Davidson 2004

Davidson, R.J. (2004)

What does the prefrontal cortex "do" in affact: perspectives on frontal EEG asymmetry research

Biological Psychology, 67, 157-182, 219-233

Historical appraisal alpha asymmetry and emotion

1979 EEG asymmetry first reported, at that time p 220 ' research on CNC substrates of emotional processes largely restricted to non-human species with focus on the subcortical'

But p222 we now know that  ' Emotion and motivation are instantiated in complex circuitry involving both cortical and sub cortical components'

Work presented up to 2004 has evolved with little connection to this  recent core neuroscience on structure and function - D argues that this state of affairs must change therefore  D  specifies some questions.

What is the PFC doing in emotion?

some facts to bear in mind

•   PFC is heterogenous (anatomically and functionally) and part of a larger network

•   Based on cell recordings-  animal studies ( 2 macaque monkeys) ' tasks that include a response component will be more likely to show affect related PFC activation asymmetry in the dorsal lateral regions and it is activity in these regions that is most likely to be reflected in scalp recorded brain signals'

•   Recent studies ' have also identified a ventromedial region of PFC that shows robust asymmetries during response inhibition tasks' ( also patient data with damage on right side I.e. r. VmQPFC ? Particularly susceptible to punishment)

p223

•   Suggestions that regions of the l.PFC play an important role in inhibiting the amygdala -' strong inverse relations between activation in the l.v.m.PFC and amygdala when subjects are asked to voluntarily down regulate  their negative affect. The findings collectively imply that what the PFC is doing in emotion is clearly NOT mediating emotional responses but rather moderating patterns of activity in other parts that control the primary emotional response'

'Unfortunately though, little work at the human level has begun to parse emotion in a fashion that derives from and honours the distinctions that are made at a neural level'

' For certain types of emotional processes the presence of a particular pattern of functional prefrontal asymmetry may be necessary but not sufficient for the emotional state in question, or may simply be contributory'

KRO - moderation ? emotional tone

Self report of conscious mood - a summary index of a range of complex emotional processes

IDs in baseline activations

p225 ' individuals with higher levels of l.sided PQF activity do indeed have a more positive profile of peripheral biological indicators' there is evidence of well being , the ability to cope with a negative event (resilience).

Reward is a factor that has been manipulated

P 225  ' it is during the period in anticipation of reward that the most pronounced l. Frontal activation is observed'

p226

Damasio v.m.PFC ' crucial substrate for affect guided decision making' - ? are there functional asymmetries Note Davidson has argued that there are functional asymmetries in dorsal prefrontal

P227

SES and asymmetry

Tomarken ( this issue) ' relations between SES and PF asymmetry in adolescence. The lower the SES, the greater the relative right-sided prefrontal activity'

Empirical and methodological issues

p221 ' the PF sector most directly associated with emotion is the sector that is least likely to be reflected in scalp-recorded brain electrical signals' hence the importance of a neurally informed strategy'  KRO - from clinical practice  we know that it would be naive to expect more than a generalised view of the activation patterns that underlying each electrode

Harmon-Jones ( this issue) Variations in levels of anger lead to increased left-frontal activation and ultimately approach behaviours. Davidson's caveat -' but only if there are response options that allow the individual to overcome whatever is thwarting the goal'

p227 articles ' establish prefrontal EEG asymmetry measures as reflecting, at least in part, trait like variations in brain function that appear to predict interesting and important features of affective style'

Reference electrode some studies report that method robust to location, some do not. Important to take into account that EEG recordings reflect the potential difference between two locations and there is no electrically neutral location anywhere on the body

other frequency bands

Oakes et al, 2004 ' although alpha shows the predicted inverse relation with metabolism ' ' the frequency band most consistently and strongly associated with glucose metabolism was gamma'

Pizzagalli refs for comparisons between frequency bands

Davidson 1988

Davidson, R.D. (1998)

EEG measures of cerebral asymmetry: Conceptual and methodological issues

J. Neuroscience, 39, p 71-89

Comparisons with other neuroscience methods

cf FMRI fewer constraints on task presentation and performance

Critical periods can be flagged ie examine epoch during which facial expression is recorded

Distinctions between Hemisphere specialisation and hemisphere activation

Hemisphere Specialisation

Preparedness to do a task, one hemisphere less accomplished than the other for a particular task

Hemisphere Asymmetries in Activation

p87 ' Activation refers to the degree to which a particular hemisphere is working or engaged'

p 73 ' Activation is typically defined operationally on the basis of the methods used in a particular study to measure this construct'

p 75 ' A hemisphere may become selectively activated as a function of priming'  this means that the task parameters may influence the activation level e.g. The requirement to respond with one hand or another hand (KRO think about cortical activity at a primary level).

