Caroline Owen

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COMPARISON OF PREFERENCE-RELATED BRAIN ELECTRICAL
ACTIVITY IN RESPONSE TO ODOUR
Caroline Owen John Patterson
Sensory Neuroscience Laboratory, Swinburne
University of Technology Hawthorn, VIC, Australia
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Introduction

• Changes in brain electrical activity associated
  with physiological responses to an odour
  independent of subjective detection
• Changes in responses between different odours and
  associated with reported preference or hedonic
  responses to the odours
• To further investigate these differences in
  responses
• Subjective responses correlated with objective
  physiological responses
• To investigate differences in perceptual
  responses to a low concentration odour delivered
  during natural respiration.

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Continuous Respiration Olfactometer
3. Odour delivery syringe system
air/odour delivery
1. Respiratory facemask
syringe motor drive output
2. Serial interface device
respiratory information
input to pressure transducer
Sensory Neuroscience Laboratory
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EGI and CRO Recording System
Sensory Neuroscience Laboratory
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Method

• Test odour D-limonene (citrus sweet orange lemon
  odour)
• Odour and air delivered at pseudo random ratio of
  13, synchronised with natural inspiration
• 4 repeated recording sessions total of 20
  minutes per subject
• 16 screened subjects (8 m, 8 f), non-smokers,
  right handed
• Mean age 23.4 years ( 6.6), range 18 - 40
  years
• Normal range of olfactory ability (Sniffin
  Sticks)
• Mean TDI score 34.53, range 30.75 - 40.5
• Like Group n 13 Mean preference 2.17
  0.6
• Dislike Group n 3 Mean preference 6.34
  0.54

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Results Like - Left Frontal Odour vs Air
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Dislike - Left Frontal Odour vs Air
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Like - Right Frontal Odour vs Air
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Dislike - Right Frontal Odour vs Air
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Like vs Dislike - Left Frontal
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Like vs Dislike - Right Frontal
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Right Temporal - Air vs Odour
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Left Temporal Air vs odour
Amplitude Scale equates to 5 µV
Sensory Neuroscience Laboratory
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Results Topographic Mapping
220 ms post-stimulus
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Results Power Spectrum
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Results Power Spectrum 2
Sensory Neuroscience Laboratory
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Discussion

• Amplitude Dislike larger amplitudes than Like
• Dislike smaller negative peak at 200-225 ms LF cf
  RF larger positive peak at 400 ms LF cf RF
• Latency Delay in negative peak for Dislike cf
  Like
• Dislike negative peak at 200-225 ms
• Like negative peak at 150-175 ms
• Power Spectrum Frequency differences cf
  preference group
• Large hemispheric differences 4-7 Hz for both
  groups
• Like Stronger LF cf RF odour differences 4-7
  8-12 Hz
• Dislike Stronger RF cf LF odour differences 8-12
  13-17Hz
• Large differences 13-17 Hz for Dislike group cf
  Like group

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Conclusion

• Differences in electrophysiological activation of
  odour cf air associated with the preference
  response
• Differences in LF RF early responses
  (pre-450ms)
• Comparative air responses with each group
• Dislike response associated with larger
  amplitudes and latency differences cf Like
  response
• Possible reflection of odour preference in
  differences in frequency responses
• Potential as method for quantifying
  electrophysiological responses to low
  concentration odour during natural respiration,
  independent of subjective reporting

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Acknowledgements
CRC for International Food Manufacture
Packaging Science Dairy Research Development
Corporation Bonlac Foods Ltd Dr Peter Cadusch
Dr Mark Schier Simon Danckert