[Connections of the thalamic and telencephalic centers of the auditory system in turtles].

In the turtles Emys orbicularis and Testudo horsfieldi connections of the thalamic (n. reuniens) and telencephalic (medio-ventral part of the dorsal ventricular edge--DVE) centers of the auditory system have been revealed by means of the retrograde and anterograde horseradish peroxidase (HP) transport method. At a local HP administration into the n. reuniens, the labelled neurons are detected bilaterally in the midbrain: in the auditory center (n. centralis of the torus) and predominantly in the somatic nucleus (n. intercollicularis); in the thalamus--ipsilaterally among the marked fibers of the dorsal peduncle of the forebrain lateral bundle, in the anterior and posterior parts of the suprapeduncular nucleus, in the nucleus of the ventral supraoptic chiasm. The HP anterograde transport is followed in the thalamic n. anterior and n. ventralis, in the forebrain lateral bundle as far as the medial part of the DVE. When HP is injected into the DVE auditory zone, retrogradely labelled neurons are revealed ipsilaterally along the whole pathway of the auditory center (n. reuniens), as well as in the n. anterior and n. ventralis, in the posterior part of the suprapeduncular nucleus, in the posterior commissure nucleus, in the caudal nucleus. Most of these thalamic nuclei are connected with the somatosensory system. The principle of the structural-functional organization of the auditory system in reptiles is discussed; it ensures the interaction between the auditory and somatic impulses making a necessary base for the audition-controlled behaviour.