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The basolateral limbic circuit and self-stimulation of the medial prefrontal cortex in the rat
1Department of Physiology, Faculty of Medicine, University of Granada, Spain.
Abstract:
The effects of lesions of the basolateral nucleus of the amygdala (ABL) and the mediodorsal nucleus of the thalamus (MD) on self-stimulation (SS) of the medial prefrontal cortex (MPC) were investigated. Spontaneous motor activity (SMA) was measured as a control for possible non-specific effects of the lesions. Bilateral electrolytic lesions of ABL or MD produced a parallel transient decrease of SS and SMA. However, combined lesion of ABL and MD produced clearly different effects on both parameters. SMA decreased during the 1st day post-lesion and recovered to control levels by the 3rd day post-lesion. SS, on the contrary, was significantly decreased during the first five days post-lesion and after that time SS rate recovered to control levels. These results suggest the involvement of the basolateral limbic circuit in the neural substate underlying SS behavior of the MPC.
Insights
Lesions to the basolateral amygdala (ABL) and mediodorsal thalamus (MD) transiently reduced self-stimulation (SS) and motor activity. Combined ABL and MD lesions revealed distinct effects on SS and spontaneous motor activity (SMA) in rats.
Area of Science:
- Neuroscience
- Behavioral Neuroscience
Background:
- The basolateral nucleus of the amygdala (ABL) and mediodorsal nucleus of the thalamus (MD) are implicated in reward and motivation.
- Self-stimulation (SS) of the medial prefrontal cortex (MPC) is a model for reward-seeking behavior.
Purpose of the Study:
- To investigate the effects of ABL and MD lesions on SS of the MPC.
- To differentiate the roles of ABL and MD in SS and spontaneous motor activity (SMA).
Main Methods:
- Bilateral electrolytic lesions were made in the ABL and/or MD of rats.
- Self-stimulation of the MPC and spontaneous motor activity were measured.
- Lesion effects were compared to control levels.
Main Results:
- Single ABL or MD lesions caused transient decreases in both SS and SMA.
- Combined ABL and MD lesions differentially affected SS and SMA.
- SMA recovered within 3 days post-lesion, while SS remained suppressed for 5 days.
Conclusions:
- The basolateral limbic circuit, involving the ABL, plays a significant role in the neural basis of MPC self-stimulation.
- Differential effects of combined lesions suggest distinct roles for ABL and MD in reward-related behaviors.