<\/p>\n
Further evidence of this bias comes from the reaction of the mice when they were first put into learning situations. Before they knew whether the new associations would be positive or negative, the release of neurotensin from their thalamic neurons decreased. The researchers speculate that new stimuli are assigned a more negative valence automatically until their context is more certain and can redeem them.<\/p>\n
\u201cYou\u2019re more responsive to negative experiences versus positive experiences,\u201d Hao Li said. If you almost get hit by a car, you\u2019ll probably remember that for a very long time, but if you eat something delicious, that memory is likely to fade in a few days.<\/p>\n
Ryan is more wary of extending such interpretations to humans. \u201cWe\u2019re dealing with laboratory mice who are brought up in very, very impoverished environments and have very particular genetic backgrounds,\u201d he said.<\/p>\n
Still, he said it would be interesting to determine in future experiments whether fear is the actual default state of the human brain\u2014and if that varies for different species, or even for individuals with different life experiences and stress levels.<\/p>\n
The findings are also a great example of how integrated the brain is, Wen Li said: The amygdala needs the thalamus, and the thalamus likely needs signals from elsewhere. It would be interesting to know which neurons in the brain are feeding signals to the thalamus.<\/p>\n
A recent study published in Nature Communications<\/em> found that a single fear memory can be encoded in more than one region of the brain. Which circuits are involved probably depends on the memory. For example, neurotensin is probably less crucial for encoding memories that don\u2019t have much emotion attached to them, such as the \u201cdeclarative\u201d memories that form when you learn vocabulary.<\/p>\n For Tasker, the clear-cut relationship that Tye\u2019s study found between a single molecule, a function, and a behavior was very impressive. \u201cIt\u2019s rare to find a one-to-one relationship between a signal and a behavior, or a circuit and a function,\u201d Tasker said.<\/p>\n Neuropsychiatric Targets<\/p>\n The crispness of the roles of neurotensin and the thalamic neurons in assigning valence might make them ideal targets for drugs aimed at treating neuropsychiatric disorders. In theory, if you can fix the valence assignment, you might be able to treat the disease, Hao Li said.<\/p>\n It\u2019s not clear whether therapeutic drugs targeting neurotensin could change the valence of an already formed memory. But that\u2019s the hope, Namburi said.<\/p>\n Pharmacologically, this won\u2019t be easy. \u201cPeptides are notoriously difficult to work with,\u201d Tasker said, because they don\u2019t cross the blood-brain barrier that insulates the brain against foreign materials and fluctuations in blood chemistry. But it\u2019s not impossible, and the field is very much headed toward developing targeted drugs, he said.<\/p>\n Our understanding of how the brain assigns valence still has important gaps. It\u2019s not clear, for example, which receptors the neurotensin is binding to in amygdala neurons to flip the valence switch. \u201cThat will bother me until it is filled,\u201d Tye said.<\/p>\n Too much is also still unknown about how problematic valence assignments may drive anxiety, addiction, or depression, said Hao Li, who was recently appointed as an assistant professor at Northwestern University and is planning to explore some of these questions further in his new lab. Beyond neurotensin, there are many other neuropeptides in the brain that are potential targets for interventions, Hao Li said. We just don\u2019t know what they all do. He\u2019s also curious to know how the brain would react to a more ambiguous situation in which it wasn\u2019t clear whether the experience was good or bad.<\/p>\n These questions linger in Hao Li\u2019s brain long after he packs up and goes home for the night. Now that he knows which network of chatty cells in his brain drives the emotions he feels, he jokes with friends about his brain pumping out neurotensin or holding it back in response to every bit of good or bad news.<\/p>\n \u201cIt\u2019s clear that this is biology, it happens to everyone,\u201d he said. That \u201cmakes me feel better when I\u2019m in a bad mood.\u201d<\/p>\n Original story<\/em> reprinted with permission from<\/em> Quanta Magazine, an editorially independent publication of the<\/em> Simons Foundation<\/em> whose mission is to enhance public understanding of science by covering research developments and trends in mathematics and the physical and life sciences.<\/em><\/p>\n<\/div>\n","protected":false},"excerpt":{"rendered":" Further evidence of this bias comes from the reaction of the mice when they were first put into learning situations. Before they knew whether the new associations would be positive or negative, the release of neurotensin from their thalamic neurons decreased. The researchers speculate that new stimuli are assigned a more negative valence automatically until […]<\/p>\n","protected":false},"author":1,"featured_media":1238584,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[21],"tags":[],"class_list":["post-1238582","post","type-post","status-publish","format-standard","has-post-thumbnail","category-celebrity-gossip"],"_links":{"self":[{"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/posts\/1238582","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/comments?post=1238582"}],"version-history":[{"count":0,"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/posts\/1238582\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/media?parent=1238582"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/categories?post=1238582"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ghanamma.com\/2022\/wp-json\/wp\/v2\/tags?post=1238582"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}