Hemiballismus complicating stereotactic thalamotomy.

The pathology of poststereotactic hyperkinesis has been rarely documented and the pathophysiology is still poorly understood. In a case of hemiballismus following thalamotomy for parkinsonism, detailed anatomical studies showed bilateral cortical pseudolaminar necrosis and no involvement of the subthalamic nuclei by the thalamic lesions. The structural and functional effects of surgical lesions upon the preexisting pharmacological abnormalities present in parkinsonism probably constitute the substrate necessary for occurrence of hemiballismus following stereotactic surgery.     

Inhibition of apomorphine-induced yawning and penile erection by neurotensin.

The yawns and penile erection elicited in rats by apomorphine (100 micrograms/kg SC) are dose-dependently suppressed by the enkephalinase-resistant analog of NT, [D-Trp11]NT, intracerebroventricularly (ICV) injected (10-120 ng per rat). This antagonistic effect was shared by NT (0.75-3 micrograms per rat) administered ICV. The yawns induced by pilocarpine (2 mg/kg IP) were similarly antagonized by [D-Trp11]NT (30-120 ng per rat). The enkephalinase inhibitor acetorphan (5 mg/kg IV) reduced in a naloxone (2 mg/kg, SC)-resistant manner the apomorphine-induced penile erection or yawning.     

Long-term follow-up results of bilateral thalamotomy for parkinsonism.

27 patients who underwent bilateral thalamotomy for parkinsonism over the past 10 years have been clinically evaluated. Mean follow-up period was 6.2 years after second surgery. In these cases, 8 returned to full social life without any medication, 4 were capable of social life with medical treatment, 6 were self-sufficient and 3 were semi-self-sufficient in ADL, respectively. Therapeutic drug doses were reduced in all cases. L-Dopa-induced dyskinesia was not observed after second surgery. Speech disturbance, which was not severe, was recognized in 12 cases as a complication.     

Food-reinforced yawning in Macaca tonkeana

An operant conditioning paradigm comprising continuous food-reinforcement, fixed-ratio responding, and extinction procedures was used to evaluate the possibility that adult male macaques can control their rate of yawning. Two non-food-deprived Macaca tonkeana quickly learned to produce yawns for food rewards. They also increased the rate of production according to fixed-ratio requirements, and showed initial response peaks followed by diminished rates of yawning during extinction. The results indicate that adult male macaques can yawn voluntarily. Further work along these lines may help distinguish among different types of yawning as indicated in the literature.     

Male yawning is more contagious than female yawning among chimpanzees (Pan troglodytes)

Yawn contagion is not restricted to humans and has also been reported for several non-human animal species, including chimpanzees (Pan troglodytes). Contagious yawning may lead to synchronisation of behaviour. However, the function of contagious yawning is relatively understudied. In this study, we investigated the function of contagious yawning by focusing on two types of signal providers: close social associates and leaders. We provided a captive chimpanzee colony with videos of all individuals of their own group that were either yawning, or at rest. Consistent with other studies, we demonstrated that yawning is contagious for chimpanzees, yet we did not find any effect of relationship quality on yawn contagion. However, we show that yawn contagion is significantly higher when the video model is a yawning male than when the video model was a yawning female, and that this effect is most apparent among males. As males are dominant in chimpanzee societies, male signals may be more relevant to the rest of the group than female signals. Moreover, since chimpanzees form male-bonded societies, male signals are especially relevant for other males. Therefore, we suggest that the sex-differences of yawning contagion among chimpanzees reflect the function of yawning in the synchronisation of behaviour.     

Influence of modified casomorphins on yawning behavior of rats.

