Abstract
The reinforcement omission effect (ROE), reflected by response rates that are higher after reinforcement omission than after reinforcement delivery, has been attributed to both motivational and attentional consequences of the surprising reinforcement omission. These processes depend on the operation of separate amygdala areas and their connections with other brain systems. The interaction between the amygdala and orbitofrontal cortex has been suggested to be important in the modulation of motivational processes. The present study sought to verify whether the mechanisms involved in the ROE depend on the integrity of the orbitofrontal cortex. Prior to acquisition training, rats received bilateral excitotoxic lesions of the orbitofrontal cortex or sham lesions. Following postoperative recovery, the rats were trained on a fixed-interval 12 s limited-hold 6 s signaled schedule of reinforcement. After the acquisition of stable performance, the training was changed from a 100% to 50% schedule of reinforcement. The results showed that rats in both groups exhibited the ROE, with no differences in performance between groups following nonreinforcement. These data do not support the hypothesis that the orbitofrontal cortex is included in the neural substrates related to ROE modulation. The results also showed no difference in response rates between groups in the periods that preceded and followed nonreinforcement. These findings confirm previous studies that showed that the ROE is not related to the facilitation of behavior induced by nonreinforcement.
Highlights
In animals that respond on intermittent schedules of reinforcement, response rates are often higher after reinforcement omission than after reinforcement
No difference in performance was found between lesioned rats and sham-lesioned rats in the periods that followed reinforcement omission (3 s LH N and 6 s LH N)
These data indicate that the OFC lesions did not interfere with the reinforcement omission effect (ROE)
Summary
In animals that respond on intermittent schedules of reinforcement, response rates are often higher after reinforcement omission than after reinforcement. Amsel, & Roussel (1952) reported that the introduction of partial reinforcement in the first goal of a double runway paradigm led to the greatest response on the second runway immediately after omission than after reinforcement delivery. This effect was explained by increments in the drive induced by primary frustration (Amsel, & Roussel, 1952; Papini, & Dudley, 1997; Papini, 2003). Another interpretation may be made in terms of behavioral transient inhibition after reinforcement delivery induced by demotivation or the resetting of the
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