Neuroscience 2007, the 37th annual meeting of the Society for Neuroscience @2007.11.3-7

Program#/Poster#: 279.10/EE26

Title: Development of membrane properties of layer III pyramidal neurons in macaque visual cortical areas V1 and TE

Location: San Diego Convention Center: Halls B-H
Presentation Start/End Time: Sunday, Nov 04, 2007, 2:00 PM - 3:00 PM

Authors: A. MARUYAMA1, A. ISHIKAWA2, D. HOSOYAMA3, Y. YOSHIMURA4, H. TAMURA3,1, H. SATO5, *I. FUJITA3,1;
1CREST, JST, Toyonaka, Japan; 2Osaka Univ, Grad Sch. Frontier Biosci, Osaka 560-0043, Japan; 3Lab. Cognitive Neurosci, Osaka Univ, Grad Sch. Frontier Biosci, Osaka 560-8531, Japan; 4Res. Ins. Envrn. Med., Nagoya, Japan; 5Osaka Univ, Grad Sch. Med., Osaka 560-0043, Japan

Intrinsic membrane properties of layer III pyramidal neurons differ between the striate (V1) and inferior temporal (TE) cortices in adult macaque monkeys (Ishikawa et al., SFN, this year). We studied how these area-specific properties develop postnatally. Whole-cell patch-clamp techniques were applied to slices prepared from animals (Macaca fuscata, M. fascicularis) of different ages. When we compared neurons sampled from young (10 days old, PND10) and adult animals, we found a common pattern of developmental changes between the two ages in V1 and TE; 1) the membrane time constant was shorter in neurons sampled from adults than those in PND10, 2) inward rectification in response to hyperpolarization (gdepolarizing sagh) was weak or absent in neurons in PND10 and became evident in adulthood, 3) the maximum rate of firing in response to depolarizing current injection was higher and 4) the duration of individual action potentials was shorter in neurons sampled from adults than those in PND10. Examination of a 7-month old monkey revealed a striking difference in the maturation of neurons between V1 and TE. In terms of the membrane time constant, the maximum firing rate, and the duration of action potentials, V1 neurons were similar to those in adults, while TE neurons were similar to those in PND10. In V1, neurons from the 7-month old monkey exhibited an intermediate degree of gdepolarizing sagh between neurons from PND10 and those from adults, while the degree of gdepolarizing sagh of TE neurons in the 7-month old monkey was no larger than that of TE neurons from PND10. The results demonstrate that electrophysiological properties of cortical neurons in monkeys mature over a prolonged period after birth, and those in V1 mature earlier than those in TE.