Autism And Mirror Neurons

1. Autism And Mirror Neurons

2. Autism Spectrum Disorder(ASD) • Affected people exhibit a wide range in the magnitude in their symptoms These patients show deficits in: • Communication and Socialization • Theory of Mind • Empathy Is a dysfunctional mirror neuron system responsible for this phenotype?

3. Mirror Neuron(MNs) • First discovered in Macaque monkeys found to: • Mediate imitation • Basis of action understanding Associates observed actions with motor representations of that action

4. Mirror Neurons and Autism • Mu rhythm desynchronizes during observed movement and own movement • Control participants showed Mu rhythm suppression when observing and performing action • ASD participants had same suppression when performing action, but very little or no suppression when observing same action • This proposes a deficit in Mirror neuron activity in ASD

5. Mirror Neurons Localized to Broca’s Area • Goldin-Meadow, 1999) Localized a population of mirror neurons in the F5 region of the Macaque brain that were active during the presentation of a communicative mouth gesture • -(Buccino et al., 2004) Found communicative facial gestures also elicit mirror neuron activity in the human Broca’s Area

6. Mirror Neurons Involved in Language Processing in Motor Cortex • -(Hauk, 2004) with fMRI, found that when subjects would read passages concerning various body features(face, hands etc.) there would be corresponding activity in the related motor cortex regions. • -(Fadiga, 2002) Presented subjects with phonemes and found motor cortex activity at areas concerned with tongue manipulation during speech.

7. Theory of Mind 2 Models “Theory Theory” • observing patterned behaviors in others allows humans to develop theories to explain and predict mental states “Simulation Theory” • brain simulates the mental processes of others: “putting themselves in the other’s shoes” • Mirror neurons thought to play a role in ToM

8. Imitation, ToM, and Autism Imitation thought to play a role in theory of mind • MN activation allows others to generate an executive plan like the one being observed • Mechanism seems to follow simulation model • Mirror Neuron Dysfunction can account for social problems

9. Mirror Neurons and Empathy Empathy: The ability to identify with the feelings, thoughts, or mental states of other people (putting yourself “in the shoes” of someone else) Humans are normally able to do this quite well once fully developed- BUT autistic people seem to have a lack of empathy. What allows us to interpret the feelings of other people? Mirror Neurons!… along with a few other structures

10. One proposed pathway of emotional interpretation: • Another person’s action is visually encoded by the superior temporal cortex • Mirror neurons in the posterior parietal cortex interpret the movement • Mirror neurons in the inferior frontal cortex infer the goal or intent of the action • Parts of the insula, which receive input from all three cortical areas, project to the limbic system • The limbic areas process emotionally relevant content • Meanwhile, the mirror neurons also project back to the superior temporal cortex to allow imitation

11. The Insula Bridge Between Action Representation and Emotion

12. Mirror Neurons and Empathy • Dapretto et al (2006): fMRI recordings for the observation and imitation of various emotional expressions • Autistic children had: • MORE activity in the right visual and left anterior parietal areas (visual and motor attention) • LESS activity in the insula and amygdala (emotion) • NO activity in the mirror neuron system of the inferior frontal gyrus

13. Mirror Neurons and Consciousness Mirror neurons probably play a huge role in many aspects of our conscious state, particularly involving interaction with other people (language, theory of mind, empathy) Are these abilities crucial to our consciousness? Does the lack of them (as in autism, at least to some extent) alter the way we experience the world?

14. Bibliography Buccino et al. “Neural circuits involved in the recognition of actions performed by nonconspecifics: an fMRI study” Journal of Cognitive Neuroscience 16(2004): 114-26. Carr, L, M Iacoboni, MC Dubeau, JC Mazziotta, GL Lenzi. “Neural mechanisms of empathy in humans: A relay from neural systems for imitation to limbic areas.” Proceedings of the National Academy of Sciences 100 (2003): 5497-5502. <http://www.pnas.org/cgi/content/full/100/9/5497>. 31 May 2007. Dapretto, M, MS Davies, JH Pfeifer, AA Scott, M Sigman, SY Bookheimer & M Iacoboni. “Understanding emotions in others: mirror neuron dysfunction in children with autism spectrum disorders.” Nature Neuroscience 9 (2006): 28-30. <http://chd.ucsd.edu/articles05_06/Dapretto06.pdf>.15 May 2007 Dupont S, V Bouilleret, D Hasboun, F Semah, M Baulac. “Functional anatomy of the insula: new insights from imaging.” Surgical and Radiological Anatomy 25 (2003): 113-119. <http://people.hnl.bcm.tmc.edu/jli/reference/41.pdf>. 31 May 2007. Fadiga et al. “Speech listening specifically modulates the excitability of tongue muscles” European Journal of Neuroscience 15(2002):399-402. Goldin-Meadow. “The role of gestures in communication and thinking” Trends in Cognition 3(1999):419-29. Hauk et al. “Neurophysiological distinction of action words in the fronto-central cortex” Human Brain Mapping 21(2004): 191-201. Preston SD and FMB de Waal. “Empathy: Its ultimate and proximate bases.” Behavioral and Brain Sciences 25 (2002): 1-20. <http://peacecenter.berkeley.edu/BBS_PrestondeWaal.pdf>. 15 May 2007. Oberman LM, Hubbard EM, McCleery JP, Altschuler EL, Ramachandran VS, Pineda JA., EEG evidence for mirror neuron dysfunction in autism spectral disorders, Brain Res Cogn Brain Res.; 24(2):190-8, 2005-06 Rizzolatti G., Craighero L., The mirror-neuron system, Annual Review of Neuroscience. 2004;27:169-92 Terje Falck-Ytter, Gustaf Gredebäck & Claes von Hofsten, Infants predict other people's action goals, Nature Neuroscience 9 (2006) Elisabeth L. Hill; Uta FrithPhilosophical Transactions: Biological Sciences, Vol. 358, No. 1430, Autism: Mind and Brain. (Feb. 28, 2003), pp. 281-289.