Cours 4 Flashcards

Question

Conclusion (?) Quoi vs. où

Answer 1

En créant des lésions artificielles - Si on retire le lobe temporal (lésion au système « ventral »), on retire la capacité d’identifier les caractéristiques des objets (QUOI) - Si on retire le lobe pariétal (lésion au système « dorsal »), on retire la capacité de reconnaître la position des objets dans l’espace (OÙ) Double dissociation entre flux du QUOI et du OÙ - Deux « patients » avec lésions complémentaires (créé en lab) - On « bloque » l’action d’un système en laissant l’autre intact et vice-versa = influence premier processus cognitifs (ex. reconnaissance d’objet) mais lorsqu’on retire un autre système (autre aire cérébrale) ça affecte un processus cognitifs différent = on peut donc conclure une double dissociation. The what and where pathways are also called the ventral pathway (what) and the dorsal pathway (where), because the lower part of the brain, where the temporal lobe is located, is the ventral part of the brain, and the upper part of the brain, where the parietal lobe is located, is the dorsal part of the brain. The term dorsal refers to the back or the upper surface of an organism; thus, the dorsal fin of a shark or dolphin is the fin on the back that sticks out of the water. Figure 3.32 shows that for upright, walking animals such as humans, the dorsal part of the brain is the top of the brain. (Picture a person with a dorsal fin sticking out of the top of his or her head!) Ventral is the opposite of dorsal, hence it refers to the lower part of the brain.

Answer 2

coordination between perceiving and action that is carried out by two separate streams in the brain, as described in the text. This simple action requires continually perceiving the position of the cup, and of her hand and fingers relative to the cup, while calibrating her actions in order to accurately grasp the cup and then pick it up without spilling any coffee But as with everything else about perception, this ease and apparent simplicity are achieved with the aid of complex underlying mechanisms. Psychologists have long recognized the close connection between perceiving objects and interacting with them, but the details of this link between perception and action have become clearer as a result of physiological research that began in the 1980s. This research has shown that there are two processing streams in the brain—one involved with perceiving objects, and the other involved with locating and taking action toward these objects. This physiological research involves two methods: brain ablation—the study of the effect of removing parts of the brain in animals, and neuropsychology—the study of the behavior of people with brain damage Applying this idea of what and where pathways to our example of a person picking up a cup of coffee, the what pathway would be involved in the initial perception of the cup and the where pathway in determining its location— important information if we are going to carry out the action of reaching for the cup. In the next section, we consider another physiological approach to studying perception and action by describing how studying the behavior of a person with brain damage provides further insights into what is happening in the brain as a person reaches for an object. With our knowledge that perception and action involve two separate mechanisms, we can add physiological notations to our description of picking up the coffee cup as follows: The first step is to identify the coffee cup among the vase of flowers and the glass of orange juice on the table (perception or what pathway). Once the coffee cup is perceived, we reach for the cup (action or where pathway), taking into account its location on the table. As we reach, avoiding the flowers and orange juice, we position our fingers to grasp the cup (action pathway), taking into account our perception of the cup’s handle (perception pathway), and we lift the cup with just the right amount of force (action pathway), taking into account our estimate of how heavy it is based on our perception of the fullness of the cup (perception pathway).

Answer 3

Sujet unique - D.F., patiente avec agnosie de forme visuelle v Lésion au système « ventral » v Problème de reconnaissance d’objets (QUOI) selon les chercheurs car ça touche la région du quoi v Elle a un problème avec : forme, orientation, taille v Pas un problème de système visuel (car elle est capable de reconnaitre des objets si elle les touche mais pas avec ses yeux) pas un problème physique des nerf optique ou rétine car elle est capable de différencier les couleurs Tâches multiples - Orientation d’une fente - Épaisseur d’une plaque

Answer 4

1. Pas de perception de l’espace mais bien juste le quoi Autre option : choisir de façon QCM l’image qui correspond à la fente devant moi La patiente a eu beaucoup de difficulté et performe moins bien que le groupe contrôle 2. Oriente la plaquette et l’insérer = mouvement et but Performance = vraiment meilleur Encore info qui correspond au quoi, mais elle utilise ses infos car il y a un mouvement et un but Selon les chercheurs elle ne devrait pas être capable = résultat inattendu

Answer 5

Condition perceptuelle: Patiente doit choisir la plus petite ou la plus grande plaquette placée devant elle v Résultat: impossible de discriminer différentes tailles Patiente doit reproduire épaisseur d’une plaquette avec pouce et index V Mesure de la distance entre pouce et index mesurée à l’aide de caméra Résultat: montre la même distance entre le pouce et l’index peu importe l’épaisseur de la plaquette (incapable de faire la tache) **Condition perceptuelle + mouvement avec but**: Patiente doit étirer le bras et saisir une plaquette entre son pouce et son index Résultat: Patiente place son pouce et son index à une distance proportionnelle à l’épaisseur de la plaquette (et la distance change et elle aussi = quoi malgré lésion car but et mouvement) Conclusion : - Patiente montre un déficit au niveau du traitement de l’objet et de ses caractéristiques (agnosie) - Elle peut toutefois utiliser cette information (QUOI) si la tâche implique le mouvement vers un but - Indice d’une **dissociation entre un système de perception visuospatial et un système de contrôle visuospatial de l’action** (pas entre quoi et où) Donc ne correspond pas à QUOI vs. OÙ = INVALIDE!

