Fridlund & Cacioppo(1986)

Fridlund & Cacioppo (1986)

Guidelines for Human Electromyographic Research

Psychophysiology, 23, 567-589

Based on a survey from over 100 psychophysiologists experienced in EMG.

P568 ‘ The EMG signal is a quasi random train of motor unit action potentials discharged by the contraction of striate ( KRO check) muscle tissue. This signal train is characterized by a frequency range from several Hz to over 2 kHZ and by amplitudes ranging from fractions of a millivolt to several hundred microvolt’ p574 ‘ the raw or filtered EMG signal is a stochastic train of motor unit action potentials’ p576 ‘ the motor unit action potential is bipolar and asymmetrical about electrical zero’

Technical considerations

1 Noise

Video/computer/TV other lab or home based sources of interference

2. Electrodes

Ground at 1 point only

Advantage of surface ( Ag-AgCl0 electrodes – broad ( non-selective) detection of firings of aggregates of motor units that correlate well with the overall level of contraction of the muscle groups but can’t always attribute activation to a particular muscle. 0.25 cm with 1 cm between is recommended for facial muscles

Advantage of fine wire- ‘They do not obstruct small movements as much as surface electrodes. Many electrodes can be used simultaneously without hiding facial areas from camera view’

Electrode Placement

• Avoid arrangements that straddle the motor endplate
• Try to identify anatomical landmarks that are uniform between participants
• Ease of attachment ( eg not too many skin folds)

Davis (1952) manual a good resource used by most researchers to date

Diagrams page 571

Orbicularis oculi inferior orbital portion (constricts the eye fissure ). The first electrode is attached 1 cms inferior to the exacanthion (outer commisure of the eye fissure). The second electrode is placed 1 cm medial to, and slightly inferior to, the first, so that the electrode pair runs parallel to the lower lip border’. ( ad hoc)

Zygomotor major ( pulls the lip corner up and back). One electrode is placed midway along an imaginary line joining the chellion and the preauricular depression ( the bony dimple above the posterior edge of the zygomatic arch) and the second electrode is placed 1 cm inferior and medial to the first ( i.e. toward the mouth) along the same imaginary line. ( based on available information)

Ground midline approx 3-4 cms superior to the upper borders of the inner brow.

Preparation

JFET amplifiers reduce the need for electrode site preparation

Measure resistance with voltmeter.

Relative advantage & disadvatage of monopolar versus bipolar recording

3. Filters

Primary energy 10-200 Hz, p573 ‘between 10-30 Hz power due in great part to the firing of motor units; beyond 30 Hz the shapes of the motor units action potentials are more important’ note p574 ‘preamplifier noise is most intrusive below 10 Hz and above 500-1000 Hz.’

P574 ‘ there may be implications for pass band selection for discriminating ‘fast’ versus ‘slow’ motor units, and for detecting ‘proximal’ versus ‘distal’ motor units

4. Recording & Presenting data

A/D conversion rate ( for my purposes need to be able to detect on and off)

Storage for repeated analysis

5. measurement

3 things to note

do not assume amplifier gain accuracy, check it directly

need to ensure that the measurement scale for each channel is equivalent

p579 ‘ recording EMG signals with AC-coupled amplifiers ( or DC amplifiers with zero offsets) ensures that the average value will be zero. Simple averaging of the raw EMG signal is thus uninformative’

Validity checks very important especially construct validity

Psychological consideration

1 social context

p580 ‘psychophysiological assessment is mostly non-invasive but can be psychologically intrusive’

hint

use neutral rather than technical vocabulary

observation may inhibit facial expression

facility to beckon experimenter at will

2 experimenter bias

p583 ‘ especially important when tasks involve emotion and social interaction’

Duchenne smile Ekman et al 1990

 

The Duchenne Smile:  Emotional Expression and Brain Physiology II

Ekman, P., Davidson, R., & Friesen, W.

Journal of Personality and Social Psychology, 1990, vol 58, 2, 342-353.

 

Duchenne in 1872 as quoted in this paper

 

p342 ‘The emotion of frank joy is expressed on the face by the combined contraction of the zygomaticus major muscle and the obricularis oculi.  The first obeys the will but the second is only put to play by the sweet emotion of the soul; the …. Fake joy, the deceitful laugh, cannot provoke the contraction of this latter muscle…. The muscle around the eye does not obey the will; it is only brought into play by true feeling, by an agreeable emotion.  Its inertia, in smiling, unmasks a true friend’  (1862/in press)’

 

? KRO does this imply that Duchenne thought that there was a cortical influence?

 

Duchennne demonstrated this by comparing 'the smile' elicted by stimulating zygomatic major with a spontaneous smile of enjoyment.  As a result the smile resulting from the simultaneous activation of zygomatic and orbicularis has been named the Duchenne smile (Ekman, 1989).  Ekman indicates that this finding undermines  the view that facial expression is not universal.  P350. ‘ Clearly the Duchenne smile, in which the orbicularis oculi, pars lateralis muscle, that orbits the eye is contracted in addition to the zygomatic major muscle’s pull on the lip corners, is a better sign of enjoyment than other kinds of smiles.’  Ekman (1985) has identified and described 14 other types of smile. (Ekman and Frieson, 1982)  p343 ‘ enjoyment smiles can be distinguished from other smiles not only on the basis of the muscles that produce the smile (i.e. the Duchenne smile) but also on the timing and duration of the smile.’

