Neural correlates of facial expression perception: Using adaptation to shift

the emotion perceived in unambiguous expressions

Phil PellAnne RichardsMarty Sereno

Background• Pell and Richards (submitted) found that the emotion perceived in

even seemingly ‘unambiguous’ expressions can be modified using adaptation

100% Fear 100% Disgust70% Fear 70% Disgust

Post Disgust adaptation

Post Fear adaptation

Test morphs Adaptation face Condition

Fear

Disgust

Fear

Disgust

Fear

Disgust

Fear perceived as Disgust

Fear perceived as Fear

Disgust perceived as Fear

Disgust perceived as Disgust

Design:• Faces from two different continua: Fear-Disgust and Disgust-Joy (1

male and 1 female face for each)

• Each set of 40 morphs (fear, disgust, joy, disgust) is viewed after adaptation to one end-point face (i.e. 100% face) or the other

• Gives us 8 conditions - each set of faces perceived as one of two emotions

• Up to 40 trials per condition - depends on how effective the adaptation effect is (should vary from 70-90%)

Hypotheses:• Expect to see enhanced activity in the insula when subjects perceive

disgust faces; irrespective of the test stimulus

• Possible (but unlikely) that the amygdala and ventral striatum will show enhanced activity to fear and joy respectively

• Look for a conjunction between different cross-boundary shifts

Proposed Study• 16-20 normal, healthy volunteers• Partial brain fMRI coving all key areas and whatever else is

possible within 2s (TR: 2s, TE: 40ms, 3.23 mm resolution)• 2 runs of 8 blocks - 35 adaptation trials 20 morphs, 5 ‘top-up’

trials and 8 dummy events – all faces are categorized• Fixed event timings (adaptors: 1450ms, trials: 2400ms) • All faces within a block are from the same identity• 40 min EPI + 10 min structural + 15 min prep = 1 hr 5 min• GLM in SPM - regressors used model morph events (divided

according to expression perceived) and adaptation period. • May also include a parametric variable to account for the decay

of the adaptation effect across the test phase• ROI: Amygdala, and insula (any regions identified in the group

analysis)