Changes in rat brain gangliosides following active avoidance conditioning

Brain gangliosides of rats trained in a conditioned avoidance Sidman task and undisturbed rats in their cages were studied. The (14C) acetate was injected intracerebrally seven days before the starting of 30 days training. Thirty-seven days after injection all rats were killed and ganglioside fractions were isolated from neocortex, hippocampus, brain stem, cerebellum and residual cerebral tissue of each one brain. Trained rats had higher levels of (14 C)-labeled polysialogangliosides (G1, G2, G3) in hippocampus and neocortex than the controls. Regarding the rest of the brain areas, a significant increase of G2 in the residual cerabral tissue of the trained as compared with the controls was found. The results suggest that the sialic acid rich gangliosides of only certain parts of the brain are affected by the Sidman avoidance conditioning of the animals. © 1977

Oculomotor areas of the primate frontal lobes: A transneuronal transfer of rabies virus and [14C]-2-deoxyglucose functional imaging study

We used the [14C]-2-deoxyglucose method to study the location and extent of primate frontal lobe areas activated for saccades and fixation and the retrograde transneuronal transfer of rabies virus to determine whether these regions are oligosynaptically connected with extraocular motoneurons. Fixation-related increases of local cerebral glucose utilization (LCGU) values were found around the fundus of the inferior limb of the arcuate sulcus (AS) just ventral to its genu, in the dorsomedial frontal cortex (DMFC), cingulate cortex, and orbitofrontal cortex. Significant increases of LCGU values were found in and around both banks of the AS, DMFC, and caudal principal, cingulate, and orbitofrontal cortices of monkeys executing visually guided saccades. All of these areas are oligosynaptically connected to extraocular motoneurons, as shown by the presence of retrogradely transneuronally labeled cells after injection of rabies virus in the lateral rectus muscle. Our data demonstrate that the arcuate oculomotor cortex occupies a region considerably larger than the classic, electrical stimulation-defined, frontal eye field. Besides a large part of the anterior bank of the AS, it includes the caudal prearcuate convexity and part of the premotor cortex in the posterior bank of the AS. They also demonstrate that the oculomotor DMFC occupies a small area straddling the ridge of the brain medial to the superior ramus of the AS. Our results support the notion that a network of several interconnected frontal lobe regions is activated during rapid, visually guided eye movements and that their output is conveyed in parallel to subcortical structures projecting to extraocular motoneurons