M. Skinner*1,2, R. Ford1, S. Eldeghaidy2, S. Francis2, J. Hort1.

Mapping brain activity to

‘phantom' taste in thermal tasters

1 Sensory Science Centre, University of Nottingham, UK. 2Sir Peter Mansfield Imaging Centre, University of Nottingham, UK.

What is thermal taster status?

Two phenotypes identified

• Thermal taster (TT)

• Thermal non taster (TnT)

• Salty • Umami • Metallic • Minty • Spicy

WARMING TRIAL

COOLING TRIAL

Bitter

Sour

TT’s more sensitive to other oral stimuli

• Taste

• Trigeminal (Hort et al, 2016; Green & George, 2004)

Sweet

Food Choice?

2

(Cruz & Green, 2000)

(Yang et al, 2014)

Testing for TT status

Warming trial

gLMS

Cooling trial

(Cruz & Green, 2000)

3

Exploring thermal taste

Multidisciplinary approach • Sensory Science & functional Magnetic Resonance Imaging (fMRI)

Perceptual response • Captured by Sensory Science techniques

Brain activation • Captured by fMRI techniques

Time

On

Off Off Off Off Off

Stimulus

On On On

4

• Activated brain areas require more oxygen

• Blood oxygen level dependent (BOLD) contrast

• Brain activation maps

Study aims

Perceptual response • Can we identify the temperature range at which phantom

taste is perceived during the warming and cooling trials? • Does this differ across TT’s?

Brain response • Do we see activation in the gustatory cortex when phantom

taste is reported?

5

What mechanism drives phantom taste?

Traditional testing

Screening

• Classify TT/TnT

Warming trial Cooling trial

2 replicates

12 thermal tasters recruited

6

gLMS

Modified phantom taste testing

• 10 replicates

Temporal response

Rating Rating

7

Reproducibility of phantom taste

• Phantom taste is reproducibly reported across replicates • Phantom taste is reproducibly reported across replicates • Phantom taste is reported at a certain temperature range

8

Temperature & phantom taste

A different response is reported for phantom taste and temperature

Subject 01

Warming trial

Cooling trial

Subject 08

9

Inter-individual responses

Warming trial

10

• Phantom taste is reported during a certain temperature range • The response is variable across TT’s

Inter-individual responses

Cooling trial

11

fMRI brain imaging

• 3 T Philips Achieva scanner, 32-element SENSE head coil

• fMRI data acquired with double-echo gradient EPI (TE: 20 ms, 45 ms),

3mm3 isotropic voxel size, 36 transverse slices, TR = 2.5 s

12

fMRI testing

Control task

Subject 01

Subject 10

13

What does the brain show?

Brain activation in regions associated with taste processing

Taste cortex

(anterior insula)

Gustatory nerve fibres are activated by temperature in TT’s 14

• Could co-innervation of gustatory and trigeminal nerves

innervating the fungiform papillae be involved? (Hort et al, 2016)

Conclusions

• The temperature range at which

phantom taste is perceived can be

isolated, but is variable across TT’s

• Brain regions associated with taste processing are

activated in response to temperature stimulation,

accounting for the perceived ‘phantom’ taste

Is ‘phantom taste’ really a phantom? 15

SSC

• Martha Skinner

• Joanne Hort

• Rebecca Ford

Acknowledgments

Thank you for your attention!

SPMIC

• Susan Francis

• Sally Eldeghaidy

Unilever

• Anna Thomas

• Marco Hoeksma

• Timo Giesbrecht

www.nottingham.ac.uk/biosciences/research/research-themes/taste-map/taste-map.aspx 16