Control of Phasic Firing by a Background Leak Current in Avian Forebrain Auditory Neurons

Author(s)

Dagostin, Andre A. ^[1] ; Lovell, Peter V. ^[2] ; Hilscher, Markus M. ^{[3, 4]} ; Mello, Claudio V. ^[2] ; Leao, Ricardo M. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, BR-14049 Ribeirao Preto - Brazil

^[2] Oregon Hlth & Sci Univ, Dept Behav Neurosci, Portland, OR 97201 - USA

^[3] Univ Fed Rio Grande do Norte, Inst Brain, BR-59072970 Natal, RN - Brazil

^[4] Vienna Univ Technol, Inst Anal & Sci Comp, A-1040 Vienna - Austria

• Document type: Journal article
• Source: FRONTIERS IN CELLULAR NEUROSCIENCE; v. 9, DEC 10 2015.
• Web of Science Citations: 4

Abstract

Central neurons express a variety of neuronal types and ion channels that promote firing heterogeneity among their distinct neuronal populations. Action potential (AP) phasic firing, produced by low-threshold voltage-activated potassium currents (VAKCs), is commonly observed in mammalian brainstem neurons involved in the processing of temporal properties of the acoustic information. The avian caudomedial nidopallium (NCM) is an auditory area analogous to portions of the mammalian auditory cortex that is involved in the perceptual discrimination and memorization of birdsong and shows complex responses to auditory stimuli We performed in vitro whole cell patch clamp recordings in brain slices from adult zebra finches (Taeniopygia guttata) and observed that half of NCM neurons fire APs phasically in response to membrane depolarizations, while the rest fire transiently or tonically. Phasic neurons fired APs faster and with more temporal precision than tonic and transient neurons. These neurons had similar membrane resting potentials, but phasic neurons had lower membrane input resistance and time constant. Surprisingly phasic neurons did not express low-threshold VAKCs, which curtailed firing in phasic mammalian brainstem neurons, having similar VAKCs to other NCM neurons. The phasic firing was determined not by VAKCs, but by the potassium background leak conductances, which was more prominently expressed in phasic neurons, a result corroborated by pharmacological, dynamic-clamp, and modeling experiments. These results reveal a new role for leak currents in generating firing diversity in central neurons. (AU)

• FAPESP's process: 08/04618-0 - Molecular, synaptic and electrophysiological characterization of the neurons from the Nidopallium Caudomediallis, a brain area responsible for auditory processing in songbirds
• Grantee: Ricardo Mauricio Xavier Leão
• Support Opportunities: Regular Research Grants
• FAPESP's process: 12/09421-6 - Study of the salycilate effects on the neurotransmission and excitability of the neurons from the Dorsal Cochlear Nucleus (DCN)
• Grantee: Ricardo Mauricio Xavier Leão
• Support Opportunities: Regular Research Grants
• FAPESP's process: 08/10015-7 - Electrophysiological, synaptic and molecular characterization of the neurons of the medial caudal Nidopallium, an area responsible for auditory processing in songbirds
• Grantee: André Luiz Andreotti Dagostin
• Support Opportunities: Scholarships in Brazil - Doctorate