"While the study of anatomical connections between brain regions provides important information about developing pain processes, the existence of a connection is not evidence of its function. Connections viewed under the microscope between the thalamus and the cortical plate at 24 weeks, for example, may or may not transmit information from nociceptors upon tissue damage. Fetal magnetoencephalography has been used to effectively record fetal auditory and visual evoked responses and spontaneous brain activity of cortical origin from 28 weeks and fetal brain activation to sound has been demonstrated using functional magnetic resonance imaging (fMRI) from 33 weeks. It has not been possible to record directly from human fetal cortex to establish when cortical neurons first begin to respond to tissue damaging inputs. Near infrared spectroscopy with preterm infants in intensive care, however, has demonstrated localised somatosensory cortical responses in premature newborn infants (from 24 weeks) following noxious heel lance36 and venepuncture. More recently, EEG has demonstrated a clear, time-locked, nociceptive-evoked potential in preterm infants following heel lance. Thus, there is direct evidence of neural activity in primary sensory cortex following tissue damage in very premature infants equivalent to 24 weeks of gestational age."
January 1, 1970