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Are you thinking... about thinking?

Scientists have made a groundbreaking discovery about a deep brain structure called the thalamus, giving us rare insight into consciousness itself.


How do thoughts actually stick in our brain?


Ever wondered how your brain picks out things; one particular car in traffic; the sound of a familiar voice—all amid the constant barrage of ‘stuff’ going on around you?


This process of thinking about how we think about what we think about is usually the domain of uni students majoring in philosophy and funny cigarettes, but no.


Scientists have just made a groundbreaking discovery about a deep brain structure called the thalamus, which might give us a rare insight into consciousness itself.


The mysterious thalamus


In a fascinating study covered by Smriti Mallapaty in Scientific American, researchers peered into the brain’s hidden depths to explore the moment when we notice what’s around us.


This phenomenon is known as ‘conscious perception’.


While the brain’s outer layer, the cortex, has long been known to play a role, the thalamus, a tiny region at the brain’s centre, has been trickier to research.


Being hidden deep in the brain, it can only be accessed through invasive surgery that is potentially dangerous and, let’s be honest, pretty hard to get past the ethics committee.

So any advance in our knowledge of this part of our grey mush is precious.


Consciousness … it’s a curly one!


To make things more complicated, by its definition consciousness is hard to define, let alone study. Take a deep breath and consider this.


We can only use our own conscious processes to observe our experience of the world. This can lead to a vicious circle of ‘trying to perceive my perceptions!’


While you can explain the feeling of having a sore throat or stabbing pain to a doctor, how do you describe the processes of realising that you are thinking about a physical sensation, or the moment of having a thought itself?


Even more difficult is the process of measuring consciousness in animals. Just try to ask your dog, “Hey Mitzy are you aware of your dogness?” and see how it lands.



Let’s get thinking


If only we could get our hands on some people with thin electrodes injected deep into their brains…


Thankfully, Mingsha Zhang and his team at Beijing Normal University had exactly that in a group of patients being treated for severe headaches.


These patients were ‘ready-made’ for an experiment that monitored the elusive thalamus.

Zhang asked participants to spot an icon flashing on a screen, designed to be noticed only half the time. As they did this, the researchers recorded activity in both the thalamus and cortex.


“This is the first time that such simultaneous recordings have been made in people doing a task that is relevant to consciousness science,” said Christopher Whyte, a systems neuroscientist at the University of Sydney, in the Scientific American article.


What did they find?


When participants noticed the icon, their thalamus lit up earlier and stronger than the cortex.

Could the thalamus be acting like a gatekeeper, deciding what gets through to the cortex?


As Mac Shine, another University of Sydney neuroscientist put it, “This suggests that the thalamus acts as a filter and controls which thoughts get through to awareness and which don’t”.


Or as I like to think of it; perhaps the thalamus is the brainy bouncer for the VIP party in your mind!


Keep thinking


This discovery could reshape how we think about consciousness, one of science’s most challenging subjects.


But questions remain: did Zhang and his team really capture the moment of awareness, or just attention?


Do animals process information in a similar way? Could a non-biological agent, say a hyper-powerful AI large language model, ever become conscious – Skynet I’m looking at you buddy?


More research is coming, and as the UN’s 2025 Year of Quantum shines a light on science’s most miniscule mysteries, it’s a thrilling time to be curious about our own brain’s tiny wonders.


Here's to more thinking, about thinking.


Find the original paper "Human high-order thalamic nuclei gate conscious perception through the thalamofrontal loop," in Science here. Or read the Scientific American article here


That’s all from me for now. If you'd like more geeky fun, please check out my other newsletters below, or connect with me on LinkedIn and/or X.


Yours in nerdiness,

Adam

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