Xaolin Hu / Dr. Donald Edwards
Topic: A two-layer mutual inhibition behavior network for adaptability & social behavior
Abstract:
A major question in both neuroscience and robotics concerns the network mechanisms for making adaptive decisions in changing environmental contexts. One hypothesis considered in both fields is that of ‘winner-take-all' networks of competing centers, each of which mediates one pattern of behavior. The competition is mediated by mutual inhibition among these centers, where the inhibition is governed by a pattern of inhibitory coefficients. Earlier work showed that a network of nine mutually inhibitory centers could lead to adaptive decision-making when used to govern the behavior of each member of a group of model crayfish faced with finding food and shelter in the face of competition while avoiding capture by a predator. One problem with this mechanism arises when the inhibitory coefficients are fixed: the network may be well tuned to govern behavior in one context, but not well tuned when the context changes. We wish to determine whether the range of adaptive behavior can be significantly extended by adding a second layer of control that would alter the pattern of mutual inhibition according to which of several ‘behavioral states' is active. This layer would function much as hormonal systems alter the behavioral states of animals to make them more or less receptive to social/environmental/internal signals. We will test this mechanism in the control of both real and simulated robots as their behavioral context changes, and in the behavior of five model crayfish as they form a dominance hierarchy. The behavior of the model crayfish will be compared to that of five groups of juvenile crayfish as they form a dominance hierarchy. The results of these tests will allow us to alter or expand the scope of the decision architecture by incorporating hybrid states, mutual excitation, and mechanisms for learning, memory, and planning. It will also guide experimentation in crayfish neurethology by providing experimentally testable hypotheses about the neural mechanisms for decision-making.
Specific Aims:
• To develop and test the ability of an additional network layer of ‘behavioral states' to extend the ability of the ‘behavioral choice' layer to produce adaptive patterns of behavior under a wider range of external and internal conditions.
• To determine whether the two layer model can account for the change in social dominance interactions that occurs among small groups of juvenile crayfish as the hierarchy matures. We will perform statistical analysis of both simulation results and real crayfish data and compare them to find out which aspects of their group behavior during hierarchy formation can be captured by the model.
• To determine whether the two layer model enables both simulated agents and real robots to socially interact and cooperate to accomplish defined tasks. We will implement and test this decision architecture in real mobile robots behaving in real physical environments
Erin B. McClure / Eddy Nahmias
Title: Neurobiological, emotional, & cognitive components of social anxiety:behavioral & fMRI studies
Abstract:
What causes social anxiety? Our goal is develop methodologies designed to answer this question at the level of both cognitive and emotional processes and at the level of neurobiological activity. Our experimental paradigm will use real-life social interactions to measure differences between socially anxious individuals and controls in their behavioral patterns, emotional responses, cognition, and neural activity (using fMRI). Elucidating these differences will be highly significant in: (1) providing objective markers that can be used to identify and treat individuals suffering from social anxiety, (2) suggesting functional connections between cognitive and emotional neural systems involved in social anxiety, and (3) creating new experimental paradigms to study both social anxiety and Theory of Mind (ToM), the ability to understand others' behavior in terms of mental states (e.g., desires, beliefs, and intentions).
Prior research has been inconclusive regarding specific differences in behavior or neural activity between socially anxious individuals (SAs) and controls. However, the PI (McClure) has carried out research suggesting that in the Prisoner's Dilemma (PD) game, which involves social interaction and conflict, SAs, as compared to controls, are more likely to cooperate, respond more slowly, and experience more distress about interactions involving conflict. Our first experimental goal is to reproduce and expand upon these significant findings.
One possible unifying explanation for anxiety is that it is caused by situations of uncertainty in which people feel incapable of understanding or predicting what will happen. On this model, social anxiety would stem from social situations in which a person lacks an understanding of other people's intentions or lacks confidence in predicting their behavior in terms of their intentions. Our second experimental goal is to test this hypothesis by measuring differences between SAs and controls in success in the PD game (a measure of one's ability to predict others' behavior), speed of play (a measure of certainty), and confidence regarding predictions about others' intentions and behavior. Such differences would suggest a link between the emotional components of social anxiety and cognitive processes—notably, Theory of Mind. For instance, individuals with autism, who have diminished ToM abilities, also feel extreme anxiety in social situations. Prior research has successfully used interactive games such as PD to test ToM abilities.
Once we can establish significant differences between SAs and controls in specific behavioral, emotional, and cognitive measures during the PD task, this will then allow us to examine the neurobiological activity underlying these differences. Prior research using fMRI and PET scans has indicated that, relative to controls, SAs show differential activity in the amygdala and orbitofrontal cortex (OFC) during tasks that elicit social anxiety. (It is intriguing that these same brain areas have also been implicated in ToM tasks.) We will use fMRI to analyze neural activity in participants as they play PD games. Our hypothesis is that SAs will exhibit differential activity in at least these regions of interest, the amygdala and OFC, during the task and especially during conflicts (e.g., their own or co-player's defections, particularly after a series of cooperative interactions).
The success of these experiments would elucidate some of the specific behavioral, emotional, and cognitive components of social anxiety, establish the neurobiological activity associated with these components, and open the door for future research on theory of mind and social anxiety, including clinical interventions for this detrimental psychological condition. We are confident that the data obtained using a B&B Seed Grant over the next year would be sufficient to demonstrate the viability of these research paradigms in order to apply successfully for external funding.