 

Pre 1990s research rarely recognized this distinction an observation that applies to both anthropological as well as experimental studies. P343 (Ekman et al., 1988) ‘suggested that the failure to distinguish among smiles may account for contradictory findings in studies of interpersonal deception.  They reviewed 12 studies conducted over the last 10 years that found that subjects smiled equally often when telling the truth as when telling a lie…… This did not happen in their study, in which the Ducehenne smile was distinguished from other smiles’

 

KRO raises the questions

1.    Is excitation of orbicularis the indication of an involuntary 'happy' response?

2.    Are the 'recievers' able to detect these differences - must be some research literature on this.

 

Social versus solitary

 

p344 'Some investigators (Andrew, 1963; Kraut, 1978; Smith,1985)

KRO need to do lit search

have taken the position that facial expressions should not be conceptualized in terms of emotions, but only as social interactive signals. In a solitary, private situation they expect that facial expressions will not occur or, if they do, they will not be related to subjective emotional experience or physiological changes. We believe that this view that facial expressions occur only during social interaction is incorrect. …………..Although the social context often occasions and amplifies an expression of emotion, it may also dampen or inhibit an emotional expression.’ ‘Emotional experience and expression would not, from our vantage point, be absent when an individual is alone.' 

 

 

P344 ‘Ekman and Friesen (1969) coined the phrase "display rules" to describe

attempts to manage facial expression, in terms of who can show what emotion to

whom and when.

KRO need lit search on display rules

 

Hemisphere asymmetry ( specialization) for emotion

 

p344

 

‘A growing literature that has established differences between the two hemispheres of the brain in their involvement in certain positive and negative emotions suggests that there would be different physiological activity associated with the Duchenne smile as compared to other kinds of smiling (see Davidson, 1984, 1987; Silberman & Weingartner, 1986; and Tucker & Frederick, 1989, for reviews). The evidence on hemispheric activity and emotion comes from a diversity of sources, including studies of the emotional consequences of unilateral brain damage (e.g., Robinson, Kubos, Starr, Rao, & Price, 1984), of unilateral injections of sodium amytal in patients prior to neurosurgery (e.g., Lee, Loring, Meador, & Flanigin, 1988; Rossi & Rosadini, 1967), and of asymmetries in regional brain activation in normals using measures based on both brain electrical activity and regional cerebral blood flow (e.g., Davidson, 1984,1987).’

 

KRO some of these refs may be worth checking

 

‘The asymmetries associated with the production of emotion have been most consistently observed in the frontal and anterior temporal regions. Subjects show relative left-sided activation during certain positive emotions compared with negative emotions and more relative right-sided activation during certain negative emotions compared with positive emotions. It is important to note that the findings are always described as relative differences between two or more conditions. Predictions in terms of absolute asymmetry are not offered, at least with small sample sizes, because there are large and stable individual differences in absolute asymmetry, upon which phasic effects are superimposed. Thus, in a subject with extreme right frontal activation, happiness may not produce absolute left frontal activation. Rather, compared with disgust, one would expect more left frontal activation during happiness.'

 

Experimental design – not several aspects of this design have critical implications

 

Used a situation where participants were not trying to communicate

Participants not told about the video recording until afterwards

Used silent films.  5 films , 1 to establish a baseline then two that were expected to produce a positive and two that were expected to produce a negative

37, right handed female participants.

Amusing films used for positive experience and therefore Ekman et al go on to describe the difference between amusement and happiness and experiential issues in general.

Aim p344 ‘ to examine types of smiling and cerebral hemisphere activity in adults’ therefore measured EEG.

 

Ecological comment

P344  and example ‘When watching positive films, two other kinds of smailes may occur, anticipatory smiles, when someone anticipates the likelihood of soon experiencing enjoyment; and positive-negative blends, when the film evokes a memory that blends enjoyment  that blends with some negative emotion’

 

EEG Recording Procedure

 

KRO follow up any subsequent work on asymmetry and EEG activation

 

The EEG was recorded from the left and right frontal, central, anterior temporal, and parietal regions (F3, F4, C3, C4, T3, T4, P3, P4) all referred to vertex (Cz) using a lycra stretchable cap (Electro-Cap). For more information about these recordings, as well as more details about the procedure, emotion-arousing stimuli, and video recordings, see the accompanying article (Davidson, Ekman, Saron, Senulis, & Friesen, 1990). That article also describes in the introduction eight methodological desiderata for psychophysiological research on emotion that are relevant to this study as well.

 

'In this experiment the onset and offset of each facial action had to be determined to

coordinate the facial actions with the EEG record.'

