Correction to Waller et al. (2006).

Reports an error in "Intramuscular Electrical Stimulation of Facial Muscles in Humans and Chimpanzees: Duchenne Revisited and Extended" by Waller, et al (Emotion, 2006[Aug], Vol 6[3], 367-382). The address provided for the on-line supplemental materials was incorrect. The correct address at which the supplemental materials can be viewed is the following: http://dx.doi.org/10.1037/1528-3542.6.3.367.supp (The following abstract of the original article appeared in record 2006-10747-003.) The pioneering work of Duchenne (1862/1990) was replicated in humans using intramuscular electrical stimulation and extended to another species (Pan troglodytes: chimpanzees) to facilitate comparative facial expression research. Intramuscular electrical stimulation, in contrast to the original surface stimulation, offers the opportunity to activate individual muscles as opposed to groups of muscles. In humans, stimulation resulted in appearance changes in line with Facial Action Coding System (FACS) action units (AUs), and chimpanzee facial musculature displayed functional similarity to human facial musculature. The present results provide objective identification of the muscle substrate of human and chimpanzee facial expressions- data that will be useful in providing a common language to compare the units of human and chimpanzee facial expression. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Classifying chimpanzee facial expressions using muscle action.

The Chimpanzee Facial Action Coding System (ChimpFACS) is an objective, standardized observational tool for measuring facial movement in chimpanzees based on the well-known human Facial Action Coding System (FACS; P. Ekman & W. V. Friesen, 1978). This tool enables direct structural comparisons of facial expressions between humans and chimpanzees in terms of their common underlying musculature. Here the authors provide data on the first application of the ChimpFACS to validate existing categories of chimpanzee facial expressions using discriminant functions analyses. The ChimpFACS validated most existing expression categories (6 of 9) and, where the predicted group memberships were poor, the authors discuss potential problems with ChimpFACS and/or existing categorizations. The authors also report the prototypical movement configurations associated with these 6 expression categories. For all expressions, unique combinations of muscle movements were identified, and these are illustrated as peak intensity prototypical expression configurations. Finally, the authors suggest a potential homology between these prototypical chimpanzee expressions and human expressions based on structural similarities. These results contribute to our understanding of the evolution of emotional communication by suggesting several structural homologies between the facial expressions of chimpanzees and humans and facilitating future research. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Selection for universal facial emotion.

Facial expression is heralded as a communication system common to all human populations, and thus is generally accepted as a biologically based, universal behavior. Happiness, sadness, fear, anger, surprise, and disgust are universally recognized and produced emotions, and communication of these states is deemed essential in order to navigate the social environment. It is puzzling, however, how individuals are capable of producing similar facial expressions when facial musculature is known to vary greatly among individuals. Here, the authors show that although some facial muscles are not present in all individuals, and often exhibit great asymmetry (larger or absent on one side), the facial muscles that are essential in order to produce the universal facial expressions exhibited 100% occurrence and showed minimal gross asymmetry in 18 cadavers. This explains how universal facial expression production is achieved, implies that facial muscles have been selected for essential nonverbal communicative function, and yet also accommodate individual variation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Functional organisation of the facial motor system in man

To investigate human corticobulbar projections, electromyographic responses from orbicularis oculi and orbicularis oris muscles were recorded in 11 healthy subjects after transcranial magnetic stimulation. Selective activation of lower facial motoneurones of one hemisphere was reached with the round coil 4 cm lateral to the vertex on a line to the external auditory meatus with stimulus intensities from 45 to 55% (100% = 1.5 T). The mean latency of the OR muscle was 11.5 +/- 1.77 ms contralaterally. Ipsilateral cortical responses were observed in 5 subjects (45%) at a mean latency of 13.88 +/- 2.17 ms. Corticobulbar innervation may have affected bilateral responses in the lower facial muscles as those persisted even after lidocaine blockade of both supraorbital nerves. The functional importance of ipsilateral projections to the lower facial muscles in man is lower than that of the contralateral projections, as evidenced by the fact that they cannot be observed in all subjects or in all motor units. The influence of the trigeminal sensory afferents was excluded from the study after blockade of both supraorbital nerves.     

Facial expression categorization by chimpanzees using standardized stimuli.

