Mapping touch and nociception in the human infant brain

• Main Author: Williams, G. R.
• Published: University College London (University of London) 2013
• Subjects: 618.92
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.626257

Infants often experience clinically-essential painful procedures. The aim of this thesis was to measure, using functional magnetic resonance imaging (fMRI) and electroencephalography (EEG), activation patterns in the infant brain in response to noxious and non-noxious cutaneous stimulation. Using fMRI we assessed somatosensory and nociceptive circuitry in infants undergoing brush, three forces of von Frey, or pinprick stimulation of the foot. First we established optimum parameters and protocols specific for this study. Next, we characterised brain activity and somatotopy, and then considered modulation of activity related to stimulus intensity, stimulus modality, clinically-required sedation, age, and clinical background. Brain regions activated included primary and secondary somatosensory cortices, precuneus, insula, frontal, occipital, motor and cingulate cortices. Activations were somatotopic and di ered according to intensity, modality or clinical background. This is the first study to use fMRI to demonstrate brain activations in response to brush, von Frey hair and pinprick stimulation in human newborn infants. EEG recordings of lance in infants show a noxious-specific deflection at Cz which is not seen in adults undergoing experimental pain. To determine whether this di erence is due to age or stimulus modality we measured EEG activity to lance in healthy adult volunteers. Lance and innocuous tactile stimulations were applied to fifth finger beds, one of which was sensitised with mustard oil. Pain scores were recorded, and verbal descriptors were used to estimate peripheral fibre activation. EEG was compared to infant data collected in a previous study. Brain activity to lance in adults was di erent from control, and was modulated by sensitisation. EEG activity was related to pain score and verbal descriptors. The same stimulation initiated a distinct pattern of activity in infants which di ered from adults. This is the first study to characterise EEG responses to lance in adults, and to compare results with lance in newborn infants.