05 February 2014
23 Parents Describe Their Kids’ Creepy Imaginary Friends (That Are Probably Actually Demons)
11 September 2013
'Love hormone' oxytocin may play wider role in social interaction than previously thought
Some genetic evidence suggests the awkward social interaction that is a hallmark of autism-spectrum disorders may be at least in part oxytocin-related. Certain variations in the gene that encodes the oxytocin receptor - a cell-surface protein that senses the substance's presence - are associated with increased autism risk.
Malenka, the Nancy Friend Pritzker Professor in Psychiatry and Behavioral Sciences, has spent the better part of two decades studying the reward system - a network of interconnected brain regions responsible for our sensation of pleasure in response to a variety of activities such as finding or eating food when we're hungry, sleeping when we're tired, having sex or acquiring a mate, or, in a pathological twist, taking addictive drugs. The reward system has evolved to reinforce behaviors that promote our survival, he said.
For this study, Malenka and lead author Gül Dölen, MD, PhD, a postdoctoral scholar in his group with over 10 years of autism-research expertise, teamed up to untangle the complicated neurophysiological underpinnings of oxytocin's role in social interactions. They focused on biochemical events taking place in a brain region called the nucleus accumbens, known for its centrality to the reward system.
In the 1970s, biologists learned that in prairie voles, which mate for life, the nucleus accumbens is replete with oxytocin receptors. Disrupting the binding of oxytocin to these receptors impaired prairie voles' monogamous behavior. In many other species that are not monogamous by nature, such as mountain voles and common mice, the nucleus accumbens appeared to lack those receptors.
"From this observation sprang a dogma that pair bonding is a special type of social behavior tied to the presence of oxytocin receptors in the nucleus accumbens. But what's driving the more common group behaviors that all mammals engage in - cooperation, altruism or just playing around - remained mysterious, since these oxytocin receptors were supposedly absent in the nucleus accumbens of most social animals," said Dölen.
The new discovery shows that mice do indeed have oxytocin receptors at a key location in the nucleus accumbens and, importantly, that blocking oxytocin's activity there significantly diminishes these animals' appetite for socializing. Dölen, Malenka and their Stanford colleagues also identified, for the first time, the nerve tract that secretes oxytocin in the region, and they pinpointed the effects of oxytocin release on other nerve tracts projecting to this area.
Mice can squeak, but they can't talk, Malenka noted. "You can't ask a mouse, 'Hey, did hanging out with your buddies a while ago make you happier?'" So, to explore the social-interaction effects of oxytocin activity in the nucleus accumbens, the investigators used a standard measure called the conditioned place preference test.
"It's very simple," Malenka said. "You like to hang out in places where you had fun, and avoid places where you didn't. We give the mice a 'house' made of two rooms separated by a door they can walk through at any time. But first, we let them spend 24 hours in one room with their littermates, followed by 24 hours in the other room all by themselves. On the third day we put the two rooms together to make the house, give them complete freedom to go back and forth through the door and log the amount of time they spend in each room."
Mice normally prefer to spend time in the room that reminds them of the good times they enjoyed in the company of their buddies. But that preference vanished when oxytocin activity in their nucleus accumbens was blocked. Interestingly, only social activity appeared to be affected. There was no difference, for example, in the mice's general propensity to move around. And when the researchers trained the mice to prefer one room over the other by giving them cocaine (which mice love) only when they went into one room, blocking oxytocin activity didn't stop the mice from picking the cocaine den.
In an extensive series of sophisticated, highly technical experiments, Dölen, Malenka and their teammates located the oxytocin receptors in the murine nucleus accumbens. These receptors lie not on nucleus accumbens nerve cells that carry signals forward to numerous other reward-system nodes but, instead, at the tips of nerve cells forming a tract from a brain region called the dorsal Raphe, which projects to the nucleus accumbens. The dorsal Raphe secretes another important substance, serotonin, triggering changes in nucleus accumbens activity. In fact, popular antidepressants such as Prozac, Paxil and Zoloft belong to a class of drugs called serotonin-reuptake inhibitors that increase available amounts of serotonin in brain regions, including the nucleus accumbens.
As the Stanford team found, oxytocin acting at the nucleus accumbens wasn't simply squirted into general circulation, as hormones typically are, but was secreted at this spot by another nerve tract originating in the hypothalamus, a multifunction midbrain structure. Oxytocin released by this tract binds to receptors on the dorsal Raphe projections to the nucleus accumbens, in turn liberating serotonin in this key node of the brain's reward circuitry. The serotonin causes changes in the activity of yet other nerve tracts terminating at the nucleus accumbens, ultimately resulting in altered nucleus accumbens activity - and a happy feeling.