The ability to recognize and accurately interpret facial expressions are critical social cognition skills in primates, yet very few studies have examined how primates discriminate these social signals and which features are the most salient. Four experiments examined chimpanzee facial expression processing using a set of standardized, prototypical stimuli created using the new ChimpFACS coding system. First, chimpanzees were found to accurately discriminate between these expressions using a computerized matching-to-sample task, and recognition was impaired for all but one expression category when they were inverted. Third, a multidimensional scaling analysis examined the perceived dissimilarity among these facial expressions revealing 2 main dimensions, the degree of mouth closure and extent of lip-puckering and retraction. Finally, subjects were asked to match each facial expression category using only individual component features. For each expression category, at least 1 component movement was more salient or representative of that expression than the others. However, these were not necessarily the only movements implicated in subject's overall pattern of errors. Therefore, similar to humans, both configuration and component movements are important during chimpanzee facial expression processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronic electrical stimulation of the facial nerve causes signs of facial nucleus hyperactivity

The proximal segment of the facial nerve in rats was stimulated electrically daily for a duration of 2-10 min. After 4-8 weeks of such stimulation, 12 of 18 rats developed abnormal muscle responses that could be demonstrated by recording the electromyographic response from lower face muscles (the mentalis muscle) while the temporal branch of the facial nerve was being stimulated electrically. This abnormal electromyographic response consists of activity that appears in the latency range 6.5-15 ms. In addition, these chronically stimulated rats developed signs of facial synkinesis on the side that had been chronically stimulated. This could be demonstrated by recording electromyographic activity when the blink reflex was being elicited by electrical stimulation of the ophthalmic nerve. Rats in which electrodes had been implanted but which had not been stimulated did not develop any abnormal electromyographic activity. The abnormal electromyographic activity that could be recorded in rats that had been stimulated chronically could not be recorded 4-8 weeks after the stimulation had been terminated. We interpret these results to indicate that chronic electrical stimulation of the facial nerve can render the facial motonucleus hyperactive, and that the signs of this hyperactivity (abnormal muscle response and synkinesis) are similar to those typically seen in patients with hemifacial spasm. We thus presume that these results support the hypothesis that it is the irritation of the facial nerve from a compressing blood vessel that causes the facial nucleus to become hyperactive in patients with hemifacial spasm.     

Electrophysiologic evaluation of denervated muscles in incomplete paraplegia using macro electromyography

OBJECTIVE: To evaluate denervated muscles in persons with incomplete paraplegia due to thoracolumbar spinal injury (TLSI) using macro electromyography in determining indications for functional electrical stimulation (FES). DESIGN: A randomized clinical trial and a criterion standard. SETTING: A department of orthopedic surgery in a university hospital. PATIENTS AND OTHER PARTICIPANTS: Eighteen patients with incomplete paraplegia, including 11 with TSLI, and 50 healthy adults. INTERVENTION: Area and amplitude of macro motor unit potential (macro MUP) were measured at the tibialis anterior, the vastus lateralis, and the vastus medialis. The normal limits of macro MUP parameters were defined based on values from healthy subjects. Abnormal denervated muscles were detected by macro EMG and conventional EMG in paralytic patients. The correlation between macro MUP parameter values and muscle forces of the tibialis anterior and quadriceps femoris induced by electrical stimulation was analyzed. MAIN OUTCOME MEASURES: The number of abnormal muscles, parameter values, and muscle force induced by electrical stimulation. RESULTS: Abnormal muscles were found only in the TLSI patients and 13 abnormal muscles were detected by macro EMG only. The abnormal muscles defined by macro EMG showed insufficient contraction induced by electrical stimulation. The increase of parameter value negatively correlated with the muscle force (tibialis anterior area r=-.797, amplitude r=-.866; quadriceps area r=-.866, amplitude r=-.893; p < .001). CONCLUSIONS: These results suggest that macro EMG is useful in detecting denervated muscles, in determining indications for FES, and in predicting FES effects before implantation of electrodes.     

A differential neural response in the human amygdala to fearful and happy facial expressions

The amygdala is thought to play a crucial role in emotional and social behaviour. Animal studies implicate the amygdala in both fear conditioning and face perception. In humans, lesions of the amygdala can lead to selective deficits in the recognition of fearful facial expressions and impaired fear conditioning, and direct electrical stimulation evokes fearful emotional responses. Here we report direct in vivo evidence of a differential neural response in the human amygdala to facial expressions of fear and happiness. Positron-emission tomography (PET) measures of neural activity were acquired while subjects viewed photographs of fearful or happy faces, varying systematically in emotional intensity. The neuronal response in the left amygdala was significantly greater to fearful as opposed to happy expressions. Furthermore, this response showed a significant interaction with the intensity of emotion (increasing with increasing fearfulness, decreasing with increasing happiness). The findings provide direct evidence that the human amygdala is engaged in processing the emotional salience of faces, with a specificity of response to fearful facial expressions.     

