Final answer:
A neuroscientist would expect to find a negative correlation between gray matter volume in the amygdala and hippocampus and the distance of residence from the World Trade Center on 9/11, reflecting the link between traumatic stress and brain structure changes.
Step-by-step explanation:
A neuroscientist studying the effects of proximity to the 9/11 World Trade Center attacks on brain structure would likely expect to find a negative correlation between gray matter volume in the amygdala and hippocampus and the distance of residence from the World Trade Center among a sample of New York City participants. This expectation is based on research indicating that exposure to traumatic stress, such as the events of 9/11, can be associated with reductions in the volume of the hippocampus, a brain region implicated in stress-related disorders like PTSD. In addition, individuals who were closer to the attacks may have experienced more intense stress, potentially leading to greater changes in brain structure.