Update README.md

ch9/sir/README.md

@@ -2,7 +2,7 @@ Back to [All Sims](https://github.com/CompCogNeuro/sims) (also for general info
 
 # Introduction
 
-This simulation illustrates the dynamic gating of information into PFC active maintenance, by the basal ganglia (BG). It uses a simple Store-Ignore-Recall (SIR) task, where the BG system learns via phasic dopamine signals and trial-and-error exploration, discovering what needs to be stored, ignored, and recalled as a function of reinforcement of correct behavior, and learned reinforcement of useful working memory representations.  The model is the current incarnation the our original PBWM framework [O'Reilly & Frank, 2006](#references).
+This simulation illustrates the dynamic gating of information into PFC active maintenance, by the basal ganglia (BG). It uses a simple Store-Ignore-Recall (SIR) task, where the BG system learns via phasic dopamine signals and trial-and-error exploration, discovering what needs to be stored, ignored, and recalled as a function of reinforcement of correct behavior, and learned reinforcement of useful working memory representations.  The model is the current incarnation the our original PBWM framework ([O'Reilly & Frank, 2006](#references)).
 
 The SIR task requires the network to Recall (when the R unit is active) the letter (A-D) that was present when a Store (S) input was active earlier. Ignore (I) trials also have a letter input, but, as you might guess, these are to be ignored. Trials are randomly generated, and there can be a random number of Ignore trials between a Store and Recall trial, so the model must learn to maintain the stored information in robust working memory representations in the PFC, until the next Recall trial, with variable numbers of intervening and unpredictable distractors between task-relevant events.