Neurostimulation for obstructive sleep apnea: investigations

Neurostimulation of the upper airway muscles (accessory muscles of respiration) was accomplished in anesthetized dogs and sleeping humans by electrical stimulation of the hypoglossal nerves. Such stimulations relieved partial airway obstructions in dogs. They also aborted (shortened) obstructive sleep apnea events in humans who suffer with obstructive sleep apnea syndrome. In one subject, stimulations delivered in advance of apneic events (by automatic cycling) prevented apneas. Neurostimulation for obstructive sleep apnea may be an important concept for future research and development.     

Visual Kin Recognition and Family Resemblance in Chimpanzees (Pan troglodytes).

The male-offspring biased visual kin recognition in chimpanzees (Pan troglodytes) reported by L. A. Parr and F. B. M. de Waal (1999) was replicated with human (Homo sapiens) participants and a principal components analysis (PCA) of pixel maps of the chimpanzee face photos. With the same original materials and methods, both humans and the PCA produced the same asymmetry in kin recognition as found with the chimpanzees. The PCA suggested that the asymmetry was a function of differences in the distribution of global characteristics associated with the framing of the faces in the son and daughter test sets. Eliminating potential framing biases, either by cropping the photos tightly to the faces or by rebalancing the recognition foils, eliminated the asymmetry but not human participants' ability to recognize chimpanzee kin. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

MyoD and Myf-5 differentially regulate the development of limb versus trunk skeletal muscle

The myogenic progenitors of epaxial (paraspinal and intercostal) and hypaxial (limb and abdominal wall) musculature are believed to originate in dorsal-medial and ventral-lateral domains, respectively, of the developing somite. To investigate the hypothesis that Myf-5 and MyoD have different roles in the development of epaxial and hypaxial musculature, we further characterized myogenesis in Myf-5- and MyoD-deficient embryos by several approaches. We examined expression of a MyoD-lacZ transgene in Myf-5 and MyoD mutant embryos to characterize the temporal-spatial patterns of myogenesis in mutant embryos. In addition, we performed immunohistochemistry on sectioned Myf-5 and MyoD mutant embryos with antibodies reactive with desmin, nestin, myosin heavy chain, sarcomeric actin, Myf-5, MyoD and myogenin. While MyoD(-/-) embryos displayed normal development of paraspinal and intercostal muscles in the body proper, muscle development in limb buds and brachial arches was delayed by about 2.5 days. By contrast, Myf-5(-/-) embryos displayed normal muscle development in limb buds and brachial arches, and markedly delayed development of paraspinal and intercostal muscles. Although MyoD mutant embryos exhibited delayed development of limb musculature, normal migration of Pax-3-expressing cells into the limb buds and normal subsequent induction of Myf-5 in myogenic precursors was observed. These results suggest that Myf-5 expression in the limb is insufficient for the normal progression of myogenic development. Taken together, these observations strongly support the hypothesis that Myf-5 and MyoD play unique roles in the development of epaxial and hypaxial muscle, respectively.     

The relationship between surface potentials and the number of active motor units

One of the assumptions inherent in a technique recently devised for enumerating motor units in human muscles is that the surface potentials from active motor units summate in a linear fashion. We present an electrical model of a muscle which predicts that a linear relationship between the number of active units and the electrical response recorded at the surface overlying the muscle would not be expected. The extent of the non-linearity, and hence the error in the calculation of the number of motor units in a given muscle, depends upon the ratio between the mean conductance of the motor units themselves and that of the external conduction pathway through which the electrical signal is fed (Gu/Ge). The extent of non-linearity is assessed experimentally in human hypothenar muscles using a "collision" technique. The average underestimate introduced into the calculation of the number of motor units in this particular case was concluded to be 26%. The value of Gu/Ge derived from these experiments, in 2 subjects, was checked by simulating an intramuscular action potential and determining the attenuation at the surface. The 2 independently obtained values were sufficiently close to suggest that the model may be a valid one. We conclude that caution should be employed in the interpretation of experiments which purport to determine the number of motor units in a muscle by means of surface recordings.     

Garlic powder and plasma lipids and lipoproteins: a multicenter, randomized, placebo-controlled trial

BACKGROUND: Some wrinkles and unsightly facial expressions are due to overactivity of the underlying facial musculature. Botulinum A exotoxin reversably paralyses selected muscles. Botulinum toxin has been used to correct facial cosmetic concerns. OBJECTIVES: This paper describes the authors' experience with the cosmetic use of botulinum toxin. The areas that can be treated, the appropriate technique for each area and special considerations such as dose, dilution, and relevant anatomy are discussed. RESULTS: Our results have been published previously and are referenced in this paper. CONCLUSIONS: Botulinum toxin is safe and effective in the management of some facial lines and wrinkles. Its use is associated with a high degree of patient and physician satisfaction.     

