- Date:
- December 8, 2018
- Source:
- Cold Spring Harbor Laboratory
- Summary:
- What does the brain do when things go bump in the night? Researchers are looking at neural activity in the amygdala by studying how mice react when they hear a sound they've been taught to fear.
- These heatmaps show activity in 756 neurons found in the BLA region of a mouse brain. Spikes in excitement (red) represent responses over time to neutral sounds (c & d), a water reward (e), or a startling puff of air. Maps like these also show how the brain inhibits (blue) an undesired reaction. Black represents moments of non-responsiveness.Credit: Li Lab, CSHL/2018How is it that a sound can send a chill down your spine? By observing individual brain cells of mice, scientists at Cold Spring Harbor Laboratory (CSHL) are understanding how a sound can incite fear.Investigator Bo Li focuses on a part of the mouse brain called the amygdala where sights, sounds, and other stimuli take on positive or negative associations through experience. The continuous process of learning and unlearning that occurs in the amygdala appears impaired in people with anxiety disorders or major depression. Understanding brain cell, or neuron activity in the amygdala could result in better treatments.In the October issue of Nature Communications, Li and postdoctoral researcher Xian Zhang describe profound changes in neuron activity when they trained animals to fear a particular sound and associate another sound with a reward. "If you look at the patterns of brain cell activity in the amygdala, you can know whether the animal is expecting a reward or fearing a punishment," Li explains.Li and Zhang used a microscope with a lens small enough to implant in the brain of a mouse, to track the firing activity of specific neurons before, during, and after an animal's training. They taught the animals to associate particular sounds with reward or punishment and saw the behavior of neurons evolve. The experiment associated one tone with an annoying puff of air -- the punishment. The reward tone was a refreshing drop of water to drink.At first, neurons sensitive to sound responded to each tone by firing randomly. But when one tone was repeatedly accompanied by the puff of air, the neurons fired in a very specific pattern. This pattern closely resembled the firing pattern of another type of brain cell that fires when the mouse actually experienced the punishment. Likewise, when a tone was repeatedly paired with a sip of water, the sound-sensitive neurons fired in a pattern similar to neuron activity when the mouse received the water reward.
As the firing patterns became more specific, the animals licked in response to the reward-associated tone -- anticipating water. They blinked in response to the punishment-associated sound -- anticipating an air puff.The researchers also switched the meaning of each tone. When the "reward" sound was repeatedly accompanied by an air puff, the neurons let go of the established "reward" firing pattern and adopted the "punishment" pattern. "We think this is how sound acquires meaning," Li says.https://m.facebook.com/groups/1714678378824286?ref=bookmarks
This month, Smithsonian published a fascinating article about the history of chickens and how they basically took over the world. Obviously, chickens couldn't have established their empire without reproduction, so I thought I'd take a behind-the-scenes look at how chickens became so prominent. As it turns out, chicken procreation is a lot weirder than I thought. Here are just a few of the finer points. 1) Asymmetrical gonads Here's how gonads are usually arranged: males have two testes, and females have two ovaries. Both genders usually have one gonad on the right side of their body and one on the left. It's pretty simple. In contrast, hens only have one functional ovary. In fact, most birds have this lopsided anatomy probably because it's more practical for flight. Birds need to be light and compact in order to fly, so they only develop one of their gonads. For most male birds, the right testes is also smaller than the left. This tren...