SHAPES OF RECEPTIVE-FIELD CENTERS IN OPTIC TECTUM OF GOLDFISH

An attempt was made to learn whether the shape and size of receptive field centers determined from tectal and optic nerve recordings could be used as criteria to distinguish between recordings of nerve fiber endings and tectal neurons. The occurrence and mean size of the 4 field types for tectal and optic nerve recordings were determined. The elongated, irregular and multi-center tectal fields were often much larger than the circular tectal fields. For circular and elongated fields, the field size scarcely changed with the intensity, diameter of the stimulus and the (photopic) background intensity. This was in contrast to the multi-center fields which varied more with stimulus parameters. In a part of tectal neurons apparently no regrouping took place of receptive fields of lower order neurons into receptive field centers with a high degree of complexity of shape.