Les sens chimiquesProf. Alan Carleton

UNIGE, Faculté de médecine, Département de Neurosciences Fondamentales

• Le système olfactif principal

• Organe voméronasal et détection des phéromones

• La perception des goûts

Les sens chimiques

GUSTATION

Une expérience multisensorielle

FLAVEUR: Ensemble des

sensations olfactives,

gustatives et tactiles ressenties lors

de la

dégustation d'un produit

alimentaire.

Les cinq composantes du goût

AmerSucré UmamiSalé Acide

Organisation anatomique

Epiglotte

Langue

Palais

Cavité nasale

Les bourgeons du goût et papilles gustatives

Organisation des bourgeons du goût

20 mm

Bourgeons du goût:

Homme (10000)

Rat (1000)

500 CV

Caffeine

Quinine

Glucose

Aspartame

GlutamateNaCl

KCl

Acide acétique

Des molécules induisant la perception d’un goût

Guanosine

monophosphate

AmerSucré UmamiSalé Acide

Acide citrique

Récepteurs gustatifs

ENAC PKD2L1

Récepteurs du salé et de l’acide

Salé Acide

Canaux ioniques

Récepteurs du sucré, umami et amer

40 T2RsT1R2/T1R3 T1R1/T1R3

AmerSucré Umami

Perte de la perception sucré chez

des animaux carnivores

T1R2/T1R3 T1R1/T1R3

Sucré Umami

X

?

Perte de la perception sucré chez

des animaux carnivores

The cell biology of taste. Chaudhari and Roper (2010) JCB

Transduction

ATP

5-HT

T1R2-T1R3 T1R1-T1R3 ENACEpithelial Na Chan.

PKD2L1TRP channel

Transduction (Taste GPCR)

The cell biology of taste. Chaudhari and Roper (2010) JCB

Representation sensorielle sur la langue

Codage des goûts au niveau de la langue

Vers le cerveau

Gustatoray pathways in the human brain

Noyau du

tractus solitaire

Représentation corticale des goûts

La perception des goûts

La représentation cérébrale des goûts

Accolla et al. (2008) Journal of Neuroscience

Marella et al. (2006) Neuron

Schoenfeld et al. (2004) Neuroscience

Gilbertson et al. J Neurosci (2001)

Codage de l’information sensorielle

Codage de l’information sensorielle

Mouse behaviour

Mueller et al. Nature (2005)

Codage de l’information sensorielle

Cortical neurons

Stapleton et al. J Neurosci (2006)

Représentation sensorielle dans le cortex

Vision Audition

Location of the gustatory cortex in the rodent brain

mca

rhv

S1BF

GC

S1

Pir

lot

GC

rs

IC

• Changes in Reflectance upon activation

• Functional Population Activity

• Successfully used to establish spatial organization of other sensory areas

• Good Spatial Resolution

Methods – Intrinsic imaging

Functional localization of the gustatory cortex

Accolla, Bathellier, Petersen and Carleton. Journal of Neuroscience (2007) 27:1396-1404

Signals are taste specific

Represention des goûts dans le cortex

B

Pleasant

Unpleasant

A

SweetSalty

BitterSour

mca

rhv

Somatosenrory

Gustotopic map in the taste cortex

Gustotopic map in the taste cortex

Une représentation corticale gustotopique

Carleton et al. (2010) Trends in Neurosciences

Accolla et Carleton. (2008) PNAS

Accolla et al. (2007) Journal of Neuroscience

Chen et al. (2011) Science

Valeur hédonique des goûts

Apprentissage gustatif: exemple de l’aversion

d’un aliment

Control AVERSION à

La saccharine

Extinction

Carleton et al. (2010) Trends in Neurosciences

Accolla et Carleton. (2008) PNAS

Changement de la représentation gustotopique après

apprentissage

Accolla et al. (2008) Journal of Neuroscience

saccharinequinine

CORTEX après

OLFACTION

Organization of the human olfactory system

Organization of the olfactory systems

Photo: courtesy of Prof. Rodriguez (UNIGE)(Omp-TauLacZ) Tg mouse

Grueneberg

Ganglion (GG)

