Meeting Summary
Social Neuroscience and Behavior: From Basic to Clinical Science
July 15, 2005 – July 16, 2005
Washington, DC
Note: A complete summary of this workshop was published under: Cacioppo, J.T., et al. Social neuroscience: progress and implications for mental health. Perspectives on Psychological Science, 2(2), 99-123, 2007.
Workshop Findings
In July of 2005, the National Institute of Mental Health (NIMH) convened a workshop to examine the field of social neuroscience and to examine how this field could contribute to basic and clinical research relevant to an understanding of mental disorders. Over a two day period, seventeen scientists representing a variety of disciplines met and discussed a range of topics related to the field of social neuroscience. The workshop divided its discussions into four different thematic areas and breakout sessions focused intensively on: 1) Current opportunities for rapid scientific advances in this field; 2) Impediments to scientific progress; 3) The role of interdisciplinary research in spanning research across multiple levels of analysis; and 4) Clinical implications of current and future findings, specifically with regard to a better understanding of mental disorders. Within these areas, the participants were asked to consider the following issues:
- Current Opportunities: Right now, what are the greatest opportunities for major scientific advances in this field? What should be done to capitalize on these opportunities? What is the time frame for seeing significant benefits/findings (at basic science level) from these new discoveries?
- Impediments to Progress: What are the most significant impediments to scientific progress in this field? What can be done to mitigate these impediments? How long will it take to overcome them?
- Levels of Analysis: How can we most effectively make connections across different levels of analysis in this field? What constitutes interdisciplinary research for social neuroscience? What benefits accrue from such an approach?
- Clinical Implications: Which clinical problems are poised to benefit most directly from new basic research in social neuroscience and behavior? What needs to happen scientifically for this to occur? What is a reasonable time frame for seeing clinical benefits accrue from basic research in this area?
Each breakout group presented a summary of their deliberations to the workgroup as a whole for further discussion. These deliberations (both within the breakout groups and in the plenary sessions), lead to the following observations:
Current Opportunities
Much remains to be learned from a systematic and in-depth analysis of normative behaviors in order to understand how behaviors become disordered in a variety of mental illnesses. This approach to analysis applies equally to ongoing efforts in human research as well as laboratory animals. The behavioral science research community is in a perfect position to take this analysis forward, combining the results with the latest advances being made in the neurosciences.
To this point, much of the research in this and related fields has involved the science of group averages, but there is a great opportunity for major advances to be made through the study of individual differences. There is a convergence of interest in this approach from a variety of perspectives, including the study of personality differences, developments in our understanding of how variations in individual genes can contribute to changes in complex behaviors, and technical advances in functional neuroimaging that can now support sophisticated studies of individual variations in neural responses. Of particular interest in the imaging field is the emerging ability to study intrinsic versus evoked activity and a growing appreciation of the information contained in baseline measures of neural activity. This interest in the power of studying individual differences applies equally to animal and human studies. The committee believed that the field was poised to make major advances in this area over the next five years, calling for complementary approaches to the study of individual differences in humans and laboratory animals, particularly nonhuman primates.
It was noted that the companion field of cognitive neuroscience has largely focused on the adult human brain (and adult animals). Mental disorders often are characterized by a distinct developmental trajectory in the emergence of their pathophysiology. Deficits in cognitive and social processes are hallmarks of mental disorders. This makes it critical to understand complex social behaviors within a developmental context. The committee particularly pointed out that the field of developmental neurobiology, to a significant degree, has focused on the cellular and molecular level. While much is known in developmental psychology about milestones associated with the maturation of the human brain, much less is known about development within the context of how distinct neural systems mature within the brain. The participants emphasized the need for taking a systems level approach in studying developmental issues of importance in order to understand normal and abnormal social information processing. Techniques are rapidly becoming available to make these kinds of systems-level developmental studies feasible in children. For example improvements in imaging technology permit further refinement of fiber tracing techniques (e.g., diffusion tensor imaging), allowing the study of pathway development in children.
As with other breakout groups, the Opportunities group highlighted the importance of understanding the role of intrinsic (vs. evoked), activity within the relevant neural systems. The group suggested that intrinsic activity, which is metabolically expensive for the nervous system to maintain, might be at least as important as evoked activity in providing insight into the relationship between activation of and between multiple neural systems and behavior. Other breakout groups commented on this point as well.
