fMRI – What is love?

This is not about the famous/infamous MRI experiment by Dutch scientist Dr. W Schultz who imaged coitus with MRI. I’m talking about fMRI used to examine romantic love. I got the idea from a post about crowdsourcing from Kristie D for Summer Holmquist . Crowdsourcing was used to transcribe an interview with Helen Fisher, who is involved with the fMRI studies (interview transcript here: http://goo.gl/qdIsL).

fMRI Functional MRI or fMRI can be acquired using several different types of  MRI scans. I’ve talked about anatomical vs. functional MRI before (http://goo.gl/yNm5g, , http://goo.gl/Locwu, and  indirectly here http://goo.gl/1Ezx4). Functional MRI focuses on function and often requires an anatomical image for guidance, often at higher spatial resolution. Common types of functional MRI are Blood Oxygen Level Dependent (BOLD), Dynamic Contrast Enhanced (DCE), and Diffusion Weighted Imaging (DWI). There are more but these are quite common. BOLD MRI was used in the romance novels discussed here. It takes advantage of the fact that deoxygenated hemoglobin is paramagnetic while oxygenated blood (hemoglobin) is not. It uses T2 relaxation but not T1. I can discuss relaxivity in another post. Similar to positron emission tomography (PET) with F-18 labeled fluorodeoxyglucose  (FDG), BOLD can detect brain activity via changes in oxygenation. PET with FDG detects changes in metabolism, i.e., glucose uptake. DCE-MRI uses a contrast agent, typically gadolinium based. Images are acquired rapidly and the uptake of contrast agent can be modeled to generate parametric images that tell something about the pharmacokinetics/pharmacodynamics. DWI is based on models of diffusion. Parametric images of diffusion can be generated. DCE-MRI and DWI are often used to detect cancer as the tumor often has higher perfusion (DCE-MRI) and “restricted” diffusion (DWI, think more tumor cells relative to say muscle).

In 2005 Aron, Fisher et al use fMRI to answer the question of which reward/motivation system is involved in early-stage romantic love. 

Reward, motivation, and emotion systems associated with early-stage intense romantic love.

J Neurophysiol. 2005 Jul;94(1):327-37. Epub 2005 May 31.  http://goo.gl/XNs0M  

The results suggest that romantic love uses subcortical reward and motivation systems to focus on a specific individual, that limbic cortical regions process individual emotion factors, and that there is localization heterogeneity for reward functions in the human brain.

In 2012 they followed up with long-term intense romantic love. 

Neural correlates of long-term intense romantic love.

Soc Cogn Affect Neurosci. 2012 Feb;7(2):145-59. Epub 2011 Jan 5. http://goo.gl/dClfu 

Overall, results suggest that for some individuals the reward-value associated with a long-term partner may be sustained, similar to new love, but also involves brain systems implicated in attachment and pair-bonding.

Notice in the attached figure the functional image has much lower resolution compared to the anatomic image (the BOLD is color overlaid on the greyscale anatomic). It would have been nice to correlate with PET imaging as it has higher sensitivity. Of course I have to plug our own lab. High spectral and spatial MRI (HiSS) MRI can be considered as an advanced version of BOLD MRI.  In pre-contrast HiSS images, vasculature can be detected based on susceptibility differences between blood vessels and surrounding tissue that cause T2*, resonance frequency, and other changes in water the lineshape.  The water peak-height can give exceptional contrast from a HiSS MRI relative to standard anatomic MRI.  An example showing conventional vs. HiSS MRI http://goo.gl/IiZ6U.

#ScienceSunday  ScienceSunday curated by Allison Sekuler Robby Bowles and Rajini Rao and often invaded by me.