Michael Petrides, Selection between Competing Responses Based on Conditional Rules, [in:] S.A. Bunge, J.D. Wallis (eds.), Neuroscience of Rule-Governed Behavior,Oxford University Press 2008, pp. 3-22.
Thesis 1: Lateral frontal cortex plays a major role in both the acquisition and the execution of conditional rules that enable appropriate selection of a response from several competing alternatives.
Thesis 2: In this process, a functional interaction between the frontal cortex and the hippocampal memory system is essential.
(b) Experimental setting
Experiment 1: Patients with lateral frontal cortex excisions were given the following task. Five hand gestures were associated with five color signals. Each color signal was a stimuli to present one of the gestures. The associations were taught by a trial&error method. The patients learned the gestures easily and easily reproduced them from memory. However, they were seriously impaired when it came to connect the signal (the color) with the response (the gesture).
Experiment 2: In a similar experiment, the learning technique was changed from trial&error to demonstration (an experimenter demonstrated which of the stimuli is connected to which of the responses). The results were similar: patients with lateral frontal cortex excisions were severely impaired. It seems that the impairment is not dependent of the method of learning the „rules”.
Experiment 3: Similar results were obtained in experiments involving macaque monkeys.
Experiment 4: The activity of the lateral frontal cortex in conditional rules acquisition and execution was confirmed on brain scans (Brass et. al. 2005).
2. Critical comments
(a) The main problem with this research is whether it is justified to speak of conditional rules here. Certainly, this is an instance of a „stimulus – response” learning and executing. However, one can object that we have to do with rules here. What we call rules is probably connected to a more complex brain functions.
(b) It would be interesting to compare these results with the research on brain activity during speech production (the learning and utilization of linguistic rules), as well as on moral reasoning.