human: Given a node-centered hypergraph: <hypergraph>, where nodes represent authors and hyperedges represent groups of authors who co-authored the same paper.

Details of the hypergraph:
Center node: "Posteromedial cortex glutamate and GABA predict intrinsic functional connectivity of the default mode network."
  Abstract: Abstract   The balance between excitatory glutamatergic projection neurons and inhibitory GABAergic interneurons determines the function of cortical microcircuits. How these neurotransmitters relate to the functional status of an entire macro-scale network remains unknown. The posteromedial cortex (PMC) is the default mode network (DMN) node with the greatest functional connectivity; therefore, we hypothesized that PMC glutamate and GABA predict intrinsic functional connectivity (iFC) across the entire DMN. In 20 healthy men, we combined J-resolved magnetic resonance spectroscopy to measure glutamate and GABA in the PMC and resting fMRI followed by group Independent Components Analysis to extract the entire DMN. We showed that, controlling for age and partial GM volume in the MRS voxel, PMC glutamate and GABA explained about half of the variance of DMN iFC (represented by the network's beta coefficient for rest). Glutamate correlated positively and GABA correlated negatively with DMN iFC; in an alternative statistical model which included the glutamate/GABA ratio, the ratio correlated positively with DMN iFC. Age had no independent association with DMN iFC. No other network was associated with PMC glutamate or GABA. We conclude that regional neurotransmitter concentrations in a network node strongly predict network but not global brain iFC.

Connected through hyperedge HE-1 (induced by source paper "Big GABA: Edited MR spectroscopy at 24 research sites"):
  with members:
    - "Advanced Hadamard-encoded editing of seven low-concentration brain metabolites: Principles of HERCULES"

Connected through hyperedge HE-2 (induced by source paper "Effects of aging on default mode network activity in resting state fMRI: Does the method of analysis matter?"):
  with members:
    - "Age Differences in Deactivation: A Link to Cognitive Control?"
    - "Decreased functional connectivity by aging is associated with cognitive decline"

Question: Please tell me which research area the center author belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Economics