 

 

EEG analysis

Power bands for baseline and active periods of smiling ( therefore duration of the smile had to be measured and indicated for EEG record) Relied on artefact free EEG of at least 1.02 ms or longer which occurred concurrently with  Duchenne ( D) and other (O) type of smiles during positive films only. DVs were power density in milli volts/Hz in the alpha and beta bands. Authors predication was that major effects would occur in the alpha band  with a lower value indicating greater activation.  KRO rather naïve way of distinguishing between alpha and beta

 

Results

 

1.  p347   There is  an 'Interaction between film type ( + or - ) and the number of Duchenne smiles and also their duration.  Duchenne smiles to + film interspersed with other types of smile e.g. anticapatory

 

 

2.  p350 - the Duchenne smile was found, as predicted, to be related to enjoyment—in terms of when it occurs and how it relates both to subjective experience and distinctive physiological changes—and other smiling was not.'

 

' The stimulus films we used to arouse positive emotions showed amusing events, not other types of positive emotions, and as expected, Duchenne smiles correlated with the report of amusement rather than contentment. Although Duchenne smiles also were correlated with reports of the more general term happiness, partial correlations showed that this was due to the correlation between happiness and amusement ratings. If other situations were examined in which the subjects experienced relief, contentment, or sensory pleasure rather than amusement, we would expect Dsmiles to correlate with the subjective experience of those emotions, not amusement, but this remains to be demonstrated.

 

3.  p351  'these data are consistent with earlier reports that facial expressions of emotion do occur when people are alone (Ekman, 1972; Ekman et al., 1980) and contradict the theoretical proposals of those who view expressions solely as social signals'

 

 

4.  asymmetry results

p351  note only 13/37 participant results deemed suitable .'The cerebral asymmetry findings indicate that, as predicted, the two types of smiling differ in the pattern of regional brain activity with which each is associated. Duchenne smiles are associated with more left-sided anterior temporal and parietal activation compared with other smiles. Although the left-sided anterior temporal activation was predicted to accompany positive affect, it is not clear what activation of the left parietal region might reflect in this study. Other EEG asymmetry studies have found that verbal cognitive activity reliably increases left parietal activation (e.g., Davidson et al., in press; Ehrlichman & Wiener, 1979). It is therefore possible that in the present context, the Duchenne smiles were accompanied by more verbal thinking compared with other smiles. In future studies it would be useful to assess cognitive activity in addition to experienced emotion, in order to evaluate this suggestion. The lack of any difference in central EEG activity between the Duchenne smiles and other smiles suggests that the differences in asymmetry between these smile types that were seen in other regions are not a function of differences in motor asymmetry, because central EEG asymmetries are very sensitive to motor differences between the two sides of the body (e.g., Coles, Gratton, Bashore, Eriksen, & Donchin, 1985; Kutas & Donchin, 1974)'

 

 

p 351 'Other smiles show a pattern of activation asymmetry similar to what has been reported for withdrawal-related negative affect (see Davidson et al., 1990). In fact, when we examined other smiles, we found that the majority did contain facial actions denoting negative emotion.

 

 

Contrary to prediction, Duchenne smiles did not differ significantly from baseline. This is the same pattern as was found for happy facial expressions in the accompanying article (Davidson et al., 1990). Davidson (1984) has reasoned that positive emotion is associated with left-sided anterior activation relative to a baseline only when the positive emotion is accompanied by approach behavior. As we noted in the accompanying article (Davidson et al., 1990), not all forms of positive affect include an approach component. The Duchenne smile marks a number of rather different positive affective states, not all of which involve approach. For example, contentment may not involve either approach or withdrawal.'

 

 

 

 

 

Hess, Sabourn, Kleck (2007)

Post auricular and eye blink startle response to facial expressions

Hess, U., Sabourn, G., Kleck, R.E. (2007)

Psychophysiology, 44 , 431-435

Facial morphological cues depend on the sex (KRO and? race) of the expressor and in this way gender (? sex & race) can modulate the perception of facial expression – (see Hess functional equivalence hypothesis for interaction with expression).

Both the startle blink reflex & the post auricular reflex are modulated by emotional state; + for unpleasant, - for pleasant for the eye blink; - for unpleasant, + for pleasant for post auricular. The amplitude of this effect varies with the stimulus used to induce emotional state facial expression being less reliable than some other stimuli despite other indicators that facial expressions is important for both for inducing of emotion, the contagion effect, Baliry, Herrera & Hess, 1999, Hess & Blairy, 2001) and for signalling emotional state whether spontaneously or voluntarily

Recognising commonalities with communicative signal systems of animals could be extrapolated to the assumption that anger signals dominance and happiness affiliation. Keating et al 1981; Senior et al, 1999, Berry & McAuthur, 185,1986) claims in humans these dispositions, dominance and affiliation, are signalled by facial morphology which tends to be gender typical, for example male square jaw and female round face and large eyes. At the same time specific patterns of facial movement can also signal anger and happiness.

P432 Hess, Adams & Kleck (2007) have proposed ‘a functional equivalence hypothesis that postulates that facial expressive behaviour & morphological cues to dominance and affiliation are similar in their effects on emotional attributions This notion also implies that there are interactions between facial expression and facial morphology in the decoding of expressions of emotion’

Three aims

1. Assess eye blink startle and post auricular responses during exposure to emotional facial expressions.

They occur. In discussion the authors consider the function of valence which they see as a ‘shortcut referring to an underlying association of negative valence and withdrawal or submission and positive valence and approach’ they also imply that valence is carried by expression. KRO this would be compatible with the idea of the neural input as sub cortical and therefore more primitive.

