1

Les Actions Dirigées

vers un But

2

Qu’est-ce qu’une action?

• Les actions sont décomposables

Mvt 1.1.1.1 Mvt 1.1.1.2 Mvt 1.1.1.3

Sub-action 1.1.1 → Sub-goal 1.1.1

Mvt 1.1.2.1 Mvt 1.1.2.2 Mvt 1.1.2.3

Sub-action 1.1.2 → Sub-goal 1.1.2

Action 1.1 → Goal 1.1

Intention 1.

3

Qu’est-ce qu’une action?

• Codage des paramètres des mouvements

(élémentaires) dans le cortex moteur primaire

– La direction du mouvement

4

5

Qu’est-ce qu’une action?

• Codage des paramètres des mouvements

(élémentaires) dans le cortex moteur et prémoteur

– La direction et la force du mouvement

Experimental device showing the pointer and the display panel with the light-emitting diodes (LEDs).

Stars indicate the starting position and circles the targets to be pointed at. White circles indicate that a

weak force movement was to be performed (green LED) and black circles indicate that a strong force

movement was to be performed (red LED). (Riehle & Requin, 1995)

Cf. Protocole de

préparation

6

Discharge pattern of a neuron exhibiting both direction-related and force-related preparatory

activity recorded in the premotor cortex of monkey F during eight types of trials in which prior

information about direction (A-D) and force (E-H) was provided. Trials were arranged in relation

to the occurrence of the signals. The prior information content and the type of movement are

indicated. Trials were only arranged timelocked to the occurrence of the signals. (Riehle & Requin, 1995)

During the PP, only

7/397 neurons (2%)

exhibited selective

activity changes in

relation to prior

information about

force only.

7

Qu’est-ce qu’une action?

• La représentation des actions dans les

cortex prémoteur et pariétal

– Il existerait des prototypes d’actions,

paramétrables

• Saisir

• Tirer

• Pousser

• Placer

• Etc.

8

Qu’est-ce qu’une action?

• La représentation des actions en fonction

des objets dans le cortex pariétal: AIP

Propriétés

motrices

(Murata et al. 2000)

(Anterior intraparietal area)

9

Qu’est-ce qu’une action?

• La représentation des actions en fonction

des objets dans le cortex pariétal: AIP

Propriétés

visuelles

(Murata et al. 2000)

(Anterior intraparietal area)

10

Qu’est-ce qu’une action?

• La représentation des actions dans le

cortex prémoteur: F5 (mouvement vs. Action)

(Umilta et al. 2008)

11

12

13

Activity of two neurons recorded in area F5. Rasters and histograms (10 trials) illustrate the neurons’ discharge recorded during grasping with normal pliers (Upper) and reverse pliers (Lower). Both

rasters and histograms are aligned with the end of the grasping closure phase (asterisks). The traces below each histogram indicate the instantaneous hand position (average of the voltage

changes values occurred during neuronal recording) recorded with the potentiometer and expressed as a function of the distance between the pliers handles. Trace down indicates that the hand

closes, and the distance between handles decreases, whereas trace up indicates that the hand opens, and the distance between handles increases. The values shown on the vertical axes

indicate the potentiometer-measured voltage. With normal pliers (Upper), Unit 210 (Left) began to fire during hand closure (trace down), reaching the maximum at approximately the moment in

which the food was grasped; with the reverse pliers (Lower), this unit started to fire with the hand opening (trace up), also reaching its maximum when the food was grasped. Unit 199 (Right)

started to fire in normal pliers (Upper) condition during hand opening (trace up), reaching its maximum at the beginning of the hand closure. With reverse pliers (Lower), the neuron started to fire

during the hand closure (trace down), reaching its maximum during hand opening. Unit 210: peak force, averaged across 10 trials, 2.8 N and 10.2 N with normal and reverse pliers, respectively.

Unit 199: peak force, averaged across 10 trials, 3.9 N and 9.3 N with normal and reverse pliers, respectively. (Umilta et al. 2008)

14

Qu’est-ce qu’une action?

• La représentation du but de l’action dans

le cortex pariétal (IPL, inferior parietal lobule)

(Fogassi et al. 2005)

15

(Fogassi et al. 2005)

Discharge of two IPL neurons during active grasping. Unit 122 strongly discharges when the monkey grasps a piece of food

to eat (top), whereas it does not respond when the monkey grasps an object (center) or a piece of food (bottom) to place.

Unit 43 strongly discharges when the monkey grasps a piece of food to eat (top), whereas the discharge is significantly

weaker when the monkey grasps a piece of food to place into a container positioned near the mouth (center) or near the

grasped object location (bottom).

16

Qu’est-ce qu’une action?

• La représentation du but de l’action dans

le cortex frontal inférieur

(Iacoboni et al. 2005)

17

Qu’est-ce qu’une action?

• La représentation du but de l’action dans

le cortex frontal inférieur

(Iacoboni et al. 2005)

18

Le concept de programme moteur

• Détermination du but (cf. Physiologie, Éthologie, Psychologie…)

• Analyse sensorimotrice

• Sélection des prototypes d’actions, mouvements

et paramètres (programme multidimensionnel et multi-échelles)

La préparation à l’action, c’est

la réduction de l’incertitude

spatiotemporelle…

Information sur l’action

Temps de

réaction

19

Population vector

(Grammont & Riehle)

Programme moteur

et cerveau polyglotte

20

21

Qui est aux commandes ?

• La décision d’agir

– Le potentiel de préparation motrice (EEG)Action (EMG)

"Readiness potential"

"Bereitschaftspotential“

22

Qui est aux commandes ?

• La décision d’agir

– Le protocole de B. Libet

(Libet et al. 1983)

23(239 ms)

Qui est aux commandes ?

• La décision d’agir

– Le protocole de B. Libet

(Libet et al. 1983)

24

Qui est aux commandes ?

• Action intentionnelle et conscience du temps

– S’attribue-t-on l’intention d’une action a priori ou

a posteriori ?

(Haggard et al. 2003)

25

(Haggard et al. 2003)

26

Qui est aux commandes?

• Action intentionnelle et conscience du temps

– S’attribue-t-on l’intention d’une action a priori ou

a posteriori?

(Haggard et al. 2003)

27

Bibliographie

• Neurosciences (ed. De boeck)

• Neurosciences Cognitives (ed. De Boeck)

• Cerveau & Comportement (ed. De Boeck)

• Neurosciences: Contrôle et apprentissage

moteur (ed. Ellipse)

• Cerveau et motricité (ed. PUF)

• Time of conscious intention to act in relation to

onset of cerebral activity (readiness potential).

Libet et al. Brain.1983; 106: 623-642