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Neuroscience on Desire
Once scientists began studying the structure of the brain, and looking at activity in different areas, they began to gather evidence that feelings of desire occur in the brain regions that are also associated with reward and addiction. Helen Fisher, a scientist who has done fMRI studies of people who are in love, published a book called Why We Love that sums up a lot of the findings in this area. She suggests that love and its loss are functionally similar to addiction and getting sober.Somebody a long time ago had it right.
Other neuroscientists have focused on the sexual side of desire, exploring what your brain is doing when you get turned on and have orgasms. One of the pioneers in this field, neuroscientist Barry Komisaruk, have mapped the brain regions that become active in women who are aroused and orgasmic. It turns out that there is no single “pleasure center” in the brain - orgasms tend to light up a wide variety of brain regions related to everything from memory to higher reason. They’ve also discovered that, in women at least, orgasmic impulses can reach the brain even when the spinal cord is damaged, which suggests that there are non-spinal nerve connections between the vagina and the brain. (via)
(via psyche-yourself)
It has always been assumed that the first thing that happens is that we have the experience an emotion, and then and only then do we start reacting to the situation physiologically. But over a hundred years ago, William James, the father of American psychology, and Carl Lange, a Danish psychologist, separately introduced the idea that we have it all backwards: First, they said, we have physiological responses to a situation, and only then do we use those responses to formulate an experience of emotion. This is called the James-Lange theory.
Walter Cannon and Phillip Bard came up with a variation on the James-Lange idea in 1929: They suggested that there are neural paths from our senses that go in two directions. One goes to the cortex, where we have a subjective experience, and one goes to the hypothalamus, where the physiological processes begin. In other words, the experience of an emotion, and the physiological responses occur together. This is (as you might expect by now) called the Cannon-Bard theory.
In 1937, James Papez noted that the physiological side of emotion is not just a matter of the hypothalamus, but is a complex network of neural pathways — the Papez circuit. In 1949, Paul McLean completed and corrected Papez’s ideas, and called the larger complex the limbic system, which is what we call it today. It included the hypothalamus, the hippocampus, and the amygdala, and is tightly connected with the cingulate gyrus, the ventral tegmental area of the brain stem, the septum, and the prefrontal gyrus.
Paul McLean is also the founder of the triune brain theory. He suggested that there is a certain evolutionary quality to the structure of the brain. Reptiles, he said, function entirely in terms of instinct, and their brains are little more than what we call the brain stem in people. He called it the archipallium or reptilian brain, and it includes the medulla, cerebellum, the pons, and the olfactory bulbs. Above this is the paleopallium, or old mammalian brain. This is the limbic system and the portions of the brain we call the old cortex. Of course, this adds emotions to the reptilian picture, and allows for simple learning. And on top of the paleopallium is the neopallium (aka new mammalian or rational brain, or neocortex). This is where more advanced activities occur, including awareness. McLean adds that, in human beings, these three “brains” don’t always behave cooperatively, which leads to some of the unique problems we have!
- The researchers looked at MRI brain scans of a large group of healthy adults. In particular, they were looking for the paracingulate sulcus (PCS), a fold near the front of the brain. There’s a lot of variability in the PCS: some people have quite distinctive folds, others have barely any. It’s in a part of the brain known to be important in keeping track of reality, which is why the researchers chose to study it. Of the 53 people selected for the study, some had this fold on both sides of their brain, some had it on one side, and some had no fold.
- The participants saw some full well-known word pairs (“Jekyll and Hyde”) and some half pairs (“Jekyll and ?”). If they only saw half of a pair, they were asked to imagine the other half (“Hyde”). After each pair or half pair, either the participant or the experimenter said the whole pair aloud.
- Once they’d seen all the pairs, the participants were asked two questions about each phrase: Did you see both words of the pair, or just one? And who said the phrase aloud, you or the experimenter?
- People who didn’t have the fold on either side of their brains did worse on both questions—remembering if something was real or imagined, and remembering who’d done something—than people whose brains had the fold. But they felt as confident in their answers, meaning they didn’t realize they’d been mixing up internal and external events.
Along with schizophrenia, the PCS would also be a place of interest for study on the ability to lucid dream.
(via fuckyeahpsycharticle)
This would be one sad neuro blog if I didn’t mention researchers from the University of California, Berkeley, “using fMRI and computational models, were able to decipher and reconstruct movies from our minds” by associating brain activity of subjects with the video being viewed, piecing it together and replaying it.
Watch that video. Amazing. And blurry. Here’s what it means:
While watching the first set of trailers, the fMRI measured blood flow through the visual cortex and this information was directed to a computer, which portrayed the brain as tiny three-dimensional cubes called “voxels,” or volumetric pixels. For each voxel, there was a model that detailed how motion and shapes in the movie are translated into brain activity. The computer program learned to relate visual patterns in the trailers with corresponding brain activity. Via“…the technology can only reconstruct movie clips people have already viewed. However, the breakthrough paves the way for reproducing the movies inside our heads that no one else sees, such as dreams and memories, according to researchers.” ViaA highly technical and creative experiment showing an interpretation of what our brain “sees” so that one day we may be able to see what is going on in the minds of non verbal patients, e.g. coma, stroke or severe autism.
(via fuckyeahpsycharticle)
Terrible headline from Popular Science on this one. The study they are talking about is titled Effect of prefrontal transcranial magnetic stimulation on spontaneous truth-telling (a little different, huh?) and used transcranial magnetic stimulation to send a tiny electrical pulse to a specific part of the brain, the dorsolateral prefrontal cortex -see below. This area has been found to play a large role in deception and complex thinking.
So in this experiment 16 people (it’s really tough to get a large number of people willing to let you zap thier brain for some reason) had left or right hemisphere stimulation to “ test whether spontaneous propensity to lying can be changed by brain stimulation”.
The eight people who had their left DPC stimulated lied more often, the researchers said. The ones with the right DPC stimulated were more likely to tell the truth.
Although not as flashy, the actual study is more amazing than a science writer’s grabby headline, since it’s closer to the truth, on more than one level.
(via fuckyeahpsycharticle)
Conjoined twins sharing a brain
Krista and Tatiana are joined by the head, in medical terms this is known as craniopagus. They are one in 2.5 million babies.
Douglas Cochrane of British Columbia Children’s Hospital, the twins’ neurosurgeon, describes their condition as their thalamus being linked by a bridge. He says that is the input that one of the twins receives crosses that bridge it is entirely possible that the sense crosses to the other twin’s brain. Their brains are connected by a live wire.
In the company of the New York Times reporter, Krista and Tatiana refer to themselves with certainty as “I”. They both simultaneously say “I have two pieces of paper” and repeat the phrase.
They never refer to themselves as “we”, always as one person. Although ordinarily people have the ability to default to the idea of “self” and “I”, these two feel what the other feels. They are two people living with the same sensory input. But this begs the question how far it goes beyond the sensory aspect.