Specific subfields in the areas of social neuroscience and psychology appear to be particularly well-placed to make advances or are particularly critical to achieving significant progress in the understanding of mental disorders. The following highlights were taken from discussions about these subfields:
- Studies of the antecedents and consequences of social motivation should include work in animals and normal humans as well as specific populations such as Williams Syndrome, schizophrenia, and autism, where important preliminary data exist. There is a well-established, anatomically, physiologically, and behaviorally grounded body of knowledge in the field of motivated behavior. Together with recent insights from the study of the genetics of specific psychopathologies, there is an opportunity to make real progress in understanding the pathophysiology of these diseases through understanding the mechanisms of social motivation.
- It will be increasingly important to understand the dynamic relationship between control processes, self-regulation, and emotion. Separately, these concepts have received increasing attention in recent years but need to be studied together. Regulatory mechanisms are critical to our understanding of disordered behavior at many different levels, from their role in specific pathologies (e.g., OCD, binge eating) to the more practical but critically important considerations of treatment adherence, including engagement in treatment programs, taking medications, and simply following clinical care recommendations.
- The manner in which self-representation is instantiated in humans, while central to our understanding of behavior in health and disease, remains fragmentary and therefore needs to be studied. Understanding of the self provides one anchor point in describing our relationship with others. To the extent that we can hope to fully explicate and treat disorders of a fundamental social nature, we must fully appreciate formation of a self concept and its consequences.
- Affect recognition and personal perception, while central to normal social behavior, is poorly understood from a neurobiological perspective, yet present knowledge suggests many important opportunities for research. This is the companion anchor point to understanding the self: understanding others and recognizing their response to an interaction with us. This is fundamental to fully describing social behavior, and thus, appreciating how social behavior becomes disordered.
In summary, there appears to be potential for significant advances to be made in this field over the next five to ten years.
Impediments to Progress
Currently, social neuroscience research utilizes both human and animal subjects. However it was noted that there is, despite individual exceptions, an overall lack of communication between researchers in the human and animal social neuroscience fields. Much stands to be gained from an increased interplay between these research areas, and steps should be taken to facilitate such an exchange. For example, studies in many species have identified the roles of the neuropeptides, oxytocin and vasopressin, and their receptors in the regulation of several aspects of social behavior, yet very few studies have examined their role in human social behavior. This is partly due to the lack of appropriate tools to probe specific neural systems in humans that are well studied in animal models. For example, pharmacological and PET ligands that cross the blood-brain barrier and that could be used to examine oxytocin and vasopressin receptors in the human brain would provide an excellent tool for translating the animal findings to humans.
The existing literature in the field of animal research addresses various aspects of socially relevant behavior, such as parental behavior, pair bonding, sexual behavior, and conspecific aggression. Despite the existence of these and other models, there is much to be gained from the development of new animal models that employ increasingly sophisticated behavioral analyses. Many studies of rodent social behavior are carried out in small, sterile cages which likely limit the range of social behaviors expressed. Furthermore, these studies are limited in their analysis of the behavior, and these studies are often limited by a “single gene, single brain region, single behavior” mentality. Rodent researchers should be encouraged to consider developing more sophisticated and complex testing arenas and analyzing behaviors in more detail in order to better understand the roles of specific genes in the regulation of complex social behaviors.
This group echoed the importance of focusing on individual differences in behavior in this area of research. By studying why individuals (human or animal) react differently to different treatments or situations, insights may be gained into the neurobiology of social behavior.
It was noted that the focus of much current work in human neuroscience and behavior involves the use of brain scanners, particularly fMRI. The physical demands of the scanning environment pose a particularly serious challenge to studies of social behavior, which must be overcome in order to continue to make significant advances. The space limitation of the scanning tube, scanner noise, and the need to restrain the head and to restrict overall movement all present challenges, especially when trying to study the neural correlates of complex social behaviors. The well-known limits on the temporal resolution of the fMRI signal are challenging for paradigms involving the dynamic interchange between two individuals or an individual and the environment, particularly when taking into account social or emotional variables.
Behavioral measures used by human researchers (clinical and basic) and animal researchers are often not comparable. In fact, DSM IV classification of human disorders is not optimal for investigation of the neurobiological correlates of behavior. Rather, it is critical that individual behavioral components of disorders, or endophenotypes, be quantified and emphasized whenever possible. This would facilitate the development of animal models for human disorders, since most human psychiatric conditions do not have an equivalent animal model. Autism spectrum disorder is one condition which is comprised of many phenotypes, often differing between individuals. These different phenotypes may have useful animal homologues that could be individually tractable to neuroscience analysis. The workgroup suggested that clinicians and animal researchers work together to compile a document that describes in detail the appropriate animal behavioral tests that might probe these behavioral components. By understanding the neurobiological and genetic factors that regulate these components, it should be possible to gain insights into the etiologies of these disorders. This suggestion to increase the focus on endophenotypes was echoed by other breakout groups, including the Clinical group. If one is to enable a translational research agenda, then it is critical to develop an understanding of the disorders at the level of well-characterized component behaviors that will permit translation across the human-animal model axis as well as the normal-disordered behavior axis.