' testing must be performed on a sample assumed to be homogenous with respect to individual differences in hemisphere specialisation'

Within subject designs therefore preferred although there can be floor/ceiling effects ie task effect not apparent because baseline measure already at ceiling/ floor

Dissociations between specialisation and activation

'Dissociations between these two aspects is common' ' The hemisphere specialised to process a particular stimulus is not necessarily the one most activated'

p73 ' it is not necessarily the case that differences in activation are paralleled by differences in specialisation'

rostral -caudal differences in hemisphere specialisation and activation

Anterior hemisphere  regions associated with affective processing

Posterior hemisphere regions associated with cognitive processing

I.e. activations are relatively orthogonal

 p76 ' stimuli which differ in affective valence systematically influence activation asymmetries in frontal brain electrical activity in the absence if any simultaneous measures in parietal asymmetry, while tasks which are designed differentially to require verbal versus visual spatial produce changes in parietal and temporal asymmetry in the absence of any modifications in frontal asymmetry processing produce changes in parietal and temporal asymmetry'

This has been checked by the author by taking both frontal and parietal/temporal measures at the same point in time and performing across(rostral-caudal) (e.g. r frontal v r parietal/temporal correlations) p87 ' it makes little sense to talk of a whole hemisphere being activated or specialised for a particular function'

Methodological Issues

1.  metrics of asymmetry

Require the sites to be homologous

Choose the dependent measure; oscillation, ratio/raw

 ( note for ratio measures (R-L)/(R+L) higher ratios are produced by less alpha in the left hemisphere and/or more alpha in the right hemisphere, both of which are associated with more relative left sided activation ( less alpha is taken to be indicative of more activation'

Between group as opposed to within group studies

Small differences ( between hemisphere) may be more significant than overall activations

2. Artefact

Blink & eye movement

EMG What is the spectrum characteristics, how to detect

p78' facial expression , there are reports of asymmetry. ' in our experience most severe in the beta range'  ( but doesn't evidence this) ' the presence of muscle artefact is sufficiently likely in certain scalp locations ( e.g. Temporal leads) as to make meaningful assessment of beta almost impossible' ' in our laboratory, we sample the EEG at 250 Hz and compute power density in a high frequency band (70-80Hz) which does not contain any neurogenic activity and is presumably a function of muscle activity exclusively' ( KRO does that view still hold?)

3 Reference electrode

Laplacian operator for dealing with  questions  that arise concerning the contribution of the reference electrode

Or

Record A1 and A2 with same reference, then average these channels to form a new reference

H-J 2010

Harmon-Jones, Gable, P.A., Peterson, C.S.

The role of asymmetric frontal cortical activity in emotion related phenomena. A review and update

Biological Psychology, 84, 451- 462

Greater left than right neural activity ( defined as reduced alpha power) associated with positive affect ( approach/no approach) behaviours.

Carotid Amytal, rTMS, findings interpreted as losing inhibitory influences of the affected hemisphere. Hemisphere specialisation evidenced by asymmetry in neural activation, right versus left as the DV, usually assessed by EEG specifically alpha power (KRO but see Davidson 1988 for the conceptual difference between hemisphere specialisation and hemisphere activation and how the two need not be related)

Methodological issues

State variables-environmental e.g. Time of day and time of year influences on cortisol levels may explain disparate findings about trait influences.

Manipulations of emotion, p 454 'some may not  evoke sufficient emotional intensity to engage asymmetrical frontal activations for all individuals' , ' Moreover, the intermixing of multiple types of affective stimuli may weaken motivational affects'

Measuring motivational direction. Motivational direction can be measured by using behavioral inhibition/activation system scales BIS/BAS of Carver and White (1994).

Motivational intensity can be potentiated by trait, and the opportunity to act. Led to experiments comparing supine and upright whilst Ps were given insulting feedback. Frontal activations diminished when supine. This finding has implications for the choice of technique ..          .     ,  . .   .  , .  ,    . ...

, fMRI ( when Ps need to be supine) and EEG(when they do not).

Gross & Levinson  (blinking associated with anger due to emotion suppression activity)

Manipulations

Neurofeedback

Used with AHSD by monitoring theta and alpha levels

In experimental settings Ps have been trained by 'rewarding' or 'not' with tones of differing frequency. 32 minutes training per day, feedback every 2 seconds. One group trained to increase relative right. Then zygomatic and corrugated monitored while  Ps watched films . The relative right group produced more corrugater.

P453 ' this research suggests that asymmetric frontal cortical activity is casually involved in emotional responses'

Hand contractions

Hand and face contractions activate contralateral hemisphere and in turn lead to spreading activation in that hemisphere and therefore alpha suppression is the consequence. tested and affirmed by  comparing uni lateral hand contractions (4 mins) then  Ps watched a mildly positive approach -orientated radio editorial while EEG recorded  Then an attitude scale used to measure motivation?

Guilt

'Does asymmetric frontal cortical activity fluctuate in response to motivational intensity changes?' ' guilt is hypothesised to serve two functions that operate in temporal sequence' (Amodio et al , 2007). Guilt first causes a reduction in approach motivation once one is aware of having committed a social transgression.  This reaction is followed by an increase in approach motivation when one is presented with an opportunity to engage in behaviour to repair the transgression.