2. Happiness when displayed by a women is more appetitive, whereas anger when shown by a man is more threatening.

Therefore expect

potentiated post auricular for female happiness when compared to male happiness

potentiated eye blink for male anger compared to female anger

Results consistent with this hypothesis.

3. Non social emotional scenes used to validate the emotional modulation of the post auricular response as reported by Benning et al, 2004

Results consistent.

Experiment

Undergraduates, (facial & scene) images as stimuli, post auricular measured as EMG to 50 ms duration white noise at 95dB.

When the social mirror breaks: deficits in automatic , but not voluntary , mimicry of emotional facial expressions in autism.

McIntosh, D.N., Reichmann-Decker, A., Winkielman, P., & Wilbarger, J.L. (2006)

Developmental Science 9:3 295-302.

KRO ideas from this   empathy as a form of mimicry

Lundquist & Dimberg, 1995 Facial expressions are contagious Journal of Psychophysiology, 9, 203-211.  

Method

ASD  & control group

Viewed happy and angry expressions ( KRO is this sufficient ? - doesn't it have to be real a point that needs to be explored before finalising rationale for PhD)

Compared automatic mimicry ( just watch) and voluntary 'make an expression like this one' ( KRO -ehem)

Used EMG to collect data  zgomotor and corrugator ( no rationale given for these two muscles shouldn't they consider some controls eg frontalis and ocularis ) 

Worth checking out the EMG recording   & analysis details , article in PhD folder - social imitation autism also the following references

Fridlund & Cacioppo (1986) Guidelines for human EMG research Psychophysiology, 23, 567-589.

Tassinary, L.G., & Cacioppo, J.T. (2000) 

Analysis EMG response classified as either congruent or incongruent based on which muscle was activated in  response to a particular picture.

Results

Compared to normal functioning ASD did not exhibit as much automatic mimicry.

ASD & typical participants provided similar response patterns in the voluntary situation.

The Neuropsychology of Facial Expression:  A Review of the Neurological and Psychological Mechanisms for Producing Facial Expression

Rinn, W.E. (1984)

Psychological Bulletin 95 (1) 52-77

face movement as another communication channel p52 ' so powerful is the communicative impact of the face that it is difficult to separate the message from the medium.  We tend to describe facial behaviors not in anatomical terms but in terms of the emotions portrayed'

Measurement 

subjective judgements - which of two faces looks happier/ sadder?

-

• constructs such as happiness/sadness refer to internal states with an implied statement about emotional meaning
  
• agreeing criteria for the judgement
  
• can be influenced by stereotype bias
  

objective 

descriptive method

1.  descriptive in terms of movement of the skin.  Blurton-Jones 1971

identifies 9 anatomical components , for example involving brow, mouth, eye and uses these to provide a list of descripters e.g. for the eye wide, bit wide, normal, bit narrow, very narrow, upper lid down.

2. description in terms of the facial muscles involved.  Darwin(1872/1965, Ekman & Freisen, 1978). The Facial Action Coding System (FACS).

+

more detailed 

more direct  reflection of the action of the nervous system

can provide information about the modulation of spontaneous expression  by voluntary control

p54 ' The FACS is a catalog of all perceptible 'action units' (AUs) that the face is capable of producing and the muscular basis of these AUs.  Action units are not facial gestalts but discrete movements of some part of the face'  Some AUs involve more than one muscle & some muscles are involved in more than one AU.  ' Therefore AUs do not correspond to specific facial muscles but are defined in terms of movement of the facial skin'  ' FACS manual lists the most frequently observed combinations of AUs for each of six common emotional expressions.

3.   Maximally Discriminative Facial Movement Coding System (Max). Izard(1979)

Based on  muscle movement but not comprehensive; ' appearance changes that do not discriminate between different emotions are not dealt with' 'describes nine fundamental emotional expressions ( those posited by Izard's differential emotion theory) .  Max is easier to use and may be preferred when interested in emotion-based facial movement (KRO but assumes that theoretical basis is acceptable)  developed affectogram ( Izard & Dougherty) to represent change of emotion on a time line, and be used for comparison between  and within individuals

EMG measurement of the electrical potentials in muscles

p55 Schwartz et al (1976a& 1976b)   have reliably demonstrated 'that various patterns of facial muscle activity reliably accompany the experience ( KRo imagination actually)  of different emotional states'  These authors used the method with groups of depressed patients and showed that 'in clinically depressed patients , the facial muscle response to happy imagery showed the same patterns as for non depressed subjects but in markedly attenuated form ( KRO ? finding highly relevant for  supporting the rationale for exploring online experience) 

Video

can be used to make subjective judgement as well as the descriptive analyses described above

Recommended even for face-to-face encounters in order to capture the richness of facial expression and other non verbal communication, also some very short others sustained both are reasons to be missed when just part of the conversation. 

important to control for viewing angles  when making perceptual (gestalt)  judgements.  This caution is based on the evidence that the right hemisphere is superior to the left when processing faces and emotional expression.

