After three years of painstaking work that has involved using new technologies to identify and trace neural cell progenitors in ways not previously possible, and to track them as they migrate to positions in the maturing cortex, Huang and colleagues, including Dr. Hiroki Taniguchi now at the Max Planck Florida Institute, have demonstrated that chandelier cells are born in a previously unrecognized portion of the embryonic brain, which they have named the VGZ (ventral germinal zone).
Huang, who has been on a decade-long quest to develop means of learning much more about the cortex's inhibitory cells (sometimes called "interneurons"), points out that while they are far less numerous than the excitatory pyramidal cells all around them, cells including chandelier cells that inhibit or modulate excitatory-cell messages play an indispensable role in balancing message flow and ultimately in determining the functional organization of excitatory neurons into meaningful groups.
This is all the more intriguing in the case of chandelier cells, Huang explains, because of their distinctive anatomy: one cell that can regulate the messages of 500 others in its vicinity is one that we need to know about if we want to understand how brain circuits work. Unlike other inhibitory cells, chandelier cells are known to connect with excitatory cells at one particular anatomical location, of great significance: a place called the axon initial segment (AIS) the spot where a "broadcasting" pyramidal cell generates its transmittable message. To be able to interdict 500 "broadcasters" at this point renders a single chandelier cell a very important player in message propagation and coordination within its locality.
Because of the strategic importance of such cells throughout the cortex, it has been a source of frustration to neuroscientists that they (and other inhibitory cells) have been difficult to classify. Huang has pursued a strategy of fol
|Contact: Peter Tarr|
Cold Spring Harbor Laboratory