Overview
During tactile (touch) exploration, humans typically use their hands, which are densely innervated with mechanoreceptors that convert tactile input into neural signals. The high receptor density of the hands enables fine sensory acuity, allowing individuals to discriminate subtle differences between stimuli.
About this opportunity
Olfaction, the sense of smell, is a chemical sensory modality that detects airborne odorants. The olfactory cortex receives direct input from the olfactory bulb and is strongly connected to limbic brain regions, which support emotional, motivational, and hedonic responses to odours.
While touch and smell are often studied independently, emerging evidence suggests that the two senses interact in meaningful ways. For example, unpleasant odours have been shown to reduce the perceived smoothness of surfaces, alter the sensory qualities of products, and decrease the pleasantness of touch experiences. However, the neural mechanisms underlying this tactile-olfactory interaction remain poorly understood.
Through the University of Liverpool-Unilever Brain & Behaviour collaboration (https://www.liverpool.ac.uk/population-health/research/groups/unilever-brain-behaviour-collaboration/), we are uniquely positioned to address this gap. The Brain and Behaviour Lab is equipped to investigate tactile-olfactory integration using both behavioural and neuroimaging methods. Our recent work has explored brain activation during active tactile exploration and the time course of olfactory modulation of visual processing using EEG. However, no research to date has directly examined the neural mechanisms of tactile-olfactory integration.
This project aims to address this important scientific gap by investigating how the brain integrates tactile and olfactory information, and how this integration influences emotional responses. The findings will contribute to fundamental neuroscience and have real-world impact to support product development or therapeutic applications
We will address this challenge through a series of studies with the following objectives:
- Employ multimodal neuroimaging (EEG and fMRI) to quantify the neural mechanisms involved in tactile-olfactory integration.
- Identify whether olfactory-tactile integration solely modulates activity in primary sensory cortices (somatosensory and olfactory) and/or recruits additional integrative brain regions including emotional and motivational systems.
The Department of Psychology at the University of Liverpool is a vibrant research institute, with over 60 academics and more than 70 PhD students. The department includes three EEG labs equipped with advanced stimulus control, data acquisition and analysis workstations. The successful candidate will join a collaborative research group of five PhD students working on aligned neuroimaging projects. MRI scanning will take place on campus in the Liverpool Magnetic Resonance Imaging Centre (LiMRIC), which houses a Siemens 3T scanner and is supported by full-time radiographers. Together, these facilities provide a robust infrastructure for successful completion of high-quality experimental studies and to support the student’s development.
As part of this PhD, the successful candidate will also undertake an industrial placement with Unilever’s Biosciences team at the Port Sunlight Research Lab. The long-standing collaboration between the University of Liverpool and Unilever has supported UKRI-funded PhD students since 2010, offering a unique opportunity to bridge academic research with real-world application.
Further reading
Demattè, M. L., Sanabria, D., Sugarman, R. & Spence, C. Cross-Modal Interactions Between Olfaction and Touch. Chem Senses 31, 291–300 (2006).
Croy, I., Angelo, S. D’ & Olausson, H. Reduced Pleasant Touch Appraisal in the Presence of a Disgusting Odor. PLoS One 9, e92975 (2014).
Cook, S., Fallon, N., Wright, H., Thomas, A., Giesbrecht, T., Field, M., & Stancak, A. (2015). Pleasant and unpleasant odors influence hedonic evaluations of human faces: An event-related potential study. Frontiers in human neuroscience, 9, 661.
Cook, S. et al. Pleasant and unpleasant odour-face combinations influence face and odour perception: An event-related potential study. Behavioural Brain Research 333, 304–313 (2017).
Henderson, J. Fallon, N et al. Tactile estimation of hedonic and sensory properties during active touch: an electroencephalography study. European Journal of Neuroscience (2023) doi:10.1111/ejn.16101.
Henderson, J., Fallon , N., et al. Neural correlates of texture perception during active touch. Behavioural Brain Research 429, 113908 (2022).