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1Department of Psychiatry, Ludwig Maximilian University Munich; 2Department of Neurology, Stadtroda. Corresponding author: G. Juckel; Dept. of Psychiatry, Ludwig Maximilian University Munich, Nussbaumstr. 7, 80336 München, Germany; E-mail: firstname.lastname@example.org
|OBJECTIVE: Facial expressions seem to be closely related to limbic
processes. Abnormal facial expressions were described often in schizophrenic
patients, but the specific nature of this disturbance is still unclear.
Since facial activity in total seems to be not specifically disturbed in
schizophrenics, analysis of movement details during facial expressions
could be a more promising tool. METHODS: Seven chronic schizophrenic patients
(DSM III-R: 295.6, all males and medicated, 32.3±7.3 years) were
investigated while watching a humorous movie. Movements of the corner of
the mouth were assessed during laughing by a light-signal device with high
spatial and temporal resolution. RESULTS: Starting to laugh at an emotional
stimulus, schizophrenic patients exhibited a faster speed of left and right
corner of the mouth than matched healthy controls (2.02±0.42 cm/s
versus 0.82±0.41 cm/s, t-test: p=0.0002). There was no overlap between
the two groups. CONCLUSIONS: This faster beginning of the facial movement
"laughing" could be an objective and specific measure of abnormal facial
expression in schizophrenic patients which is correlated to the clinical
picture of manneristic and parathymic behaviour. Possibly, the changed
movement of starting a facial expression reflects a disturbed transformation
of emotions into facial movements in the so-called limbic-motor interface
-the nucleus accumbens- in schizophrenic patients (German J Psychiatry
1998; 1: 6-9).
Key words: facial activity, facial expressions, schizophrenia
Received: October 13, 1997
Revised version: January 12, 1998
Published: January 13, 1998
Disturbances in emotional and mood state are central characteristics in schizophrenic patients. Emotional states are expressed by motor activity in man like locomotor, gestic or facial activity. Facial expressions are the result of movements of the facial muscles which are innervated by the facial nucleus. This nucleus is highly connected to limbic structures (Rinn, 1984). Therefore, facial expressions could reflect dysfunctions in limbic structures in schizophrenics. Facial expressions in schizophrenic patients are often described as bizarre and manneristic movements and were already observed long before the introduction of neuroleptics (Rogers, 1992). With objective methods, facial expressions in psychiatric patients were investigated more or less unsystematically. Using, for example, video analysis, the Facial Action Coding System (Ekman and Friesen, 1978), EMG or computer-based approaches (Schneider et al., 1990), the result of such studies was in general that the facial activity is nonspecifically reduced in schizophrenic and depressed patients with or without medication. Neuroleptics especially induce a decrease in facial activity during treatment (Schneider et al., 1992). It can be therefore assumed that possibly only movement details of facial expressions, but not facial activity in total, are specifically changed in schizophrenic patients. Since it has been suggested that schizophrenic patients are in general characterised by a dysfunction of the integration of the limbic and the motor system, which is especially visible in the initation and co-ordination of motor programs (Cassaday et al., 1991), analysis of starting a facial movement (so-called "on-set" phase) could be a promising tool to investigate such a specific dysfunction in schizophrenia. Using a new sensitive method for the assessment of facial activity, we measured the initial speed of oro-facial movements induced by emotional stimuli in chronic schizophrenic patients under neuroleptics. Due to the known slowness of reactivity, the negative symptoms and the neuroleptic treatment, slower speed in these patients than in healthy subjects at starting a facial movement was expected.
Material and methodsFacial activity was measured in 7 chronic schizophrenic inpatients (diagnosed by DSM IIIR (295.6); all males; mean age: 32.3±7.3 years; all treated with different neuroleptics) after stabilisation. All patients showed pronounced residual negative symptoms. Seven matched healthy subjects (males; mean age: 30.4±6.8 years) were used as controls.
The volunteers sat in a comfortable chair and watched a short humorous
movie (Loriot: "The oblique picture") presented on a television screen.
A special camera recorded high frequency flash signals emitted by light
diodes placed at well-defined points of the face (right and left corner
of the mouth). Movements of the whole head were extracted by the data of
two reference light diodes. Spatial resolution was below 1 mm, temporal
resolution was up to 300 Hz. Therefore, it was possible to record very
small and brief facial movements exactly. The digitalized signals of the
light diodes corresponding to their movements while "laughing" were represented
graphically as a function of space and time (Fig. 1). A regression
line through the points of this curve between the beginning and the maximum
of the movement indicates the speed of the corners of the mouth at the
begin of "laughing" [cm/s].
Schizophrenic patients exhibited a significantly faster speed of movement
of the left and right corner of the mouth after emotional stimuli inducing
laughter than the healthy controls (Tab. 1). There was no difference
between the left and right corner of the mouth concerning speed in the
DiscussionIn contrast to the expectation mentioned above and the literature showing reduced total facial activity in schizophrenic patients, fine analysis of facial expressions in schizophrenics revealed they exhibit a faster initial speed of facial movements than the healthy controls during the start of laughing. This result seems to be remarkable because there is a clear separation between schizophrenic and healthy subjects by this variable. Possibly, this faster speed of starting laughter is correlated to the fast, downward shooting movements in the otherwise very calm face of schizophrenics which are clinically designated as maniristic and parathymic and which was called "mimic disintegration" (Heimann and Spoerri, 1957).
Due to the small sample size, interpretation of the finding is limited.
Since there was no difference between the two groups concerning the intensity
of emotional experience of the movie, it could be assumed that the transformation
of the emotional experience of humour into the facial movement "laughing"
is disturbed in schizophrenics. The morphological substrate of this transformation
seems to be the so-called limbic-motor interface, i.e. the nucleus accumbens
(Mogenson et al., 1980). It is well known that this nucleus plays an important
role in starting motor programs induced by emotional processes in limbic
structures (Heimer et al., 1982). The volume of the nucleus accumbens and
the neurone number are reduced in schizophrenic patients (Bogerts et al.,
1990; Pakkenberg, 1990). Since the dopaminergic and serotonergic system
are involved in modulating neuronal excitability of the nucleus accumbens
as well as in the pathophysiology of schizophrenia, it can be speculated
whether or not disordered motor activity in schizophrenic patients may
be caused by dysfunctional dopaminergic and serotonergic neurotransmission
in the nucleus accumbens. This will be investigated by different pharmacological
interventions in a current study.
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