| Abstract: | The negative symptoms of schizophrenia (SZ) are associated with a pattern ofreinforcement learning (RL) deficits likely related to degraded representationsof reward values. However, the RL tasks used to date have required activeresponses to both reward and punishing stimuli. Pavlovian biases have been shownto affect performance on these tasks through invigoration of action to rewardand inhibition of action to punishment, and may be partially responsible for theeffects found in patients. Forty-five patients with schizophrenia and 30demographically-matched controls completed a four-stimulus reinforcementlearning task that crossed action (“Go” or “NoGo”) and the valence of theoptimal outcome (reward or punishment-avoidance), such that all combinations ofaction and outcome valence were tested. Behaviour was modelled using asix-parameter RL model and EEG was simultaneously recorded. Patientsdemonstrated a reduction in Pavlovian performance bias that was evident in areduced Go bias across the full group. In a subset of patients administeredclozapine, the reduction in Pavlovian bias was enhanced. The reduction inPavlovian bias in SZ patients was accompanied by feedback processing differencesat the time of the P3a component. The reduced Pavlovian bias in patients issuggested to be due to reduced fidelity in the communication between striatalregions and frontal cortex. It may also partially account for previous findingsof poorer “Go-learning” in schizophrenia where “Go” responses or Pavlovianconsistent responses are required for optimal performance. An attenuated P3acomponent dynamic in patients is consistent with a view that deficits in operantlearning are due to impairments in adaptively using feedback to updaterepresentations of stimulus value. |
