Martinotti cell

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Schematic diagram illustrating the morphological and biochemical features of subpopulations of cortical GABA neurons in the primate DLPFC. The diagram illustrates the calcium-binding proteins-parvalbumin (blue), calbindin (red) and calretinin (yellow)-and the locations of inhibitory synaptic inputs to a pyramidal neuron (green) by different morphological classes of cortical GABA neurons. The chandelier (Ch) and wide arbor (WA) or basket neurons provide inhibitory input to the axon initial segment (ais) and the cell body proximal dendrites, respectively, of pyramidal neurons. By contrast, the calbindin-expressing double bouquet (red DB), neurogliaform (Ng) and Martinotti (M) neurons tend to provide inhibitory inputs to the distal dendrites of pyramidal neurons. Finally, calretinin-expressing (yellow) DB and Cajal-Retzius cell (CRC) appear to target both pyramidal cell distal dendrites and other GABA (G) neurons. (Lewis DA, Hashimoto T, Volk DW: Cortical inhibitory neurons and schizophrenia. Nature Reviews Neuroscience 6:312-324, 2005.)

Basic information

Martinotti cells are small and multipolar neurons with short branched dendrites. They are spread diffusely throughout the layers of the cerebral cortex. Their axons ascend to the cortical layer I to form axonal arborizations. The arbors transgress many columns in layer I and make contacts with the distal tuft dendrites of pyramidal cells. Martinotti cells express somatostatin and sometimes calbindin but not parvalbumin or vasoactive intestinal peptide.

Recent research suggests that Martonotti cells are associated with a cortical dampening mechanism. When the pyramidal neuron approaches hyperexcitation, Martinotti cells initiate inhibitory signals to the surrounding neurons. Martonotti cells where first described in the late 19th Century by the Italian physician Giovonni Martinotti.

Anatomy

Any Pyramidal cell that faces the opposite direction of the Betz cells (it's longest dendrite faces the opposite of all other Betz cells) is a Martinotti cell. A small multipolar nerve cell with short branching dendrites scattered through various layers of the cerebral cortex; its axon ascends toward the surface of the cortex.

Molecular profile

  • Neurotransmitter: Somatostatin and sometimes Calbindin

Physiology

Research suggests Martinotti cells play a central role in information processing in the cortical space column. They have also been proposed to be involved in memory formation and storage (Eccles 1983) and in neurodegenerative diseases (Beal et al. 1988).

At the electrophysiological level MC’s have been reported to display “regular” or “burst” firing patterns to depolarizing somatic current injections (Kawaguchi & Kusota, 1997), which have also been reported to be low threshold interneurons (Kawaguchi, 1995). A more recent study has reported regenerative calcium activity in MC’s, which may be important in the bursting type of MC’s (Goldberg et al, 2004).

Behavior

References

Yun Wang, Maria Toledo-Rodriguez, Anirudh Gupta, Caizhi Wu, Gilad Silberberg, Junyi Luo, and Henry Markram(2004) Anatomical, physiological and molecular properties of Martinotti cells in the somatosensory cortex of the juvenile rat. J Physiol.; 561(Pt 1): 65–90. doi: .1113/jphysiol.2004.073353. PMID 15331670

Sugino K, Hempel CM, Miller MN, et al (January 2006). "Molecular taxonomy of major neuronal classes in the adult mouse forebrain". Nat. Neurosci. 9 (1): 99–107. doi:10.1038/nn1618. PMID 16369481.

Gilad Silberberg, Henry Markram(2007) Disynaptic Inhibition between Neocortical Pyramidal Cells Mediated by Martinotti Cells Neuron. 2007 Mar;53(5):735-46 PMID 17329212

Kamaguchi Y & Kubota Y (1997), GABAergic cell subtypes and their synaptic connections in rat frotnal cortex. Cereb Cortex 7, 476-486.

Kamaguchi Y & Kubota (1988). Neurochemical features and synaptic connections of large physiologically-identified GABAnergic cells in the rat frontal cortex. Neuroscience 85, 677-701.