Lecture 2 - Mirror Neurons Pt2 PDF

Lecture 2 - Mirror Neurons Pt2 Broken Mirrors Theory of mind deficit is key to autism (Baron-Cohen). We don’t necessarly have the same thoughts because it’s based off of what we know But this may not be primary ** ** Imitation and MNs might...

Lecture 2 - Mirror Neurons Pt2 Broken Mirrors Theory of mind deficit is key to autism (Baron-Cohen). We don’t necessarly have the same thoughts because it’s based off of what we know But this may not be primary ** ** Imitation and MNs might be the basis of ToM deficits? Simulation Theory ‘putting themselves in the others shoes’, ‘acting as if you are the other’. False belief – a test for ToM 23/27 controls (age 4;5) passed 12/14 Downs (age 10;11) passed 16/20 Autism (age 11;11) failed Imitation and the MNS  Iacoboni et al. (1999) 3 different conditions: Imitate the middle or index finger movements Move the finger on which the x is displayed Move the right index finger for a left “x” or right middle finger for a right “x” Greater activity in the mirror neuron system (left inferior frontal cortex and right superior parietal lobe) in the first condition As there is motor activation in all 3 conditions, the additional activity in condition 1 must relate to mirror neuron activation coding for imitation. Imitation in Autism “21 experimental studies of the imitative competence of individuals with autism” “consistent finding that people with autism do not readily imitate the actions of others” Williams et al. 2006 Controls show greater activation of parietal MNS for imitation condition than individuals with ASD EEG Evidence of MN dysfunction in Autism Oberman et al. (2005) High functioning ASD v healthy controls 4 conditions: (a) watch visual noise (baseline) (b) watch bouncing ball video (c) watch moving hand video (d) move own hand Measure EEG (mu) over motor cortex compare activity in (b), (c), (d) relative to (a) Oberman et al. (2005) High functioning ASD v healthy controls, 13 years old 4 conditions: (a) watch visual noise (baseline) (b) watch bouncing ball video (c) watch moving hand video (d) move own hand Controls showed mu suppression in both conditions c) and d) Children with autism showed mu suppression only for condition d) Conclusion: Individuals with autism do not mirror hand movements MNs in autism MEG recorded from mouth opening muscles Action Execution Both children activated mouth muscles but autists later  When they are watching this action, autists neurons do not activate Cattaneo et al. (2007) Participants asked to reach for either a piece of paper to place in a pot on their shoulder, or a piece of food to place in their mouth. Both children with and without autism activated their mouth muscles while bringing the food to the mouth. Typically developing children, but not children with autism also activated their mouth muscles when watching someone else reach for the food (but not the piece of paper). Social Mirroring in Autism Dapretto et al. (2006) N = 10 high-functioning children with ASD (M age = 12) N = 10 typically developing children matched for age and IQ Participants asked to imitate different emotional expressions Activation of the (frontal) mirror neuron system was reduced in the individuals with autism The more severe the individual’s autism, the less the mirror neuron system was activated –Therefore, mirror neuron driven imitation is impaired in autism Reduced activity in frontal mirror system during emotion imitation in children with autism. Broken mirrors in Autism This theory seems perfectly logical MNS seems to play a role in imitation (as well as action understanding) \ > Imitation is impaired in autism \ > impairment in imitation and theory of mind may stem from a broken mirror system. There seems to be some evidence to support this theory. Unbroken Mirrors Southgate & Hamilton (2008), see also Hamilton (2013) on Tallis Inconsistent evidence of MNS dysfunction in autism.  The precise pattern of imitation deficits in autism is not clear. No evidence of MNS dysfunction Using Mu suppression Imaging effects without a behavioral deficit  Clinical observations point to increased imitation in autism. –Echolalia: involuntary repetition of speech patterns –Echopraxia: involuntary imitation of observed actions.  Participants randomly assigned to either the Pro- or Non-social Prime Group Priming task: select, in order, 4 words from 5 displayed on a computer screen to make a grammatically correct sentence. 24 out of 36 total trials contained a word semantically related to the target attitude (pro-social or non-social) Summary - Unbroken Mirrors The broken mirrors hypothesis was built around the idea that imitation is impaired in autism and mirror neurons are involved in imitation. However, the precise picture regarding imitation in autism is not straightforward. Nonetheless, if mirror neurons allow us to understand others (a problem in autism) they might still relate to autism. The evidence for this is also inconsistent. Plus, more on mirror neurons and action understanding in the next part of the lecture. Intuitive link between mirror neurons, imitation, action understanding, empathy, and social problems in autism. However, the case for a mirror neuron deficit in autism is extremely weak at best. Action Understanding More theoretical, much of discussion is based around interpretations of findings just spoken about Boils down to 1 point Actions are ambiguous, context provides understanding Mirror neurons cannot behave as claimed, for example, by lacoboni et al (2005): “premotor \ neuron areas are involved in understaning the untentions of others. To ascribe an intention is to infer a forthcoming new goal, and this is an operation that the motor system does automatically” The Direct Matching Hypothesis “the ‘direct-matching hypothesis’ holds that we understand actions when we map the visual representation of the observed action onto our motor representation of the same action. According to this view, an action is understood when its observation causes the motor system of the observer to ‘resonate’. So, when we observe a hand grasping an apple, the same population of neurons that control the execution of grasping movements becomes active in the observer’s motor areas. By this approach, the ‘motor knowledge’ of the observer is used to understand the observed action. In other words, we understand an action because the motor representation of that action is activated in our brain” Reviewing the Evidence Gregory Hickok - criticising mirror neurons CS: “Mary is interacting with