Orbitofrontal cortex use in inference based decision making and object reversal learning

     The Orbitofrontal Cortex (OFC) has been known to control impulsive behaviors as well as adjusting behaviors to have socially desirable responses. There is rapid study being done on the OFC to this date and many papers have been written to show the impact that it has with the decision making as well as learning. Research has also been showing how these 2 factors are directly impacted when their is damage done to the OFC. Thorsten Kahnt et. al studied how much the OFC, hippocampus (HC), and the Amygdala are being used in inference based decision making as well as association decision making. Rudebeck et. al studied how OFC lesions and Amygdala lesions impact object reversal learning in monkeys. 

    Kahnt et. al focused on association based decision making in humans and rats in this study. First, Kahnt conducted a study on humans and how they learn associations between different visual cues (Cue A -> Cue B, Cue C -> Cue D) then learned that one cue (Cue B) led to a reward and another cue (Cue D) did not lead to reward. After these 2 conditioning phases, they were asked in a probe test whether cue A or cue C would lead to a reward. These tasks where done under an fMRI to find where in the brain the most activity is occurring during these tasks. The data concluded that the OFC and HC were used the most together when both the conditioning tasks were being done and shown that these 2 regions of the brain are important to decision making in a human brain. The study then shifted to non-human primate subjects (rats) where a very similar study was done. These rodents and non-human primate subject learned that 2 objects led to 2 different rewards. The rewards consisted of 2 different foods, peanuts and M&Ms. The study showed that they were more likely to not choose the same object twice due to them learning that both objects led to two different rewards. They also found that OFC and the Amygdala were both used together to help learn what rewards came out of the objects. 

    Rudebeck et. al focused on how OFC lesions and Amygdala lesions effected object reversal learning in monkeys. In each trial, 2 objects where over food wells and the monkeys then had to displace one object and depending on the object that was displaced, a reward would be awarded. The reward object would not be changed in all of the trials and this led on for 30 trials. The study found that the monkeys who had OFC lesions where seen to have worse results than monkeys with Amygdala lesions or no lesions at all. The monkeys with Amygdala lesions were seen to have no impact compared to the no lesions group of monkeys. This shows that the OFC is crucial in learning tasks as well as association learning tasks and damage to the OFC can hinder learning. 

    These two research studies have shown that the Orbitofrontal cortex is important to both learning tasks as well as association tasks which include decision making and object reversal learning. Both of these studies have shown how much more the orbitofrontal cortex can truly do besides just impulsive behaviors and inducing socially desirable behaviors. 

References:

Rudebeck PH, Murray EA. Amygdala and orbitofrontal cortex lesions differentially influence choices during object reversal learning. J Neurosci. 2008;28(33):8338-8343. doi:10.1523/JNEUROSCI.2272-08.2008

Fang Wang, Thorsten Kahnt, Neural circuits for inference-based decision-making, Current Opinion in Behavioral Sciences, Volume 41,2021, Pages 10-14, ISSN 2352-1546, https://doi.org/10.1016/j.cobeha.2021.02.004.