Ian C. Ballard

This study finds reduced striatal hemodynamic latency in early psychosis, particularly in dorsal striatal regions, suggesting it may be an indirect marker of dopamine dysfunction.

The paper shows that prefrontal cortex organizes visual evidence by representational abstraction, with distinct regions processing lower- and higher-level similarity during decision-making.

The paper maps dopamine physiology using hemodynamic latency from fMRI, showing distinct patterns in the nucleus accumbens and linking them to addictive behaviors and substance use disorders.

This study identifies distinct dopamine mechanisms for behavioral control and model-based knowledge formation using PET, fMRI, and pharmacological interventions.

The paper quantifies structural connectivity between the hippocampus and reward regions in humans using diffusion MRI, finding region-specific connectivity patterns along the hippocampal axis.

The paper investigates how emotional context shapes action goal representations in the lateral frontal pole using neuroimaging and pattern similarity analysis.

The paper investigates how the brain learns from transient goals using behavior, modeling, and neuroimaging, finding that executive function and reward circuits interact to support flexible learning.

This study shows the hippocampus forms conjunctive representations that influence striatal prediction errors in reinforcement learning.

This paper improves parameter identifiability in reinforcement learning models by jointly modeling reaction times and choices, enhancing the power to detect correlations with learning rates.

The paper uses rTMS to disrupt dlPFC activity and shows it reduces the magnitude effect, providing causal evidence for dlPFC's role in impulsivity.

The paper shows that striatum responses reflect a surprise signal from a Bayesian rule-learning model, not reward prediction error, during explicit rule learning.