What might brain implants do to humanity?

I wrote this in February 2016, before I knew of Neuralink’s existence. It was in response to the following question:

What are the biggest ways in which the world 20 years from now will probably be different from today? What are the biggest “X factors” (changes that are not probable, but are possible and could be huge)?

Implants + Internet = ImplanTelepathy™!

Batman Forever' (1995) and the Brain Drain Moment | That Moment In
Continue reading

Neural correlates of consciousness – how exactly can we find them?

This is a slightly edited version of an answer I wrote on Quora: What is the best way to understand consciousness?

File:Digesting Duck.jpg - Wikimedia Commons

This emoticon captures my attitude towards questions about consciousness:


Consciousness seems to be invisible to scientific methods. The only way to incorporate consciousness into science is to change the definition of science so it includes subjective experience. I am not really comfortable with doing this, because it waters down science to the point where it becomes indistinguishable from introspective philosophy. Science is useful because of what makes it different from philosophy: it makes predictions that can be tested objectively. Truly subjective experiences seem to be ruled out by definition.

My favorite way to think about consciousness is inspired by Indian philosophy, though the general idea crops up all over the place:

Consciousness is not a phenomenon: it is the precondition for the appearance of phenomena. The mind is not a thing to be observed, but the medium by which things are observed.

This is emphatically not a scientific statement, but that’s okay: science is only one of many ways to look at the universe.

So let’s examine the scientific approach to consciousness in detail!

Continue reading

On the neuroscience of creativity

https://www.oldbookillustrations.com/wp-content/uploads/2018/02/attributes-art-illustration.jpgI was asked the following question on Quora recently:

What part of the brain is responsible for linear thinking? What part of the brain is responsible for creativity?

Thinking [1] [2] is very poorly understood, but broadly speaking in seems to involve the prefrontal cortex (PFC), with a special role for the dorsolateral PFC. Other important areas include the hippocampus and parietal cortex. Ultimately, thinking involves many brain regions, and cannot be localized to one place. Thinking is a distributed process that can incorporate many different parts of the brain. And the specific content of the thoughts will influence which brain areas are involved. If you are thinking about images, visual areas will be involved. If you are thinking about movement, motor areas will be involved.

In my opinion, the distinction between “linear” and “creative” thinking is somewhat vague. At this point, the most important thing to note is that the idea that the “left brain is rational/logical and the right brain is creative/artistic/emotional” is totally wrong [3] . Both hemispheres contribute to logic as well as creativity. Moreover, the use of logic can itself be a creative activity.

Continue reading

Is thinking conscious or unconscious?

Sherlock Holmes smokes his pipe reclining on cushions and wearing a roomy overcoatThere are two ways to define thinking: each leads to a different answer to the question of whether thinking is conscious or not.

  1. Thinking as a subjective experience. If someone asks you what you are thinking about, you can introspect, and describe your thought process. You can also say that you weren’t really thinking at all.
  2. Thinking as the cause of ideas and thoughts. If you discover a thought, then you can infer that the process that led up to the thought was a form of thinking, even if there was no subjective experience associated with the process.

We can test our preference for definition 1 or definition 2 by considering an example.

Sherlock Holmes was a good chemist. When he found himself stuck while attempting to solve a mystery, he would sometimes distract himself by doing a chemistry experiment. At the end of such an experiment, he often found that a solution simply popped into his head.

Continue reading

Is the ‘resolution’ of the human eye ‘infinite’?

No measurable physical quantity is ever infinite. In other words, only theoretical concepts can be definitively labeled as infinite. But that is perhaps an epistemological claim that is unnecessary here. So let’s dive into the nitty-gritty of how visual ‘resolution’ is actually measured. As we shall see, the number of light sensitive cells in the retina does not tell us what the ‘resolution’ of the visual system as a whole is. In some circumstances our visual ‘resolution’ exceeds that of the eye considered in isolation.

Visual acuity [1] is the sharpness with which we can distinguish patterns of light on the retina of the eye. This depends on the exact location of the light falling on the retina.

Continue reading

To participate in this Consciousness Survey, you’ll need to find the answer to a very easy question

Interested in participating in a (totally unscientific) survey on consciousness and related questions? The link is in the preceding post. Once you complete the survey, you’ll be able to see the results. It should take between 20 and 45 minutes to complete, and will hopefully be stimulating, at least somewhat.

The password for the post is the last name of the philosopher who coined the term “Hard Problem of Consciousness”. It is very easy to google the answer. Capitalize in the standard way.



“Psychic cells” were silly in 1909. And they are still silly, regardless of what you call them.


Here is Korbinian Brodmann (of cortical Brodmann area fame) writing about a trend towards assigning functional roles to single neurons based on anatomical type, back in 1909:

“There has been occasional talk of “sensory cells” located in particular regions, or of sensitive or sensorial “special cells”. People have invented acoustic or optic special cells and even a “memory” (*12) cell, and have not shied away from the fantastic “psychic cell”. Apart from the fact that such so-called “special cells” have only been described in young or foetal brain with the Golgi method and mainly only in animals, and therefore lack confirmation in the adult human brain, and quite apart from the fact that no attempt has been made to determine the precise regional location of the zone within which such cells appear exclusively, it seems to me that to pose this problem is wrong.” [emphasis added]

And here is a news item from a couple of years ago:


Psychic cells indeed! Or perhaps we should call them zombie cells.

(Zombie concepts keep coming back from the dead to eat our brains. Other examples include ‘selfish genes’ and ‘pleasure molecules’.)

Which is the most evolutionarily advanced part of the human brain?

This is a potentially controversial issue, since there is no consensus yet on the evolution of the brain, beyond a very coarse-grained chronology. Broadly speaking, neocortical areas are new, hence the term “neo-cortex”. But among cortical areas, there is still some disagreement about which areas emerged most recently in primates.

Based on what we know about development in the womb, along with structural findings, my labmates, who are neuroanatomists, suggest that the “eulaminate” areas — the ones that have sharply defined layers — may be the most recent, evolutionarily, compared to the “agranular” and “dysgranular” cortices, which have less sharply defined layers. These less sharply defined areas are also labeled as “limbic”.

Continue reading

If serotonin deficiency isn’t the cause of depression, then why do SSRIs work?

Acetaminophen (a.k.a paracetamol) relieves some types of headache. But this does not mean that these headaches are caused by acetaminophen deficiency. The brain doesn’t even produce acetaminophen.

The point of this analogy is to make clear that a medicine can work even if it is not acting on the cause of the symptom. In many cases a medicine can work even when the cause of the symptom is completely unknown.

Continue reading

Less is more? A strange case of improvement in intelligence & personality after removal of prefrontal cortical tissue!

While reading a paper on the neuroscience of dreaming I came across a reference to a 1940 paper by Donald Hebb and Wilder Penfield. It’s a neurosurgery case study that is quite stunning. It shows that in some cases, removal of prefrontal brain tissue can actually cause improvements in intelligence and personality. So basically it’s the opposite of the Phineas Gage story.

Here are some excerpts from the paper:


Continue reading