Voluntary emotional facial expressions in patients with focal cerebral lesions

Effects of Viewing Pleasant and Unpleasant Photographs on Facial EMG Asymmetry

40 subjects' facial electromyographic (EMG) activity at the corrugator and zygomatic muscle regions were recorded while they were viewing pleasant and unpleasant photographs. Analysis showed that the EMG activity at the left zygomatic muscle region generated the highest power, followed by the right zygomatic, left corrugator, and right corrugator muscle regions, while viewing pleasant photographs. The EMG activity at the left corrugator muscle region generated the highest power, followed by the right corrugator, left zygomatic, and right zygomatic muscle regions, while viewing unpleasant photographs. Further statistical analysis indicated that the EMG activities at the left corrugator region generated significantly higher power than those at the right corrugator region while viewing unpleasant photographs. It was concluded that the intensity of facial EMG activity on the left side of the face was stronger than the right side of the face during the process of emotional expression.

Cerebral regulation of facial expressions of pain

Facial expression of affective states plays a key role in social interactions. Interestingly, however, individuals differ substantially in their level of expressiveness, ranging from high expressive to stoic individuals. Here, we investigate which brain mechanisms underlie the regulation of facial expressiveness to acute pain. Facial responses, pain ratings, and brain activity (BOLD-fMRI) evoked by noxious heat and warm (control) stimuli were recorded in 34 human volunteers with different degrees of facial expressiveness. Within-subject and between-subject variations in blood oxygenation level-dependent (BOLD) responses were examined specifically in relation to facial responses. Pain expression was inversely related to frontostriatal activity, consistent with a role in downregulating facial displays. More detailed analyses of the peak activity in medial prefrontal cortex revealed negative BOLD responses to thermal stimuli, an effect generally associated with the default mode network. Given that this negative BOLD response was weaker in low expressive individuals during pain, it could reflect stronger engagement in, or reduced disengagement from, self-reflective processes in stoic individuals. The occurrence of facial expressions during pain was coupled with stronger primary motor activity in the face area and-interestingly-in areas involved in pain processing. In conclusion, these results indicate that spontaneous pain expression reflects activity within nociceptive pathways while stoicism involves the active suppression of expression, a manifestation of learned display rules governing emotional communication and possibly related to an increased self-reflective or introspective focus.

Severe Myoclonic Epilepsy in Infancy - Adult Phenotype with Bradykinesia, Hypomimia, and Perseverative Behavior: Report of Five Cases

Dravet syndrome or severe myoclonic epilepsy in infancy (SMEI) is an epileptic syndrome characterised by refractory epilepsy and intellectual disability, typically presenting with febrile and afebrile generalised and unilateral clonic/tonic-clonic seizures in the first year of life and other types of seizures appearing later in the course of the disease. Five adult patients with SMEI and SCN1A mutations are reported, in which motor and behavioural abnormalities were outstanding symptoms. Bradykinesia, responding with latency, slow speaking with a thin voice, midface hypomimia and perseveration were distinctive features in all cases. These symptoms may be fit to define the adult phenotype of SMEI beyond seizure/epilepsy criteria. The motor and behavioural symptoms are discussed in the context of a possibly underlying frontal lobe/mesofrontal and cerebellar dysfunction.

Dysfunctional facial emotional expression and comprehension in a patient with corticobasal degeneration

Patients with corticobasal degeneration (CBD) frequently develop orofacial apraxia but little is known about CBD's influence on emotional facial processing. We describe a patient who developed a facial apraxia including an impaired ability to voluntarily generate facial expressions with relative sparing of spontaneous emotional faces. Her ability to interpret the facial expressions of others was also severely impaired. Despite these deficits, the patient had normal affect and normal speech, including expressive and receptive emotional prosody. As patients with corticobasal degeneration are known to manifest both orofacial apraxia and visuospatial dysfunction this patient's expressive and receptive deficits may be independent manifestations of the same underlying disease process. Alternatively, these functions may share a common neuroanatomic substrate that degenerates with CBD.

The motor cortex and facial expression: new insights from neuroscience

BACKGROUND

For more than a century, unusual and complex deficits in facial expression have been known to occur following localized brain damage. Some brain injuries leave the face with pronounced alterations in affect whereas others result in movement disorders such as blepharospasm and Meige syndrome. There is also a historic trail of clinical observations that document deficits in either voluntary or emotional control of the facial muscles following central nervous system damage.

