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

Brodmann-areas

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:

BigNeuron

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 →