Heightened level of amygdala activity may cause social deficits in autism

March 20, 2009

Something strange is going on in the amygdala - an almond-shaped structure deep in the human brain - among people with autism.

Researchers at the University of Washington have discovered an increased pattern of brain activity in the amygdalas of adults with autism that may be linked to the social deficits that typically are associated with the disorder. Previous research at the UW and elsewhere has shown that abnormal growth patterns in the amygdala are commonly found among young children diagnosed with autism.

The amygdala is popularly associated with the "fight-or-flight response" in dangerous situations. But it has other functions, including identifying faces and situations and evaluating social information such as emotions.

The new research shows that brain activation in adults with autism remains elevated long after similar brain regions of typically developed adults have stopped being activated when exposed to a series of pictures of human faces. A decrease in activation over time to the same type of information is called neural habituation and is connected with learning, according to Natalia Kleinhans, lead author of the new study and a UW research assistant professor of radiology.

"What we are seeing is hyperexcitability or overarousal of the amygdala, which suggests that neurons in the amygdala are firing more than expected," said Kleinhans, who is associated with the UW Autism Center.

"If you consider that habituation reflects learning in as simple a task as looking at a face, slowness to habituate in people with autism may contribute even more markedly to difficulty with more complex social interactions and social cognition. If the brain is not reacting typically to a static face with a neutral expression, you can imagine how difficult it may be for someone with autism to pick up more subtle social cues."

The National Institute of Child Health and Human Development and the National Institute of Mental Health funded the research, which appears in the online edition of The American Journal of Psychiatry.

The UW researchers used functional magnetic resonance imaging to examine brain activation in 19 individuals with autism and in a comparison group of 20 healthy adults. The subjects ranged in age from 18 to 44 and the two groups were matched for IQs in the low-normal range. Both groups had their brains scanned while they looked at series of faces with neutral expressions. Each face appeared on a screen for three seconds and occasionally a face would be repeated two consecutive times. When that happened subjects were instructed to push a button.

The scientists were interested in what happened in two brain regions, the amygdala and the fusiform gyrus, when the subjects viewed the faces. It turned out that the fusiform gyrus, which helps determine what kind of object a person is looking at - a face or a house, for example - showed no habituation in either group. But the differences were striking when it came to the amygdala.

"The differences we found were in the amygdala and specific to the amygdala," said Kleinhans. "They originated there and did not go across the brain."

She said one theory about autism is that when this hyperarousal occurs an individual misses important information. Those individuals with autism who had the most social impairment exhibited the highest levels of amygdala arousal.

"This is another piece of evidence that there is something wrong with the amygdala in autism that contributes to social impairment. These results help refine our understanding of functional abnormalities in autism and are a new way of thinking about social dysfunction in autism," said Kleinhans.