REVIEW SUMMARY

Recent studies in the nonhuman primate cerebral cortex reveal the existence of multiple cortical facial representations in the frontal lobe and adjacent anterior cingulate cortex. These comprise the facial representation of the primary motor cortex (M1), ventral lateral premotor cortex (LPMCv), supplementary motor cortex (M2), rostral cingulate motor cortex (M3), and caudal cingulate motor cortex (M4). Homologous facial representations reside in the human brain based on observations following cortical stimulation, functional neuroimaging, and localized surgical resection. In the nonhuman primate, all these facial representations have been found to be directly interconnected through topographically organized corticocortical connections, and each facial area has also been found to send direct corticobulbar projections to the facial motor nucleus. The facial representations of M2 and M3 are both located on the medial wall of the hemisphere, in the vascular territory of the anterior cerebral artery. Both preferentially give rise to bilateral projections to parts of the facial nucleus that innervate the upper facial musculature as demonstrated in the monkey. The facial representation of M1, LPMCv, and M4 preferentially give rise to contralateral axonal projections ending in parts of the facial nucleus that innervate the lower facial musculature. The facial representation of M1 and LPMCv both reside in the vascular territory of the middle cerebral artery (MCA). The classic clinical presentation of paralysis in the contralateral lower facial musculature and intact bilateral upper facial musculature following typical MCA in infarction in the human parallels this mapping pattern of corticobulbar connections found in the nonhuman primate.

CONCLUSIONS

Facial movements are undoubtedly under the powerful influence of the cerebral cortex and are essential for the appropriate execution of many important functions such as mastication, swallowing, and social interaction, including speech and nonverbal communication. This information provides a theoretic template for interpreting the clinical effects of neuropathologic disease and localized cortical trauma on facial movements.

Facial expressions of emotion: a cognitive neuroscience perspective

Facial expressions are one example of emotional behavior that illustrate the importance of emotions to both basic survival and social interaction. Basic facial responses to stimuli such as sweet and bitter taste are important for species fitness and governed by simple rules. Even at this basic level, facial responses have communicative value to other species members. During evolution simple facial responses were extended for use in more complex nonverbal communications; the responses are labile. The perception and production of facial expressions are cognitive processes and numerous subcortical and cortical areas contribute to these operations. We suggest that no specific emotion center exists over and above cognitive systems in the brain, and that emotion should not be divorced from cognition.

Facial expressions, their communicatory functions and neuro-cognitive substrates

Human emotional expressions serve a crucial communicatory role allowing the rapid transmission of valence information from one individual to another. This paper will review the literature on the neural mechanisms necessary for this communication: both the mechanisms involved in the production of emotional expressions and those involved in the interpretation of the emotional expressions of others. Finally, reference to the neuro-psychiatric disorders of autism, psychopathy and acquired sociopathy will be made. In these conditions, the appropriate processing of emotional expressions is impaired. In autism, it is argued that the basic response to emotional expressions remains intact but that there is impaired ability to represent the referent of the individual displaying the emotion. In psychopathy, the response to fearful and sad expressions is attenuated and this interferes with socialization resulting in an individual who fails to learn to avoid actions that result in harm to others. In acquired sociopathy, the response to angry expressions in particular is attenuated resulting in reduced regulation of social behaviour.

Emotional processing deficits in individuals with unilateral brain damage

This article presents a review of the neural mechanisms underlying emotional processing deficits (EPDs) in individuals with unilateral brain damage. First, key theoretical issues pertaining to the neuropsychology of emotion are presented. These include parameters of emotional processing, the componential approach, emotional domains, and hypotheses regarding hemispheric specialization for emotion. Second, the literature on hemispheric asymmetries for emotion is reviewed in terms of processing mode (perception and expression) and communication channel (facial, prosodic-intonational, and lexical-verbal). Studies involving normal adults and individuals with right- or left-sided brain damage are reviewed. Third, recent findings identifying the role of the right hemisphere in emotional processing are described. The article is concluded by aligning these new data with findings from the general literature, providing added support for the right-hemisphere emotion hypothesis.

Cortical innervation of the facial nucleus in the non-human primate: a new interpretation of the effects of stroke and related subtotal brain trauma on the muscles of facial expression

The corticobulbar projection to musculotopically defined subsectors of the facial nucleus was studied from the face representation of the primary (M1), supplementary (M2), rostral cingulate (M3), caudal cingulate (M4) and ventral lateral pre- (LPMCv) motor cortices in the rhesus monkey. We also investigated the corticofacial projection from the face/arm transitional region of the dorsal lateral premotor cortex (LPMCd). The corticobulbar projection was defined by injecting anterograde tracers into the face representation of each motor cortex. In the same animals, the musculotopic organization of the facial nucleus was defined by injecting fluorescent retrograde tracers into individual muscles of the upper and lower face. The facial nucleus received input from all face representations. M1 and LPMCv gave rise to the heaviest projection with progressively diminished intensity occurring in the M2, M3, M4 and LPMCd projections, respectively. Injections in all cortical face representations labelled terminals in all nuclear subdivisions (dorsal, intermediate, medial and lateral). However, significant differences occurred in the proportion of labelled boutons found within each functionally characterized subdivision. M1, LPMCv, LPMCd and M4 projected primarily to the contralateral lateral subnucleus, which innervated the perioral musculature. M2 projected bilaterally to the medial subnucleus, which supplied the auricular musculature. M3 projected bilaterally to the dorsal and intermediate subnuclei, which innervated the frontalis and orbicularis oculi muscles, respectively. Our results indicate that the various cortical face representations may mediate different elements of facial expression. Corticofacial afferents from M1, M4, LPMCv and LPMCd innervate primarily the contralateral lower facial muscles. Bilateral innervation of the upper face is supplied by M2 and M3. The widespread origin of these projections indicates selective vulnerability of corticofacial control following subtotal brain injury. The finding that all face representations innervate all nuclear subdivisions, to some degree, suggests that each motor area may participate in motor recovery in the event that one or more of these motor areas are spared following subtotal brain injury. Finally, the fact that a component of the corticofacial projection innervating both upper and lower facial musculature arises from the limbic proisocortices (M3 and M4) and frontal isocortices (M1, M2, LPMCv and LPMCd) suggests a potential anatomical substrate that may contribute to the clinical dissociation of emotional and volitional facial movement.

