A precise and adaptive neural mechanism for predictive temporal processing in the frontal cortex
The theory of predictive processing posits that the brain computes expectations to process information predictively. Empirical evidence in support of this theory, however, is scarce and largely limited to sensory areas. Here, we report a precise and adaptive mechanism in the frontal cortex of non-human primates consistent with predictive processing of temporal events. We found that the speed of neural dynamics is precisely adjusted according to the average time of an expected stimulus. This speed adjustment, in turn, enables neurons to encode stimuli in terms of deviations from expectation. This lawful relationship was evident across multiple experiments and held true during learning: when temporal statistics underwent covert changes, neural responses underwent predictable changes that reflected the new mean. Together, these results highlight a precise mathematical relationship between temporal statistics in the environment and neural activity in the frontal cortex that may serve as a mechanism for predictive temporal processing.
Frontal circuit specialisations for decision making
During primate evolution, prefrontal cortex (PFC) expanded substantially relative to other cortical areas. The expansion of PFC circuits likely supported the increased cognitive abilities of humans and anthropoids to plan, evaluate, and decide between different courses of action. But what do these circuits compute as a decision is being made, and how can they be related to anatomical specialisations within and across PFC? To address this, we recorded PFC activity during value-based decision making using single unit recording in non-human primates and magnetoencephalography in humans. At a macrocircuit level, we found that value correlates differ substantially across PFC subregions. They are heavily shaped by each subregion’s anatomical connections and by the decision-maker’s current locus of attention. At a microcircuit level, we found that the temporal evolution of value correlates can be predicted using cortical recurrent network models that temporally integrate incoming decision evidence. These models reflect the fact that PFC circuits are highly recurrent in nature and have synaptic properties that support persistent activity across temporally extended cognitive tasks. Our findings build upon recent work describing economic decision making as a process of attention-weighted evidence integration across time.
The evolutionary and psychological origins of reciprocal cooperation
If only those behaviours evolve that increase the actor’s own survival and reproductive success, then it might come as a surprise that cooperative behaviours, i.e. providing benefits to others, are a widespread phenomenon. Many animals cooperate even with unrelated individuals in various contexts, like providing care or food. One possibility to explain these behaviours is reciprocity. Reciprocal cooperation, i.e. helping those that were helpful before, is a ubiquitous and important trait of human sociality. Still, the evolutionary origin of it is largely unclear, mainly because it is believed that other animals do not exchange help reciprocally. Consequently, reciprocity is suggested to have evolved in the human lineage only. In contrast to this, I propose that reciprocity is not necessarily cognitively demanding and likely to be widespread. In my talk, I will first shed light on the mechanisms of reciprocal cooperation in Norway rats (Rattus norvegicus). In a series of studies, my colleagues and I have demonstrated that Norway rats reciprocally exchange goods and services between and within different commodities and independent of kinship. Furthermore, to understand the evolutionary origins of human reciprocity, and whether it is shared with other animals, I will then discuss evidence for reciprocity in non-human primates, which are our closest living relatives. A thorough analysis of the findings showed that reciprocity is present and, for example, not confined to unrelated individuals, but that the choice of commodities can impact the likelihood of reciprocation. Based on my findings, I conclude that reciprocal cooperation in non-human animals is present but largely neglected and not restricted to humans. In order to deepen our understanding of the evolutionary origins of reciprocity in more general, future studies should investigate when and how reciprocity in non-human animals emerged and how it is maintained.