Sensory information processing in the frog olfactory pathways. Experimental basis for modeling studies

In the frog, unitary electrophysiological recordings have been extensively used to investigate odor processing along the olfactory pathways. By compar ing spontaneous and odor-evoked activities of neuroreceptor, mitral and cor tical cells, we have collected fundamental data relating to coding abilitie s of the three olfactory levels, the olfactory mucosa, the bulb and the cor tex. Based on a synthesis of our experimental data related to GABAergic and dopaminergic involvement in the olfactory bulb, this paper aims to match t his information with computational data and to discuss some questions on bu lbar processing. This paper is also devoted to further analyze original res ults on coding properties of two functionally evidenced neuron subpopulatio ns in the olfactory cortex. Thus, the assumption according to which some co rtical neurons may work as temporal integrators while others as coincidence detectors is presented. Moreover, the pertinence that the neural code may be carried by a single spike with varying latency was demonstrated. (C) 199 8 Elsevier Science Ireland Ltd. All rights reserved.