Apomorphine-induced yawning was completely suppressed in animals treated with 5 nmol [D-Pro4]casomorphin (CM) (ICV), 10 nmol [D-Phe3]CM (ICV) or 10 nmol [D-Pip4]CM (ICV). The apomorphine-induced yawning was also decreased, by des-Tyr analogs, but only by about 50%. Physostigmine (0.15 mg/kg, IP) induced yawning. The physostigmine-induced yawning was suppressed by 5 nmol [D-Pro4]CM and 10 nmol [D-Phe3]CM. Both [des-Tyr-D-Phe3]CM and [des-Tyr-D-Pip4]CM were without effect, whereas [des-Tyr-D-Pro4]CM increased significantly the physostigmine-induced yawning. The results suggest that dopaminergic transmission can be modulated by beta-casomorphin derivatives, thus resulting in a decrease in yawning. In the case of the des-tyrosine derivatives, we can assume a dopaminergic modulation, too. An increase in serotonergic activity might be supposed for [des-Tyr-D-Pro4]CM.     

Analysis of tremulous movements after thalamotomy correlated to intrathalamic therapeutic lesions.

Residual tremulous movements after thalamotomy were examined using an accelerometer and EMG. Various types of tremor-provoking procedures were performed and the tremulous movements were classified according to the pattern of modificiation by these procedures. Four types of postoperative tremulous movements were noted, and a correlation was made to the intrathalamic therapeutic lesions.     

Computer animations stimulate contagious yawning in chimpanzees

People empathize with fictional displays of behaviour, including those of cartoons and computer animations, even though the stimuli are obviously artificial. However, the extent to which other animals also may respond empathetically to animations has yet to be determined. Animations provide a potentially useful tool for exploring non-human behaviour, cognition and empathy because computer-generated stimuli offer complete control over variables and the ability to program stimuli that could not be captured on video. Establishing computer animations as a viable tool requires that non-human subjects identify with and respond to animations in a way similar to the way they do to images of actual conspecifics. Contagious yawning has been linked to empathy and poses a good test of involuntary identification and motor mimicry. We presented 24 chimpanzees with three-dimensional computer-animated chimpanzees yawning or displaying control mouth movements. The apes yawned significantly more in response to the yawn animations than to the controls, implying identification with the animations. These results support the phenomenon of contagious yawning in chimpanzees and suggest an empathic response to animations. Understanding how chimpanzees connect with animations, to both empathize and imitate, may help us to understand how humans do the same.     

Target identification for stereotactic thalamotomy using diffusion tractography

Background

Stereotactic targets for thalamotomy are usually derived from population-based coordinates. Individual anatomy is used only to scale the coordinates based on the location of some internal guide points. While on conventional MR imaging the thalamic nuclei are indistinguishable, recently it has become possible to identify individual thalamic nuclei using different connectivity profiles, as defined by MR diffusion tractography.

Methodology and Principal Findings

Here we investigated the inter-individual variation of the location of target nuclei for thalamotomy: the putative ventralis oralis posterior (Vop) and the ventral intermedius (Vim) nucleus as defined by probabilistic tractography. We showed that the mean inter-individual distance of the peak Vop location is 7.33 mm and 7.42 mm for Vim. The mean overlap between individual Vop nuclei was 40.2% and it was 31.8% for Vim nuclei. As a proof of concept, we also present a patient who underwent Vop thalamotomy for untreatable tremor caused by traumatic brain injury and another patient who underwent Vim thalamotomy for essential tremor. The probabilistic tractography indicated that the successful tremor control was achieved with lesions in the Vop and Vim respectively.

Conclusions

Our data call attention to the need for a better appreciation of the individual anatomy when planning stereotactic functional neurosurgery.     

Changes in cerebral blood flow after stereotactic thalamotomy

Regional cerebral blood flow (rCBF), a parameter of neuronal activity in the brain, was measured by the 133Xe inhalation method in 43 patients undergoing stereotactic thalamotomy. A postoperative flow reduction of about 2% in the operated hemisphere was found, persisting in further measurements performed after a year. There was no consistent change in the pattern of regional flow distribution. The results indicate a diminished level of activity in the hemisphere subjected to thalamotomy, but the change could not be linked to any specific area or function.     

