Jones - Perspectives imitation - comment on Gallese

Susan Jones (2005)

The role of mirror neurons in imitation

A commentary on V.Gallese

“Being like me: Self-other identity, mirror units and empathy

In Hurley, S & Chater, N (2005) Perspectives on Imitation: From neuroscience to social science: Vol 1 Mechanisms of imitation and imitation in animals, Cambridge, MA,US: MIT Press 205-210.

Jones’s position as regards what is NOT the function of mirror units

• Mirror units are not direct transducers of observed behaviours to executed behaviours. P207 ‘ they respond to both sensory input and motor events; they do not respond to sensory input with motor events’

• ‘the idea that mirror units link observed actions directly to stored ‘motor plans’ also seems wrong!’ Mainly because when you consider the simplest of actions the number of factors involved make each action ( eg reaching) unique not least because of variations, even very small variations, in context.’

Jones’s critique of Gallese

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Likes Gallese’s view ‘ mirror units as sources of the experience of common experience with other people, animals or robots like ourselves’ His proposal that ‘ mirror units are part of the mechanism for the automatic, sub-personal, non-propositional recognition and understanding of others’. Also that ‘This recognition and understanding of just the nature of others’ behaviours might then feed into an understanding of the intentions and states behind these actions’ ie it might lead to empathy

(KRO mirror units as general understanding of others rather than a specific understanding of an other)

Jones sees such knowledge and understanding as a prerequisite for imitation

( KRO again

general understanding/awareness of others leads to specific ideas about the intentions etc of another which might require the process of imitation.

? – on three points for Gallese’s claim for mirror unit involvement as a transducer , by direct mapping perception to action in imitative behaviour of infants, specifically tongue protrusion behaviour. ( note his only claim for the involvement of mirror units in imitation).

1. Jones suggests that this ‘resembles the classic reflex loop rather than the mirror unit activity as observed in Gallese’s own experiments’

2. Tongue protrusion often cited as possibly imitative behaviour of young infants but this does not take place in a one to one fashion. In Meltzoff & Meltzoff experiments it was ‘wehile the model was not tongue protruding that the infant’s tongue protrusions were most numerous ie no co-concurrence ( KRO ? need co-presence for co-concurrence)

3. Jones (1996) has shown tongue protrusion behaviour to flashing light and Jones (2001) to music. Is tongue proptrusion in infants due to arousal

Jones’s proposition ( based on the positive aspects of critique of Gallese)

She sees the important property of mirror neurons that ‘ they can fire for a specific instance of a broader category of actions – but not know whether it was mine or yours . What would such cells be good for if not to blur the lines between me and you and let us each know the other to be like ourself’

Oberman et al mu rhythm ASD mirror units

Oberman, L.M., Hubbard, E.M., McCleery, J.P., Altschuler, E.L., Ramachandran, V.S., & Pineda, J.A. (2005).

EEG evidence for mirror neuron dysfunction in autism spectrum disorders

Cognitive Brain Research 24, 190-198

Review of the evidence for mirror units in humans

Can’t be studied ( KRO therefore identified and substantiated) directly in humans

P191 ‘the existence of an analogous system ( KRO to that of monkeys) in the homologous brain region ( Broca’s area, Brodmann’s area 44) has been supported by indirect population-level measures

• Ref 17 (1995)Fadiga et al using TMS ‘motor evoked potentials in response to TMS over motor cortex were enhanced when the subject observed another individual performing an action relative to when the subject detected the dimming of a light.
• Ref 39 (1995)Parsons et al used PET to map the brain areas that were active during observation of biological movement. Frontal, parietal and cerebellar regions, including the inferior premotor cortex ( Brodmann’s area 44 – Kro thought to be equivalent to F5 of monkeys) were found to be active during actual movement, imagined movement and observed movement.
• Ref 29 Iacoboni et al (1999)using FMRI found increased blood flow in Brodmann’s area 44 during both observed and performed actions. Ref 10,36 (more recent refs) seem to confirm that these areas are implicated

Also ‘Several recent studies have uncovered activations with similar properties in the parietal cortex ( 10.39) as well as superior temporal sulcus (11,40). These results suggest that the frontal mirror unit system may be one part of a broader action observation/execution network (18.38).’

