The Anterior Cingulate Gyrus Signals the Net Value of Others' Rewards

Evaluating the costs and benefits of our own choices is central to most forms of decision-making and its mechanisms in the brain are becoming increasingly well understood. To interact successfully in social environments, it is also essential to monitor the rewards that others receive. Previous studies in nonhuman primates have found neurons in the anterior cingulate cortex (ACC) that signal the net value (benefit minus cost) of rewards that will be received oneself and also neurons that signal when a reward will be received by someone else. However, little is understood about the way in which the human brain engages in cost-benefit analyses during social interactions. Does the ACC signal the net value (the benefits minus the costs) of rewards that others will receive? Here, using fMRI, we examined activity time locked to cues that signaled the anticipated reward magnitude (benefit) to be gained and the level of effort (cost) to be incurred either by a subject themselves or by a social confederate. We investigated whether activity in the ACC covaries with the net value of rewards that someone else will receive when that person is required to exert effort for the reward. We show that, although activation in the sulcus of the ACC signaled the costs on all trials, gyral ACC (ACC(g)) activity varied parametrically only with the net value of rewards gained by others. These results suggest that the ACC(g) plays an important role in signaling cost-benefit information by signaling the value of others' rewards during social interactions

Vicarious Reinforcement Learning Signals When Instructing Others

Reinforcement learning (RL) theory posits that learning is driven by discrepancies between the predicted and actual outcomes of actions (prediction errors [PEs]). In social environments, learning is often guided by similar RL mechanisms. For example, teachers monitor the actions of students and provide feedback to them. This feedback evokes PEs in students that guide their learning. We report the first study that investigates the neural mechanisms that underpin RL signals in the brain of a teacher. Neurons in the anterior cingulate cortex (ACC) signal PEs when learning from the outcomes of one's own actions but also signal information when outcomes are received by others. Does a teacher's ACC signal PEs when monitoring a student's learning? Using fMRI, we studied brain activity in human subjects (teachers) as they taught a confederate (student) action–outcome associations by providing positive or negative feedback. We examined activity time-locked to the students' responses, when teachers infer student predictions and know actual outcomes. We fitted a RL-based computational model to the behavior of the student to characterize their learning, and examined whether a teacher's ACC signals when a student's predictions are wrong. In line with our hypothesis, activity in the teacher's ACC covaried with the PE values in the model. Additionally, activity in the teacher's insula and ventromedial prefrontal cortex covaried with the predicted value according to the student. Our findings highlight that the ACC signals PEs vicariously for others' erroneous predictions, when monitoring and instructing their learning. These results suggest that RL mechanisms, processed vicariously, may underpin and facilitate teaching behaviors

The cerebellum and motor learning: Anatomical and behavioural studies of the conditioned eyeblink

The hypothesis that plasticity essential for motor learning is resident in the cerebellum is supported by studies showing that the integrity of parts of the olivo-cerebellar system (in particular, anterior interpositus nucleus, AIP) is critical for the acquisition and retention of conditioned nictitating membrane responses (CRs) - a simple form of motor learning. Some have argued that such lesions prevent performance, rather than learning. While permanent lesions cannot differentiate between these functions, reversible inactivations of AIP with muscimol (GABA-A agonist), reveal that AIP is essential for both. Experiments here evaluate the role of the AIP in extinction, the effects of AIP inactivation first on acquisition and then on extinction, and in post-conditioning consolidation processes. Experiment 1: Rabbits that had previously acquired, were first given four sessions of extinction training during inactivation, and then a further four sessions of extinction training without inactivation. They showed no CRs during inactivation, and CRs were at unextinguished levels after inactivation. Responses then extinguished normally. Extinction was therefore prevented. Experiment 2: Rabbits were given acquisition training first with inactivation of the AIP, and then without. They showed no CRs under muscimol, but acquired CRs gradually after inactivation. Muscimol therefore prevented acquisition. Subsequently, inactivations of the same site, AIP, in these animals also prevented extinction of CRs. Experiment 3: Pharmacological interventions after conditioning often disrupt acquisition. If the AIP is associated with learning-related plasticity, will AIP inactivations prevent post-conditioning consolidation processes associated with such plasticity. AIP was inactivated immediately after conditioning and learning was unaffected. When muscimol was infused subsequently during training it effectively blocked performance of CRs. So the blockades were effective, but they did not prevent muscimol-dependent consolidation processes in AIP. Inactivations of AIP with muscimol prevent extinction and acquisition, but not post-training consolidation processes. These findings are discussed in the context of the cerebellar learning hypothesis, and the anatomy and physiology of the cerebellum

Cognitive deficits from a cerebellar tumour: A historical case report from Luria's Laboratory

In 1964 an original case report from A.R. Luria's Laboratory of Neuropsychology was published in Cortex, being one of the first to draw a link between cerebellum and cognition, by highlighting the manifestation of 'pseudo-frontal' symptoms resulting from a cerebellar tumour. The findings of Luria and his team seem more consistent with modern views about cerebellar interactions with the frontal lobe and its contributions to behaviour than the views prevalent at the time of publication. The paper was originally submitted in Russian, and translated into Italian for its publication by Cortex. However, Cortex did not preserve the original manuscript in Russian. With the passage of time, and available only to the Italian readership, this case report inevitably fell into obscurity. Hence, we present a translation in English based on the published Italian version of the manuscript and discuss it in the context of Luria's general thinking about information processing in the brain and our current understanding of cortico-cerebellar system. The publication of this article gives readers an opportunity to consider the substantial influence of Soviet neuropsychology on the field internationally under Luria's leadership in the 1960s. It also shows that time is the best judge of ones scientific endeavours, and what may seem implausible today might prove to be valid and worthy of exploration tomorrow.</p

Anterior cingulate cortex : contributions to social cognition

It has been suggested that the Anterior Cingulate Cortex (ACC) plays an important role in decision-making. Activity in this area reflects processing related to two principles of Reinforcement Learning Theory (RLT): (i) signalling the predicted value of actions at the time they are instructed and (ii) signalling prediction errors at the time of the outcomes of actions. It has been suggested that neurons in the gyrus of the ACC (ACCg) process information about others' decisions and not one's own. An important aim of this thesis is to investigate whether the ACCg processes others' decisions in a manner that conforms to the principles of RLT. Four fMRI experiments investigate activity in the ACCg at the time of cues that signal either the predicted value of others' actions or that signal another's predictions are erroneous. • Experiment 1: Activity in the ACCg occurred when the outcome of another's decision was unexpectedly positive. • Experiment 2: Activity in the ACCg varied parametrically with the discrepancy between another's prediction of an outcome and the actual outcome known by the subject, in a manner that conformed to the computational principles of RLT. • Experiment 3: Activity in the ACCg varied with the predicted value of a reward, discounted by the amount of effort required to obtain it. • Experiment 4: Activity in the ACCg varied with the value of delayed rewards that were discounted in a manner that conformed to a social norm. These results support the hypothesis that the ACCg processes the predicted value of others' actions and also signals when others' predictions about the value of their actions are erroneous, in a manner that conforms to the principles of RLT.EThOS - Electronic Theses Online ServiceGBUnited Kingdo