Spatial Representations in Rat Orbitofrontal Cortex

Abstract

The orbitofrontal cortex (OFC) and hippocampus share striking cognitive and functional similarities. As a result, both structures have been proposed to encode "cognitive maps" that provide useful scaffolds for planning complex behaviors. However, while this function has been exemplified by spatial coding in neurons of hippocampal regions-particularly place and grid cells-spatial representations in the OFC have been investigated far less. Here we sought to address this by recording OFC neurons from male rats engaged in an open-field foraging task like that originally developed to characterize place fields in rodent hippocampal neurons. Single-unit activity was recorded as rats searched for food pellets scattered randomly throughout a large enclosure. In some sessions, particular flavors of food occurred more frequently in particular parts of the enclosure; in others, only a single flavor was used. OFC neurons showed spatially localized firing fields in both conditions, and representations changed between flavored and unflavored foraging periods in a manner reminiscent of remapping in the hippocampus. Compared with hippocampal recordings taken under similar behavioral conditions, OFC spatial representations were less temporally reliable, and there was no significant evidence of grid tuning in OFC neurons. These data confirm that OFC neurons show spatial firing fields in a large, two-dimensional environment in a manner similar to hippocampus. Consistent with the focus of the OFC on biological meaning and goals, spatial coding was weaker than in hippocampus and influenced by outcome identity.

Widespread coding of navigational variables in prefrontal cortex

“…A small but growing body of research suggests that, at least in rodents, there may be navigational functions outside of the hippocampal complex, including within the prefrontal cortex or its homologues (Patai & Spiers, 2021; Maisson et al, 2022). For example, neurons in somatosensory cortex, orbitofrontal cortex, and piriform cortex encode current and future spatial positions as well as the location of targets in the environment (Basu et al, 2021; Long and Zhang, 2021; Poo et al, 2022; Wikenheiser et al, 2021). This work raises the possibility that navigational functions may likewise be widespread across the prefrontal cortex.…”

Peripersonal encoding of forelimb proprioception in the mouse somatosensory cortex

“…Accordingly, muscle length inputs to a cortical neuron could be continuously tuned by activity representing spatial information in somatosensory cortex (Long and Zhang, 2021; Yin et al, 2018). Spatial activity could be acquired in fS1 based on direct connectivity from limbic structures (Fyhn et al, 2004; Swanson and Köhler, 1986) or cortical areas interconnected with the hippocampal-entorhinal formation (Sauer et al, 2022; Wikenheiser et al, 2021; Wilber et al, 2014). Encoding of space could in fact be a common feature of sensory cortical circuits (Fiser et al, 2016; Town et al, 2017).…”

A persistent prefrontal reference frame across time and task rules

“…The majority of CA1 neurons change their spatial representation over time 8,27 , suggesting that a transformation of dynamic-to-stable neuronal responses might occur during this passage of spatial information to the mPFC network. Alternatively, a subset of CA1 place cells with temporally consistent place field locations 28 , or spatially tuned neurons in other neocortical areas such as somatosensory 29 or orbitofrontal cortex 30 might support stable spatial tuning in mPFC circuits. The cellular and network processes which might underlie the transmission of spatial information remain, however, to be investigated.…”