The daily time course of contagious and spontaneous yawning among humans

Yawning, besides being a spontaneous behavior, can also be evoked by observing others yawn. However, contagious yawning does not always occur, depending possibly on several factors, such as one’s propensity to spontaneously yawn and a heightened level of sleepiness. The aim of this study is to investigate in young adults whether contagious yawning frequency varies throughout the day, and if it is related to the daily time course of spontaneous yawning frequency and level of sleepiness. For the study, 22 subjects were instructed to log hourly, throughout wakefulness, the number of spontaneous yawns and sleepiness level. Subjects were required to continue this procedure for 3 consecutive days, after which they underwent five experimental sessions occurring at regular intervals throughout the same day. During each experimental session, subjects observed others yawn (stimulus condition) and smile (control condition). Our findings show that the contagious effect of yawning is always present throughout the daytime. Both contagious and spontaneous yawning peaked in the early morning and in the late evening, according to the sleepiness time course. However, the frequency of spontaneous yawns was remarkably lower than the frequency of contagious yawns around 19:00. This difference suggests that different mechanisms control spontaneous and contagious yawning.     

Video-induced yawning in stumptail macaques (Macaca arctoides)

This study reports the first experimental exploration of possible contagious yawning in monkeys. Twenty-two stumptail macaques (Macaca arctoides) were presented with video clips of either yawns or control mouth movements by conspecifics. At a group level, monkeys yawned significantly more often during and just after the yawn tape than the control tape. Supplementary analysis revealed that the yawn tape also elicited significantly more self-directed scratching responses than the control tape, which suggests that yawning might have been caused by tension arising from viewing the yawn tape. Understanding to what extent the observed effect resembles contagious yawning as found in humans and chimpanzees requires more detailed experimentation.     

Idiopathic oromandibular dyskinesia treated by Vo complex microstereotactic thalamotomy

Two cases of oromandibular or buccolingual dyskinesia, which did not respond to medical therapy, had lesions produced in the Vo complex of the thalamus by microstereotactic surgery with almost complete relief of symptoms. It was assumed the symptom, as well as levodopa-induced dyskinesia, may depend on the striato-pallido-thalamic projection.     

Penile erection and yawning induced by oxytocin and related peptides: structure-activity relationship

The potency of several oxytocin-related peptides in inducing penile erection and yawning after injection into a lateral ventricle of male rats was compared. Substitution of two amino acids in the oxytocin molecule or deletion of the C-terminal glycinamide as in des-GlyNH2-oxytocin [oxytocin(1-8)] reduced oxytocin potency in inducing both effects, the rank order being: oxytocin greater than [Thr4,Gly7]-oxytocin congruent to isotocin [( Ser4,Ile8]-oxytocin) greater than vasopressin [( Phe3,Arg8]-oxytocin) greater than des-GlyNH2-oxytocin. Oxytocin's ability to induce penile erection and yawning was abolished by permanent opening of the disulfide bridge by reduction and carboxymethylation. Oxytocin(1-6) and oxytocin(7-9) were also inactive. Penile erection and yawning induced by oxytocin-related peptides were antagonized in a dose-dependent manner by nonapeptide antagonists with a rank order of potency that follows their antioxytocic activity (d[(CH2)5Tyr(Me)Orn8]-vasotocin congruent to [Pen1,Phe(Me)2,Thr4,Orn8]-oxytocin greater than d[(CH2)5Tyr(Me)Arg8]-vasopression). Carboxymethylated oxytocin, oxytocin(1-6), and oxytocin(7-9) were devoid of antagonistic activity. The present results suggest that central oxytocin receptors mediating the expression of penile erection and yawning are structurally related to those present in the uterus and in the mammary gland.     

Absence of contagious yawning in children with autism spectrum disorder

This study is the first to report the disturbance of contagious yawning in individuals with autism spectrum disorder (ASD). Twenty-four children with ASD as well as 25 age-matched typically developing (TD) children observed video clips of either yawning or control mouth movements. Yawning video clips elicited more yawns in TD children than in children with ASD, but the frequency of yawns did not differ between groups when they observed control video clips. Moreover, TD children yawned more during or after the yawn video clips than the control video clips, but the type of video clips did not affect the amount of yawning in children with ASD. Current results suggest that contagious yawning is impaired in ASD, which may relate to their impairment in empathy. It supports the claim that contagious yawning is based on the capacity for empathy.