Facial muscles

Two main groups. Mimitic & mastication 

Each group uses a different nerve tract and has somewhat different evolutionary origins

(i)  mimitic muscles

p57  'Most of the facial muscles attach to the facial skin and manipulate the facial features into meaningful expression'  

(ii) mastication

' on each side of the face, there are four muscles

temporalis

masseter

internal & external pterygoid

 that attach to bone and ligament and move these skeletal structures around) ' 'These muscles do respond to emotion, (KRO - could be impotant control mechanism for tesaing our production from response) as do the muscles of the neck and back, they may even have a minor effect on facial expression'

Ontogeny  & Phylogeny of facial muscles

p57 'the muscles of facial expression have their evolutionary origin  in the muscles of the breathing apparatus ( the gill arches) of vertebrate fish.'  (KRO  ???? automacity influence ) ' some of the autonomic connections to these muscles ( through the facial nerve) remain intact in humans)' 'in the human embryo, vestigial gill arches ( called the branchial arches) are present in the first few weeks of life.  The muscles of facial expression arise from the second of the five branchial arches'  'the muscles of mastication arise from the first branchial branch'  ' Gradually the arches develop into other structures, and the muscles migrate to new locations, carrying their nerve tracts with them, so that by the 8th week they have arrived at their final position.  (Crelin, 1981)

Functions & behavior of facial muscles

Ekman & Friesen (1975)  divide the face into 3 regions

1. lower face including the cheeks, mouth, lower nose and chin ( participates in language by articulating the lips).  Manipulated by many small muscles and can be moved in almost any direction  with unilateral independance of action.
   
2. eyes, lids and root of the nose (punctuating speech)
3. brows and forehead ( Darwin (1872/1965) involved in attention/concentration and mental effort .  manipulated by fewer muscles and can only move up or down together.  Few people can move brow or forehead unilaterally.
   

p57 'division based on the fact that these regions are largely motorically independent of each other and make somewhat independent contributions to the facial message'

Neural basis

Neural innervation  UMN & LMN

motor neurons

upper motor neurons (UMNs) carry motor impulses from motor centres in the brain to the brain stem or spinal cord.

lower motor neurons (LMN) carry the impulses from the brain stem or cord to the muscle itself.

p58 ' the LMN tract that innervates the muscles of facial expression (mimetic muscles) is called the seventh cranial nerve ( facial nerve)'  function of the facial nerve is to 'arrange the facial features into meaningful configurations.  That is it is specialised for communication'

LMN tract of the left face is completely independent of the right face and their respective nuclei in the pons are symmetrically paired and likewise independent.  'Thus, when the left and right side of the face behave more or less indentically , it is because more or less identical signals have been sent to both LMN nuclei; that is the intergration is accomplised by UMN circuits

another LMN tract ( trigeminal nerve, cranial nerve V) innervates the facial muscles of mastication 

brainstem nucleii

p58 ' 3 brainstem nuclei contribute fibres to the facial nerve tract'. 'Two of these are served by a particular group of fibres within the facial nerve , the nervus intermidus , ...... their functions are essentially independent' (visceral & sensory) although they serve the face region  'The fibres innervating the muscles of expression all begin in a small cluster of cell bodies ( the third of the 3 relevant brainstem nuclei), the motor nucleus of the facial nerve, located in the brain stem at the level of the pons.' 

LMN tract ( facial nerve)   pathway

• Fibres leaving the facial nerve nucleus  loop around the nucleus of the 6th cranial nerve ( involved in eye movements) before leaving the pons.
  
• First major branch given off by the facial nerve is the stapedius branch which innervates the stapedius muscle in the inner ear ( dampens vibrations of the ossicles)
  
• p58 'The organisation of the peripheral portions of the facial nerve show considerable variablility between individuals, both in the course of its branches and in the specific muscles innervated by each branch' (KRO - this could be important when setting up EMG)
  
• 'Five major branches (temporal, zygomatic, buccal, mandibular & cervical) are usually present, but the adjacent branches communicate with each other through a network called the pes anserinus or parotid plexus.  Thus the precise innervation of any given muscle in any individual cannot be stated with certainty ( Harker & McCabe, 1977).' 
  
• Temporal & to an extent the zygomatic branch carries impulses originating in either hemisphere.  Only about 75% of fibres that innervate the nuclear representation for orbicularic oculi are contralateral in origin.  This trend towards bilateral innervation is even more pronounced for the upper face.
  
• Buccal, mandibular & cervical branch carry impulses only from the contralateral hemisphere KRO alert here ? pure motor cf other
• p62 ' An important 'difference between contralaterally and bilaterally innervated muscles concerns the degree of voluntary control
  

Facial nerve nucleus

• The motor nucleus of the facial nerve is the largest of the cranial nerve nuclei and contains 7,000 to 10,000 nerve cells plus numerous glial bodies .
  
• Cell groups map to specific peripheral branches of the facial nerve.
  
