Olfactory and Visuo-Spatial short term working memory: localization of an olfactory marker in a modified Corsi Block Tapping Test

One of the main relevant Tests that analyzes the visuo-spatial component can be considered the Courses Block Tapping Test (CBTT). The visuo-spatial component is an extremely present component also in the olfactory perception, where, from the evolutionary point of view, it seems to be the further development of ancestral olfactory abilities linked to the location of the olfactory marker. In the present research, through the use of the CBTT associated with an olfactory component, it was investigated how the sense of smell can be related to tasks requiring the use of visuo-spatial memory and whether this component can be gender-dependent. In the present study, 153 healthy subjects were recruited (mean age 22.6 ± 4.3; 92 women). The Courses Test was administered according to three different sessions and modalities: 1) classical version of the CBTT; 2) Olfactory CBTT (OCBTT); 3) Semantic-Olfactory CBTT (SOCBTT). In the OCBTT, squares of paper wet with specific odorants were placed on the cubes. The layout of the block (B), the same for all subjects, was: Eucalyptus (B1); Carvone (B2); Eugenol(B3); Isoamyl Acetate (B4); Geranium (B5); Phenylethyl alcohol (B6); Hexanal (B7); Acetophenone (B8), Cinnamon (B9). During the experimentation phase the squares arranged above the cubes were smelled according to sequences and methods described for the standard CBTT. At the end of each sequence, a paper square, wet with an odorant pseudo-randomly chosen, was extracted from a pocket and administrated to the subject. Therefore, the experimenter asked to indicate on which B the odorous square corresponded to the one just presented. In this condition, the same exclusion parameters of the CBTT were used. At the beginning of the SOCBTT, the experimenter read, only one time, the complete list of the odorants used. Then the subjects performed the same task of the OCBTT, but, at the end of each sequence, the subject had to identify through the naming the odorants recognized during the sequence. The sequence of the tests was alternated for each subject to avoid a primacy or habituation effect linked to olfactory stimulation. A GLM repeated measures was performed considering as between factor the variable Group (Male and Women) and as within factors the SPAN scores obtained in the three different CBTT modalities (i.e., CBTT; OCBTT; SOCBTT). Furthermore, a correlation analysis was carried out between the three levels of the test. The results of the analysis showed a gender difference in terms of a better performance of men for CBTT, OCBTT and SOCBTT; moreover, the SPAN score was higher in CBTT, and decreased respectively in OCBTT and SOCBTT. Correlation analysis showed a positive correlation between the three CBTT variants (i.e, CBTT, OCBTT and SOCBTT). These results confirm that there is a common perceptual pathway between olfactory and visuo-spatial working memory, also evident in behavioural data. Future work will focus on validation of these test variants.