Coherent theta activity in the medial and orbital frontal cortices encodes reward value

Abstract

This study examined how the medial frontal (MFC) and orbital frontal (OFC) cortices process reward information to guide behavior. We simultaneously recorded local field potentials in the two areas as rats consumed liquid sucrose rewards and examined how the areas collectively process reward information. Both areas exhibited a 4-8 Hz "theta" rhythm that was phase locked to the lick cycle. The rhythm similarly tracked shifts in sucrose concentrations and fluid volumes, suggesting that it is sensitive to general differences in reward magnitude. Differences between the MFC and OFC were noted, specifically that the rhythm varied with response vigor and absolute reward value in the MFC, but not the OFC. Our findings suggest that the MFC and OFC concurrently process reward information but have distinct roles in the control of consummatory behavior.

Theta oscillations in anterior cingulate cortex and orbitofrontal cortex differentially modulate accuracy and speed in flexible reward learning

“…Our results confirm and extend a recent report that ACC-OFC theta coherence encodes reward value (Amarante and Laubach, 2021), since the ACC-OFC interaction we observed occurred during initial learning of both S-O and A-O tasks, but not during reversal learning. A noteworthy difference from Amarante & Laubach (2021) is that this group studied coherence during reward consumption (i.e., licks).…”

“…Our results confirm and extend a recent report that ACC-OFC theta coherence encodes reward value (Amarante and Laubach, 2021), since the ACC-OFC interaction we observed occurred during initial learning of both S-O and A-O tasks, but not during reversal learning. A noteworthy difference from Amarante & Laubach (2021) is that this group studied coherence during reward consumption (i.e., licks). We note that the increase in theta power we report here occurred immediately following a correct choice but preceded most reward collection times (1.5-2.5 sec) and consumption of the sucrose pellet.…”

“…For example, single neurons in macaque OFC and ACC encode the action that guides choice, with stronger firing patterns in OFC during a stimulus-based task and stronger ACC firing during an actionbased task (Luk and Wallis, 2013). More recently, there is reported evidence of ACC-OFC taskrelated coherence in theta to low beta (4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20) oscillations as rats respond to or choose a highervalued reward, suggesting a functional connectivity that encodes relative reward value (Amarante and Laubach, 2021;Fatahi et al, 2020;Fatahi et al, 2018). It is therefore conceivable that these two regions work in a hierarchy for reward-based learning and choice (Hunt and Hayden, 2017;Hunt et al, 2018) potentially with theta oscillations in OFC as the spectral signature that coordinates reward signals (Knudsen and Wallis, 2020;Marquardt et al, 2017) with ACC (Fatahi et al, 2018).…”

Relative salience signaling within a thalamo-orbitofrontal circuit governs learning rate

“…Activity in vmOFC is not consistent with a signaling of the subjective value of a received reward in these experiments (Amarante and Laubach, 2020; Padoa-Schioppa and Assad, 2006). This is because the subjective value of the same received reward should be equal regardless of whether the reward was predicted, and further the subjective value of the receipt of a predicted reward should be larger than the subjective value of the omission of a predicted reward.…”

“…It has previously been observed that orbitofrontal cortical neurons represent the relative value of a reward in comparison to other available options (Tremblay and Schultz, 1999) (though see (Amarante and Laubach, 2020; Padoa-Schioppa and Assad, 2008)). Such a relative value signal has also been clearly demonstrated in other brain regions (Louie et al, 2011; Ottenheimer et al, 2018).…”