Cognitive Neuroimaging Laboratory

RESEARCH

Behavior

In order to investigate individual’s physiological and psychological responses to chemosensory stimuli, we use various olfactory, trigeminal, and gustatory testing methods in combination with different rating scales and psychophysiological recording methods.

Olfactory testing

Figure: Olfactory testing using the
Sniffin’ Sticks

Most participants in our studies undergo standardized psychophysical testing of their olfactory abilities; namely ability to detect, identify, and discriminate between odors. Olfactory testing in our lab is often accomplished using a modified version of the olfactory test battery named the Sniffin’ Sticks which was developed by Drs. Gerd Kobal and Thomas Hummel. However, when special odors are required, we often opt to present odors either with the help of one of our olfactometers or via traditional bottles.

In addition to psychophysical testing, we commonly use different rating scales for the evaluation of the pleasantness, intensity, and familiarity of odorants.

Trigeminal testing

It is known that most odorants not only activate the olfactory nerve, but also the trigeminal nerve in a concentration dependent manner. To evaluate if an odorant possess a trigeminal property, we usually use a lateralization task. This task is based on the assumption that humans are only able to distinguish which nostril the odorant was applied if the odorant also activates the trigeminal system.

Currently we are using specially adapted sniffing bottles or an olfactometer which has been modified to evaluate the trigeminal percept of different odors.

Gustatory testing
For answering questions about how a mental or physiological state influences the perception of foods we occasionally investigate gustatory behavior. This is accomplished by measuring the gustatory detection threshold for different tastants and ratings of pleasantness, intensity, and familiarity for tastants.

Psychophysiological recordings

Psychophysiology developed as a discipline of its own along with the development of the recordings of physiological responses (i.e. functional neuroimaging methods). A basic assumption of psychophysiology is that behavioral, cognitive, emotional, and social events are mirrored in physiological processes. Therefore, psychophysiology is trying to understand how mental events like feelings and thoughts may have effects on bodily processes. The aim of psychophysiological recordings is to lead to a better understanding of cognitive and emotional processes. The recording of psychophysiological parameters is often regarded as a “window” into the brain and mind meaning that recordings of psychophysical events may reveal effects of mental states which are not observable in overt behavior or in verbal reports.

Depending on the aim of the study, we normally acquire measures from different physiological variables such as electrodermal activity (skin conductance, skin temperature), cardiovascular reactivity (blood pressure, heart rate), respiratory reactivity (breathing rate), and reactivity to several tasks (reaction times). This is done with the help of an integrated psychophysiology lab (www.psylab.com).