• One group ( the dorsolateral) supplies the muscles of the upper face, including some of the auricular muscles of the external ear.'  Please note that these also map to the frontalis , see section on raised brows.  Other groups innervate the stapedius muscle and the rest of the auricular muscles.
  

Animal ( rabbit, dog, cat) and human  tography share some similarities however there are also some differences that may relate to differences in function

• more differentiation for groups concerned with movements of the mouth and lower face.
  
• large cells bodies innervate the upper face and auricular muscles in animals and are insignificant in humans ie auricular less vital for humans.
  

cerebral cortex

The frontal lobes of the brain are separated from the parietal lobes by the central sulcus.  The anterior lip of the sulcus is known as the motor strip and is topographically organised in relation to the muscles of the body.

neural fibres from each region of the motor strip follow a systematic course through the internal capsule and brainstem and form synapses with brainstem and spinal cord nuclei

Corticobulbar connections

The efferent fibres from the motor strip are generally referred to as the pyramidal tract.

Fibres going to the brain stem are more specifically labeled corticobulbar tracts.

Coricobulbar pathways to the facial nucleus are of two types

1. direct - synapse directly onto the facial nucleus and topographically map the motor strip.
   
2. indirect - convey cortical influences first to interneurones in the brain stem reticular formation.  From these , relay neurons deliver the impulses to the facial nerve nucleus.  p63 ' These interneuron connections presumably do more than relay cortical influences.  Probably ( KRO- possibly)  they provide for subcortical moduation of cortical influences and carry direct motor impulses from subcortical motor areas of the brain.  Unlike the direct corticobulbar pathways, these interneurons carry impulses to both left and right facial nuclei.  ...... These indirect, bilateral paths are more common for the nuclear representation of the upper than lower face.
   

Red nucleus connection

p63 ' In addition to being bilaterally rather than contralaterally innervated, the upper face has another neurological feature that distinguishes it from the lower face.  The cell bodies representing the upper face ( and only the upper face) in the facial nerve nucleus recieve direct fibres from the contralateral red nucleus.  Although it receieves fibres from the ipsilateral frontal cortex the red nucleus is not simply a cluster of interneurons from the indirect cortico bulbar pathways.  It is a large well defined structure in the brain stem that gets much of its input from the contralateral cerebellum.' ' Courville (1996a) has suggested that the red nucleus conveys cerebellar influences to help the ears motoroically locate targets The cerebellum is believed to play a similar role ( albeit without red nucleus) in regulating targeted saccadic eye movements.'

Volitional and Emotional (spontaneous) innervation of the face

p63-p64

Volitionally induced movements of the face use different UMN pathways than those used for emotionally induced movements.

Neural basis

Impulses for volitionally induced movements emanate from the cortical motor strip - pyramidal(corticobulbar projections) tract.

Impulses for emotional facial movements arise in the phylogenically older motor system known as the extra pyramidal motor system.  The extrapyramidal system is not a unitary system but a group of highly interactive neural circuits, each of which contributes its own specialised influences to the final motor response.  ..... The system involves mostly subcortical nuclei, and its influences are conveyed to the facial nucleus through pathways other than the pyramidal tract.

SEE REFS ON PAGE 64 AND GET PR TO CHECK THESE FOR ME.

Evidence ( neurological)

1.  lesions of the cortical motor strip.

'Typically such  patients cannot retract the corners of the mouth to command on the side contralateral to the side of the lesion.  However, the same patients are commonly seen to smile bilaterally when something strikes them as amusing. The emotional smile uses the same muscles that are paralysed for voluntary control'

2.  lesions of various nuclei in the extrapyramidal motor system, especially the basal ganglia.

'Such patients commonly display a mimetic facial paralysis - a condition in which the patient retains the ability to move the facial muscles to verbal command but loses all spontaeous emotional movement.  e.g. masked face of  Parkinsons- disordered neurotransmitter system of the basal ganglia. '  Although some Parkinsons patients exhibit depression it is not causal for the the expression deficit . 

3.  facial nerve anastomosis : surgical procedure to reanimate a face paralysed by a lesion of the facial nerve

motor root of facial nerve is surgically severed.

the central stump is  avulsed  to prevent regrowth while the distal portion remains raw.

a few fibres are then teased from another cranial motor nerve , usually the spinal accessory nerve which supplies the muscles that move the shoulder so that impulses coming to this cranial nerve (spinal accessory)  will innervate the facial muscle as well as the shoulder.  Following operation stimulation of the motor strip representation of the face yields no responses.  However stimulation of the representation of the shoulder will yield movement in both shoulder and face.  Gradually the patient learns to move the face muscles volitionally, initially by attempting to move the shoulder.  In time differential control ( face v shoulder) can be achieved. Genuine emotional ( spontaneous) movement is never achieved on the affected side.

4.  pseudobulbar palsy - lesions of the cortico bulbar pathway involving the internal capsule ( MS, amyotrophic lateral sclerosis, anoxia, strokes) Hornstein 1977).

involuntary laughter or weeping which are generally indistinguishable from normal laughing and weeping but the patients are unable to report any emotional experience during these episodes. These patients typically have some degree of voluntary facial paralysis.  'It seems that the involuntary expression stem from an inability to voluntarily inhibit these motor release phenomena through normal cortical influences'

Evolutionary influences ( for a cortical & subcortical pathway for emotional expression).

