Quantitative analysis of axon collaterals of single pyramidal cells of the anterior piriform cortex of the guinea pig.
The role of the piriform cortex (PC) in olfactory information processing remains largely unknown. The anterior part of the piriform cortex (APC) has been the focus of cortical-level studies of olfactory coding, and associative processes have attracted considerable attention as an important part in odor discrimination and olfactory information processing. Associational connections of pyramidal cells in the guinea pig APC were studied by direct visualization of axons stained and quantitatively analyzed by intracellular biocytin injection in vivo.



The observations illustrated that axon collaterals of the individual cells were widely and spatially distributed within the PC, and sometimes also showed a long associational projection to the olfactory bulb (OB). The data showed that long associational axons were both rostrally and caudally directed throughout the PC, and the intrinsic associational fibers of pyramidal cells in the APC are omnidirectional connections in the PC. Within the PC, associational axons typically followed rather linear trajectories and irregular bouton distributions. Quantitative data of the axon collaterals of two pyramidal cells in the APC showed that the average length of axonal collaterals was 101 mm, out of which 79 mm (78% of total length) were distributed in the PC. The average number of boutons was 8926 and 7101, respectively, with 79% of the total number of boutons being distributed in the PC. The percentage of the total area of the APC and the posterior piriform cortex occupied by the average distribution region of the axon collaterals of two superficial pyramidal (SP) cells was about 18 and 5%, respectively.



Our results demonstrate that omnidirectional connection of pyramidal cells in the APC provides a substrate for recurrent processes. These findings indicate that the axon collaterals of SP cells in the PC could make synaptic contacts with all granule cells in the OB. This study provides the morphological evidence for understanding the mechanisms of information processing and associative memory in the APC.
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China. junli201601@126.com.|Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan. junli201601@126.com.
Junli
J
Yang
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China. gerhard.litscher@medunigraz.at.|Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria. gerhard.litscher@medunigraz.at.
Gerhard
0000-0001-6287-0130
G
Litscher
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China. szr006@163.com.
Zhongren
Z
Sun
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
Qiang
Q
Tang
Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan.
Kiyoshi
K
Kishi
Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan.
Satoko
S
Oda
Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan.
Masaaki
M
Takayanagi
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.|Privatclinic Lassnitzhoehe, 8301, Lassnitzhoehe, Austria.
Zemin
Z
Sheng
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
Yang
Y
Liu
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
Wenhai
W
Guo
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.
Ting
T
Zhang
Second Affiliated Hospital of Heilongjiang University of Chinese Medicine, Harbin, 150001, China.|Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria.
Lu
L
Wang
Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria.
Ingrid
I
Gaischek
Research Unit for Complementary and Integrative Laser Medicine, Research Unit of Biomedical Engineering in Anesthesia and Intensive Care Medicine, and TCM Research Center Graz, Medical University of Graz, 8036, Graz, Austria.
Daniela
D
Litscher
Institute of Experimental and Clinical Pharmacology, Medical University of Graz, 8036, Graz, Austria.
Irmgard Th
IT
Lippe
Department of Anatomy, School of Medicine, Toho University, Tokyo, 143-8540, Japan.
Masaru
M
Kuroda
D000818:Animals; D001369:Axons; D048429:Cell Size; D005260:Female; D006168:Guinea Pigs; D008239:Lysine / Q000031:analogs & derivatives; D008297:Male; D009830:Olfactory Bulb / Q000166:cytology; D009833:Olfactory Pathways / Q000166:cytology; D010784:Photomicrography; D066195:Piriform Cortex / Q000166:cytology*; D017966:Pyramidal Cells / Q000166:cytology*
C013411:biocytin; D008239:Lysine
Anterior piriform cortex; Axon collaterals; Neural network; Olfactory bulb; Olfactory cortex; Single neurons