Heterogeneity of principal neurons in murine olfactory bulb
Fri-P2-103
Presented by: Sana Gadiwalla
The olfactory bulb is an ideal model system to investigate sensory processing given its location, well defined circuitry, and established behavioral paradigms. Despite these advantages, our definition of its projection neurons haven’t changed since being first defined in the late 1800s: laminarly arranged mitral cells and diffusely spread tufted cells. In lieu of further classification, few studies discriminate between the two and even fewer pay heed to heterogeneity within cell types. Instead many studies choose to collapse them into a single class: mitral/tufted.
Recent work has illustrated that these neurons encode complementary olfactory information that is reflected in their physiology & morphology, hinting that they may be more distinct than originally described. Using whole-cell patch clamp electrophysiology in acute slices from mice, this project aims to find a simple way to classify projection neurons based on their intrinsic properties.
Immunohistochemistry & DIC microscopy demonstrated that projection neurons in the mitral cell layer are diverse in their soma size; a k-means analysis returned a diameter based classifier that aligns with literature. In our physiological data this classifier divides the cells into putative mitral(pMC) and putative tufted cells(pTC). Preliminary results show that the two populations are distinct in key parameters like action potential threshold (pMC(n=24) 2.8±0.34 pA/pF; pTC(n=12) 5.5±0.98 pA/pF; unpaired t-test p=0.0025) and relative afterhyperpolarization (pMC(n=20) 17.6±0.94 pA; pTC(n=9) 12.6±1.1 pA; unpaired t-test p=0.007) and homogenous in others. These results offer further proof of mitral and tufted heterogeneity and implies that they may be classified and independently evaluated in routine patch-clamp experiments.
Funding: Royal Society Research Grant RGS\R1\191481 & Isaac Newton Trust / Wellcome Trust ISSF / University of Cambridge Joint Research Grants (EG); Icelandic Research Fund Project Grant 217945-051 (PHP,EG)
Recent work has illustrated that these neurons encode complementary olfactory information that is reflected in their physiology & morphology, hinting that they may be more distinct than originally described. Using whole-cell patch clamp electrophysiology in acute slices from mice, this project aims to find a simple way to classify projection neurons based on their intrinsic properties.
Immunohistochemistry & DIC microscopy demonstrated that projection neurons in the mitral cell layer are diverse in their soma size; a k-means analysis returned a diameter based classifier that aligns with literature. In our physiological data this classifier divides the cells into putative mitral(pMC) and putative tufted cells(pTC). Preliminary results show that the two populations are distinct in key parameters like action potential threshold (pMC(n=24) 2.8±0.34 pA/pF; pTC(n=12) 5.5±0.98 pA/pF; unpaired t-test p=0.0025) and relative afterhyperpolarization (pMC(n=20) 17.6±0.94 pA; pTC(n=9) 12.6±1.1 pA; unpaired t-test p=0.007) and homogenous in others. These results offer further proof of mitral and tufted heterogeneity and implies that they may be classified and independently evaluated in routine patch-clamp experiments.
Funding: Royal Society Research Grant RGS\R1\191481 & Isaac Newton Trust / Wellcome Trust ISSF / University of Cambridge Joint Research Grants (EG); Icelandic Research Fund Project Grant 217945-051 (PHP,EG)