P458

Motivational intensity cf valence

Events vary in their impact ie motivational intensity

Do positive(valence) affects of any approach motivational intensity cause increase in relative left frontal activation.

The Mindset experiment

3 conditions

1.  High approach positive valence (the P' s actions lead to positive outcome)

2.  Low approach positive valence ( the positive is produced by someone else but the P benefits)

3.  Neutral

Result alpha asymmetry 1>2>3

Source location studies

Using alpha power as the DV left frontal dorsal lateral is associated with approach motivation

EEG v fMRI/PET

P 459 'Each technique may assess different populations of neurons. EEG signals result from very selective areas of current source activity, often corresponding to small subsets of total synaptic action in tissue volumes and largely independent of action potentials. PET/fMRI measures, in contrast, result from activity in areas requiring much hemodynamic/metabolic activity. For example, cortical stelate cells occupy roughly spherical volumes and their synaptic sources provide a " closed field" structure which makes them invisible to the EEG.    Although stellar cells contribute only 15% of the neural population they contribute disproportionally to cortical metabolic activity. Thus they have a large effect on fMRI and PET. Other cases yield strong EEG signals and weak fMRI/PET activity. EEG can be large when only a few percent of neurons in each column are "synchronously active", if a large-scale synchrony among different columns produces a large dipole in which individual columns tend to be phase locked in particular frequencies. In this case, because most neurons in each intra-column population are relatively inactive, there is minimal metabolic activity'

Other

P459

' Posterior cortical regions are asymmetrically involved in emotional perception' right parietal and right temporal parietal , as measured by alpha power !!!!!!! Even in sensory areas

p459

' the research has suggested the importance of delineating emotional experience from emotional expression and emotional valence from motivational intensity'

agent design echoes

Echoes - design of the agent

Building autonomous agents for children with autism

Aims for the agent -

p 46 ' to be able to act credibly both as a peer and as a tutor'

 achieve appropriately designed transactional support. 

Autonomy p 47 ' an agent that is able to decide independently how to act best in order to achieve a set if high level goals that have been delegated to it'

Be pro-active - engender motivation & attention

Reactive - adaptive

Have social ability - so that it can maximise the chances of the child experiencing a sense of self-efficacy

An ideal social agent with socio-emotional competence

ECHOES environment

12 learning activities that focus on two sub components that are challenging for children on the autistic spectrum -

(i) joint attention ( the ability to coordinate and share attention and emotions

(ii) symbol use -p48 ' understanding of meaning expressed through conventional gestures and words and ability to use non verbal means to share intentions'

Design for the agent

Derived from OCC and appraisal theory. OCC identifies 22 emotions. Agents provided with an affective system composed of emotional reaction rules, action tendencies, emotional thresholds, emotion decay rates

P 499 ' The agent experiences one or more of the 22 emotions of the OCC model based on its appraisal of the current external events and IRS subjective tendencies to experience certain emotions instead of others. The agents deal with these emotions by applying problem-focused or emotion-focused coping strategies

The agent

Advantages of an agent - tireless, persistent, consistent & positive

Positive, motivating, and supportive. Tends to be happy, does not get frustrated easily.

Actions - verbal (using simple language or key words), non-verbal (eye gaze and gesture)

Facial expression, a range of positive facial expressions ( involving lips, eyes, & eyebrows)

Evaluation

Response to bids for interaction ( post intervention cf Pre intention)

From the agent -  slight increase but not SS

From the human practitioner- did increase and almost reached SS

Initiation of bids

To the agent - numerical increase but not SS

To the human participant - very low and remained low

multidiscplinary - echoes

Porayanska -Pomsta et al

Key features, benefits challenges of a multi-disciplinary approach

Journal of Personal and ubiquitous Computing

Literature

22. - emotion recognition

25, 40 - understanding the mental states of others

6,18 - LFA engage with robots more than humans (shared attention, turn taking), fail to generalise to a real world context

37, 38,29 - wearables

42 - abilities of autism

46 importance of reciprocity

ECHOES a socio- cognitive intervention

Multidisciplinary - theories, practices, methods, scientific tradition. Establish common ground and draw on strengths p2 Novelty of the approach lies in the way in which different methods and techniques are combined and applied.

Goal- enable social interaction skills.

Aim - develop tools for research in this area

Affective system for an agent - emotion regulation, recognise emotions, categorise emotions, express emotions

Objects in a garden as the focus of joint attention

Monitors - head posture, eye gaze, facial expression, screen touch data

Retain the development of resources within the users community of practice

Pilot - as a small scale intervention. Subjective also contributes to the design of the resource

Theory of mind - impute others mental state

Joint attention - there is a strong visual component , both the object and the other

How are objects in ECHOES linked into a narrative?

Two challenges p122 SCERTS, on which ECHOES as an intervention is based was developed for a human-human intervention context, in which practitioners use their long term experiences. Multiple data sources on which to base the decision. ' Another challenge relates to whether the child perceives the agent as an intentional being or merely an inanimate object' reciprocity is important