Hippocampal-Prefrontal Cortical Circuit Mediates Inhibitory Response Control in the Rat

Abstract

We investigated the interdependent function of the ventral hippocampus (vHC) and ventral prefrontal cortex (vPFC) in visuospatial attention and inhibitory control using a disconnection lesion approach. Rats were trained, and several aspects of their cognitive performance tested on the 5-choice reaction time task. The animals were prepared with unilateral lesions of both the vPFC and vHC, either in the same hemisphere ("ipsilateral") or in opposite hemispheres ("disconnection"). The disconnection lesion led to both impulsive and compulsive behavior. This deficit is reminiscent of the effects of either bilateral vPFC or bilateral vHC lesions on the same task and is thought to reflect the bihemispheric disruption of the hippocampal-prefrontal circuit. With ipsilateral lesions, behavioral deficits were transient or absent altogether, suggesting that the intact hemisphere was able to exert near normal levels of behavioral control. These behavioral effects were observed in the absence of any changes to visual attention, speed of response, or general motivation. This study provides evidence that optimal inhibitory control of behavior draws upon the functional interaction between the vHC and vPFC.

Hippocampal Neural Disinhibition Causes Attentional and Memory Deficits

“…In the present study, hippocampal neural disinhibition did not affect response control on the 5CSRT test (as reflected by unchanged premature or perseverative responses), which has been shown to be markedly disrupted by both prefrontal and hippocampal lesions and/or inactivation (Chudasama and Robbins 2006;Chudasama et al 2012;Abela et al 2013;Pezze et al 2014); similar to hippocampal neural disinhibition, prefrontal disinhibition also does not affect response control ). This suggests that response control requires neural activity within the hippocampo-prefrontal circuit, but not the appropriate tuning of such activity.…”

The role of working memory and declarative memory in trace conditioning

“…While this review has discussed these two regions as independent neural substrates, it should be acknowledged that they likely function together. For example, the VH makes direct monosynaptic glutamatergic connections with the mPFC, and the mPFC may communicate indirectly to the hippocampus via midline thalamus (Chudasama, Doobay, & Liu, 2012; Dégenètais, Thierry, Glowinski, & Gioanni, 2003; Li et al, 2015; Vertes, 2002). Therefore, their roles in trace conditioning are likely intertwined.…”

Acetylcholinesterase Activity and Neurodevelopment in Boys and Girls

“…Chlorpyrifos has been reported to inhibit brain AChE activity in rats, [16][17][18][19] with significant AChE inhibition in the hippocampus, 20 a structure with important roles in memory, spatial navigation, imagination, and perhaps inhibitory control. [39][40][41] However, AChE inhibition is an indicator of exposure, and other neurotoxic mechanisms may also be present.…”