Reduction of Th1 cell activity in the peripheral circulation of patients with rheumatoid arthritis after treatment with a non-depleting humanized monoclonal antibody to CD4

Differences in early events during entry and integration of HIV-1 into peripheral blood mononuclear cells (PBMC) might contribute to the absence of AIDS-like disease in chimpanzees as compared to humans. To address this question, we first tested the in vitro susceptibility of human and chimpanzee PBMC for infection with the two HIV-1 isolates III B and RF. The results of these studies revealed that chimpanzee PBMC had a slightly lower capability to support the growth of HIV-1 as compared to human PBMC. This was accompanied by a delayed accumulation of proviral HIV-1 DNA in cultures of HIV-1-infected chimpanzee PBMC. However, no differences between cells of the two species were observed when very early events of HIV-1 infection were studied. Shortly (20 h) after infection chimpanzee and human cells harbored similar amounts of proviral HIV-1 DNA and PBMC of both species behaved comparably with respect to pre-integration latency (i.e. the ability to activate extrachromosomal HIV-1 intermediates in HIV-1 infected quiescent cells at various times after infection). These results strongly suggest that the absence of AIDS-like disease in chimpanzees cannot be correlated with defects in early events of the HIV-1 replicative cycle.     

Delayed figure reconstruction by a chimpanzee (Pan troglodytes) and humans (Homo sapiens).

A chimpanzee (Pan troglodytes) was trained to construct a copy of 3-element compound figures from a set of 9 elements. Delay intervals between sample offset and element presentation varied. The chimpanzee maintained accuracy at about 80% correct for a delay of 32 s, which was slightly higher than the mean of 4 human (Homo sapiens) Ss. Excellent visual reproductive memory in the chimpanzee as compared with that in humans was demonstrated. However, the nature of the reproductive memory was different in the 2 species in that humans better constructed meaningful figures, which represented food items, than meaningless ones, whereas the chimpanzee constructed these 2 types of figures with the same accuracy. This outcome suggests that the reproductive memory for meaningful figures of the chimpanzee may have been processed separately from symbolic processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spectral pattern of neonatal cerebral blood flow velocity: comparison with spectra from blood pressure and heart rate

BACKGROUND: Extrafusal muscle fibers of human striated skeletal muscles are known to have a uniform innervation pattern. Motor endplates (MEP) of the "en plaque" type are located near the center of muscle fibers and distributed within the muscles in a narrow band. The aim of this study was to evaluate the innervation pattern of human facial muscles and compare it with that of skeletal muscles. METHODS: Ten facial muscles from 11 human cadavers were dissected, the nerve entrance points located, and the dimensions measured. All muscles were stained in toto for MEPs using Acetylcholinesterase (AChE) and examined under the microscope to determine their location. Single muscle fibers were teased to evaluate the stained MEPs. RESULTS: The length of the different facial muscles varied from 29 to 65 mm, which correlated to the length of the corresponding muscle fibers. MEP zones were found on the muscles in the immediate vicinity of the nerves' entrance points and located eccentrically. Numbers and locations varied from muscle to muscle. Three MEP zone distribution patterns were differentiated: numerous small MEP zones were evenly spread over the muscle, a predominant MEP zone and two to three small zones were spread at random, and two to four MEP zones of equal size were randomly scattered. One MEP of the "en plaque" type was found in 73.8% of the muscle fibers and two to five MEPs were found in 26.2%. The distances between the multiple MEPs on one muscle fiber varied from 10 to 500 microm. CONCLUSIONS: This study suggests that facial muscles differ from skeletal muscles regarding distribution and number of MEPs. The eccentric location of MEP zones and multiple MEPs suggests there is an independent mechanism of neural regulation in the facial muscle system.     

Effect of repetitive stimulation on lateral spreads and F-waves in hemifacial spasm

The lateral spread (LS) response, which can be elicited in muscles innervated by other branches of the facial nerve, is electromyographycally specific for patients with hemifacial spasm (HFS), occurring about 10 ms after stimulus. The F-wave in facial muscles, which is a late response that antidromicaly propagates to the facial motonucleus and returns orthodromicaly down the same axon, revealed a trend toward enhancement in patients with HFS. The LSs were facilitated by repetitive stimulation during the microvascular decompression (MVD) operation, which has proved to be a successful treatment, and the F-waves were also facilitated by repetitive stimulation on the spasm side more than on the normal side. Greater facilitation of these responses was in direct proportion to higher stimulation rates and greater numbers of stimulations. The repetitive stimulation of the facial nerve may result in activation of the motoneuron pool and in the lowering of the threshold of somatic membranes. These results support the hypothesis that hemifacial spasm is caused by hyperexcitability of the facial motonucleus, which is increased by antidromic repetitive stimulation.     

