NEWARK, NJ – The National Institute of Mental Health estimates that in any given year, about 40 million adults (18 or older) will suffer from some form of anxiety disorder, including debilitating conditions such as phobias, panic disorders and post-traumatic stress disorder (PTSD). It is estimated that nearly 15 percent of U.S. soldiers returning from Iraq and Afghanistan develop PTSD, underscoring the urgency to develop better treatment strategies for anxiety disorders. These disorders can lead to myriad problems that hinder daily life – or ruin it altogether – such as drug abuse, alcoholism, marital problems, unemployment and suicide.

Functional imaging studies in combat veterans have revealed that the amygdala, a cerebral structure of the temporal lobe known to play a key role in fear and anxiety, is hyperactive in PTSD subjects. Potentially paving the way for more effective treatments of anxiety disorders, a recent Nature report by Denis Paré, professor at the Center for Molecular and Behavioral Neuroscience at Rutgers University in Newark, has identified a critical component of the amygdala’s neural network normally involved in the extinction, or elimination, of fear memories. Paré’s laboratory studies the amygdala and how its activity impacts behavior. His research was published online by Nature on July 9, 2008 and is scheduled to appear in the print edition later in July.

Earlier research has revealed that in animals and humans, the amygdala is involved in the expression of innate fear responses, such as the fear of snakes, along with the formation of new fear memories as a result of experience, such as learning to fear the sound of a siren that predicts an air raid.

In the laboratory, the circuits underlying learned fear are typically studied using an experimental paradigm called Pavlovian fear conditioning. In this research model on rats, a neutral stimulus such as the sound of a tone elicited a fear response in the rats after they heard it paired with an noxious or unpleasant stimulus, such as a shock to the feet. However, this conditioned fear response was diminished with repetition of the neutral stimulus in the absence of the noxious stimulus. This phenomenon is known as extinction. This approach is similar to that used to treat human phobias, where the subject is presented with the feared object in the absence of danger.

Behavioral studies have demonstrated, however, that extinction training does not completely abolish the initial fear memory, but rather leads to the formation of a new memory that inhibits conditioned fear responses at the level of the amygdala. As such, fear responses can be expressed again when the conditioned stimulus is presented in a context other than the one where extinction training took place.

For example, suppose a rat is trained for extinction in a grey box smelling of roses, and later hears the tone again in a different box, with a different smell and appearance. The rat will show no evidence of having been trained for extinction. The tone will evoke as much fear as if the rat had not been trained for extinction.

“Extinction memory will only be expressed if tested in the same environment where the extinction training occurred, implying that extinction does not erase the initial fear memory but only suppresses it in a context-specific manner,” notes Paré.

Importantly, it has been found that people with anxiety disorders exhibit an “extinction deficit,” or a failure to “forget.” However, until recently, the mechanisms of extinction have remained unknown.

As reported by Nature, Paré has found that clusters of amygdala cells, known as the intercalated (ITC) neurons, play a key role in extinction. His findings indicate that ITC cells inhibit amygdala outputs to the brain stem structures that generate fear responses. Indeed, Paré and his collaborators have shown that when ITC cells are destroyed with a targeted toxin in rats, extinction memory is impeded, mimicking the behavior seen in PTSD.

The significance of this finding derives from earlier results suggesting that PTSD reflects an extinction deficit and that the amygdala is hyperactive in this disorder. As a result, it might be possible to compensate for this abnormality and facilitate extinction with pharmacological interventions that enhance the excitability of ITC cells to inhibit amygdala output.

Research using fMRI scans shows tendencies toward kindness When a child is shown a photo of someone accidently hurting himself, portions of the brain are activated which are related to pain. Click here for more information.

Children between the ages of seven and 12 appear to be naturally inclined to feel empathy for others in pain, according to researchers at the University of Chicago, who used functional Magnetic Resonance Imaging (fMRI) scans to study responses in children.

The responses on the scans were similar to those found in studies of adults. Researchers found that children, like adults, show responses to pain in the same areas of their brains. The research also found additional aspects of the brain activated in children, when youngsters saw another person intentionally hurt by another individual.

“This study is the first to examine in young children both the neural response to pain in others and the impact of someone causing pain to someone else,” said Jean Decety, Professor in the Departments of Psychology and Psychiatry at the University of Chicago, who reported the findings in the article, “Who Caused the Pain? An fMRI Investigation of Empathy and Intentionality in Children,” published in the currrent issue of Neuropsychologia. Joining him as co-authors were University students Kalina Michalska and Yuko Aktsuki. When a child sees pain intentionally inflicted on another, portions of the brain are activated that are associated with social interaction and moral reasoning in addition to those associated with… Click here for more information.

The programming for empathy is something that is “hard-wired” into the brains of normal children, and not entirely the product of parental guidance or other nurturing, said Decety. Understanding the brain’s role in responding to pain can help researchers understand how brain impairments influence anti-social behavior, such as bullying, he explained.

For their research, the team showed 17 typically developed children, ages seven to 12, animated photos of people experiencing pain, either received accidentally or inflicted intentionally. The group included nine girls and eight boys.

While undergoing fMRI scans, children where shown animations using three photographs of two people whose right hands or right feet only were visible.

The photographs showed people in pain accidently caused, such as when a heavy bowl was dropped on their hands, and situations in which the people were hurt, such as when a person stepped intentionally on someone’s foot. They were also shown pictures without pain and animations in which people helped someone alleviate pain.

The scans showed that the parts of the brain activated when adults see pain were also triggered in children.

“Consistent with previous functional MRI studies of pain empathy with adults, the perception of other people in pain in children was associated with increased hemodymamic activity in the neural circuits involved in the processing of first-hand experience of pain, including the insula, somatosensory cortex, anterior midcigulate cortex, periaqueductal gray and supplementary motor area,” Decety wrote.

However, when the children saw animations of someone intentionally hurt, the regions of the brain engaged in social interaction and moral reasoning (the temporo-parietal junction, the paracigulate, orital medial frontal cortices and amygdala) also were activated.

The study, which was supported by the National Science Foundation, provides new insights for children between childrens’ perceptions of right and wrong and how their brains process information, Decety said. “Although our study did not tap into explicit moral judgment, perceiving an individual intentionally harming another person is likely to elicit the awareness of moral wrongdoing in the observer,” he wrote.

Subsequent interviews with the children showed they were aware of wrong-doing in the animations in which someone was hurt. “Thirteen of the children thought that the situations were unfair, and they asked about the reason that could explain this behavior,” Decety said.