Chris Englund, Andy Fink, Charmaine Lau, Diane Pham, Ray A. M. Daza, Alessandro Bulfone, Tom Kowalczyk, and Robert F. Hevner
During development, differentiating neurons and glia express a variety of transcription factors that orchestrate this process. This week, Englund et al. examine transcription factors expressed by cells destined to become cortical pyramidal neurons. These neurons can arise directly from radial glial but also may pass through a transitional phase as intermediate progenitor cells (IPCs).
2. Squirrelvision: Orientation Tuning without Columns
Stephen D. Van Hooser, J. Alexander F. Heimel, Sooyoung Chung, Sacha B. Nelson, and Louis J. Toth
In most mammals, including primates and tree shrews, the primary visual cortex is organized into columns in which the orientation preference of neurons reremains constant. The preference changes smoothly along the topographical surface of the cortex, creating an orientation map. However, rodents and lagomorphs (i.e., rabbits) seemed to have paid no attention to this organizing principal. Rather, single neurons definitely displayed orientation preference and a retinotopic map. It seems that a columnar organization of functional response properties is not a universal feature of the primary visual cortex.