Relationship between emotional expression & experience of man & drive related ,stereotypical communication patterns of non human animals.

Simple reflex circuits

In simple organisms drive-related responses are handled by simple reflex circuits which remain when more sophisticated systems evolve. p66 ' They are well suited for managing behaviours that are directly and immediately in the service of basic drives ' but they lack plasticity. For examples in humans simple reflexes are retained as brainstem circuits regulating hear rate, respiration & arousal.  Gradually from fish-birds-man a motor system has evolved to the basal ganglia & cerebral cortex of man.  Although all mammals have a cerebral cortex , its destruction eliminates only certain discrete motor functions whilst destruction of the basal ganglia has a significant effect.

More complex behaviour and the cerebral cortex

p66 ' cerebral cortex allows learning  to influence motor behaviour in a substantial way '  " the cortical (i.e. pyramidal system ) in humans is extremely plastic and versatile and is capable of executing fine, highly complex, highly controlled movements'

Frontal lobes highly developed in man, even in higher primates they constitute a strinkingly smaller proportion of the brain.  Destruction of the cortex in humans  has a hugely disparate effect when compared to non humans eg decorticate cats & dogs can perform most motor behaviours.

Discriminating cortical from subcortical features of behavior.

in practice the distinction is difficult to make especially using observational techniques and therefore it is important that the subject is unaware or not paying attention to the fact that their facial expression is being observed.

Take language as an example of a 'cortical' behavior.  Not present in infancy, needs to be learnt , highly flexible and readily changeable, may also show cultural variability.  Typically we have conscious awareness and they can easily be produced or inhibited on command.

Display rules ( Ekman & Friesen(1975) are another example of cortically managed behavior.  p68 ' The social regulation of the face does not appear to begin until late infancy and is not well developed until at least middle childhood, when frontal lobe development is complete.  Learning through reinforcement, punishment, and modeling, clearly plays a prominent role in its development ( Ekman & Oster, 1979).  Ekman (1972), Friesen (1972) have demonstrated cultural variability in display rules.  Learning through modelling ( Ekman & Oster, 1979).

'As with most cortically mediated events, normal adults have relatively good awareness of what their faces are doing when they implement display rules.

In contrast genuine emotional movements are present from early infancy, ie muscle contractions of distress and disgust present at birth, social smiles emerge from 4 weeks, interest at 3 weeks, anger & contempt at 6 months, meaningful surprise & fear in year 2.

also

p. 69 anecephalic infants (no cortex, basal ganglia, or other structures higher than the midbrain) show at least some normal facial expressions'

'The observation that congenitally blind children display a full range of spontaeous expressions demonstrates that learning through imitation is not required ( Freedman, 1964; Gooenough, 1932; Thompson, 1941)

'Timing and coordination of the various regions of the face are usually conspicuously off in posed expressions ( Ekman & Friesen, 1975) of the basic emotions'. We have difficulty with voluntarily inhibiting genuine expressions of basic emotion.

Upper face expressive behaviors

note it is important to study the upper face independently of lower face when studying facial expression.  Some idea of why that might be is available in this section.

3 expressive behaviors of the upper face are distinctive when compared to the lower face.

1.  knit brow:  contraction of corrugator during a particular  kind of mental effort as  observed by Darwin 1872/1965. p221 ' a man may be absorbed in the deepest thought and his brow will remain smooth until he encounters some obstacle in his train of reasoning or is interrupted by some disturbance, and then a frown passes like a shadow over his brow'

evidence for spontaneous - Oster(1978) infants of 3 weeks usually preceeding a smile as if trying to make sense of something new, adults are commonly unaware, Darwin commented on its universality in all cultures (KRO only the Darwin evidence cuts the mustard for me).

2.  raised brow ( check back to Chris Frith who implied this indicated trust) tendency to contract frontalis during attentive listening.  Most people can produce this voluntary but at the same time most are unaware of doing so in everyday contexts.

There is a question as to whether this is a vestige of ear perking movements used by some lower mammals.  ie in lower mammals, including chimps, frontalis is continuous with the muscles that move the ears.  With the development of the frontal lobes in man , the front part of the skull is pushed forward and the frontalis has become separated from the auricular muscles. 

3.  punctuation movements ( Ekman & Friesen) usually very brief ( 50ms) contractions of the muscles of the upper face particularly frontalis.

Although commonly bilateral most show an observable degree of asymmetry usually systematically.  p70 ' although occurring in the context of speech, a manifestly cortical and volitional behavior, theses punctuation movements have features more typical of those mediated by extrapyramidal motor centres.

Most people are unawre of these movement and most can only produce a crude approximation volitionally.

other eveidence for them being emotional expressive:

Rinn observed that they are absent in Parkinsons therefore implies that basal ganglia play a role.  ? KRO any systematic studies of this?

Congenitally blind subjects produce knit brow during puzzlement and raised brows during attentive listening and punctuation movements during speech despite the lack of opportunity to learn these through imitation.

