These results suggest that the mesocortical DA system inhibits excitations by recurrent collaterals of the PFC-MD neurones but not the excitatory MD inputs to the PFC.
Pirot
S
S
INSERM U114, Chaire de Neuropharmacologie, Collège de France, Paris, France.
Glowinski
J
J
Thierry
A M
AM
D000818:Animals; D004298:Dopamine / Q000494:pharmacology / Q000502:physiology*; D004558:Electric Stimulation; D005071:Evoked Potentials / Q000502:physiology; D006179:Gyrus Cinguli / Q000502:physiology*; D007478:Iontophoresis; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D017397:Prefrontal Cortex / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013787:Thalamic Nuclei / Q000502:physiology*; D017557:Ventral Tegmental Area / Q000502:physiology*
D004298:Dopamine