Finally, this breakout group acknowledged a fundamental problem in making progress in the field of social neuroscience: the distinct lack of effective communication between animal researchers, basic human neuroscientists, and clinicians. While there is exchange between the basic animal neurobiologists and human neuroscientists, basic and clinical researchers attend different scientific meetings, preventing the flow of information between these groups. Societies in these fields should be encouraged to hold symposia including researchers from the other field to educate its members about current research in the other field as well as the potential for translational approaches.
Levels of Analysis
In 2004 a workgroup of the National Advisory Mental Health Council issued a report “Setting Priorities for Basic Brain and Behavioral Science Research at NIMH.” This group was charged with considering the impact of the Institute’s research portfolio in terms of: relevance to the mission of NIMH; the potential traction of areas of science (those that are ripe for making progress); and the innovative nature of the research areas in question. One of the four defining principle findings from this report was that “Basic research that integrates or translates across levels of analysis — from genetic, to molecular, to cellular, to systems, to complex overt behaviors — should be given high priority.” The report went on to state that far too little integrative research is currently conducted and that this approach should be given higher priority in the future.
The breakout group considered opportunities in social neuroscience within the context of this increased emphasis on research that spans levels of analysis. The participants observed that the behavioral sciences consist of many different disciplines. To an extent, these distinct disciplines are focused on different levels of behavioral, social, and biological organization, and in certain areas, there are real borders between these disciplines that prevent effective translation among these areas. This leads to the appearance that the science in these areas is, to a certain extent, insular in its consideration of findings and theories, and as a consequence, the borders are reinforced, thus perpetuating the division among the disciplines. Social Neuroscience, as an emerging new discipline, requires approaches that span levels of analysis. This scientific area can make significant contributions at both a clinical and basic science level to an improved understanding of mental disorders. A critical aspect is a comprehensive understanding of complex behavior and the behavioral science community has much to offer. However, for this to happen effectively and efficiently, the above described barriers must begin to disappear. Thus, there is an urgent need not only to translate across multiple biological levels (e.g., from genes to molecular, cellular, systems and behavior) but also across the different levels of behavioral analysis.
The breakout group noted two additional, central principles:
- A thorough and precise understanding of abnormal behaviors resulting from mental disorders is fundamental to advancing mental health research because of the insight this will provide into the underlying pathophysiology of the diseases. However, the path to understanding abnormal behavior goes through a careful, comprehensive understanding of the relevant normative behaviors.
- Mental disorders are expressed through some of the most complex systems in the nervous system. To a significant degree, the emergent properties arising from the interaction of these component systems has contributed to the huge challenge facing researchers in this area as they attempt to understand the generation and modulation of complex behaviors, particularly in a social context. Consequently, it is of great importance for research in this area to take this factor into account, i.e., the whole is greater than the sum of its parts.
Given the above, the breakout group noted the following points as important in guiding research in this area:
- The mammalian social nervous system is sculpted by evolution and hierarchically organized. Knowledge of the origins of the human nervous system and human sociality informs our understanding of the behavior and neural functions of modern humans. The social nervous system and its emergent social behaviors are integrated with other basic processes attendant to an individual’s survival and reproduction.
- It is important to study the whole organism in order to understand sociality in a realistic context. Whether animal or human-based, there is much to be gained from studies of normal and abnormal behavior within an ecologically meaningful and valid context.
- The individual has meaning only within the context in which the individual operates (including the physical, physiological, social environments). Thus, social behaviors are context driven, including the contexts of evolution, ontogeny, function, and social ecology. Social behaviors, the impact of the social environment, and the connectivity of social nervous system are best understood in those contexts. The species-typical tendency to express social behaviors is an emergent property of the organization of the nervous system. Social engagement, social recognition, and in some cases, social bonds are normal features of mammalian social behavior.
- The most recently evolved structures of the nervous system are the most complex and also the most plastic. The more recently evolved components of the nervous system depend on the function of more ancient systems. Neocortical structures are in general subservient to systems necessary for survival. More primitive systems and behaviors, including those associated with fear and anxiety, may inhibit positive social behaviors and cognitive strategies. However, remarkably in humans and other primates, social strategies can suppress “selfish” needs in deference to the needs of others (altruism).
