Abstract
The perirhinal (PER) and lateral entorhinal (LEC) cortex function as a gateway for information transmission between (sub)cortical areas and the hippocampus. It is hypothesized that the amygdala, a key structure in emotion processing, can modulate PER-LEC neuronal activity before information enters the hippocampal memory pathway. This study determined the integration of synaptic activity evoked by simultaneous neocortical and amygdala electrical stimulation in PER-LEC deep layer principal neurons and PV interneurons in mouse brain slices. The data revealed that both deep layer PER-LEC principal neurons and PV interneurons receive synaptic input from the neocortical agranular insular cortex (AiP) and the lateral amygdala (LA). Furthermore, simultaneous stimulation of the AiP and LA never reached the firing threshold in principal neurons of the PER-LEC deep layers. PV interneurons however, mainly showed linear summation of simultaneous AiP and LA inputs and reached their firing threshold earlier. This early PV firing was reflected in the forward shift of the evoked inhibitory conductance in principal neurons, thereby creating a more precise temporal window for coincidence detection which likely plays a crucial role in information processing.
Significance Statement The perirhinal and lateral entorhinal cortices (PER-LEC) function as a gateway for information transmission between the neocortex and the hippocampus and this information flow can be modulated by the amygdala. Here, we showed that simultaneous input of the neocortex and the amygdala coincided onto principal neurons and PV interneurons of the PER-LEC deep layers. PV interneurons linearly summated these synaptic inputs and reached their firing threshold earlier. This earlier PV firing resulted in an earlier rise of the inhibitory conductance in principal neurons, likely causing a more precise temporal window for excitatory coincidence detection. This process probably indicates a significant role for the inhibitory network in regulating integration of emotion and information for processing in the PER-LEC deep layer network.
Footnotes
The authors declare to have no conflicts of interests.
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