Author/Editor		Valentinčič, Tine
Title		Olfactory discrimination in fishes
Type		članek
Source		In: Reutter K, Kapoor BG, editors. Fish chemosenses. Enfield, New Hampshire: Science publishers,
Publication year		2005
Volume		str. 66-85
Language		eng
Abstract		The taste system of fishes detects a relatively small number of chemical stimuli at high sensitivity and enables reflex responses, such as turning and biting/ snapping behaviors. The olfactory system, in contrast, detects a larger number of chemicals at relatively high sensitivity and enables learning and discrimination of the chemical stimuli. Conditioned olfactory stimuli trigger a feeding excitatory state which increases the duration and intensity of food searching behavior. Amino acids are a major class of chemical stimuli especially relevant to the stimulation of feeding behavior in teleost fishes. Fishes can discriminate any conditioned amino acid from nearly any other nonconditioned amino acid via olfaction. There are a few amino acids, such as L-isoleucine and L-valine, chemicals of similar structure, which catfish and zebrafish cannot discriminate. Catfish can also be conditioned to mixtures of amino acids. Binary and ternary mixtures of amino acids were detected initially as their more stimulatory components; additional discrimination training, consisting of 5-10 successive comparisons of conditioned with nonconditioned stimulus, enabled discrimination of the conditioned mixture from its more stimulatory component alone. Conditioning and discrimination training enabled black bullhead catfish to discriminate the conditioned multimixture of 7 amino acids from its 6-component counterparts; however, catfish could not discriminate a conditioned 12-component multimixture from its 11-component counterparts. Initially, fishes perceived the main feature of an olfactory stimulus. Additional discrimination training enabled the fish to detect small differences between the main odor and its modifications caused either by minor components in the mixture or small differences between multicomponent mixtures differing by one component.
Descriptors		FISHES OLFACTORY RECEPTOR NEURONS FEEDING BEHAVIOR AMINO ACIDS ICTALURIDAE