Camilla Birgitte Falk Jensen

Smartphones as pocketable labs: Visions for mobile brain imaging and neurofeedback

Mobile brain imaging solutions, such as the Smartphone Brain Scanner, which combines low cost wireless EEG sensors with open source software for real-time neuroimaging, may transform neuroscience experimental paradigms. Normally subject to the physical constraints in labs, neuroscience experimental paradigms can be transformed into dynamic environments allowing for the capturing of brain signals in everyday contexts. Using smartphones or tablets to access text or images may enable experimental design capable of tracing emotional responses when shopping or consuming media, incorporating sensorimotor responses reflecting our actions into brain machine interfaces, and facilitating neurofeedback training over extended periods. Even though the quality of consumer neuroheadsets is still lower than laboratory equipment and susceptible to environmental noise, we show that mobile neuroimaging solutions, like the Smartphone Brain Scanner, complemented by 3D reconstruction or source separation techniques may support a range of neuroimaging applications and thus become a valuable addition to high-end neuroimaging solutions.

Secular trends in seasonal variation in birth weight

BACKGROUND Many environmental factors have been shown to influence birth weight (BW) and one of these are season of birth. AIM The aim of the present study was to investigate the seasonal variation in BW in Denmark during 1936-1989, and to see if the variation could be explained by sunshine exposure during pregnancy. METHODS The study population was selected from the Copenhagen School Health Records Register and included 276 339 children born between 1936 and 1989. Seasonal variation was modeled using a non-stationary sinusoidal model that allowed the underlying trend in BW and the amplitude and phase of the yearly cycles to change. RESULTS There was a clear seasonal pattern in BW which, however, changed gradually across the study period. The highest BWs were seen during fall (September - October) from 1936 to 1963, but a new peak gradually grew from the early 1940s during early summer (May - June) and became the highest from 1964 to 1989. The amplitude of the fall peak started at 25.5 (95%CI 24.6; 25.9) grams and gradually disappeared. The amplitude of the early summer peak gradually arose from nothing to a peak of 18.6 (95%CI 17.7; 19.6) grams in the mid 1980s where it started to decrease again. Sunshine did not explain the seasonal variation in BW. CONCLUSION There was a clear seasonal pattern in BW in Denmark 1936-1989, which however changed across the study period. Throughout the study period we observed a peak in BW during the fall, but gradually, starting in the early 1940s, an additional early summer peak emerged and became the highest from 1964 and onwards.

Prenatal exposure to vitamin-D from fortified margarine and milk and body size at age 7 years

Background/Objectives:Prenatal vitamin-D deficiency may be associated with increased risk of obesity later in life. Using two national vitamin-D fortification programs as the setting for a societal experiment, we investigated whether exposure to vitamin-D from fortified margarine and low-fat milk during foetal life was associated with body size at 7 years of age.Subjects/Methods:Vitamin-D fortification of margarine was mandatory in Denmark from 1961 to 1985, and voluntary fortification of low-fat milk was permitted from 1972 to 1976. Using information on body mass index (BMI) Z-score at the age of 7 years of 54 270 children, who were measured during the mandatory Copenhagen School Health examination, we compared children according to whether the mothers were pregnant during the fortification programs or not. The comparisons were performed for children born just before and after initiation or termination of margarine and milk fortification periods, respectively. In total four sets of analyses were performed.Results:We observed no difference in mean BMI Z-score between children exposed to vitamin-D fortification in utero and non-exposed children. Similar results were observed for overweight and obesity.Conclusions:Prenatal exposure to vitamin-D from fortification of margarine and low-fat milk showed no association with body size at 7 years.

Neonatal Vitamin D Levels in Relation to Risk of Overweight at 7 Years in the Danish D-Tect Case-Cohort Study

Background: Vitamin D level in pregnancy may be associated with risk of overweight in the offspring later in life. Methods: In a case-cohort study based on Danish biobanks and registers we examined the association between 25-hydroxy-vitamin D (25(OH)D) level at birth and overweight at 7 years. Cases of overweight (n = 871) were randomly selected among 7-year-old children from the Copenhagen School Health Records Register (CSHRR) with a BMI above the 90th percentile. The cohort (n = 1,311) was a random sample selected among all Danish children born during the same period. Neonatal 25(OH)D was measured in dried blood spots. Results: 25(OH)D3 exhibited the expected seasonal variation. Median level of 25(OH)D3 was 20.6 (11.9-33.3) nmol/l in the overweight group and 23.4 (13.5-34.3) nmol/l in the cohort. We found no association between neonatal 25(OH)D3 level and risk of overweight at age 7 years, neither in the crude model (OR (CI) 1.00 (0.99; 1.00)) nor in a model adjusted for maternal ethnicity, educational level, civil status, parity, season and year of birth, and offspring ponderal index (OR (CI) 1.00 (0.99; 1.01)). Conclusion: Risk of overweight at 7 years of age was not associated with vitamin D level at birth.

SOA thresholds for the perception of discrete/continuous tactile stimulation

In this paper we present an experiment to measure the upper and lower thresholds of the Stimulus Onset Asynchrony (SOA) for continuous/discrete apparent haptic motion. We focus on three stimulation parameters: the burst duration, the SOA time, and the inter-actuator distance (between successive actuation points). The experimental setup is based on a set of six (6) vibrotactile actuators to investigate effects of the inter-actuator distance (over the range 4 cm to 20 cm) on the respective SOA thresholds. We found that as the burst duration increases, subjects detected the simultaneous-discrete boundary at lower SOA. Furthermore, the larger the inter-actuator distance, the more linear the relationship between the burst duration and the SOA timing. Finally, the large range between lower and upper thresholds for SOA can be utilized to create continuous movement stimulation on the skin at “varying speeds”. The results are discussed in reference to designing a tactile interface for providing continuous haptic motion with a desired speed of continuous tactile stimulation.

