Biology subjects

Wang, M. Z.

Publications and source records attributed to Wang, M. Z..

6 recordsLinked to original sources

bioRxiv2024

State-dependent Online Reactivations for Different Learning Strategies in Foraging

Reactivation of neural responses associated with navigation is thought to facilitate learning. We wondered whether reactivation is subject to contextual control, meaning that different types of learning promote different reactivation patterns. We trained macaques to forage in a first-person virtual maze and identified two distinct learning states prioritizing reward and information using unsupervised ethogramming based on low-level features. In orbitofrontal (OFC) and retrosplenial (RSC) cortices, representations of the goal, the path towards it, and recently traveled paths were strongly reactivated - online - during reward-prioritizing choices. During learning, reactivation of optimal paths increased in RSC after reward-prioritizing choices, and reactivation of uninformative paths decreased in RSC and OFC after information-prioritizing choices. Reactivation in OFC selectively covaried with ongoing RSC activity when prioritizing information; vice versa during prioritizing reward. These results highlight that cognitive states can drive learning and reactivation patterns can be tailored to the needs of the moment.

neuroscience↗

bioRxiv2021

Orthogonal but linked neural codes for value

Our ability to effectively choose between dissimilar options implies that information regarding the options values must be available, either explicitly or implicitly, in the brain. Explicit realizations of value involve single neurons whose responses depend on value and not on the specific features that determine it. Implicit realizations, by contrast, come from the coordinated action of neurons that encode specific features. One signature of implicit value coding is that population responses to offers with the same value but different features should occupy semi- or fully orthogonal neural subspaces that are nonetheless linked. Here, we examined responses of neurons in six core value-coding areas in a choice task with risky and safe options. Using stricter criteria than some past studies have used, we find, surprisingly, no evidence for abstract value neurons (i.e., neurons with the response to equally valued risky and safe options) in any of these regions. Moreover, population codes for value resided in orthogonal subspaces; these subspaces were linked through a linear transform of each of their constituent subspaces. These results suggest that in all six regions, populations of neurons embed value implicitly in a distributed population.

neuroscience↗

bioRxiv2021

Differential encoding of safe and risky offers

Common currency theories in neuroeconomics hold that neurons in specific brain regions specifically encode subjective values of offers and not stimulus-specific information. The rationale behind these theories is that abstract value encoding lets the decision maker compare qualitatively different options. Alternatively, expectancy-based theories hold that the brain preferentially tracks the relationship between options and their outcomes, and thus does not abstract away details of offers. To adjudicate between these theories, we examined responses of neurons in six reward regions to risky and safe offers while macaques performed a gambling task. In all regions, responses to safe options are unrelated to responses evoked by equally preferred risky options. Nor does any region appear to contain a specialized subset of value-selective neurons. Finally, in all regions, responses to risky and safe options occupy distinct response subspaces, indicating that the organizational framework for encoding risky and safe offers is different. Together, these results argue against the idea that putative reward regions carry abstract value signals, and instead support the idea that these regions carry information that links specific options to their outcomes in support of a broader cognitive map.

neuroscience↗

bioRxiv2020

Anatomically distinct OFC-PCC circuits relay choice from value space to action space

Economic choice necessarily involves the transformation of abstract, object-based representations to concrete, action-based ones. This transformation is both determined and delimited by the neuroanatomical organization of the regions that implement it. In choice, the orbitofrontal cortex (OFC) plays a key role in both abstract valuation and cognitive mapping. However, determining the neural processes underlying this transformation has proven difficult. We hypothesized that difficulty stems from in part from the fact that the OFC consists of multiple functionally distinct zones that are distinguished by their differing contributions to the abstract-concrete transformation, and that these functions reflect their differing long-range projections. Here we identify two such subregions, defined by stronger or weaker bidirectional anatomical connectivity with the posterior cingulate cortex (PCC). We call these regions OFCin and OFCout, respectively. We find that OFCin, relative to OFCout, shows enhanced functional connectivity with PCC, as indicated by both spike-field coherence and mutual information. We find converging evidence that the OFCin-PCC circuit, but not the OFCout-PCC circuit, relays choice signals from an abstract value space to a concrete action space. Moreover, the OFCin-PCC circuit shows a putative bidirectional mutually excitatory pattern. Together, these results support the hypothesis that OFC-PCC subareal organization is critical for understanding the implementation of offer-action transformation in economic choice.

neuroscience↗

bioRxiv2020

Curiosity, latent learning, and cognitive maps

Curiosity refers to a desire for information that is not driven by immediate strategic or instrumental concerns. Latent earning refers to a form of learning that is not directly driven by standard reinforcement learning processes. We propose that curiosity serves the purpose of motivating latent learning. Thus, while latent learning is often treated as an incidental or passive process, in practice it most often reflects a strong evolved pressure to consume large amounts of information. That large volume of information in turn allows curious decision makers to generate sophisticated representations of the structure of their environment, known as cognitive maps. Cognitive maps facilitate adaptive and flexible behavior while maintaining its adaptivity and flexibility via map updates based on new information. Here we describe data supporting the idea that orbitofrontal cortex (OFC) and dorsal anterior cingulate cortex (dACC) play complementary roles in curiosity-driven learning. Specifically, we propose that (1) OFC tracks the innate value of information and incorporates new information into a detailed cognitive map; and (2) dACC tracks the environmental demands and information availability to then use the cognitive map for guiding behavior.

neuroscience↗

bioRxiv2018

Monkeys are Curious about Counterfactual Outcomes

While many non-human animals show basic exploratory behaviors, it remains unclear whether any animals possess human-like curiosity. We propose that human-like curiosity satisfies three formal criteria: (1) willingness to pay (or to sacrifice reward) to obtain information, (2) that the information provides no instrumental or strategic benefit (and the subject understands this), and (3) the amount the subject is willing to pay scales with the amount of information available. Although previous work, including our own, demonstrates that some animals will sacrifice juice rewards for information, that information normally predicts upcoming rewards and their ostensible curiosity may therefore be a byproduct of reinforcement processes. Here we get around this potential confound by showing that macaques sacrifice juice to obtain information about counterfactual outcomes (outcomes that could have occurred had the subject chosen differently). Moreover, willingness-to-pay scales with the information (Shannon entropy) offered by the counterfactual option. These results demonstrate human-like curiosity in non-human animals according to our strict criteria, which circumvent several confounds associated with less stringent criteria.

animal behavior and cognition↗