Answer 6

the pathway from the visual cortex to the temporal lobe (which was damaged in D.F.’s brain) be called the perception pathway and the pathway from the visual cortex to the parietal lobe (which was intact in D.F.’s brain) be called the action pathway (also called the how pathway because it is associated with how the person takes action). The perception pathway corresponds to the what pathway we described in conjunction with the monkey experiments, and the action pathway corresponds to the where pathway. Thus, some researchers refer to what and where pathways and some to perception and action pathways. Whatever the terminology, the research shows that perception and action are processed in two separate pathways in the brain.

Answer 7

Résultats convergents: Ataxie optique Perenin & Vighetto (1988): Optic ataxia – A specific disruption in visuomotor mechanisms Tâches: Saisir un objet devant soi (déplacement latéral = gauche à droite) Résultat: Nombre d’erreurs significativement plus élevé que contrôles (à cause de la lésion) Discrimination de positions de points Résultat: Performance similaire aux contrôles Deux tâches impliquent le flux de traitement du OÙ Soutient une dissociation entre un système de perception visuospatial et un système de contrôle visuospatial de l’action (perception vers un but)

Answer 8

Mario Iacoboni and coworkers (2005) did an experiment in which they measured participants’ brain activity as they watched short film clips. There were three versions of the film, all showing the same motion of a hand picking up a cup, but in different contexts. **Version 1 showed a hand reaching to pick up a full cup of coffee from a neatly set up table, with food on a plate**. **Version 2 showed the same motion but the cup was on a messy table, the food was eaten, and the cup was empty**. **Version 3 showed the hand picking up an isolated cup**. Iacoboni hypothesized that viewing film clip 1 would lead the viewer to infer that the person picking up the cup intends to drink from it, that viewing film clip 2 would lead the viewer to infer that the person is cleaning up, and that viewing film clip 3 would lead to no particular inference. When Iacoboni compared the brain activity from viewing the two intention films to the activity from the non-intention film, he found that the **intention films caused greater activity than the non-intention film in areas** of the brain known to have mirror neuron properties. The amount of activity was least for the non-intention film, higher for the cleaning-up film, and was highest for the drinking film. Based on the increased activity for the two intention films, Iacoboni concluded that **the mirror neuron area is involved with understanding the intentions behind the actions shown in the films**. He reasoned that if the mirror neurons were just signaling the action of picking up the cup, then a similar response would occur regardless of whether a context surrounding the cup was present. According to this idea, mirror neurons that respond to different intentions are responding to the action that is happening plus the sequence of actions that is most likely to follow, given the context. When considered in this way, the operation of mirror neurons shares something with perception in general. Remember Helmholtz’s likelihood principle—we perceive the object that is most likely to have caused the pattern of stimuli we have received. In the case of mirror neurons, the neuron’s firing may be based on the sequence of actions that are most likely to occur in a particular context. In both cases the outcome—either a perception or firing of a mirror neuron - depends on knowledge that we bring to a particular situation. The exact functions of mirror neurons in humans are still being debated, with some researchers assigning mirror neurons a central place in determining intentions and others questioning this idea. But whatever the exact role of mirror neurons in humans, there is no question that there is some mechanism that extends the role of perception beyond providing information that enables us to take action, to yet another role—inferring why other people are doing what they are doing.

Answer 9

Researchers who were using **electrodes to record the brain activity in people with epilepsy in order to determine which part of their brains was generating their seizures** have recorded activity from neurons with the same mirror properties as those identified in monkeys. Additional work done using fMRI in neurologically normal people has further suggested that these neurons are distributed throughout the brain in a network that has been called the **mirror neuron system**

Answer 10

One possible answer is based on the theory of natural selection, which states that characteristics that enhance an animal’s ability to survive, and therefore reproduce, will be passed on to future generations. Through the process of evolution, organisms whose visual systems contained neurons that fired to important things in the environment (such as verticals and horizontals, which occur frequently in the forest, for example) would be more likely to survive and pass on an enhanced ability to sense verticals and horizontals than would an organism with a visual system that did not contain these specialized neurons. Through this evolutionary process, the visual system may have been shaped to contain neurons that respond to things that are found frequently in the environment. Although there is no question that perceptual functioning has been shaped by evolution, there is also a great deal of evidence that learning can shape the response properties of neurons through the process of experience-dependent plasticity **plasticité dépendante de l'expérience**