Trigeminal nerve links

sensory fibres of the trigeminal terminate in any of three different sensory nuclei in the brain stem. One of these , the mesencephalic trigeminal nucleus recieves input from muscle stretch and conveys sensation from the facial skin.  It sends output to both the trigeminal and facial motor nucleii and therefore appears to play a key role in reflexes involving the chewing muscles. as well as in reflexes involving the mimetic muscles.

also relevant in this context.  No evidence for muscle spindles in the muscles of facial expression.  Some believe that all muscle is insentient?' although Merton 1972 has a different view.  

Raises the question  p72 ' how is it that we are aware of the patterns of our facial muscles contractions if the muscles are insentient.

Does the trigeminal nerve carry the impulse for awareness? -  the fact that patients with complete trigeminal tractotomy , generally do not describe any loss of facial expression.

Facial Asymmetry & Hemispheric differences in emotion

Tucker, D. M. (1981). Lateral brain function, emotion,

and conceptualization. Psychological Bulletin, 89, 19-46.

for a 1981 review. By asymmetry it is claimed that the left side of the face dominates facial expression , more movement  and more intense.  

Moscovitch, M., & Olds, J. (1982). Asymmetries in spontaneous

facial expressions and their possible relation to

hemispheric specialization. Neuropsychologia, 20, 71-

81.

Most authors therefore claim a right hemisphere specialisation for emotions, and in particular negative emotions.p72  'Although this explanation has gained wide currency, it is not the only one possible.  The chief problem is that it is inconsistent with the widely accepted dictum that only higher cortical functions such as language, praxis or visual-spatial reasoning are lateralised to a hemisphere. ' 'The emotional tone of one's experience or behaviour is generally believed to be determined by subcortical systems .  The main role of higher cortical processes in emotion is in its instrumental regulation - the volitional control of emotions or in the social regulation of the face ( the implementation of display rules etc)'.

Alternative explanations

1.   Apparent right hemisphere lateralization due to left hemisphere superiority for the inhibition of emotion.  Luria (1973) & Vgotsky(1934-1962) have both identified language as a regulator of behaviour and Rinn suggests that the inhibition is greater for negative  than positive emotions.

2.  p73  'If only cortical functions are lateralized, and only volitionally induced expressions are cortical, one might expect only volitionally induced expressions to be lateralized and consequently, asymmetrically displayed on the face'  most studies have used posed expression.  Ekman, Hager & Frieson (1981) have shown that when subjects do not know they are being observed, their spontaneous expressions are essentially symmetrical

 

Unconscious Facial Reactions to Emotional Facial Expressions

Dimberg,U., Thunberg, M., & Elmehed, K. (2000)

Psychological Science, Vol II, No 1 86-89

 note  this researcher look at zygomotor only and not orbicularis? therefore ? was accepting the Duchenne smile as the genuine smile although did not mention it.

Dimmberg, 1997 'humans are predisposed to react emotionally to facial expressions'

'Neural activity in the human amygdala differs when people are exposed to different facial stimuli' ( Whalen et al, 1998)

'damage to amygdala impairs the recognition of facial expression'

'when people are exposed to pictures of emotional expressions, they spontaneously and rapidly react with distinct facial EMG displays ( Dimberg 1982,1990)'

' a critical characteristic of an automatic reaction, besides being spontaneous and rapid, is that it can occur without attention or conscious awareness'

unconcious response can be investigated by backward masking technique leads to 

RQ  If distinct facial reactions can be unconsciously elicted, then the masked happy target face would evoke larger zygomatic major muscle activity ( elevates lip to form a smile) and lower corrugator supercilii ( knits eyebrows during a frown)

design

120 students into 3 groups

happy-neutral

neurtral -neutral

angry-neutral

groups differed only in respect to the type of stimuli to which they were unconsciously exposed (30 ms) with 5 sec exposure for the neutral masking stimuli.  

Participant verbal reports when closely questioned indicated that they had not 'consciously' detected the target stimulus.

Directly after the experiment each subject was exposed to one presentation of the target-mask complex and were asked to rate for angry/happy.  Theses ratings did not differ between groups 

Although EMG results indicated a difference between groups , presumably reflecting the target,  the participant overall reported  experience of the target-mask stimulus was relatively neutral.

results

Scored EMG amplitude every 100 m secs giving 10 data points  over a 1 second period.

zygomatic - happy-neutral(up to 1.7 mv) > neutral-neutral (up to 1 mv)> angry neutral (0 mv) during .5 - 1.0 secs ( measured over 5 points)  see diagrams amplitude )

at 300ms there was a small (0.5) positive response what does this mean? Dimberg suggests a startle response.

corrugator happy-neutral <>

at approx 220 ms there was  a positive (2-5-3.0 mv response)

'it is not evident from the present study to what degree the different facial reactions originate in unconscious mimiking behavior or to what degree the facial reactions initially are read outs of underlying emotional states'

refers to Buck, R. (198o) J. Personality and Social Psychology, 38,811-824  'facial muscle activity is essential for the occurrence of emotional experience'