Vomeronasal

Organ (VNO)Main olfactory

Epithelium (MOE)

Olfactory

Bulb (OB)

Grueneberg ganglion

Grueneberg ganglion

Control lesion

Grueneberg ganglion

Chemical senses receptors

Organization of the olfactory systems

V2R

V1R

OR

Transduction in the VNO

Sexual behavior controlled by the vomeronasal organ

Sexual behavior controlled by the vomeronasal organ

Male normal et

Male castré

Male normal et

Male castré

(plus urine male

normal)

Male Trpc2-/- et

Male castré

(plus urine male

normal)

Sexual behavior controlled by the vomeronasal organ

A functional circuit underlying male sexual behaviour in the female mouse brain

Tali Kimchi, Jennings Xu & Catherine Dulac

Nature 448, 1009-1014 (2007)

Organization of the olfactory system

Organization of the main olfactory system

Organization of the main olfactory system

The main olfactory epithelium

Sensory neurons in the main olfactory epithelium

Sensory neurons in the main olfactory epithelium

Organization of the main olfactory epithelium

Transduction in the MOE

Transduction in the MOE

Transduction in the MOE

Organization of the olfactory system

The Nobel Prize in Physiology

or Medicine 2004

L. Buck R. Axel

(M50-TauLacZ) Tg mouse

~1000 olfactory

receptors in mice

Simplex and complex odors

Odor detection in mammals

cyclohexanol

CH3

O

O

O O

CH2OH

OH

OOCH3

O

anisole

acétophenone

1,8 cinéole

dl-camphre

cyclodecanone

heptanol

cyclohexanone2-heptanone

Sicard, G. and Holley, A. (1984). Receptor cell

responses to odorants: similarities and differences

among odorants. Brain Research, 292, (2), 283-96.

• One receptor is not

specific of a single

molecule

• Different odors are

detected by different

sets of receptors

Olfactory epithelium

Sensory neuron

Chemodetection

Imaging odor maps

Blood vessels

pattern

Functional Map

Different odorants evoked different glomeruli patterns

Ethyl

Butyrate

Amyl

acetate

Functional organization of cortical regions

Odor maps

Methyl BenzoateWater

Amylacetate Benzaldehyde

Hexanal

Carvone + (1) Carvone + (2)

Odor evoked glomeruli maps

A m y l a c e t a t e

M e t h y l B e n z o a t e

B e n z a l d e h y d e

Mouse C57Bl6- Odor maps from 03525

5 10 25 50 100 200

5 10 25 50 100 200

5 10 25 50 100 200

Amylacetate

Methyl Benzoate

5 10 25 50 100 200

5 10 25 50 100 200

Odor coding = Combinatorial coding

Anosmia: loss of the sense of smell

Anosmia: loss of the sense of smell

Mouse

Human

Anosmia: loss of the sense of smell

Sensory neurons Mitral cells

Olfactory bulb circuitry

Analysis of OB projections: electroporation in a single

glomerulus

Sosulski et al. Nature (2011) 472:213-216

Divergent projections towards the cortex

Sosulski et al. Nature (2011) 472:213-216

Piriform cortex organization

Temporal code and summation

Odor representation in the olfactory cortex

Stettler and Richard Axel. Neuron (2009) 63, 854-64

Lack of chemotopy and organization in the olfactory cortex

Stettler and Richard Axel. Neuron (2009) 63, 854-64

Optogenetic control of neuronal firing: Channelrhodopsin

http://www.biophys.mpg.de/en/bamberg.html

Optogenetic control of neuronal firing

http://channelrhodopsin.wikia.com/wiki/Bioengineering

http://allthingscensored.blogspot.it/2012/01/birth-of-optogenetics.html

Ensembles of piriform neurons can drive opposite behavior

Choi et al. Cell (2011) 146:1004-15