Olphactory Cognition and Conditioning Event Related Potentials towards Innovative Applications in Cognitive Neuroscience

The perception of an odour is a two-step process. First, there is a physiological process, i.e. the detection of chemical stimuli (odorous molecules) by olfactory receptors in the olfactory epithelium. Next, there is a neurologic process; olfactory neurons transduce receptors activation into neuronal electrical signals travelling along the olfactory nerve to olfactory bulb and finally, they are processed by higher cortical areas of the human brain where odour encoding and perception occur. Because of this, olfaction is a complex primal sense highly associated with attraction, mood, detection of danger and odours have the power to evoke distant memories and boost self-confidence. A lot of knowledge on olfaction has to be still get mainly regarding its relationship with other sensory stimuli as audio, visual, taste [1]. Odour recognition memory is slightly influenced by the length of retention intervals. This was observed for short intervals (few minutes) as well as longer retention period (over a year too)[2]. One approach to understanding the olfaction links to other senses is to monitor and analyse human brain activity during odours perception. By measuring event-related potentials (ERPs) by electroencephalography, it’s possible to measure the electrophysiological response of brain to a specific event, i.e. in this case the presentation of olfactory stimuli [3,4]. Aim of this study is understanding how the olfactory system, which involves and activates the limbic system, can modulate a perception on emotional face recognition. Through these results we aim to investigate and to implement innovative applications of cognitive neuroscience in order to improve basic knowledge as well as to develop novel devices for enhancing synesthetic experiences with olfactory stimuli. Method: We arrange an experiment of olfactive conditioned evoked potentials by analysing Event Related Potential (ERP) of 7 volunteers during perception of 2 odour stimuli: pleasant (rose, 2-phenyl ethanol C2H4O2) and unpleasant (acid, Acetic Acid C8H10O). Specifically, we have proposed a paradigm of operant conditioning in which the three types of odours were conditioned on images of neuter face expression [5], by a NimStim Face Stimulus Set [6], for the duration of 5 minutes to task learning, repeated for three times. Subsequently, the subject had to perform a test Face detection, implemented through NimStim Set, for a period of 10 minutes task, during a Emo No Go Paradigm Presented with E-Prime Presentation. The subject had to press a pc key during a recognition task of emotional neuter face expression in a presentation of randomized emotional expressions (fear, neuter and happy). For the odorous stimuli in the experiment, pure chemical compounds were diluted in distilled water. A dilution ratio (1:4) was suitably consider in order to realise easily perceptible, but not unpleasant, odours; the odorants and their concentration used in the test are listed in table 1 together with their odour sensory description. In addition, the distilled water was used a control for inducing an odourless stimulus. The odorous solutions (5 ml) were put into 20 ml glass vials sealed with septum till the exposure time to the volunteers. We can conclude that an unpleasant odour can modulate, in a cross modal way, the perceptions of emotional and neutral face expressions, and it can be general in a very early component (P100) and more specific, in conditioning way, in the attentive component (P300), only for neutral expressions