Expression without recognition: contributions of the human amygdala to emotional communication

A growing body of evidence from humans and other animals suggests the amygdala may be a critical neural substrate for emotional processing. In particular, recent studies have shown that damage to the human amygdala impairs the normal appraisal of social signals of emotion, primarily those of fear. However, effective social communication depends on both the ability to receive (emotional appraisal) and the ability to send (emotional expression) signals of emotional state. Although the role of the amygdala in the appraisal of emotion is well established, its importance for the production of emotional expressions is unknown. We report a case study of a patient with bilateral amygdaloid damage who, despite a severe deficit in interpreting facial expressions of emotion including fear, exhibits an intact ability to express this and other basic emotions. This dissociation suggests that a single neural module does not support all aspects of the social communication of emotional state.

Lateral asymmetries in infancy: implications for the development of the hemispheres

Cerebral asymmetry of cognitive processing of stimulus information is commonly viewed as a neocortical phenomenon. However, a number of lines of evidence give innate asymmetry of brainstem motivating systems, which anticipate experience, a key role. Spontaneous asymmetries of gesture and emotion can be observed in infants, who entirely lack language and visuo-constructive skills. Motives for communication in early life may direct subsequent development of complementary cognitive systems in left and right hemispheres. In split-brain monkeys, lateralized motive sets, intentions for manipulation by one hand, can determine which hemisphere will see and learn. Evolutionary antecedents of cerebral asymmetry appear to affect motivation, social signalling and bimanual coordination, with secondary effect in perceptual processing and learning. The hemispheres of adult humans differ in links with neurochemical system that regulate motor initiatives, exploration and attention, and the approach/withdrawal balance in social encounters. Asymmetries in emotional and communicative behaviour in infancy support evidence that an Intrinsic Motive Formation emerging in the embryo human brain stem regulates asymmetries in development and in functioning of the cerebral cortex.

Anterior opercular cortex lesions cause dissociated lower cranial nerve palsies and anarthria but no aphasia: Foix-Chavany-Marie syndrome and "automatic voluntary dissociation" revisited

Anarthria and bilateral central facio-linguovelo-pharyngeo-masticatory paralysis with "automatic voluntary dissociation" are the clinical hallmarks of Foix-Chavany-Marie syndrome (FCMS), the corticosubcortial type of suprabulbar palsy. A literature review of 62 FCMS reports allowed the differentiation of five clinical types of FCMS: (a) the classical and most common form associated with cerebrovascular disease, (b) a subacute form caused by central nervous system infections, (c) a developmental form probably most often related to neuronal migration disorders, (d) a reversible form in children with epilepsy, and (e) a rare type associated with neurodegenerative disorders. Bilateral opercular lesions were confirmed in 31 of 41 patients who had CT or MRI performed, and by necropsy in 7 of 10 patients. FCMS could be attributed to unilateral lesions in 2 patients. The typical presentation and differential diagnosis of FCMS provide important clues to lesion localization in clinical neurology. FCMS is a paretic and not an apraxic disorder and is not characterized by language disturbances. Its clinical features prove divergent corticobulbar pathways for voluntary and automatic motor control of craniofacial muscles. Precise clinico-neuroradiological correlations should facilitate the identification of the structural substrate of "automatic voluntary dissociation" in FCMS.

Factor analysis and the cerebral hemispheres: temporal, occipital and frontal functions

Three experiments are reported that use a number of lateralized tasks believed to draw on processes localized to the temporal, occipital or frontal lobes. Oblique factor analyses of the resultant asymmetries indicate the existence of nine lateralized functions, characterized as auditory lexical, facial figural, facial motive, spatial attentive, spatial positional, spatial quantitative, tactile figural, visual lexical, and visual phonetic in nature. Most functions are uncorrelated, but as in an earlier report (Boles, Neuropsychologia 29, 59-91, 1991), both positive and negative correlations are observed. These outcomes continue to be consistent with neurodevelopmental theory, and inconsistent with lateralization strength, hemisphericity, and independence views of individual differences in lateralization.