HUMAN ELECTROENCEPHALOGRAPHIC (EEG) RESPONSE TO OLFACTORY STIMULATION- 2 EXPERIMENTS USING THE AROMA OF FOOD

The present studies sought to examine the effect of olfactory stimulat ion on human Central Nervous System activity. In the first experiment (n = 21), EEG response to the 'synthetic' odours of chocolate, spearmi nt, almond, strawberry, vegetable, garlic and onion, and cumin or no o dour was recorded from 19 electrodes (F3, F4, F7, F8, Fz, T3, T4, T5, T6, P3, P4, Pz, O1, O2, C3, C4, Cz) in all EEG frequencies (delta, the ta, alpha, beta1 and beta2). Exposure to the odour of chocolate was as sociated with significant reductions in theta activity when compared w ith the odours of almond and cumin, with a trend towards significance when compared with no-odour control. Exposure to the odour of spearmin t was associated with a significant reduction in EEG theta when compar ed with the no-odour control. No significant effects were observed in other frequencies. In a second experiment (n = 15), EEG response to th e odours of real foods (chocolate, baked beans, rotting pork) and two controls (no odour and hot water) was recorded as in Experiment 1. The odour of chocolate was associated with significantly less theta activ ity than was any other stimulus. It is hypothesised that the alteratio ns in theta reflect shifts in attention or cognitive load during olfac tory perception, with a reduction in theta indicating a reduced level of attention. (C) 1998 Elsevier Science B.V. All rights reserved.