Maturation of Intrinsic and Synaptic Properties of Layer 2/3 Pyramidal Neurons in Mouse Auditory Cortex

• Published in: Journal of neurophysiology 2008-06, Vol.99 (6), p.2998-3008
• Main Authors: Oswald, Anne-Marie M, Reyes, Alex D
• Format: Article
• Language: English
• Subjects: Age Factors; Animals; Animals, Newborn; Auditory Cortex - cytology; Auditory Pathways - physiology; Dose-Response Relationship, Radiation; Electric Stimulation - methods; Excitatory Postsynaptic Potentials - physiology; Excitatory Postsynaptic Potentials - radiation effects; In Vitro Techniques; Lysine - analogs & derivatives; Lysine - metabolism; Mice; Neuronal Plasticity; Patch-Clamp Techniques - methods; Pyramidal Cells - physiology; Pyramidal Cells - radiation effects; Synapses - physiology; Synapses - radiation effects
• ISSN: 0022-3077; 1522-1598
• DOI: 10.1152/jn.01160.2007

Center for Neural Science, New York University, New York, New York Submitted 20 October 2007; accepted in final form 13 April 2008 We investigated the development of L2/3 pyramidal cell (PC) circuitry in juvenile mice from postnatal day 10 (P10) to P29. Using whole cell recordings in an in vitro thalamocortical slice preparation, we examined the connection architecture and intrinsic and synaptic properties of PCs. The excitatory connections between PCs were highly localized: the probability of connection between PCs declined with intersomatic distance from 0.18 to about 0.05 over 150 µm, but did not vary with age. However, the mean and variance of the intrinsic and synaptic properties of PCs changed dramatically between P10 and P29. The input resistance, membrane time constant, and resting membrane potential decreased, leading to reduced neural excitability in older animals. Likewise, there were age-dependent decreases in the amplitude and decay time of the excitatory postsynaptic potentials as well as short-term synaptic depression. Both the intrinsic and synaptic properties underwent a transitional period between P10 and P18 prior to reaching steady state at P19–P29. We show that these properties combine to produce age-related differential synaptic responses to low- and high-frequency synaptic input that may contribute to differences in auditory processing during development. Address for reprint requests and other correspondence: A.-M. M. Oswald, Center for Neural Science, New York University, 4 Washington Place, Rm 809, New York, NY 10003 (E-mail: ammoswald{at}nyu.edu )