Organization of afferents to the orbitofrontal cortex in the rat

Abstract

The prefrontal cortex (PFC) is usually defined as the frontal cortical area receiving a mediodorsal thalamic (MD) innervation. Certain areas in the medial wall of the rat frontal area receive a MD innervation. A second frontal area that is the target of MD projections is located dorsal to the rhinal sulcus and often referred to as the orbitofrontal cortex (OFC). Both the medial PFC and OFC are comprised of a large number of cytoarchitectonic regions. We assessed the afferent innervation of the different areas of the OFC, with a focus on projections arising from the mediodorsal thalamic nucleus, the basolateral nucleus of the amygdala, and the midbrain dopamine neurons. Although there are specific inputs to various OFC areas, a simplified organizational scheme could be defined, with the medial areas of the OFC receiving thalamic inputs, the lateral areas of the OFC being the recipient of amygdala afferents, and a central zone that was the target of midbrain dopamine neurons. Anterograde tracer data were consistent with this organization of afferents, and revealed that the OFC inputs from these three subcortical sites were largely spatially segregated. This spatial segregation suggests that the central portion of the OFC (pregenual agranular insular cortex) is the only OFC region that is a prefrontal cortical area, analogous to the prelimbic cortex in the medial prefrontal cortex. These findings highlight the heterogeneity of the OFC, and suggest possible functional attributes of the three different OFC areas.

β1-Integrins in the Developing Orbitofrontal Cortex Are Necessary for Expectancy Updating in Mice

“…The connections between the PL and ventrolateral OFC (the OFC subregion affected here) are bidirectional (Heidbreder and Groenewegen, 2003;Hoover and Vertes, 2011), but we think the behavioral consequences of contralateral infusions are attributable to PL¡OFC projections, given that ␤1-integrins are located at the postsynaptic synapse (Mortillo et al, 2012). PL¡OFC projections terminate in all layers and are largely, though not exclusively, intrahemispheric (Sesack et al, 1989;Murphy and Deutch, 2018). Thus, crossing fibers could account for an intermediate effect observed in the ipsilateral PL¡OFC condition.…”

Medial orbitofrontal inactivation does not affect economic choice

“…While we interpreted our result as consistent with the parallel support of economic choice by a number of neural circuits, an alternative explanation is that the lateral OFC is simply the wrong part of OFC. The OFC is increasingly recognized as consisting of several subregions ( Heilbronner et al, 2016 ; Izquierdo, 2017 ; Murphy and Deutch, 2018 ; Rudebeck and Murray, 2011a ; Walton et al, 2011 ), and medial OFC is implicated in signaling common currency value by human imaging studies ( Levy and Glimcher, 2011 ; Plassmann et al, 2010 ; Plassmann et al, 2007 ) and in mediating value-guided behaviors in rats ( Bradfield et al, 2015 ; Münster and Hauber, 2017 ), monkeys ( Noonan et al, 2010 ) and humans ( Camille et al, 2011 ; Noonan et al, 2017 ). Here we tested whether the medial region might be the critical site in OFC responsible for calculating economic value by optogenetically inactivating this region in rats engaged in the aforementioned task.…”

Deep brain stimulation of the orbitofrontal cortex prevents the development and reinstatement of morphine place preference

“…The OFC receives highly processed sensory inputs from several modalities, including olfaction, taste, visceral afferents, somatic sensation, and vision . It also receives afferents from the thalamus, amygdala, and midbrain dopamine neurons and sends projections to the lateral hypothalamic and ventral tegmental areas . This connection profile supports a role for the OFC in reward‐related behaviors.…”