Jaime A. Pineda

Modulation of mu suppression in children with autism spectrum disorders in response to familiar or unfamiliar stimuli: the mirror neuron hypothesis.

In an early description of the mu rhythm, Gastaut and Bert [Gastaut, H. J., & Bert, J. (1954). EEG changes during cinematographic presentation. Clinical Neurophysiology, 6, 433-444] noted that it was blocked when an individual identified himself with an active person on the screen, suggesting that it may be modulated by the degree to which the individual can relate to the observed action. Additionally, multiple recent studies suggest that the mirror neurons system (MNS) is impaired in individuals with autism spectrum disorders (ASD), which may affect their ability to relate to others. The current study aimed to investigate MNS sensitivity by examining mu suppression to familiarity, i.e., the degree to which the observer is able to identify with the actor on the screen by using familiar versus unfamiliar actors. The participants viewed four 80s videos that included: (1) stranger: an unfamiliar hand performing a grasping action; (2) familiar: the childs guardian or siblings hand performing the same action; (3) own: the participants own hand performing the same action; (4) bouncing balls: two balls moving vertically toward and away from each other. The study revealed that mu suppression was sensitive to degree of familiarity. Both typically developing participants and those with ASD showed greater suppression to familiar hands compared to those of strangers. These findings suggest that the MNS responds to observed actions in individuals with ASD, but only when individuals can identify in some personal way with the stimuli.

The human mirror neuron system: A link between action observation and social skills

The discovery of the mirror neuron system (MNS) has led researchers to speculate that this system evolved from an embodied visual recognition apparatus in monkey to a system critical for social skills in humans. It is accepted that the MNS is specialized for processing animate stimuli, although the degree to which social interaction modulates the firing of mirror neurons has not been investigated. In the current study, EEG mu wave suppression was used as an index of MNS activity. Data were collected while subjects viewed four videos: (1) Visual White Noise: baseline, (2) Non-interacting: three individuals tossed a ball up in the air to themselves, (3) Social Action, Spectator: three individuals tossed a ball to each other and (4) Social Action, Interactive: similar to video 3 except occasionally the ball would be thrown off the screen toward the viewer. The mu wave was modulated by the degree of social interaction, with the Non-interacting condition showing the least suppression, followed by the Social Action, Spectator condition and the Social Action, Interactive condition showing the most suppression. These data suggest that the human MNS is specialized not only for processing animate stimuli, but specifically stimuli with social relevance.

ERPs evoked by different matrix sizes: implications for a brain computer interface (BCI) system

A brain-computer interface (BCI) system may allow a user to communicate by selecting one of many options. These options may be presented in a matrix. Larger matrices allow a larger vocabulary, but require more time for each selection. In this study, subjects were asked to perform a target detection task using matrices appropriate for a BCI. The study sought to explore the relationship between matrix size and EEG measures, target detection accuracy, and user preferences. Results indicated that larger matrices evoked a larger P300 amplitude, and that matrix size did not significantly affect performance or preferences.

The effects of self-movement, observation, and imagination on /spl mu/ rhythms and readiness potentials (RP's): toward a brain-computer interface (BCI)

Current movement-based brain-computer interfaces (BCIs) utilize spontaneous electroencephalogram (EEG) rhythms associated with movement, such as the mu rhythm, or responses time-locked to movements that are averaged across multiple trials, such as the readiness potential (RP), as control signals. In one study, we report that the mu rhythm is not only modulated by the expression of self-generated movement but also by the observation and imagination of movement. In another study, we show that simultaneous self-generated multiple limb movements exhibit properties distinct from those of single limb movements. Identification and classification of these signals with pattern recognition techniques provides the basis for the development of a practical BCI.

