Central Nervous System Processing of Floral Odor and Mother’s Milk Odor in Infants

Abstract

Newborns have a functioning sense of smell at birth, which appears to be highly significant for feeding and bonding. Still, little is known about the cerebral odor processing in this age group. Studies of olfactory function relied mostly on behavioral, autonomic and facial responses of infants. Aim The aim of the present study was to investigate central odor processing in infants focusing on EEG-derived responses to biologically significant odors, namely a food and a non-food odor. Material and Methods A total of 21 term-born, healthy infants participated (11 boys, 10 girls; age range 2-9 months, mean 5.3±2.2 months). Odor stimuli were presented using a computer controlled olfactometer. Breast milk was used as food odor. Farnesol was presented as a non-food odor. In addition, odorless air was used as a control stimulus. Each stimulus was presented 30 times for 1 second with an inter-stimulus-interval of 20 seconds. EEG was recorded from 9 electrodes and analyzed in the frequency domain. Results EEG amplitudes in the delta frequency band differed significantly after presentation of food (breast milk) odor in comparison to the control condition and the non-food odor (farnesol). These changes were observed at the frontal recording positions. Conclusion The present study indicates that central odor processing differs between a food and a non-food odor in infants. Results are interpreted in terms of focused attention towards a physiologically relevant odor (breast milk) suggesting that olfactory stimuli are of specific significance in this age group.

Electroencephalogram response in premature infants to different odors: a feasibility study

“…However, in 2001 a research group demonstrated, using near-infrared spectroscopy, that a change in blood oxygenation of premature infants could be detected in the orbitofrontal cortex after olfactory stimulation with disinfectant and detergent [3]. Electroencephalogram (EEG) techniques have broadly been used to measure central odor processing in adults and children [4][5][6]. EEG has a high temporal resolution and is more stable to movement artifacts compared to magnetic resonance imaging (MRI).…”

“…From the age of 28–29 weeks of gestation, a change in EEG to external stimuli can be observed [ 7 ]. The aim of the present study was to investigate the possibility of detecting central odor processing in premature infants by analyzing olfactory-induced EEG changes using Fast Fourier transformation (FFT) as an already established method in older term-born infants [ 6 ]. The previous study from our group demonstrated that EEG method and FFT analysis were feasible for mature infants and showed that EEG amplitudes in the δ frequency band differed significantly after the presentation of breast milk in comparison to an odorless control stimulus and farnesol odor, especially in frontal recording positions [ 6 ].…”

“…The aim of the present study was to investigate the possibility of detecting central odor processing in premature infants by analyzing olfactory-induced EEG changes using Fast Fourier transformation (FFT) as an already established method in older term-born infants [ 6 ]. The previous study from our group demonstrated that EEG method and FFT analysis were feasible for mature infants and showed that EEG amplitudes in the δ frequency band differed significantly after the presentation of breast milk in comparison to an odorless control stimulus and farnesol odor, especially in frontal recording positions [ 6 ]. Physiologically, predominant EEG activity is in lower frequencies in preterm infant compared to term born or mature infants, leading to potentially higher susceptibility of the EEG recording to interference with the stimulus processing frequencies.…”

“…More specifically, the aim of this feasibility study was to investigate central odor processing in premature infants using EEG analyses with a focus on whether (1) a study set up developed for older infants is transferable to preterm infants [ 6 ] and (2) different olfactory stimuli result in different EEG changes of premature infants.…”

“…Stimuli were administered using a nasal cannula. The parameters were collected identically in a previous study, which investigated similar parameters in older term newborns [ 6 ]. Three odors have been used: breast milk of their own mother, farnesol diluted 1:10 with 1,2-propranediol and vanilla (4-hydroxy-3-methoxybenzaldehyd) with a concentration of 3 g per 100 mL of 1,2-propanediol.…”