fMRI STUDY OF SMELL: PERCEPTUAL, COGNITIVE AND SEMANTIC COMPONENTS OF CORTICAL ELABORATION OF 3

FAMILIAR AROMAS.

Laura Romoli PhD PP Battaglini , B.R.A.I.N. Trieste

Furio Suggi Liverani (illycaffè s.p.a.)

AIMS

STUDYING HOW 3 FAMILIAR AROMAS ARE ELABORATED BY THE BRAIN

SPECIFICALLY:

WHICH ARE THE ACTIVACTIONS IN COMMON BETWEEN ALL THE STIMULI?

WHICH ACTIVACTIONS ARE DISTINCTIVE FOR EACH AROMA?

THERE IS ANY DIFFERENCE IN THE ELABORATION OF THE STIMULI DURING THE FIRST PHASE OF ELABORATION AND THE SECOND (SEE PARADIGM)? AND, IF YES, WHICH?

LIMITS OF THE STUDY

TECNICHAL DIFFICULTS TO DELIVERY AROMAS TO THE SUBJECTS SITUATED IN THE MR SCANNER

POOR fMRI LITERATURE REGARDING THE STUDY OF PERCEPTUAL AND COGNITIVE ASPECTS OF SMELL

INTEREST OF THE STUDY: INNOVATIVE!

OLFACTORY SYSTEM

THE COMPLEXITY OF THE SMELL CORTICAL ELABORATION

SMELL AND PERCEPTION

PERCEPTION INTEGRATES A GREAT NUMBER OF SENSATION (SINGLE SENSORY STIMULI)

PERCEPT: THE RESULTING MENTAL RECREATION OF THE DISTAL STIMULUS

DETENCTION OF THE STIMULUS

RECOGNITION : THE MOMENT IN WHICH THE STIMULUS REACHS THE CEREBRAL CORTEX (REACTIVACTING A NEURONAL NODE)

SMELL AND COGNITION

MEMORY

EMOTION

LANGUAGE

HEDONISM

MATERIAL AND METHODS

TECHNIQUE: fMRI PHILIPS GYROSCAN ACHIEVA 1,5 TIn collaboration with Cattinara Hospital, Trieste, Italy

SUBJECTS: 13 HEALTY RIGHT-HANDED SUBJECTS (5 MALES, MEAN AGE 34,9 y.o.) ALL SUBJECTS WERE TESTED WITH THE BRIEF SMELL IDENTIFICATION TEST

TR 2171

288 DYNAMIC IMAGES

TIME OF ACQUISITION: 10.51 MIN

STIMULI: CITRUS FRUIT, CHOCOLATE, FLOWER, PURE AIR (NEUTRAL, AS CONTROL)

EXPERIMENTAL DESIGN

Participants received 2 seconds of aroma’s stimulation directly in their nose through 4 polythene tubes converging in a facial mask

Previously instructed to do not move and pay attention to the aroma, trying to recognize it.

Trial 24 sec

aroma 2”

air washing 5”

during 5” after 5”

Timing for analysis

EXPERIMENTAL DESIGN_2

3 repetitions of the paradigm

each repetition consisted of 12 tasting trials (4 citrus, 4 chocolate, 4 flower, randomly organized) alternated by neutral (12)

STIMULUS TRIAL

NEUTRAL TRIAL

STIMULI

citrus: edible, generally associated with the orange or the lemon; extremely scented. This stimulus is characterized by the color, varying from orange to

yellow (all nuances belonging to the same family of colour).

chocolate : edible; generally more linked to its taste than its smell; “child” taste and normally associated with one of the most familiar

satysfying/rewarding sweets.

flower : not edible; this aroma result difficult to categorize, due to the fact that the variability of flowers is so huge in nature, increased by the fact

that a lot of products (e.g. detergents) are flower scented.

