fMRI reveals neural activity overlap between adult and infant pain

Abstract

Limited understanding of infant pain has led to its lack of recognition in clinical practice. While the network of brain regions that encode the affective and sensory aspects of adult pain are well described, the brain structures involved in infant nociceptive processing are completely unknown, meaning we cannot infer anything about the nature of the infant pain experience. Using fMRI we identified the network of brain regions that are active following acute noxious stimulation in newborn infants, and compared the activity to that observed in adults. Significant infant brain activity was observed in 18 of the 20 active adult brain regions but not in the infant amygdala or orbitofrontal cortex. Brain regions that encode sensory and affective components of pain are active in infants, suggesting that the infant pain experience closely resembles that seen in adults. This highlights the importance of developing effective pain management strategies in this vulnerable population.

Keywords: development; fMRI; human; infant; neuroscience; pain.

Figure 1.. Comparison of nociceptive-evoked brain activity in selected brain regions that are active in both adults and infants.

Significantly, active voxels across each stimulus intensity level are presented for (A) adult and (B) infant participants (applied force: adults 32–512 mN; infants 32–128 mN). Each colour represents activity in a different anatomical brain region. (A) Adult activity is overlaid onto a standard T1 weighted MNI template and (B) infant activity is overlaid onto a standard T2 weighted neonatal template, corresponding to a 40-week gestation infant. ACC: anterior cingulate cortex; S1: primary somatosensory cortex: PMC: primary motor cortex; SMA: supplementary motor area. DOI: http://dx.doi.org/10.7554/eLife.06356.003

Figure 2.. Noxious-evoked brain activity in response to the maximal presented stimulus in adults (512 mN) and infants (128 mN).

Red-yellow coloured areas represent active brain regions (threshold z ≥ 2.3 with a corrected cluster significance level of p < 0.05). An image of a midline sagittal brain slice (right panel) identifies the location of each example slice in the horizontal plane. (A) Adult activity is overlaid onto a standard T1 weighted MNI template and (B) infant activity is overlaid onto a standard T2 weighted neonatal template, corresponding to a 40-week gestation infant. DOI: http://dx.doi.org/10.7554/eLife.06356.005

Figure 2—figure supplement 1.. Relationship between percentage change in BOLD signal and stimulus intensity (force) in four example active brain regions in adult and infant participants.

A: Contralateral insula; B: Contralateral primary somatosensory cortex (S1); C: Anterior cingulate cortex (ACC); and D: Ipsilateral cerebellum. The crosses represent activity in individual participants. Red and blue lines are fitted regression lines and dashed lines show 95 % confidence intervals. DOI: http://dx.doi.org/10.7554/eLife.06356.006