Volume 107, April 2015, Pages 61–68
Highlights
BEFORE
AFTER
The level of sex hormone progesterone predicts the subjective vividness of mental images in two separate samples.
The level of sex hormone progesterone predicts the sensory strength of mental images, measured objectively.
Abstract
“Mystery surrounds the cause of large individual differences in mental imagery vividness and strength, and how these might map onto mental disorders. Here, we report the concentration of sex hormones predicts the strength and vividness of visual mental imagery. We employed an objective measure of imagery utilizing binocular rivalry and a subjective questionnaire to assess imagery. The strength and vividness of imagery was greater for females in the mid luteal phase than both females in the late follicular phase and males. Further, imagery strength and vividness were significantly correlated with salivary progesterone concentration. For the same participants, performance on visual and verbal working memory tasks was not predicted by progesterone concentration. These results suggest sex hormones might influence visual imagery, but not general working memory. As hormone concentration changes over time, this implies a partial dynamic basis for individual differences in visual mental imagery, any dependent cognition and mental disorders.
“Progesterone is also used to ease withdrawal symptoms when certain drugs (benzodiazepines) are discontinued.
“When many of us think of progesterone , we think of it as being a hormone strictly for women. However, men need progesterone too. Progesterone helps to counteract the effects of estrogen on the male body. Not only is progesterone found in males, but men rely on the alleged "female hormone" to preserve their masculinity. In fact, progesterone is a precursor to testosterone - the male sex hormone.
“Men with low levels of progesterone have a higher risk of developing health conditions, such as osteoporosis, arthritis, prostatism and prostate cancer.
“In addition to testing testosterone levels, men should also consider having other hormones tested to get a clearer picture of what's going inside their bodies. This includes estrogen, progesterone, cortisol, DHEA and thyroid hormones. Hormonal balance is like a jig-saw puzzle - without all of the pieces in place, it just doesn't work.
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Mouse brain connection to immune system
“In a stunning discovery that overturns decades of textbook teaching, researchers at the University of Virginia School of Medicine have determined that the brain is directly connected to the immune system by vessels previously thought not to exist. That such vessels could have escaped detection when the lymphatic system has been so thoroughly mapped throughout the body is surprising on its own, but the true significance of the discovery lies in the effects it could have on the study and treatment of neurological diseases ranging from autism to Alzheimer’s disease to multiple sclerosis.
“Instead of asking, ‘How do we study the immune response of the brain?’ ‘Why do multiple sclerosis patients have the immune attacks?’ now we can approach this mechanistically. Because the brain is like every other tissue connected to the peripheral immune system through meningeal lymphatic vessels,” said Jonathan Kipnis, PhD, professor in the UVA Department of Neuroscience and director of UVA’s Center for Brain Immunology and Glia (BIG). “It changes entirely the way we perceive the neuro-immune interaction. We always perceived it before as something esoteric that can’t be studied. But now we can ask mechanistic questions.”. . .
Antoine Louveau
Even Kipnis was skeptical initially. “I really did not believe there are structures in the body that we are not aware of. I thought the body was mapped,” he said. “I thought that these discoveries ended somewhere around the middle of the last century. But apparently they have not.”. . .
The discovery was made possible by the work of Antoine Louveau, PhD, a postdoctoral fellow in Kipnis’ lab. The vessels were detected after Louveau developed a method to mount a mouse’s meninges – the membranes covering the brain – on a single slide so that they could be examined as a whole. “It was fairly easy, actually,” he said. “There was one trick: We fixed the meninges within the skullcap, so that the tissue is secured in its physiological condition, and then we dissected it. If we had done it the other way around, it wouldn’t have worked.”
Jonathan Kipnis
After noticing vessel-like patterns in the distribution of immune cells on his slides, he tested for lymphatic vessels and there they were. The impossible existed. The soft-spoken Louveau recalled the moment: “I called Jony [Kipnis] to the microscope and I said, ‘I think we have something.'”
As to how the brain’s lymphatic vessels managed to escape notice all this time, Kipnis described them as “very well hidden” and noted that they follow a major blood vessel down into the sinuses, an area difficult to image. “It’s so close to the blood vessel, you just miss it,” he said. “If you don’t know what you’re after, you just miss it.”
“Live imaging of these vessels was crucial to demonstrate their function, and it would not be possible without collaboration with Tajie Harris,” Kipnis noted. Harris, a PhD, is an assistant professor of neuroscience and a member of the BIG center. Kipnis also saluted the “phenomenal” surgical skills of Igor Smirnov, a research associate in the Kipnis lab whose work was critical to the imaging success of the study.
Tajie Harris
Abstract
Structural and functional features of central nervous system lymphatic vessels
One of the characteristics of the central nervous system is the lack of a classical lymphatic drainage system. Although it is now accepted that the central nervous system undergoes constant immune surveillance that takes place within the meningeal compartment, the mechanisms governing the entrance and exit of immune cells from the central nervous system remain poorly understood. In searching for T-cell gateways into and out of the meninges, we discovered functional lymphatic vessels lining the dural sinuses. These structures express all of the molecular hallmarks of lymphatic endothelial cells, are able to carry both fluid and immune cells from the cerebrospinal fluid, and are connected to the deep cervical lymph nodes. The unique location of these vessels may have impeded their discovery to date, thereby contributing to the long-held concept of the absence of lymphatic vasculature in the central nervous system. The discovery of the central nervous system lymphatic system may call for a reassessment of basic assumptions in neuroimmunology and sheds new light on the aetiology of neuroinflammatory and neurodegenerative diseases associated with immune system dysfunction.
“Structural and functional features of central nervous system lymphatic vessels” by Antoine Louveau, Igor Smirnov, Timothy J. Keyes, Jacob D. Eccles, Sherin J. Rouhani, J. David Peske, Noel C. Derecki, David Castle, James W. Mandell, Kevin S. Lee, Tajie H. Harris and Jonathan Kipnis in Nature. Published online June 1 2015 doi:10.1038/nature14432
Probably after Progesterone
Aad’s comments. Aad is a psychiatric nurse in the Netherlands. We share ideas.
What i immediately wondered about were the immunoprivileged loges as they are sustained in the brains, the testes, eyeballs, perhaps the pulpa of the molars and other niches/poches. i think this newly found lymphatic trafficway lifts the curtain about the neuro-immunologic implications,whereas these loges are functional within this mechanical system in a cyclic
interesting also the remark about the ageing of these vessels during the ageing of our brain
and mopeds through the bush making a more astute and dynamic mappology possible.
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