Pure air: neutral stimulus to compare to all stimuli during the analysis and usefull as washing stimulus during the experiment

Timing, amount and order of presentation were controlled by the

computerized olfactometer

TIMING OF ANALYSIS

DURING

period of 5 sec corresponding to the aroma’s stimulation (2 sec) and the few sec immediately after

it is supposed to be the perceptual level of cortical elaboration

AFTER

period of 5 sec corresponding to the seconds after the aroma’s

stimulation during which subjects had to do nothing

it is supposed to be the semantic/hedonistic level of

cortical elaboration

DATA ANALYSIS

the fMRI data were analysed using the SPM5 packagehttp://www.fil.ion.ucl.ac.uk/spm/software

the images were first corrected to remove the effects of subjects moving whilst in the MR scanner which would reduce the power of the analysis

the brain images for each subjects were “morphed” to make them all the same shape so that we can be sure that each part of the brain image

refers to the same brain region in all subjects

we then carried out statistical analysis to detect the particular effects that we are interested in (e.g. smelling citrus aroma compared with smelling

neutral –air)

DATA ANALYSIS_2

the analysis were conducted for each aroma (compared to neutral), both for the during period and after period

we had to excluded 2 subjects (6 blocks of functional images) from analysis (movement artifacts)

the analysis were conducted on 33 blocks of functional images (11 subjects)

we found differences both for each aroma and for timing of elaboration

RESULTS

CITRUS DURING

ANATOMY (MNI coordinates)

Right/Left BA 17

Right/Left BA 18

Right Middle Occipital Gyrus

Left Postcentral Gyrus (BA2/1)

CITRUS AFTER

ANATOMY (MNI coordinates)

Right SMA

BA 6

Left Superior Frontal Gyrus

Left Middle Frontal Gyrus

CHOCOLATE DURING

ANATOMY (MNI coordinates)

Left Inferior Frontal Gyrus (p.triang.)

Left Middle Frontal Gyrus

Right Calcarine Gyrus(BA 17/18)

Cerebellar Vermis (lobule V)

CHOCOLATE AFTER

ANATOMY(MNI coordinates)

Left Superior Frontal Gyrus (BA6)

Right Mid Orbital Gyrus

Right Superior Medial Gyrus

Left Inferior Frontal Gyrus (p.orbit)

FLOWER DURING

ANATOMY(MNI coordinates)

BA 3aBA 6

Left/right Inferior Frontal Gyrus (p.triang.)

Right Middle Cingulate CortexLeft Middle Frontal Gyrus

Left/right Inferior Frontal Gyrus (p.orbit.)

Right Middle Temporal GyrusLeft Anterior Cingulate Cortex

Left Insula Lobe

FLOWER AFTER

ANATOMY(MNI coordinates)

Left Anterior Cingulate Cortex

Right/Left Superior Frontal Gyrus

Left Inferior Frontal Gyrus (p.orbit)

Left Superior Medial Gyrus

Left/Right Middle Frontal Gyrus

Left Precentral Gyrus

TIME’S EFFECT

TIME’S EFFECTCITRUS

During

BILATERAL OCCIPITAL LOBE;

LEFT SOMATOSENSORY CORTEX (sensory mirror neurons)

Citrus works as a synestetyc stimulus: the

olfactory stimulus reactivates the semantic

node of citrus

After

Cortical elaboration becomes more central and frontal: these area are the

common areas involved in the elaboration of hedonic, emotional and

olfactory

The activation becomes more similar to the cortical

elaboration found for other olfactory stimuli (hedonistic

judgment)

TIME’S EFFECTCHOCOLATE

During

Frontal areas, visual areas (BA 17,18), right cerebellar vermis

Frontal areas (hedonistic/emotional

judgment), occipital activation (visual

(imagination)

After

The elaboration becomes only frontal (attention, hedonism, emotion)

Working memory, memory retrieval, semantic labels and

hedonist judgment

TIME’S EFFECTFLOWER

During

Spread activation : frontal areas, limbic system, hippocampal region and

somatosensory

Peculiarity of the stimulus: flower activates more strongly

motor control regions, and cortical areas involved in

retrieve of autobiographical memories

After

Activation remain the same; little anatomical modification, without

functional change

Retrieve of autobiographical memories, motory and sensory imagination and sematic labels

of olfactory

CONCLUSION

each aroma seems to stimulate different cerebral regions according to its semantic characteristics, especially during the early phase of elaboration

from the results it seems that :

Citrus: it is characterized by the perceptual aspects, especially visual, during the first phase of elaboration

Chocolate: involves stronger the cingulate cortex and the frontal cortex immediately

Flower: seems to be the most difficult stimulus to describe and recognize, and the one that most activated areas implicated in the recollection of

autobiographical memory

CONCLUSION_2

this experiment confirms that odors can affect a variety of perceptual, motor and cognitive functions

in addition

we found that the timing of elaboration is an important aspect of odors responses and seems to be linked to the type of stimulus

THANKS FOR YOUR ATTENTION!