Recognition of point-light biological motion: Mu rhythms and mirror neuron activity

Changes in power in the mu frequency band (8-13Hz) of the electroencephalogram (EEG) is thought to indirectly reflect the activity of mirror neurons in premotor cortex. Activation of these neurons by self-performed, observed or imagined motor actions is assumed to produce asynchronous firing and a reduction in mu rhythm oscillation (referred to as mu suppression) in sensorimotor cortex. A recent fMRI study by Saygin et al. [Saygin AP, Wilson SM, Hagler Jr DJ, Bates E, Sereno MI. Point-light biological motion perception activates human premotor cortex. J Neurosci 2004;24:6181-8] revealed that the premotor brain regions containing mirror-neurons are also activated in response to point-light human motion. The perceived movement of these light cues are integrated into one percept of a complete human action (e.g. jumping jacks), rather than seen as individual moving lights. The present study examined whether recruitment of the mirror neuron system, as reflected in mu rhythm suppression, mediates recognition of point-light biological motion. Changes in mu power were recorded while subjects viewed point-light biological motion videos, matched scrambled versions of these animations, and visual white-noise (baseline). The results revealed that point-light biological animations produced mu suppression relative to baseline, while scrambled versions of these animations did not. This supports the hypothesis that the mirror neuron system is involved in inferring human actions by recovering object information from sparse input.

Learning to control brain rhythms: making a brain-computer interface possible

The ability to control electroencephalographic rhythms and to map those changes to the actuation of mechanical devices provides the basis for an assistive brain-computer interface (BCI). In this study, we investigate the ability of subjects to manipulate the sensorimotor mu rhythm (8-12-Hz oscillations recorded over the motor cortex) in the context of a rich visual representation of the feedback signal. Four subjects were trained for approximately 10 h over the course of five weeks to produce similar or differential mu activity over the two hemispheres in order to control left or right movement in a three-dimensional video game. Analysis of the data showed a steep learning curve for producing differential mu activity during the first six training sessions and leveling off during the final four sessions. In contrast, similar mu activity was easily obtained and maintained throughout all the training sessions. The results suggest that an intentional BCI based on a binary signal is possible. During a realistic, interactive, and motivationally engaging task, subjects learned to control levels of mu activity faster when it involves similar activity in both hemispheres. This suggests that while individual control of each hemisphere is possible, it requires more learning time.

Mirroring and mu rhythm involvement in social cognition: Are there dissociable subcomponents of theory of mind?

Tager-Flusberg and Sullivan [Tager-Flusberg, H., Sullivan, K., 2000. A componential view of theory of mind: evidence from Williams syndrome. Cognition 76, 59-90] have argued for a distinction between the social-perceptive component of theory of mind (ToM), involving judgment of mental state from facial and body expressions, and the social-cognitive component, which is representation-based and linked to language and theory-building. This is analogous to the distinction made by others [Gallese, V., Keysers, C., Rizzolatti, G., 2004. A unifying view of the basis of social cognition. Trends in Cognitive Science 8, 396-403] between representing the mental state of another as if it was ones own (simulation theory), which requires involvement of the mirror neuron system, and explicit or declarative reasoning about mental states (theory theory), which does not. This componential view of ToM was tested by examining mirroring, as indexed by EEG mu rhythm suppression, in subjects performing tasks assumed to tap both dimensions. Mu suppression was positively correlated with accuracy on the social-perceptual task but not in the social-cognitive task. In a ToM control task requiring judgments about person-object interactions accuracy was correlated with mu suppression. This implies that mirroring is involved in making judgments about emotions and person-object interactions. However, mirroring is insensitive to the distinction between correct and incorrect inferences in the social-cognitive task suggesting that additional mechanisms are needed to make mental attributions of beliefs and intentions. These results are consistent with a refined componential view of ToM.

