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This Article Full Text Full Text (PDF) All Versions of this Article: 98/2/939    most recent 00423.2007v1 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 Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Mehaffey, W. H. Articles by Turner, R. W. Search for Related Content PubMed PubMed Citation Articles by Mehaffey, W. H. Articles by Turner, R. W.

Regulation of Burst Dynamics Improves Differential Encoding of Stimulus Frequency by Spike Train Segregation

¹Hotchkiss Brain Institute, University of Calgary, Calgary, Alberta; and ²Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada

Submitted 13 April 2007; accepted in final form 16 June 2007

Distinguishing between different signals conveyed in a single sensory modality presents a significant problem for sensory processing. The weakly electric fish Apteronotus leptorhynchus use electrosensory information to encode both low-frequency signals associated with environmental and prey signals and high-frequency communication signals between conspecifics. We identify a mechanism whereby the GABA_B component of a feedback pathway to the electrosensory lobe is recruited to regulate the intrinsic burst dynamics and coding properties of pyramidal cells for these behaviorally relevant input signals. Through recordings in an in vitro slice preparation and a reduced model of pyramidal cells, we show that recruitment of dendritic GABA_B currents can shift the timing of a backpropagating spike and its influence on an intrinsic burst mechanism. This regulation of burst firing alters the coding properties of pyramidal cells by improving the correlation of burst and tonic spikes with respect to low- or high-frequency components of complex stimuli. GABA_B modulation of spike backpropagation thus improves the segregation of burst and tonic spikes evoked by simulated sensory input, allowing pyramidal cells to parcel the spike train into coding streams for the low- and high-frequency components. As the feedback pathway is predicted to be activated in circumstances where environmental and communication stimuli coexist, these data reveal a novel means by which inhibitory input can regulate spike backpropagation to improve signal segregation.

This article has been cited by other articles:

				W. H. Mehaffey, L. Maler, and R. W. Turner Intrinsic Frequency Tuning in ELL Pyramidal Cells Varies Across Electrosensory Maps J Neurophysiol, May 1, 2008; 99(5): 2641 - 2655. [Abstract] [Full Text] [PDF]