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Graphical abstract, Highlights • Distinct anatomical inputs define anterior and posterior regions in rat lateral OFC. • Anterior–posterior differences as distinct as established medial–lateral ones in OFC. • Amygdala inputs to OFC predominantly target posterior lateral OFC. • Submedius thalamic input patterns are a key characteristic of distinct OFC subregions. • Anatomical heterogeneity within the OFC maps onto recent functional heterogeneity., The orbitofrontal cortex (OFC) has been anatomically divided into a number of subregions along its medial–lateral axis, which behavioral research suggests have distinct functions. Recently, evidence has emerged suggesting functional diversity is also present along the anterior–posterior axis of the rodent OFC. However, the patterns of anatomical connections that underlie these differences have not been well characterized. Here, we use the retrograde tracer cholera toxin subunit B (CTB) to simultaneously label the projections into the anterior lateral (ALO), posterior lateral (PLO), and posterior ventral (PVO) portions of the rat OFC. Our methodological approach allowed us to simultaneously compare the density and input patterns into these OFC subdivisions. We observed distinct and topographically organized projection patterns into ALO, PLO, and PVO from the mediodorsal and the submedius nuclei of the thalamus. We also observed different levels of connectivity strength into these OFC subdivisions from the amygdala, motor cortex, sensory cortices and medial prefrontal cortical structures, including medial OFC, infralimbic and prelimbic cortices. Interestingly, while labelling in some of these input regions revealed only a gradient in connectivity strength, other regions seem to project almost exclusively to specific OFC subdivisions. Moreover, differences in input patterns between ALO and PLO were as pronounced as those between PLO and PVO. Together, our results support the existence of distinct anatomical circuits within lateral OFC along its anterior–posterior axis.

Highlights • Neurons in the whisker system are selective to spatial and dynamical properties – features – of sensory stimuli. • At each stage of the pathway, different neurons encode distinct features, generating a rich population representation. • Whisker touch is robustly represented; neurons respond to touch-driven fast fluctuations in forces at the whisker base. • Cortical neurons have more complex and context-dependent selectivity than subcortical, e.g., to collective whisker motion. • Understanding how these signals are integrated to construct whisker-mediated percepts requires further research., Our sensory receptors are faced with an onslaught of different environmental inputs. Each sensory event or encounter with an object involves a distinct combination of physical energy sources impinging upon receptors. In the rodent whisker system, each primary afferent neuron located in the trigeminal ganglion innervates and responds to a single whisker and encodes a distinct set of physical stimulus properties – features – corresponding to changes in whisker angle and shape and the consequent forces acting on the whisker follicle. Here we review the nature of the features encoded by successive stages of processing along the whisker pathway. At each stage different neurons respond to distinct features, such that the population as a whole represents diverse properties. Different neuronal types also have distinct feature selectivity. Thus, neurons at the same stage of processing and responding to the same whisker nevertheless play different roles in representing objects contacted by the whisker. This diversity, combined with the precise timing and high reliability of responses, enables populations at each stage to represent a wide range of stimuli. Cortical neurons respond to more complex stimulus properties – such as correlated motion across whiskers – than those at early subcortical stages. Temporal integration along the pathway is comparatively weak: neurons up to barrel cortex (BC) are sensitive mainly to fast (tens of milliseconds) fluctuations in whisker motion. The topographic organization of whisker sensitivity is paralleled by systematic organization of neuronal selectivity to certain other physical features, but selectivity to touch and to dynamic stimulus properties is distributed in “salt-and-pepper” fashion.