Attentional modulation of desensitization to odor

Abstract

Subjective and behavioral responsiveness to odor diminishes during prolonged exposure. The precise mechanisms underlying olfactory desensitization are not fully understood, but previous studies indicate that the phenomenon may be modulated by central-cognitive processes. The present study investigated the effect of attention on perceived intensity during exposure to a pleasant odor. A within-subjects design was utilized with 19 participants attending 2 sessions. During each session, participants continuously rated their perceived intensity of a 10-minute exposure to a pleasant fragrance administered using an olfactometer. An auditory oddball task was implemented to manipulate the focus of attention in each session. Participants were instructed to either direct their attention toward the sounds, but still to rate odor, or to focus entirely on rating the odor. Analysis revealed three 50-second time windows with significantly lower mean intensity ratings during the distraction condition. Curve fitting of the data disclosed a linear function of desensitization in the focused attention condition compared with an exponential decay function during distraction condition, indicating an increased rate of initial desensitization when attention is distracted away from the odor. In the focused-attention condition, perceived intensity demonstrated a regular pattern of odor sensitivity occurring at approximately 1−2 minutes intervals following initial desensitization. Spectral analysis of low-frequency oscillations confirmed the presence of augmented spectral power in this frequency range during focused relative to distracted conditions. The findings demonstrate for the first time modulation of odor desensitization specifically by attentional factors, exemplifying the relevance of top-down control for ongoing perception of odor.Electronic supplementary materialThe online version of this article (10.3758/s13414-018-1539-2) contains supplementary material, which is available to authorized users.

Validation of Olfactory Network Based on Brain Structural Connectivity and Its Association With Olfactory Test Scores

“…The level of odour-related arousal can be an important factor for determining the level of thalamic activation ( Sorokowska et al, 2016 ). While continuous olfactory stimulation is known to cause desensitisation, this decrease in olfactory responsiveness can be modulated by olfactory attention ( Fallon et al, 2018 ). As such, our findings support that olfactory attention may be partly regulated by the thalamus, which falls within the framework of recent animal studies ( Courtiol, 2019 ) and human functional olfactory studies ( Zhou et al, 2019 ).…”

Olfactory habituation to food and nonfood odours

“…Moreover, when the odours were presented intermittently (i.e., short-duration odour stimuli), the perceived odour intensity was higher following the hazardous description as compared with the healthy description. All in all, reduced olfactory habituation is exhibited when attention is focused on odour stimuli (Fallon et al, 2018).…”

Odor habituation can modulate very early olfactory event-related potential

“…To understand the processes underlying odor habituation, studying neuronal activities in the brain could be important. While odor habituation can be affected by top-down modulation, such as attention 4 , during habituation, neuronal activities in the central nervous system are changed earlier than those in the peripheral nervous system 3 , 5 . In the olfactory system, odorants are detected by olfactory sensory neurons (OSNs) in the olfactory epithelium.…”