Connectivity and Causality in Brain Imaging

• Activity Number: 285
• Type: Topic Contributed
• Date/Time: Tuesday, August 2, 2011 : 8:30 AM to 10:20 AM
• Sponsor: Biometrics Section
• Author(s): Martin A. Lindquist*+
• Companies: Columbia University
• Keywords: brain ; fMRI ; connectivity ; causal inference ; structural equation models

Abstract

To date human brain mapping has primarily been used to construct maps indicating regions of the brain that are activated by certain tasks. Recently, there has been an increased interest in augmenting this type of analysis with connectivity studies that seek to describe how brain regions interact and how these interactions depend on experimental conditions and behavioral measures. Often researchers discriminate between functional connectivity, the undirected association between two or more fMRI time series, and effective connectivity, the directed influence of one brain region on the physiological activity recorded in other brain regions. In this talk we argue that this distinction is not entirely clear or relevant. Instead, the validity of the conclusions made from any connectivity method will depend strongly on certain key assumptions which are often poorly specified and difficult to check. We conclude by showing how ideas from causal inference can provide a mathematical framework for determining these assumptions.