Information on FRATx (current version FRATx10.m) FRATx.m was used to produce all the simulations of Krasne et al (2011). The program was written in Matlab 7.4.0 (R2007a). The zip file obtainable at ModelDB includes (1) the Matlab code of the program, (2) a supplement to the paper itself, which includes a mathematical description of the model as well as simulations that there was not room for in the original paper (the supplement is also available at http:/escholarship.org/uc/item/3hk369c4 ) and (3) a manual that explains how to use the program and that provides additional information on the program. FRATx.m was derived from an earlier program (frat.m) that was written for educational purposes. The student program, frat.m, program is available at http://mdcune.psych.ucla.edu/modules/frat. It is a compiled version, and the necessary Matlab runtime environment needed for using it is available for free at the website. The student program is designed to allow students to do standard types of behavioral neuroscience experiments to try to arrive at an understanding of the neural circuitry that underlies fear learning in the automaton. In order to make this problem tractable for the students, the amygdala of frat.m, unlike that of FRATx.m, has only a single LA-like nucleus (the x in FRATx, refers to the "extra" nuclei of the program's amydala over and beyond those of the mono-nucleate frat program). However frat.m has features not present inb FRATx: an explicit cortex, hippocampus, thalamus, etc laid out in a two-dimensional stereotaxic atlas and a variety of utilities for doing realistic kinds of experiments. Students can implant stimulating electrodes and recording extracellular microelectores, infuse various drugs, make lesions, etc. We have had considerable experience using it for teaching at UCLA and we encourage its use elsewhere. We cannot offer support, but when possible we will try to address occasional questions on an informal basis.