[Effect of electric stimulation of the locus coeruleus on transcallosal response in parietal associative cortex of the cat brain].

The influence of conditioning locus coeruleus (LC) stimulation on various components of transcallosal field response was investigated in the parietal cortex of the cat brain. Conditioning LC simulation caused a decrease in fast positive wave amplitude and facilitated slow negative wave. It is concluded that LC suppresses excitatory and facilitates inhibitor processes evoked in the parietal cortex by transcallosal stimulation.

[The effect of electrical stimulation of the locus coeruleus on the neuronal activity of the parietal associative cortex].

In experiments performed on cats operated under ketamine anaesthesia and subsequently immobilized by myorelaxin it was demonstrated that locus coeruleus (LC) being stimulated by a train of pulses can exert influence on 79% of parietal cortex neurons. Inhibition of the background activity for 300-700 ms or a decrease in its frequency by 16-32% were observed in them after the LC stimulation. During intracellular recording neurons with background activity and "silent" neurons responded to LC stimulation by hyperpolarization (5-7 mV) lasting for 120-500 ms with latency of 30-90 ms.

[Topography of catecholamine-containing neurons of the locus coeruleus in the cat].

Topography of catecholamine-containing (CA) neurons of the cat locus coeruleus was studied using a combination of the catecholamine histofluorescence method and rapid embedding of the brain tissue into the paraffin wax. The distribution of CA neurons was examined at frontal and sagittal sections of the brain stem. Unlike that shown previously the quantity of CA neurons in the rostral pole of the locus coeruleus was somewhat higher while at the frontal level of P--2.

[Distribution of norepinephrine-containing neurons projecting to the parietal associative cortex and spinal cord in the cat locus coeruleus].

The distribution of neurons projecting to the parietal associative cortex and spinal cord in the locus coeruleus (LC) of the cat was examined by the retrograde transport of the horseradish peroxidase (HRP) and catecholamine histofluorescence technique. It was demonstrated that neurons projecting to the parietal cortex were localized predominantly in the dorsal LC and the most dense labeling was observed at the coronal section corresponding to frontal plane P-1. Neurons projecting to the spinal cord were concentrated in the ventral LC and the largest quantity of labeled neurons was found in the frontal plane P-3.