The NSAID dexketoprofen trometamol is as potent as mu-opioids in the depression of wind-up and spinal cord nociceptive reflexes in normal rats

The aim of this study was to examine the potency of the antinociceptive effects of the non-steroidal antiinflammatory drug (NSAID), Dexketoprofen Trometamol (the active enantiomer of ketoprofen) on spinal cord nociceptive reflexes. These effects were compared with those of the mu-opioid receptor agonist fentanyl in normal animals. The experiments were performed in male Wistar rats anaesthetised with alpha-chloralose. The nociceptive reflexes were recorded as single motor units in peripheral muscles, activated by mechanical and electrical stimulation. Both dexketoprofen and fentanyl inhibited responses evoked by mechanical and electrical stimulation with doses in the same nanomolar range (dexketoprofen ID50s: 100 and 762 nmol kg-1 and fentanyl: 40 and 51 nmol kg-1, respectively). Dexketoprofen and fentanyl also significantly inhibited wind-up. Since fentanyl has been shown to be some 1000 times more potent than morphine in this type of experiments, we conclude that dexketoprofen has central analgesic actions in normal animals and depresses nociceptive responses with a potency similar to that of mu-opioid agonists.     

Playing with the face: Playful facial “chattering” and signal modulation in a monkey species (Theropithecus gelada).

Darwin (1872), in The expression of emotions in man and animals, underlined that human facial expressions represent a shared heritage of our species with nonhuman primates. Play is a fertile field to examine the role of facial expressions that we share with our common ancestors because the primate play face is homologous to human laughter. Here, we focus on the use of two playful expression variants (PF: play face, mouth opened with only the lower teeth exposed; FPF: full play face, lower/upper teeth and gums exposed via the actively retraction of the upper lip) in Theropithecus gelada. During ontogeny PF was replaced by FPF; in older subjects PF was virtually absent. The ontogenetic transition appears to reflect the phylogenetic sequence of the two playful displays with FPF considered a derived form of PF. This age-trend bias of facial displays is probably due to their different roles in communication. The correspondence between facial signals emitted and elicited is a valuable criterion to evaluate playmates' attentional state. Adults were more sensitive than immatures in responding to the play faces of others. Probably, previous playful experience, social competence, and neural circuit maturation are at the basis of adult sensitiveness. Similar to humans, where unconscious laughing is deserved for close friends and/or relatives, FPF was extremely frequent during gelada mother-offspring play. Probably, under some intimate circumstances, facial displays should be primarily linked to the spontaneous expression of emotional states of the sender more than to the strategic transfer of actual information to the receiver. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Electrical activation of the expiratory muscles to restore cough

Many patients with spinal cord injury have paralysis of their expiratory muscles and, consequently, lack an effective cough. The purpose of the present study was to evaluate the utility of lower thoracic spinal cord stimulation (SCS) to activate the expiratory muscles. Studies were performed on 15 anesthetized dogs. A quadripolar stimulating electrode (Medtronic Model 3586) was inserted epidurally and on the ventral surface of the lower thoracic spinal cord. Changes in airway pressure, airflow, and internal intercostal and abdominal muscle length were monitored to assess the effects of electrical stimulation. Spinal stimulation applied at the T9-T10 spinal level provided maximal changes in airway pressure generation in preliminary experiments. All subsequent studies were therefore performed with the electrode positioned at this level. The expiratory muscles were stimulated supramaximally over a wide range of lung volumes which were expressed as the corresponding change in airway pressure. The pressure-generating capacity of the expiratory muscles was evaluated by the change in airway pressure produced by SCS during airway occlusion. Peak expiratory airflow was also monitored following release of occlusion. At FRC, deflation (-10 cm H2O) and inflation (+ 30 cm H2O), SCS resulted in positive airway pressures of 44 cm H2O +/- 4 SE, 28 cm H2O +/- 3 SE, and 82 cm H2O +/- 7 SE. The relationship between airway pressure expiratory airflow generation and lung volume was linear (slope = 1.34 +/- 0.04) over the entire vital capacity range. Our results indicate that: (1) a major portion of the expiratory muscles can be activated reproducibly and in concert by electrical stimulation, and (2) this technique may be a clinically useful method of restoring cough in spinal cord injured patients.