"There are at least 14 different subtypes of serotonin receptor," said Dölen. "We've identified one in particular as being important for social reward. Drugs that selectively act on this receptor aren't clinically available yet, but our study may encourage researchers to start looking at drugs that target it for the treatment of diseases such as autism, where social interactions are impaired."
Malenka and Dölen said they think their findings in mice are highly likely to generalize to humans because the brain's reward circuitry has been so carefully conserved over the course of hundreds of millions of years of evolution. This extensive cross-species similarity probably stems from pleasure's absolutely essential role in reinforcing behavior likely to boost an individual's chance of survival and procreation.
Source: http://ow.ly/oMDEV
31 October 2011
Moment huge beast tried to play pat-a-cake with a toddler
Photographer Dyrk Daniels noticed the 370lb Golden Bengal Tiger had taken an interest in the child, who was leaning against his glass enclosure.
As the tiger, called Taj, headed over to her, Mr Daniels got his camera ready, expecting him to snarl and bang against the glass.
Tender moment: Rather than banging against the glass, the tiger gently put its paw up to the little girl's hand
But amazingly the tiger hung his head, stretched a paw out to her hand and rubbed his cheek against where the girl's face was.
Father-of-two Dyrk Daniels, 47, went to Cougar Mountain Zoo in Issaquah, Washington State, to photograph the Bengal tigers.
When he got to the enclosure there were several children and families in the area, so he decided to let them see the tigers first before he tried to photograph them himself.
‘That is when I noticed this little girl was leaning against the glass with both hands out stretched staring at the ‘big kitties’,’ he said.
Gentle giant: As the tiger headed over to the glass partition towards the little girl, photographer Dyrk Daniels thought the big cat would snarl and frighten her
Bonding: The tiger put its face right down so the little girl could look it straight in the eye
‘I noticed that Taj had taken an interest in the girl and was heading towards her.
‘I thought for certain that the little girl would need therapy after the encounter and fear cats for the rest of her life.
‘I could not believe my eyes when Taj approached the girl, bowed his head and then placed his huge right paw exactly in front of where the little girl's left hand was.
‘It was incredible to watch. Taj let down his right paw, rubbed his cheek against the glass where the little girl's face was and moved off.’
Far from being scared, the little girl was so excited that she started clapping as she walked back afterwards towards her mother.
‘I have never seen such tenderness from such a large predator,’ Mr Daniels said.
25 October 2011
Ran over a child twice 'because it was cheaper than paying the hospital bills'
A lorry driver ran over a five-year-old boy – and then reversed over him to make sure he was dead in an apparent attempt to avoid footing hospital bills for the child.
The sickening incident happened in Luzhou, western China, when driver Ao Yong hit Xiong Maoke as he left home to walk to school.
Witness Zhang Shifen said: ‘I saw the truck move back a little and then move forward again. Xiong became wrapped up in the wheel and the truck continued forward another ten yards.’
The tragedy comes just a week after two-year-old Yue Yue was knocked down by two vehicles on a busy market street. The child was ignored by 18 passers-by before someone came to her aid. She died in hospital a few days later.
Fatal: Xiong Maoke's mother sits beside the truck that killed her five-year-old son. The image of the child's body has been pixelated by MailOnline
Sickening: The truck that killed Xiong as he was walked home to school in Luzhou, western China
In this latest incident passers-by said the lorry driver jumped from his cab after hitting the boy. They claimed Yong then asked: ‘How much shall I pay?’
After the latest incident, Yong denied reversing over the boy to kill him. Last night, police and government staff insisted Xiong died on impact.
Their investigation ruled that Yong was the first person to call the police after his truck hit the boy in the village of Yunfeng, in Luzhou, Sichuan province.
They said his body was not removed immediately because angry villagers were demanding instant compensation from the driver.
In heartrending scenes, the boy's mother sat shocked next to the covered body of her five-year-old son.
A string of such horrific cases have led to soul-searching in China, where the economic boom has been blamed for fuelling materialism at the cost of compassion.
Handing over compensation if an accident victim dies is seen by many Chinese as cheaper than paying for lengthy hospital treatment. The Communist regime does not provide free healthcare for its 1.3billion citizens.
Ignored: In a similar incident the previous week, Yue Yue was left with horrific brain injuries and never recovered
The fear of high medical bills is also thought to be behind a second accident in China in which toddler Yue Yue was knocked down by two vehicles on a busy market street.
The gruesome ordeal, captured by security cameras, showed the bleeding child was ignored by 18 passers-by before she was picked up by a scrap picker and given to her mother, who rushed to the street looking for her.
A week after the accident, she died in hospital.
Two drivers suspected of running over the Chinese toddler were arrested on Sunday.
The Beijing News and other outlets reported that police in the city of Foshan concluded their initial investigation and ordered the two men formally arrested, a step that almost always leads to a trial.