Spatio temporal media components for neurofeedback

A class of Brain Computer Interfaces (BCI) involves interfaces for neurofeedback training, where a user can learn to self-regulate brain activity based on real-time feedback. These particular interfaces are constructed from audio-visual components and temporal settings, which appear to have a strong influence on the ability to control brain activity. Therefore, identifying the different interface components and exploring their individual effects might be key for constructing new interfaces that support more efficient neurofeedback training. We discuss experiments involving two different designs of neurofeedback interfaces and suggest further research to clarify the influence of different audiovisual components and temporal settings on neurofeedback effect.

Does prenatal exposure to vitamin D-fortified margarine and milk alter birth weight? A societal experiment - CORRIGENDUM.

In our recent paper ‘Does prenatal exposure to vitamin D-fortified margarine and milk alter birth weight? A societal experiment’ published in British Journal of Nutrition we explored the association between a national vitamin D fortification programmes of margarine and milk and birth weight. Based on available official documents from the Nordic Council of Ministers the initiation of vitamin D fortification of margarine was introduced in 1961. However, we have recently uncovered evidence from old law texts that questions this onset date. This information source suggests that mandatory fortification apparently started even before World War II for vitamin D and for vitamin A. While this new evidence makes the onset date of the vitamin D fortification of margarine uncertain all sources of information that we have come across confirms that the date of termination of the fortification programme was indeed in 1985. For the voluntary vitamin D fortification of milk insecurity has arisen about the termination date in 1976. A similar Ministerial order that cancelled the permission to fortify milk in 1976 appears to have been issued in 1974 as well. Which of the two Ministerial orders that in reality cancelled the milk fortification is unclear. The voluntary vitamin D fortification of milk was, however, confirmed to commence in 1972 by all law texts. During the study period margarine was also fortified with vitamin A, and the new evidence reveals that the vitamin A dose was increased by 25% (from 20 to 25 IU/g) in 1962. There were also minor increases in 1971 from 25 to 26 IU/g and in 1985 from 26 to 28 IU/g. Therefore, we request the editor and readers to disregard the estimates based on analyses in 1961 and 1976, and to keep in mind that changes in vitamin A fortification also took place (Fig. 1). In the original paper we investigated potential effects of prenatal exposure to vitamin D fortification on mean birth weight and risk of low and high birth weight. We found no difference in risk of low and high birth weight between exposed and non-exposed children. Contrary to our expectations, we found inconsistent effects of the vitamin D fortification on mean birth weight; the mean birth weight was lower among exposed than non-exposed in all analyses except in the analyses based on margarine fortification in 1961 (Fig. 2). However, the mean difference in birth weight did not exceed 60 grams, and we questioned the clinical relevance.

Your heart might give away your emotions

Estimating emotional responses to pictures based on heart rate measurements: variations in Heart Rate serves as an important clinical health indicator, but potentially also as a window into cognitive reactions to presented stimuli, as a function of both stimuli, context and previous cognitive state. This study looks at single-trial time domain mean Heart Rate (HR) and frequency domain Heart Rate Variability (HRV) measured while subjects were passively viewing emotionally charged images, comparing short random presentations with grouped sequences of either neutral, highly arousing pleasant or highly arousing unpleasant pictures. Based on only a few users we were not able to demonstrate HRV variations that correlated with randomly presented emotional content due to the inherent noise in the signal. Nor could we reproduce results from earlier studies, which based on averaged values over many subjects, revealed small changes in the mean HR only seconds after presentation of emotional images. However for longer sequences of pleasant and unpleasant images, we found a trend in the mean HR that could correlate with the emotional content of the images. Suggesting a potential for using HR in single user Quantified Self applications to assess fluctuations over longer periods in emotional state, rather than dynamic responses to emotional stimuli.

Response to ‘Prenatal exposure to vitamin-D from fortified margarine and milk and body size at age 7 years’

Response to ‘Prenatal exposure to vitamin-D from fortified margarine and milk and body size at age 7 years’

Emotional responses as independent components in EEG

With neuroimaging studies showing promising results for discrimination of affective responses, the perspectives of applying these to create more personalised interfaces that adapt to our preferences in real-time seems within reach. Additionally the emergence of wireless electroencephalograph (EEG) neuroheadsets and smartphone brainscanners widens the possibilities for this to be used in mobile settings on a consumer level. However the neural signatures of emotional responses are characterized by small voltage changes that would be highly susceptible to noise if captured in a mobile context. Hypothesizing that retrieval of emotional responses in mobile usage scenarios could be enhanced through spatial filtering, we compare a standard EEG electrode-based analysis against an approach based on independent component analysis (ICA). By clustering scalp maps and time series responses we identify neural signatures that are differentially modulated when passively viewing neutral, pleasant and unpleasant images. While early responses can be detected from the raw EEG signal, we identify multiple early and late ICA components that are modulated by emotional content. We propose that similar approaches to spatial filtering might allow us to retrieve more robust signals in real-life mobile usage scenarios, and potentially facilitate design of cognitive interfaces that adapt the selection of media to our emotional responses.