- Humans may owe their success as a species to their capacity to be highly social. Studying sociality is intrinsically important to understanding both normal and abnormal behavior. Moreover, the genetic and physiological underpinnings of various components of sociality, including the tendency to form social bonds, can be found and studied in non-primates, including rodents and unconventional animal models.
Taken as a whole, these points resonate with a critical observation of the Impediments group, which highlighted the importance of focusing on individual component behaviors relevant to psychopathologies and the delineation of behavioral endophenotypes to better understand the behavioral and neural characteristics of mental disorders.
Clinical Implications
As a starting point, the breakout group came up with a list of social and social-relevant processes for which there is good evidence for a link to well-defined clinical problems relevant to mental illness. These processes included:
Emotion Regulation: Relevant clinical issues include: Depression, Bipolar Disorder, Anxiety Disorders, Borderline Personality Disorder, Antisocial Personality Disorder (including impulsivity), Obsessive-compulsive Disorder, Schizophrenia (including affective blunting, anxiety), and Post-traumatic Stress Disorder
Self Processes: This area of basic research includes self-consciousness, self-esteem, self-image, source-monitoring, identity, and neglect. Relevant clinical issues include Depression, Eating Disorders, Schizophrenia, and Borderline Personality Disorder
Social Functioning: Basic research in this area includes social cognition, social competence, social motivation, social displays, and social dynamics. Relevant clinical issues include Schizophrenia and Autism.
Theory of Mind (including empathy, sympathy, perspective-taking): Relevant Clinical issues include Antisocial Personality Disorder and Autism
Personality/Individual differences: Relevant Clinical issues include modulators of risk factors, symptoms, and treatment efficacy in a range of disorders
The breakout group pointed out that all of the above are relatively well-developed areas of knowledge where it is currently feasible to begin applying findings to the appropriate clinical problems. Consequently, these are also examples of areas where further development of basic research, across multiple levels of analysis, will be of direct relevance to understanding mental disorders.
As with the “Levels of Analysis” group, these comments from the “Clinical” group fit well with an emphasis point from the “Impediments” group: through a careful examination of these component processes, we should be able to build a more comprehensive understanding of social behaviors and their neural correlates that might well represent clinically relevant endophenotypes for mental disorders.
Challenging topics include how to most effectively foster basic research of immediate relevance to clinical issues as well as how to enhance basic to clinical translational research. In the process of considering these issues, several items are worth mentioning:
- There can be limitations in the effectiveness of patient input in psychiatric disease diagnosis and treatment. This points to the need, echoed elsewhere in this report, for more well-developed endophenotypes for psychiatric disease, based on measures not limited to patient input. Social neuroscience studies of normative social interactions can create a “dictionary” of behaviors/neural events that can be considered as we explore the issue of better endophenotypes for these diseases.
- Participants discussed whether social deficits are part of the etiology of psychiatric diseases, directly implicated as a primary event in the development of the disease or whether social deficits are secondary consequences of the underlying primary pathophysiology. This issue cannot be addressed in the absence of fruitful basic social neuroscience approaches to fundamental social processing.
- The committee noted the existence, to some extent, of a divide between clinical and basic researchers. From the clinical side, if scientists engaged in basic research made a clearer case for the relevance of their findings to an improved understanding of mental disorders then this would greatly enhance the ability to translate basic research into clinically relevant findings. It was noted that this should mean something more than simply having basic researchers justify their research agenda based on clinical relevance. Instead, when clinical considerations, at any level, informs and modifies the basic research agenda, the case for relevance is demonstrably stronger.
Summary
In reviewing the findings of the workshop as a whole, based not only on the breakout group reports but the comments and interactions that took place in the plenary session, a number of points stand out:
- The importance of endophenotypes for the understanding of psychiatric disease and the significance of the contribution that can be made in this area through greater understanding of complex social behaviors and their neural basis
- The importance of emergent properties in complex systems: dynamic social interactions are a prime example
- The importance of basic researchers making a better case for the relevance of their work to an improved understanding of mental disorders. Participants recognized that what is meant by relevance for basic research is different from what is meant by relevance for translational research.
- Recognition that the developmental time course of many psychiatric diseases increases the need to properly consider developmental issues in social neuroscience
- The importance of understanding baseline states in the nervous system as important contributors to the generation of complex behaviors
- The importance of social context as a determinant or modulator of complex behavior including, at a technical level, the effects of the MRI scanning environment on the purported process under investigation