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This Article Full Text Full Text (PDF) All Versions of this Article: 94/6/3884    most recent 01163.2004v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via ISI Web of Science (2) Citing Articles via Google Scholar Google Scholar Articles by Sakakibara, M. Articles by Lukowiak, K. Search for Related Content PubMed PubMed Citation Articles by Sakakibara, M. Articles by Lukowiak, K.

Potassium Currents in Isolated Statocyst Neurons and RPeD1 in the Pond Snail, Lymnaea stagnalis

¹Laboratory of Neurobiological Engineering, Graduate School of High-Technology for Human Welfare, Tokai University, Numazu; ²Department of Physiological Science, School of Medicine, Tokai University, Isehara, Japan; and ³Department of Physiology and Biophysics, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada

Submitted 10 November 2004; accepted in final form 2 August 2005

To begin to determine the underlying neural mechanisms of memory formation, we studied two different cell types that play important roles in different forms of associative learning in Lymnaea. Statocyst neurons (hair cells) mediate classical conditioning, whereas RPeD1 is a site of memory formation induced by operant conditioning of aerial respiration. Because potassium (K⁺) channels play a critical role in neuronal excitability, we initiated studies on these channels in the aforementioned neurons. Three distinct K⁺ currents are expressed in the soma of both the hair cells and RPeD1. In hair cells and RPeD1, there is a fast activating and rapidly inactivating 4-aminopyridine (4-AP)-sensitive A current (I_A), a tetraethyl ammonium (TEA)-sensitive delayed rectifying current, which exhibits slow inactivation kinetics (I_KV), and a TEA- and 4-AP-insensitive Ca²⁺-dependent current (I_Ca-K). In hair cells, the activation voltage of I_A; its half-maximal steady-state activation voltage and its half-maximal steady-state inactivation were at more depolarized levels than in RPeD1. The time constant of recovery from I_A inactivation was slightly faster in hair cells. I_A in hair cells is also smaller in amplitude than in RPeD1 and is activated at more depolarized potentials. In like manner, I_KV is smaller in hair cells and is activated at more depolarized potentials than in RPeD1.