Friday, November 13, 2009

How you feel - the brain's bottom up and top down pathways

Ochsner et al use MRI to examine what is now becoming a common distinction, to consider the extent to which emotions arise via low-level processes that provide quick, bottom-up affective analyses of stimuli, versus high-level, top-down cognitive appraisal processes that draw upon stored knowledge. They did this by examining responses in trials with normatively aversive images (bottom-up trials) and also in novel trials in which participants cognitively interpreted neutral images as aversive (top-down trials). Here is the abstract, followed by a summary figure.
Emotions are generally thought to arise through the interaction of bottom-up and top-down processes. However, prior work has not delineated their relative contributions. In a sample of 20 females, we used functional magnetic resonance imaging to compare the neural correlates of negative emotions generated by the bottom-up perception of aversive images and by the top-down interpretation of neutral images as aversive. We found that (a) both types of responses activated the amygdala, although bottom-up responses did so more strongly; (b) bottom-up responses activated systems for attending to and encoding perceptual and affective stimulus properties, whereas top-down responses activated prefrontal regions that represent high-level cognitive interpretations; and (c) self-reported affect correlated with activity in the amygdala during bottom-up responding and with activity in the medial prefrontal cortex during top-down responding. These findings provide a neural foundation for emotion theories that posit multiple kinds of appraisal processes and help to clarify mechanisms underlying clinically relevant forms of emotion dysregulation.

1 comment:

  1. I've always thought it's nice that the "top-down", "higher thought processing" parts of the brain, roughly speaking, are literally on top of the "lower" bits, at least when you're standing up!