Inhibitory control deficits in rats with ventral hippocampal lesions

• Published in: Cerebral cortex (New York, N.Y. 1991) Vol. 23; no. 6; pp. 1396 - 1409
• Main Authors: Abela, Andrew R, Dougherty, Stephen D, Fagen, Erin D, Hill, Carolyn J R, Chudasama, Y
• Format: Journal Article
• Language: English
• Published: United States 01-06-2013
• Subjects: Analysis of Variance; Animals; Attention - drug effects; Attention - physiology; Choice Behavior - drug effects; Choice Behavior - physiology; Citalopram - pharmacology; Discrimination (Psychology) - drug effects; Discrimination (Psychology) - physiology; Dopamine Uptake Inhibitors - pharmacology; Dose-Response Relationship, Drug; Food Preferences - drug effects; Food Preferences - physiology; Hippocampus - injuries; Hippocampus - physiology; Impulsive Behavior - chemically induced; Impulsive Behavior - physiopathology; Inhibition (Psychology); Male; Photic Stimulation; Piperazines - pharmacology; Rats; Rats, Long-Evans; Reaction Time - drug effects; Reaction Time - physiology; Reversal Learning - drug effects; Serotonin Uptake Inhibitors - pharmacology; Sucrose - administration & dosage; Sweetening Agents - administration & dosage; impulsivity; serotonin; hippocampus; perseveration; dopamine
• ISSN: 1047-3211; 1460-2199
• DOI: 10.1093/cercor/bhs121

Two experiments are reported in which rats with selective hippocampal lesions were tested on 2 prefrontal-dependent tasks. In Experiment 1, we compared the effects of lesions of the ventral hippocampus (vHC), dorsal hippocampus (dHC), and sham control surgery on the 5-choice reaction time task. Whereas rats with lesions of the dHC were indistinguishable from sham controls, those with vHC lesions showed increased premature responses and reduced accuracy throughout the experiment. The subsequent administration of systemic escitalopram (5 mg/kg), a selective serotonin reuptake inhibitor, reduced the number of premature responses in the vHC animals to control levels. In contrast, systemic injections of GBR 12909, a dopamine reuptake inhibitor, failed to ameliorate the impulsive deficit in the vHC group and, in addition, elevated perseverative responding in the vHC group only. In Experiment 2, we tested a separate group of rats with vHC lesions on a touchscreen visual discrimination and reversal learning task. Rats with vHC lesions acquired the visual discrimination as well as sham controls and showed normal inhibitory control of a previously reinforced response during reversal learning. These data support a role for the vHC in inhibitory control functions, especially in the inhibitory control of impulsive actions.