The desire to know: representations of information value in mouse orbitofrontal cortex during information seeking

Animals often seek knowledge of no apparent extrinsic value, suggesting that knowledge is a source of intrinsic value. Therefore, the desire to acquire information may be an innate motivational drive. We have developed a task in mice to study the neural mechanisms that compute the value of informative stimuli that drive information seeking. Mice are provided with odor cues in a center port that dictate entry into one of two side ports. The side ports offer water reward with identical probability and differ only in whether they provide an information odor cue that reveals the reward outcome. We found that mice strongly preferred the information port and also traded water reward to obtain information. We performed calcium imaging with miniature microscopes in orbitofrontal cortex, a brain region that represents value and task variables and has been previously implicated in information seeking. Decoding analysis and dimensionality reduction revealed a population representation predictive of information that emerged in orbitofrontal cortex during learning. We not only observed a representation predictive of information, we also observed a representation upon the receipt of information. The population response was largely shared between the side port water- and no water-predicting odors, suggesting that information is an unconditioned stimulus that reinforces the representation of information-predicting odor. Moreover, the representation predictive of information was distinct from the representation predictive of water reward. Thus, mice seek information of no extrinsic value, and the value of information is encoded in a distinct representation in the orbitofrontal cortex.