FMRI STUDY OF SMELL: PERCEPTUAL, COGNITIVE AND SEMANTIC COMPONENTS OF CORTICAL ELABORATION OF 3...
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Transcript of FMRI STUDY OF SMELL: PERCEPTUAL, COGNITIVE AND SEMANTIC COMPONENTS OF CORTICAL ELABORATION OF 3...
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!