Martin Schaefer

Karolinska Institutet | KI · Department of Clinical Neuroscience

Although stress is an increasing global health problem in cities, urban green spaces can provide health benefits. There is, however, a lack of understanding of the link between physiological mechanisms and qualities of urban green spaces. Here, we compare the effects of visual stimuli (360 degree virtual photos of an urban environment, forest, and...

Olfactory dysfunction is a prevalent non-motor symptom of Parkinson's disease (PD). This dysfunction is a result of neurodegeneration within the olfactory bulb (OB), the first processing area of the central olfactory system, and commonly precedes the characteristic motor symptoms in PD by several years. Functional measurements of the OB could there...

Significance Whether an odor's perceived valence induces an approach response or triggers avoidance is critical for survival, and yet little is known about the neural mechanisms supporting this decision. Using electrophysiological measures from the human olfactory bulb (OB), the first processing stage of the olfactory system, and measures of full-b...

More than 50 years ago, it was proposed that breathing shapes pupil dynamics. This widespread idea is also the general understanding currently. However, there has been no attempt at synthesizing the progress on this topic since. We therefore conducted a systematic review of the literature on how breathing affects pupil dynamics in humans. We assess...

A core function of the olfactory system is to determine an odor's valence. The central processing of odor valence is initiated in the olfactory bulb, but the neural mechanisms by which this important information is communicated to, and from, the olfactory cortex (piriform cortex) in humans are not known. To assess communication between the two node...

Several studies suggest that breathing entrains neural oscillations and thereby improves visual detection and memory performance during nasal inhalation. However, the evidence for this association is mixed, with some studies finding no, minor, or opposite effects. Here, we tested whether nasal breathing phase influences memory of repeated images pr...

Recent studies have indicated that breathing shapes the underlying oscillatory brain activity critical for episodic memory, potentially impacting memory performance. However, the literature has presented conflicting results, with some studies suggesting that nasal inhalation enhances visual memory performance, while others have failed to observe an...

More than fifty years ago it was proposed that breathing shapes pupil dynamics [7, 16]. This widespread idea is also the general understanding currently. However, there has been no attempt at synthesizing the progress on this topic since. We therefore conducted a systematic review (preregistered on Prospero; ID CRD42022285044) of the literature on...

The use of oral contraceptives (OC) in the form of a hormonal pill has been widespread for decades. Despite its popularity and long-time use, there is still much ambiguity and anecdotal reports about a range of potential side effects. Here, we addressed the potential effect of OC use on chemosensory perception. Previous research has almost exclusiv...

Determining the valence of an odor to provide information to guide rapid approach-avoidance behavior is thought to be one of the core tasks of the olfactory system, yet little is known of its initial neural mechanisms or subsequent behavioral manifestation in humans. In two experiments, we measured the functional processing of odor valence percepti...

Background Anorexia nervosa (AN) is a severe disorder, for which genetic evidence suggests psychiatric as well as metabolic origins. AN has high somatic and psychiatric comorbidities, broad impact on quality of life, and elevated mortality. Risk factor studies of AN have focused on differences between acutely ill and recovered individuals. Such com...

: Noise from city traffic is one of the most significant environmental stressors. Natural soundscapes, such as bird songs, have been suggested to potentially mitigate or mask noise. All previous studies on masking noise use self-evaluation data rather than physiological data. In this study, while respondents (n = 117) watched a 360° virtual reality...

Chemosignals are used by predators to localize prey and by prey to avoid predators. These cues vary between species, but the odor of blood seems to be an exception and suggests the presence of an evolutionarily conserved chemosensory cue within the blood odor mixture. A blood odor component, E2D, has been shown to trigger approach responses identic...