[Direct connections between the hippocampus and the retrosplenial cortex in the rat]

The connections of the retrosplenial field of the limbic cortex and hippocampal formation in the rat were studied by the horseradish peroxidase method. After dry horseradish peroxidase application into dorsocaudal part of the retrosplenial cortex labelled cells were found in the rostral pole of the hippocampal field Ca3 and in the presubiculum. After ionophoretic injection of HRP into the rostral pole of the hippocamp labelled cells were found in the layers V and VI of the retrosplenial field of the limbic cortex and in the prosubiculum. The data obtained show reciprocal direct connections between the rostral pole of the hippocamp and retrosplenial field of the limbic cortex, as well as direct efferent projections of the dorsal subiculum to the rostral pole of the hippocamp.