2What are Mirror Neurons? Mirror neurons are cells that fire when a monkey (or person?) performs an action or when it views another animal performing that same action
3What are Mirror Neurons? Located in conjunction with a frontoparietal action planning network:posterior inferior frontalpre-motor areas that represent impending actionsMany cells are “motor dominant”: they fire when monkey grasps or reaches, but are independent of visual inputinferior parietalsensory area that integrates somatosensory, visual and auditory signalsMany cells are “visuo-dominant” or “visuomotor-dominant”: they fire when monkey sees a graspable object or a stimulus that could be interacted withThese regions are densely interconnected
4What are Mirror Neurons? Mirror neurons are in regions immediately adjacent to these frontal and parietal areasMotor properties of mirror neurons are same as “non-mirror” neurons but…Sensory properties are differentThese cells do not fire when monkey sees a graspable objectThey do fire when monkey sees another monkey (or a person!) perform actions relative to objects
5What can Mirror Neurons Represent? Some cells are precisely tuned to the specific actionse.g. using two fingers to pick up an objectOthers are broadly tuned to any action that accomplishes the same goalE.g. using any combination of hand and fingers to pick up an object
6What can Mirror Neurons Represent? Mirror neurons represent abstract actions and goalsCells will not fire when grasping is pantomimedCells will fire when grasping is real and visibleCells will also fire when grasping happens behind an occluding screen, as long as the monkey has seen that there is an object to be grasped behind the screen!
7What can Mirror Neurons Represent? Mirror neurons represent abstract actions and goalsSome mirror neurons will even fire in response to the sound of an action being performede.g. the sound of breaking a peanut shell
8What can Mirror Neurons Represent? Mirror neurons represent intended actionsSome cells fire more when monkey grasps food with intention to eat it – or when monkey observes a human grasping food to eat itSome cells fire more when monkey grasps food with intention to place it in a container – or when monkey observes a human placing food in a container
9Mirror Neurons in Humans? The existence of mirror neurons in humans is inferredWe don’t record directly from human cortex!
10Mirror Neurons in Humans? fMRI studies have found evidence for two brain regions associated with imitative actionsTask 1: watch actionTask 2: perform actionTask 3: imitate action
11Mirror Neurons in Humans? Based on work with monkeys, it was presumed that mirror neuron areas would exhibit a specific pattern of BOLD response:Task 1 < Task 2 < Task 3Two regions exhibited such a response
12Mirror Neurons in Humans? Mirror Neuron System (MNS) in Humans seems to be part of a system that mediates empathyfMRI data revealed MNS areas plus limbic areas became activated during observation of emotional facesMNS areas became more activated during imitation of an emotional facial expression
13Mirror Neurons Dysfunction in Autism? Some evidence supports a theory (speculation?) that a dysfunction of the MNS underlies social isolation disorders such as autism spectrum disorder (ASD)Some structural abnormalitiesMEG data shows abnormal propagation of signals in the MNS when imitating lip movements in individuals with Asperger’s SyndromefMRI data shows that BOLD signal in MNS during viewing and imitating emotional expressions is negatively correlated with severity of Autism Spectrum Disorder