Tracking these neural functions in infants proved a challenge."The key to establishing that the brain is involved in infant sleep is demonstrating changes in brain activity as it cycles in and out of sleep," Blumberg said.But some measurements of surface brain activity, like EEG (electroencephalogram), don't show much activity in the surface layer of the brain-the cortex-in very young mammals. As a result, some researchers have questioned whether infant and adult sleep are fundamentally different."If cortical activity is considered a key feature for demonstrating adult sleep but this activity doesn't occur in infants, then can we say that infants sleep?" Blumberg asked, evoking the old philosophical saw about whether a chair missing a leg is still a chair.But the team was able to measure infant brain activity using a variety of techniques.
It was a challenge working with tiny animals that alternately sleep and wake at 10- to 15-second intervals. "First, we used a tracing technique to see which parts of the brain would light up," Blumberg said.They found crucial activity in the midbrain—an area known to be important for adult sleep. Next, recording electrodes were placed in these regions to determine if they contain neurons that exhibit activity specific to sleep and wakefulness."Some neurons became active when [an infant rat] went to sleep, some when it woke up. Some neurons became active when the animal was twitching, so they are not only sleep-active but [specific to] REM sleep," Blumberg said.The team was able to further pinpoint neural functions by creating lesions in specific parts of the brain. These procedures induced some rats to sleep as much as 95 percent of the time, or prevented others from sleeping to the same degree.
第二段第三句应该是：They found crucial activity in the midbrain-an area known to be important for adult sleep.
我能看懂意思，就是组织不好语言，请不要糊弄人好吗？