Nobuaki Tamamaki (Kumamoto University)
“Adult neurogenesis in the mammalian neocortex”
Although adult neurogenesis is a common phenomenon in the non-mammalian neocortex, the scale of adult neurogenesis in the neocortex appears to decrease significantly as the phylogeny approaches the human being. In apparent contrast, the limbic area of the telencephalon appears to be a site of continuous generation of neurons. In particular, the medial edge of the mammalian telencephalon, the dentate gyrus, produces granule cells constantly throughout life in humans, while the subventricular zone (SVZ) surrounding the lateral ventricle continuously produces GABAergic granule cells for the olfactory bulb. Granule cells produced in the dentate gyrus are integrated into the circuitry of the hippocampus and save new information, whereas granule cells produced in the SVZ of the lateral ventricle migrate rostrally and are integrated into the olfactory circuitry. In other words, these new neurons are not integrated into the neocortex. However, if a significant number of new neurons is produced in the neocortex and integrated into the neocortical circuit, we cannot deny the possibility that these new neurons ruin the circuits for memory and thought in the human neocortex. On the other hand, Macklis expressed repellence that the synchronous apoptotic degeneration of corticothalamic neurons may induce generation of the same number of neurons in the neocortex and may recreate the same circuit as was originally present. In this case, neurogenesis in the neocortex will not disturb the circuit in the neocortex, and would be welcomed. Therefore, our goal is to find out the hidden neuron progenitors around the neocortex, and stimulate the neuron progenitors to turn them into neurons. I will have an honor to show you how the neocortex maintain its function so long in our brain.
1. Yamaguchi M, Seki T, Imayoshi I, Tamamaki N, Hayashi Y, Tatebayashi Y, Hitoshi S. (2015) Neural stem cells and neuro/gliogenesis in the central nervous system: understanding the structural and functional plasticity of the developing, mature, and diseased brain. J Physiol Sci. 2015 Nov 17.
2. Huang J, Chen J, Wang W, Wei YY, Cai GH, Tamamaki N, Li YQ, Wu SX. (2013) Birthdate study of GABAergic neurons in the lumbar spinal cord of the glutamic acid decarboxylase 67-green fluorescent protein knock-in mouse.Front Neuroanat. 2013 Dec 9;7:42.
3. Ninomiya S, Esumi S, Ohta K, Fukuda T, Ito T, Imayoshi I, Kageyama R, Ikeda T, Itohara S,Tamamaki N. (2013) Amygdala kindling induces nestin expression in the leptomeninges of the neocortex. Neurosci Res. 2013 Feb;75(2):121-9.