Postsynaptic potentials of tectal neurons evoked by electrical stimulation of the pretectal nuclei in bullfrogs ( Rana catesbeiana)

• Published in: Brain research 2005-08, Vol.1052 (1), p.40-46
• Main Authors: Li, Xiaohong, Tsurudome, Kazuya, Matsumoto, Nobuyoshi
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; Bullfrog; Electric Stimulation; Electrical stimulation; Evoked Potentials - physiology; Evoked Potentials - radiation effects; Excitatory Postsynaptic Potentials - radiation effects; Eye and associated structures. Visual pathways and centers. Vision; Female; Functional Laterality; Fundamental and applied biological sciences. Psychology; In Vitro Techniques; Intracellular recording; Male; Neural Inhibition - physiology; Neural Inhibition - radiation effects; Neurons - radiation effects; Optic tectum; Postsynaptic potential; Pretectum; Rana catesbeiana; Reaction Time - physiology; Reaction Time - radiation effects; Superior Colliculi - cytology; Synaptic Transmission - physiology; Synaptic Transmission - radiation effects; Vertebrates: nervous system and sense organs; Visual Pathways - radiation effects
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2005.06.010

Postsynaptic responses of the tectal cells to electrical stimulation of pretectal (Lpd/P) nuclei were intracellularly recorded in the bullfrog ( Rana catesbeiana). The pretectal stimulation elicited mainly two types of responses in the ipsilateral tectum: an EPSP followed by an IPSP and a pure IPSP. The latter predominates in the tectal cells responding to ipsilateral pretectal stimulation. In a few cells, biphasic hyperpolarization appeared under stronger stimulus intensities. Only one type of response was found in the contralateral tectum, a pure IPSP. The antidromically invaded tecto-pretectal projecting cells were recorded in both tecta, which revealed reciprocal connections between the tectum and particular pretectal nuclei. This paper demonstrates the synaptic nature underlying pretectotectal information transfer. EPSPs with short latencies were concluded to be monosynaptic. Most IPSPs were generated through polysynaptic paths, but monosynaptic IPSPs were also recorded in both optic tecta. Nearly 98% of impaled tectal cells (except for intra-axonally recorded and antidromically invaded cells) showed inhibitory responses to pretectal stimulation. The results provide strong evidence that pretectal cells broadly inhibit tectal neurons as suggested by behavioral and extracellular recording studies.