Monitoring mu rhythm as an indirect method of investigating mirror units in humans

P191 claim ‘ at rest sensorimotor neurons spontaneously fire in synchrony leading to large amplitude EEG oscillations in the 8-13 frequency band. When subjects perform an action, these units fire asynchronously, thereby decreasing the power of the mu-band EEG oscillations ( 41,48). Because the motor properties of the mirror neurons are indistinguishable from those of neighbouring premotor, motor or sensorimotor neurons, mu wave suppression during self-performed actions is likely to be the a

result of activation of several neuronal systems …….During observed hand movement , however, the mirror neuron system is the only network that has been identified to be active in this area of the cortex. ( KRO assumption, speculation?)

Mu power recorded from electrodes on scalp locations C3, Cz & C4 is reduced in normal adults by self initiated movement and observed movements (5,14,26,42)

Rationale for this research

Calls on evidence that ‘human mirror neuron system has been implicated in a variety of higher-level cognitive processes …imitation, language, theory of mind and empathy (refs 54 & 46) all of which are characteristic of ASD.

P191 ‘ once another individuals actions are represented and understood in terms of one’s own actions, it is possible to predict the mental state of the observed individual, leading to theory of mind deficits’ ‘ Empathy may critically depend on one’s ability to understand the observed facial expressions in terms of one’s own motor representations’ ( KRO but first time that the paper mentions facial expression as part of imitative movement)

Research methodogy

ASDs & controls NOTE age range 6-47 did correlation against age , reported as no correlation rather than reporting individual r values ( calculated r across three conditions and three targeted electrode placements and two participant groups ie across nine values of r for each participant group). Also don’t know the distribution of ages in the two groups. All male.

4 conditions – (i) moving own hand, (ii) watching a video of a moving hand, (iii) watching a video of two bouncing balls ( non –biological motion) (iv) watching white visual noise (baseline). (KRO absence of noise and other wild features)

Counting task , number of times the movement stopped, to control for attentional aspects.

EEG

Mastoid refes. F3, Fz,F4,C3,Cz,C4,P3,Pz,P4,T5,T6,O1,& O2 using a cap. But used recordings from C3,Cz & C4 claiming that p194 ‘although data were obtained from electrodes across the scalp, mu rhythmn is defined as oscillations measured over sensorimotor cortex thus only data from C3, Cz and C4 presented’

Data collected for 170 seconds per condition at a sampling rate of 500 HZ. Recognised that recodings at C3,Cz & C4 might be affected by changes in awareness ( KRO therefore alpha) and therefore first 10 s of each block were removed to eliminate the possibility of attentional transients. Also claims that since eyes were open throughout then any alpha rhythm would be at attenuated. EOG used to monitor artefact (eye & head only) and used to remove artefact from records. Integrated power measurement in 8-13 Hz range. P193 ‘data were segmented into epochs of 2 seconds beginning at the start of the segment, FFT were performed on the epoched data (1024 points). A cosine window was used to control for artefacts resulting from data splicing’

2 measures of mu suppression

(1i) power ratio observed hand movement /baseline

(1ii) power ratio self hand movement/baseline

(2i) power ratio observed hand movement /ball movement

(2ii) power ratio self hand movement/ball movement

1 controls for individual differences

2 controls for counting

Based comparison between two groups on log ratios with less than zero indicating suppression and more than zero indicating enhancement.

Results

Based on recordings at C3, CZ, C4 p195 ‘ there was a lack of suppression in the ASD group during the observed hand movement condition suggestive of a dysfunction in the mirror neuron system’ ‘ Furthermore the lack of suppression during the observation conditions in the ASD group is contrasted with significant suppression to their own movement., which is indicative of normal functioning of other sensorimotor systems involved in self-performed actions. P194 ‘No other electrodes showed a consistent pattern of suppression in the frequency band of interest’ (KRO but why was this data not presented as it would be useful to see.)

Discussion

Was the counting task a confounding factor? ( differential effect on the ASD subjects) Didn’t have to count in the baseline condition but did in the bat and ball so that explanation seems unlikely.

Supporting evidence from other work

P195 based on ref 37 ‘ averaging MEG to the presentations of a woman performing orofacial gestures and instructed to imitate. Activations in inferior temporal lobe and primary motor cortex were weaker and had greater latency in the AS group when compared with the control group’

Authors recognise the potential for a low level explanation ‘ p196 ‘ the impaired visual processing of biological motion. This would result in reduced activation in visual areas thought to be involved in biological motion perception’

Differences could be due to inhibitory influences from other brain processes and therefore brain regions.

Further work: looking at metaphorical statements of movement egg rap the idea, reach for the stars.