Hepatic Resection in the Management of Complex Injury to the Liver

BACKGROUND Nonoperative management has become the standard for >80% of the blunt liver injuries. In the cases where operation is required, current operative management emphasizes packing, damage control, and early utilization of interventional radiology for angiography and embolization. Liver resection is thought to have minimal role in the management of hepatic injury because of the high morbidity and mortality in many reports. The objective of this study was to show that the management of complex liver injuries with anatomic or nonanatomic resection can be accomplished by experienced trauma surgeons, in conjunction with liver surgeons in some cases, with low morbidity and mortality related to the procedure. Delayed, planned anatomic resection was also applied. METHODS This is a retrospective, observational study, on patients admitted to the University of Pittsburgh Medical Center (UPMC)-Presbyterian from December 1986 through March 2001. The patients included in this report underwent hepatic resection for complex liver injuries (grade 3, 4, and 5) according to the American for Association the Surgery of Trauma-Organ Injury Scale. Age, sex, mechanism of trauma, type of resection (nonanatomic, segmentectomy, lobectomy, and hepatectomy), surgical complications, hospital length of stay, and mortality were the variables analyzed. RESULTS Two hundred sixteen adult patients were admitted with complex liver injury, during the period of December 1986 to March 2001. Fifty-six patients of this series underwent liver resection: 21 anatomic segmentectomies, 23 nonanatomic resections, 3 left lobectomies, 8 right lobectomies, and 1 hepatectomy with orthotopic liver transplant. The median age was 31 years (range, 15-83 years). The Injury severity Score average was 34 +/- 10 (range, 16-59). Mechanism was blunt in 62.5% and penetrating in 37.5%. The grades of hepatic injury were 9 grade III, 32 grade IV, and 15 grade V. A total of 28.5% (16 of 56) of patients had concomitant hepatic venous injury. The overall morbidity was 62.5%. The morbidity related to liver resection was 30%. The overall mortality of the series was 17.8%. Mortality from liver injury was 9% in this series of patients undergoing liver resection for complex hepatic injury. CONCLUSIONS This study demonstrates that liver resection should be considered as a surgical option in patients with complex injury, as initial or delayed management, and can be accomplished with low mortality and liver related morbidity.

Atypical Cross Talk Between Mentalizing and Mirror Neuron Networks in Autism Spectrum Disorder

IMPORTANCE Converging evidence indicates that brain abnormalities in autism spectrum disorder (ASD) involve atypical network connectivity, but it is unclear whether altered connectivity is especially prominent in brain networks that participate in social cognition. OBJECTIVE To investigate whether adolescents with ASD show altered functional connectivity in 2 brain networks putatively impaired in ASD and involved in social processing, theory of mind (ToM) and mirror neuron system (MNS). DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study using resting-state functional magnetic resonance imaging involving 25 adolescents with ASD between the ages of 11 and 18 years and 25 typically developing adolescents matched for age, handedness, and nonverbal IQ. MAIN OUTCOMES AND MEASURES Statistical parametric maps testing the degree of whole-brain functional connectivity and social functioning measures. RESULTS Relative to typically developing controls, participants with ASD showed a mixed pattern of both over- and underconnectivity in the ToM network, which was associated with greater social impairment. Increased connectivity in the ASD group was detected primarily between the regions of the MNS and ToM, and was correlated with sociocommunicative measures, suggesting that excessive ToM-MNS cross talk might be associated with social impairment. In a secondary analysis comparing a subset of the 15 participants with ASD with the most severe symptomology and a tightly matched subset of 15 typically developing controls, participants with ASD showed exclusive overconnectivity effects in both ToM and MNS networks, which were also associated with greater social dysfunction. CONCLUSIONS AND RELEVANCE Adolescents with ASD showed atypically increased functional connectivity involving the mentalizing and mirror neuron systems, largely reflecting greater cross talk between the 2. This finding is consistent with emerging evidence of reduced network segregation in ASD and challenges the prevailing theory of general long-distance underconnectivity in ASD. This excess ToM-MNS connectivity may reflect immature or aberrant developmental processes in 2 brain networks involved in understanding of others, a domain of impairment in ASD. Further, robust links with sociocommunicative symptoms of ASD implicate atypically increased ToM-MNS connectivity in social deficits observed in ASD.

The role of the left inferior frontal gyrus in social perception: an rTMS study.

Perceiving and interpreting social information richness is something that humans do automatically whenever they engage in social interactions. Numerous studies have identified neural substrates, including mirror neurons that may enable such social perception. In this study, we temporarily disrupted activity in the left inferior frontal gyrus (LIFG) using repetitive transcranial magnetic stimulation (rTMS). We investigated whether this cortical region, that is hypothesized to include mirror neurons, plays a central role in social perception. The LIFG was stimulated in the experimental condition (n=18), the vertex was targeted in the control condition (n=19). Disrupting LIFG, but not vertex, increased reaction times during an emotion recognition task, and eliminated the suppression of the 8-12Hz EEG μ rhythm, postulated as an index of mirroring activity. The results of this study provide further evidence for the role of the human mirror neuron system (MNS) in social perception, and indicate that the MNS can be measured with EEG.