an object (e.g. a cup). According to how she is grasping the cup, we can understand why she is doing it (e.g. for drinking or for moving it). This kind of understanding can be mediated by the parieto-frontal mirror mechanism in virtue of its motor chain organization.” From Rizzolatti & Sinigaglia (2010), Nature Reviews Neuroscience. p.271 GH: Actions are ambiguous. If I observed you reaching, I can simulate that movement. But what does it mean (what will the outcome be)? That depends entirely on non-motoric context... If there is a teacup in front of you, then you might be reaching to grasp it and I will therefore want to simulate reaching-to-grasp-a-teacup… The problem with this, for the motor-simulation account of “outcome understanding”, is that you pretty much need to know the outcome (the target of the action) in order to activate the correct simulation. CS: “according to how she is holding it we can understand why she is doing it (e.g. for drinking or for moving it)” GH: “Suppose we have successfully simulated the reaching-to-grasp-a-teacup motor program, but we want to know more: why is the person reaching for the teacup? For this we need to simulate the correct motor chain. How do we know whether to simulate grasping-to-drink versus grasping-to-clear versus something else? It depends not at all on the action itself – the initial grasping actions can be identical; it depends on the non-motoric context. If you are halfway through your tea and I see you reaching again toward the cup, I will want to simulate the grasping-to-drink motor chain. If you are done with your tea, I may want to simulate the grasping-to-clear chain. If the teacup belongs to someone else and I know that you do not even like tea, but like its aroma, I might want to simulate the grasping-to-smell chain. Again, based on the initial reaching movement alone, I have no idea which motor chain to simulate. In order to select the correct motor chain, I need to infer the goal of the movement based on the broader context and then activate the corresponding motor chain. So in some ways, the understanding (outcome prediction) needs to precede the motor simulation. This contextual understanding presumably involves some degree of inferential reasoning, the process that motor simulation is supposed to avoid.” “The goals of an action are not in the actions themselves…they are in the consequences of the actions and these consequences are, for the range of actions we are considering here, sensory. Therefore, to understand an action, we must understand the sensory goal(s) of the action. Action understanding is a function of perceptual, not motor systems.” Action Hierarchies “Just as the mechanism of imitation is always emulation at a lower level, the mechanism of motor mirroring is always reconstruction” Imitation vs goal emulation Having bound hands vs free hands Direct Matching When you see the finger move you need to either tap or lift your finger (separate blocks). BUT these studies do not require understanding of goals, so there may be no propagation up the motor system. Action Reconstruction From a visual perspective the 2 situations are identical, so this can’t be propagation through the motor system. Rather, the context determines the goal, which then feeds into the mirror activation. If mirror neurons aren’t required for action understanding through direct matching, then what is the point in mirroring (and mirror neurons)? What is the point of Mirror neurons? Mirror neurons and associative learning Mirror neurons and action anticipation The social function of mirror neurons The Origin of Mirror Neurons  Mirror Neurons can be retrained Where do they come from? “mirror neurons may be a byproduct of associative learning” “mirror neurons come from sensorimotor experience, and much of this experience is obtained through interaction with others. Therefore, the mirror neuron system is a product, as well as a process, of social interaction.” Catmur et al. (2007) Motor evoked potentials recorded from the first dorsal interosseus (index finger), and the abductor digiti minimi (little finger). Before training, MEPs showed muscle specific modulation dependent on which action was being observed –When observing an index finger movement, MEPs were increased in the index finger muscle, and the same relationship for the little finger. Participants then underwent “countermirror” training – i.e. they moved their little finger whenever they observed an index finger movement. The effect of action observation on MEPs changed following training, so that now participants  activated their index finger when observing a little finger movement. Mirror Neurons and Action Anticipation Action anticipation enables the observer to verify and revide goal attribution It is always a benefit to be ahead of events Prediction improves perception Action coordination between individuals Co-operative an joint actions So mirror neurons might serve a social purpose after all “an important purpose of the MNS is not to understand or even to predict, but rather to respond, in real-time and in a socially appropriate fashion, to the actions of others” Participants release index finger of their left or right hand from a response board as indicated by a number (1: left index finger, 2: right index finger) and form one of three gestures (communicative, intransitive or transitive) as shown on screen Depending on the presented hand stimulus (left or right hand), the response hand was lifted either congruently or incongruently in response to the number Responses were faster to complementary actions than to mirror actions for the communicative gesture, while transitive and intransitive gestures showed the typical congruency effect with faster responses for mirror actions than for complementary actions  Video clips to evoke complementary gestures (social condition), e.g. offering to pour coffee in the cup close to you non-complimentary gestures (non-social condition), e.g. pouring coffee in their own cup TMS over left motor cortex MEPs recorded with EMG electrodes over right hand first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles Mirror neurons help prepare for interaction with other people? Summary Although mirror neurons fire differently for different goals, this doesn’t mean that they are involved in action understanding –They do encode goals, but based on context and not simulation Mirror neurons may develop though associative learning Mirror neurons may help us to predict actions, and to allow joint action and social responding #PS495