University of Washington

---

---

	The Human Amygdala by Paul J. Whalen PhD (Editor), Elizabeth A. Phelps PhD (Editor) Building on pioneering animal studies, and making use of new, noninvasive techniques for studying the human brain, research on the human amygdala has blossomed in recent years. This comprehensive volume brings together leading authorities to synthesize current knowledge on the amygdala and its role in psychological function and dysfunction. Initial chapters discuss how animal models have paved the way for work with human subjects. Next, the book examines the amygdala's involvement in emotional processing, learning, memory, and social interaction. The final section presents key advances in understanding specific clinical disorders: anxiety disorders, depression, schizophrenia, autism, and Alzheimer's disease. Illustrations include 39 color plates....
	Tickle Your Amygdala by Neil G Slade (Author), Neil G Slade (Illustrator) TICKLE YOUR AMYGDALA shows you how to turn on the best part of your brain- as simple as imagining a feather inside your head. And now, the latest brain science and brain imaging has proven that thought really is the most incredible Mind Over Gray Matter! This book will show you how to turn on the most powerful Brain Radar in the entire You-Niverse. Its waiting for you right between your ears. Part One: The Illustrated Tickle Your Amygdala is a fun, simple, and quick explanation to help you get the general idea of what amygdala tickling is all about. Part Two: The Amygdala Tickling Three Course Gourmet Presentation includes Detailed Explanations of Amygdala Tickling, Amygdala Interviews, and Ways to Do It, including the science behind amygdala tickling and 52 Ways to Tickle- Thats a new...
	What Freud Didn't Know: A Three-Step Practice for Emotional Well-Being through Neuroscience and Psychology by Timothy B. Stokes Ph.D. (Author) What Freud Didn’t Know,combines neuroscience and psychology to explain how the amygdala region of the brain evolved to unconsciously record, store, and activate emotional memory loops and imagery associated with painful events, especially those of childhood. This book is the first to bring together diverse, post-Freudian discoveries to produce a coherent three-step practice for understanding problematic aspects of the human mind which can be mastered easily, in a clinical or self-help setting.
	The Frontal Lobes Supercharge (Neil Slade Brain Books) by Neil Slade Brain Books The Frontal Lobes Superchargeis a fun, illustrated, super-handbook with complete directions how to self-stimulate those previously "secret" switches and areas of the brain- and easily turn on incredible pleasure, genius creativity, super intelligence, and tap into pre-existing circuits for extra-sensory and paranormal abilities. Please see http://www.neilslade.com/flbook.html for all details. Turn on incredible creativity, intelligence, pleasure, and even paranormal abilities as easy as clicking on a light switch! The Frontal Lobes Supercharge is an easy to use do-it-yourself manual for turning on untapped areas of each and every person’s brain- "the other 90%". Author Neil Slade presents his revolutionary lessons with methods and exercises...
	The Amygdala: A Functional Analysis by John P. Aggleton (Editor) The amygdala is a central component of the limbic brain system and is known to be vital to understanding aspects of emotions, memory and social behavior. Dysfuction of the structure is also thought to contribute to a variety of disorders, including autism, Alzheimer's Disease and schizophrenia. The nature of its contribution to these fundamental aspects of behavior and cognition, and its relationship with other regions of the brain has remained elusive. However, since Aggleton's first book on the subject - The Amygdala: Neurobiological Aspects of Emotion, Memory, and Mental Dysfunction (1992) - there have been some major advances in our understanding of the processes involved and a dramatic rise in the volume of research. Scientists are now able to define its contribution in an...
	The Prefrontal Cortex, Fourth Edition by Joaquin Fuster (Editor) This is the fourth edition of the undisputed classic on the prefrontal cortex, the principal "executive" structure of the brain. Because of its role in such cognitive functions as working memory, planning, and decision-making, the prefrontal cortex is critically involved in the organization of behavior, language, and reasoning. Prefrontal dysfunction lies at the foundation of several psychotic and neurodegenerative disorders, including schizophrenia and dementia. * Written by an award-winning author who discovered "memory cells"-the physiological substrate of working memory * Provides an in-depth examination of the contributions of every relevant methodology, from comparative anatomy to modern imaging * Well-referenced with more than...
	AMYGDALA by Evan Miller (Author) Shane Martin was born with a mental trigger that sends him into a PCP-like state of mind; a time bomb starts the day that trigger is pulled. Feeling no pain or remorse and disassociating further from reality, he begins hurting people- to the point of murder. Now, with his only savior paralyzed by fear at the very sight of him, Shane is practically unstoppable. If Shane can't be saved in time, he'll begin hurting those he holds dearest; and the only way to stop him will be to kill him.
	Volumetry of amygdala and hippocampus and memory performance in [An article from: Psychiatry Research: Neuroimaging by M. Basso (Author), J. Yang (Author), L. Warren (Author), M.G. MacAvoy (Author), Varma (Author) This digital document is a journal article from Psychiatry Research: Neuroimaging, published by Elsevier in 2006. The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser. Abstract: Magnetic resonance imaging (MRI) is showing increased utility in examining medial temporal lobe atrophy and its relationship to memory performance in Alzheimer's disease (AD). We studied 56 AD patients and 42 older healthy subjects with neuropsychological assessment and MRI. Hippocampal and amygdaloid volumes (normalized to intracranial volume) were contrasted between AD patients and healthy controls and correlated with neuropsychological performance. Comparisons between AD patients and healthy controls...
	The Limbic Brain by Andrew L. Lautin (Author) This book is at once a textbook on neuroanatomy, specifically the features of the limbic brain, and a history of medicine. It weaves together the historical and scientific strands of research on the limbic brain, which houses consciousness and emotion in mammals, especially man, and in which there is now growing interest among researchers, specifically those involved in the behavioral neurosciences.