Coull, J. T., Cotti, J., & Vidal, F. (2016). Differential roles for parietal and frontal cortices in fixed versus evolving temporal expectations: Dissociating prior from posterior temporal probabilities with fMRI. Neuroimage, 141, 40-51.
Goal: identify neural substrates of fixed and evolving temporal expectation
Task Type: visual; fixed v evolving (hazard function) timing; explicit bc told to use cues to help with timing (neutral cue wouldnt give any information though)
Methods: 16 healthy adults, fMRI, cued visual reaction time task: four cues gave temporal information about the timing of target presentation and one neutral cue which gave no information about target, participants were asked to press a button as fast as they can when they saw the target and to utilize the information about temporal presentation of the target in the temporal cues and that the neutral cue wouldnt help them predict the timing of the target presentation but to still respond as fast as possible; presentation of temporal and neutral trials was intermixed; 2 (cue: temporal, neutral) x 4 (timing: 533, 950, 1467, 2083ms) factorial design; whole brain analysis to generate activation maps of three contrasts (a) temporal > neutral main effect of cue (b) main effect of foreperiod in both neutral and temporal trials (c) interaction of cue and foreperiod to look for activity increasing with foreperiod duration in the neutral but not temporal conditions; anatomically-defined ROI analyses to investigate left parietal cortex (left inferior and superior parietal cortices) and right prefrontal cortex (right inferior and middle frontal gyri)
Results:
- Behaviorally, rt was significantly faster on temporal cued v neutral cued trials and rt also significantly faster as foreperiod increased in the neutral trials (rt was pretty constant across temporal conditions)
- Behaviorally, greater individual differences in benefits of the hazard function (faster RTs with longer foreperiods) correlated with faster response times during temporal cues
- Left inferior parietal cortex, left superior parietal cortex, and right superior parietal cortex were more active for temporal compared to neutral cues
- Hazard function activity: left inferior parietal cortex (specifically, left inferior parietal sulcus) increased with foreperiod duration in neutral > temporal conditions; also region in right inferior frontal cortex showed same pattern of activity
- ROI analysis of left inferior parietal cortex (anatomically-defined): main effect of cue during the temporal compared to the neutral trials; increased activity with foreperiod duration during neutral compared to temporal trials
- ROI analysis of left superior parietal cortex (anatomically-defined): main effect of cue during the temporal compared to the neutral trials
- ROI analysis of left inferior frontal gyrus (anatomically-defined): increased activity as a function of foreperiod duration during the neutral compared to temporal trials
- ROI analysis of left middle frontal gyrus (anatomically-defined): no main effects in any of the three contrasts
- ROI analysis of left middle frontal gyrus (functionally-defined): no main effects in any of the three contrasts
Big Take Aways:
- Reflecting the dorsal attention and ventral attention pathways, activity in the superior parietal cortex is oriented toward longer term goals, while activity in the inferior parietal cortex and intraparietal cortex dynamically orient toward more immediate stimulus-driven processes.
- The superior parietal regions were activated bilaterally, while the inferior parietal regions were left-lateralized. This aligns well with the findings in Coull & Nobre (1998) that found temporal attention to be preferentially left-lateralized.
- This study identifies a common neural architecture supporting both fixed and evolving temporal predictability (left inferior parietal cortex) as well as behavioral evidence for a common mechanism supporting temporal expectation across both conditions.
- Additionally, activity in both the inferior frontal gyrus and the middle frontal gyrus increased with longer foreperiods in the neutral but not in the temporal conditions tracking the dynamics of the hazard function.