Eric Vanman / David Washburn
Title: Psychophysiological measurement of affect in rhesus macaques
Abstract:
Studies of the neurophysiology of emotion reveal that human affect can be monitored through peripheral psychophysiological measures, such as skin conductance response (SCR) and facial electromyography (fEMG). These two measures can be particularly useful in combination, with SCR providing a linear index of general arousal (low to high), and fEMG differentiating positive versus negative responses. SCR and fEMG are also well-suited for use with nonhuman primates, whose largely inaccessible affective processes are a key component of brain function and thus of growing importance in areas such as affective and social neuroscience, clinical neuropsychology, and animal cognition and communication. Two recent studies show that peripheral psychophysiological measures can in fact be used with primates, and we propose to extend this work by programmatic development and validation of SCR and fEMG recording protocols with rhesus macaques ( Macaca mulatta ). Doing so will set the stage for submission of two external funding proposals centered on this methodology.
Four different testing regimens will be used, each designed to induce positive or negative affect occurring as anticipatory or as reactive responses. Anticipatory responses will be examined in monkeys receiving signals of extra-large food rewards or time-out penalties while performing a visual discrimination, and when the subjects are engaging in risky reward-seeking behavior in a “gambling” task. Reactive responses will be measured in animals receiving large rewards or penalties unexpectedly, and during non-conscious perception of photographs of conspecifics showing affiliative or threatening facial expressions. The proposed work with SCR responds to reviewers' concerns on a previous external funding application, builds directly on Amiez et al.'s (2003) application to rhesus monkeys, and will by itself be a sufficient foundation for the two proposals we envision. The fEMG measure has not previously been applied to rhesus monkeys, but is also deemed to have a strong likelihood of success. The research takes advantage of a rare combination of facilities, trained subjects, and collaborating investigators with a unique combination of experience and interests.
Marise Parent / Timothy Bartness
Title: Pathological effects of a hugh fructose diet on body weight and memory
Abstract:
Over the past 20 years, there has been an alarming increase in the consumption of simple sugars, such as fructose, in the North American diet. Extensive intake of fructose causes a variety of pathological changes, including insulin insensitivity. Diet-induced insulin resistance is considered to be a major cause of the explosive increase in cardiovascular disease, obesity, Syndrome X, and Type II diabetes over the past two decades. In rodents, insulin resistance is observed as soon as two weeks after a high fructose diet. The findings of a very recent study indicate that the damaging effects of a high fructose diet extend to the brain. Specifically, fructose feeding produces hippocampal insulin resistance and impairs hippocampal long term depression (Mielke, et al, 2005, J. Neurochem. 93 : p. 1568-78). Hippocampal long term depression is a form of synaptic plasticity that is dependent on a decrease of AMPA receptors, which is in turn facilitated by insulin. The research proposed herein aims to test the hypotheses that a high fructose diet impairs hippocampal dependent memory and alters hippocampal insulin and AMPA receptor number. Another consequence of a high fructose diet in humans and rodents is hyperlipidemia, and one likely consequence of hyperlipidemia is an increase in body weight and body fat mass. Surprisingly, the evidence in this regard is conflicting.
One possible reason for the conflict is that, although total weight may not be affected, body fat distribution may change. Another potential factor is that the existing studies vary in the duration of the high fructose diet. As a result, this research will also test the hypotheses that prolonged exposure to a high fructose diet increases body weight, body fat, and changes body fat distribution. Finally, we also propose to test the hypothesis that a return to a normal diet will reverse the effects of elevated fructose consumption or prevent further deterioration.
Aras Petrulis / Ann Murphy
Title: Neuroanatomy of Sexual Solicitation: Vaginal marking in female golden hamsters
Abstract:
The vast majority of research on the neurobiology of female sexual behavior has focused on the receptive posture (lordosis) that the female rodents display when interacting with males. Consequently, much less is known about the neural systems that regulate motivational aspects of female reproduction such as proceptive, solicitational or signaling behaviors required for reproductive synchrony. This is unfortunate, as problems with motivation, rather than receptivity per se, underlie most cases of sexual dysfunction in humans and other animals. To address this issue, we will define the neural network that underlies one such stereotyped signaling behavior (vaginal marking) in female golden hamsters. To do so, we will first identify, through selective ablations of peripheral nerves, the striated and smooth muscles involved in vaginal marking behavior and odor secretion. Second, we will identify the motor control pathways controlling vaginal marking throughout the neuroaxis by the selective placement of the retrograde, trans-synaptic tracer, pseudorabies virus (PRV), within vaginal marking-relevant muscle groups. Third, as lordosis behavior is inhibitory to vaginal marking, we will identify, using injections of two isogenic strains into lordosis and vaginal-marking muscles, the neural location(s) at which this interaction takes place. Lastly, as vaginal marking are dependent on estrogen, we will determine the location of estrogen-responsive segments of the vaginal marking pathways by immunohistochemical localization of estrogen receptor alpha and PRV. Identifying the anatomical connectivity of this circuitry is critical for future attempts at establishing the functional nature of these identified circuits.
Diana L. Robins / Tricia Z. King
Title: Neurophysiological mechanisms underlying emotion perception
Abstract:
This seed grant will explore the neural mechanisms involved in the perception of emotion. The methodology combines the presentation of novel movie stimuli with emotional cues in both facial expression and tone of voice with the methodologies of functional MRI (fMRI) and electromyelography (EMG). This multilevel investigation will identify underlying neurophysiological factors contributing to emotion perception, in both typical individuals and individuals with autism spectrum disorders, a clinical population known to have difficulty with emotion perception. The central aim of this study is to examine the facial bias evidenced when participants are presented with conflicting visual and auditory emotional cues. Participants will be exposed to movies and required to label the emotion perceived during both functional MRI and psychophysiological experimental paradigms. The results of this study will demonstrate the feasibility of conducting this research at Georgia State University and will be used as pilot data to support RO1 applications to NIH. |
