World
How our brain traces old memories?
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London :A team of German scientists has found out what actually happens if we try to remember things that took place years or decades ago?
The study revealed that the neural networks involved in retrieving very old memories are quite distinct from those used to remember recent events.
“For the very first time we were able to show that the retrieval of old and recent memories are supported by distinct brain networks,” said Magdalena Sauvage, professor at Ruhr-University Bochum in Germany.
When we remember events which occurred recently, the hippocampus — the portion of the brain, thought to be the centre of emotion, memory, and the autonomic nervous system — is activated, said the paper appeared in the journal eLIFE.
Hippocampus contains the cornu ammonis regions 1 and 3 (CA1 and CA3), which plays a major role in retrieving recent memories.
For the study, the team monitored brain activity in mice during the retrieval of memories that are one day to one year old – e.g. up to the mouse-equivalent of 40 human years.
For their study they applied a high-resolution molecular imaging technique, which detects the expression of a particular gene tied to plasticity processes and this way sheds light on cognitive processes.
The CA3 region, believed to be the place of memory storage in the hippocampus, no longer plays a role when we remember very old memories.
Rather, the involvement of the CA1 region persists and the cortical areas — largest part of the brain — adjacent to the hippocampus become involved.
The reason for the differential involvement of the hippocampal sub-regions could lie in the mechanisms supported by CA3.
In CA3, memories can be retrieved on the basis of single features of an original memory, which are used as cues.
“Since the memory for single features degrades over time, we speculate that they might ultimately be of no more use as cues, hence retrieving memory would then essentially rely on CA1 and other processes taking place in the parahippocampal region of the brain,” explained Sauvage.
World
Lockdowns in China Force Urban Communities to Defy Censorship and Vent Frustration Online
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Shanghai’s rich middle class is leading a wave of online dissent over the strict and prolonged lockdowns imposed in various parts of the country. Chinese internet censorship is struggling as patience is wearing thin in many urban centers, coming up with creative forms of online protests.
Social Media Posts Revealing Lockdown Tension in Shanghai
Drawn-out lockdowns are nothing new in China as authorities insist with the nation’s zero-Covid policy since the start of the pandemic. Currently over This time around, however, metropolitan areas like Shanghai are increasingly difficult to keep quiet, given that its more than 25 million residents have seen weeks of total isolation along with food shortages and many other service interruptions.
Dozens of towns and reportedly over 300 million Chinese citizens have been affected by lockdowns of different severity. As expected, urban netizens have been most outspoken over their difficulties by finding creative ways to get around state censorship and bans placed on topics, news comments and spontaneous campaigns.
Shanghai residents have been using mobile proxies and hijacking seemingly unrelated hashtags to talk about healthcare issues, delivery failures and the overall severity of their situation. The “positive energy” that the Chinese government wants to transmit during the recent prolonged series of lockdowns does not come naturally to those counting food supplies and online censors are working hard to filter words, trending topics and undesired social media sharing.
WeChat groups and message threads are under constant monitoring. Posts questioning the zero-Covid approach have been quickly deleted, including by leading Chinese health experts like Dr. Zhong Nanshan. Video footage is soon censored and protests and investigations are quickly made to disappear.
Where this has not worked, officials have exposed banners with warnings and outright threats like “watch your own mouth or face punishment”, while drones have been patrolling the city skies. Yet, if anything, this has led to further tensions and unspoken confrontation with Shanghai’s educated and affluent middle class.
Creative Online Solutions Harnessing Civic Energy
Announcements by Chinese social media that they would be publishing the IP addresses of users who “spread rumors” have not helped either. Tech industry research has shown that much of Asia’s tech-savvy population has a habit of using mobile proxies and other privacy tools, quickly finding workarounds to browse the internet freely and talk to the world about the hottest topics.
The sheer volume of forbidden posts is already a challenge for the very censorship system, experts explain. Unable to track all trending hashtags, state workers overlook topics that speak about the US, Ukraine or other popular news. Linking human rights elsewhere to their situation, Chinese online dissidents establish their informal channels and “hijack” the conversation to share personal or publicly relevant information about the Covid suppression in their town.
Sarcastic and satirical posts still dominate. Others hope to evade the censors by replacing words from famous poems or the national anthem. One thing is certain – social media, when harnessed with the right creativity, has proven its ability to mount pressure on the government in even some of the most strictly controlled tech environments like China.