Computer-controlled stimulation for functional magnetic resonance imaging studies of the neonatal olfactory system.
Bottom Line: The system was used to present the odour of infant formula milk in a validation group of seven neonatal subjects at term equivalent postmenstrual age (median age 40 weeks).A safe, reliable and reproducible pattern of stimulation was delivered leading to well-localized positive BOLD functional responses in the piriform cortex, amygdala, thalamus, insular cortex and cerebellum.The described system is therefore suitable for detailed studies of the ontology of olfactory sensation and perception during early human brain development.
Affiliation: Centre for the Developing Brain, Division of Imaging Sciences & Biomedical Engineering, Kings College London, St. Thomas' Hospital, London, UK.Show MeSH
Mentions: As proposed by Johnson and Sobel ((19)), an olfactometer can be conceptualized into three major subsystems: (i) the airflow preparation apparatus; (ii) the odour-sourcing apparatus; (iii) the delivery apparatus (see Fig. 1). Although custom designed, the described system is constructed entirely from off-the-shelf pneumatic parts (Festo Cooperation, Esslingen am Neckar, Germany); and to minimize infective risk, readily available single-use clinical equipment. Both the airflow preparation and odour-sourcing subsystems are placed in the scanner control room, with precise control of the timing of stimulation achieved via a data acquisition card (DAQ) and custom software (Labview v11.0; National Instruments, Austin, TX, USA) (15). The system airflow (medical grade air) is supplied via the hospital compressed breathing air supply wall socket, with the flow rate into the system (up to 2 L/min) set via a one-way flow control valve. This flow rate was chosen empirically following pilot experiments with adult subjects, and selected at a level at which the odour could be easily detected by the subject without causing any discomfort. As an additional safety feature and to ensure consistency during stimulus delivery, a flow sensor with an LCD display was then integrated into the system to provide an accurate quantification of the air flow entering the system.
Affiliation: Centre for the Developing Brain, Division of Imaging Sciences & Biomedical Engineering, Kings College London, St. Thomas' Hospital, London, UK.