Introducing the brain: a newly found calcium ion spike (Introduction)

by David Turell , Friday, July 05, 2024, 18:02 (151 days ago) @ David Turell

Along with the usual sodium ion spike:

https://www.sciencealert.com/a-first-of-its-kind-signal-was-detected-in-human-brains?ut...

"Back in 2020, researchers from institutes in Germany and Greece reported a mechanism in the brain's outer cortical cells that produces a novel 'graded' signal all on its own, one that could provide individual neurons with another way to carry out their logical functions.

"By measuring the electrical activity in sections of tissue removed during surgery on epileptic patients and analyzing their structure using fluorescent microscopy, the neurologists found individual cells in the cortex used not just the usual sodium ions to 'fire', but calcium as well.

"This combination of positively charged ions kicked off waves of voltage that had never been seen before, referred to as a calcium-mediated dendritic action potentials, or dCaAPs.

***

"In neurons, the signal is in the form of a wave of opening and closing channels that exchange charged particles such as sodium, chloride, and potassium. This pulse of flowing ions is called an action potential.

"Instead of transistors, neurons manage these messages chemically at the end of branches called dendrites.

***

"Dendrites are the traffic lights of our nervous system. If an action potential is significant enough, it can be passed on to other nerves, which can block or pass on the message.

"This is the logical underpinnings of our brain – ripples of voltage that can be communicated collectively in two forms: either an AND message (if x and y are triggered, the message is passed on); or an OR message (if x or y is triggered, the message is passed on).

"Arguably, nowhere is this more complex than in the dense, wrinkled outer section of the human central nervous system; the cerebral cortex. The deeper second and third layers are especially thick, packed with branches that carry out high order functions we associate with sensation, thought, and motor control.

***

"While the team had carried out similar experiments on rats, the kinds of signals they observed buzzing through the human cells were very different.

More importantly, when they dosed the cells with a sodium channel blocker called tetrodotoxin, they still found a signal. Only by blocking calcium did all fall quiet.

"Finding an action-potential mediated by calcium is interesting enough. But modelling the way this sensitive new kind of signal worked in the cortex revealed a surprise.

"In addition to the logical AND and OR-type functions, these individual neurons could act as 'exclusive' OR (XOR) intersections, which only permit a signal when another signal is graded in a particular fashion.

"'Traditionally, the XOR operation has been thought to require a network solution," the researchers wrote.

***

"Exactly how this new logic tool squeezed into a single nerve cell translates into higher functions is a question for future researchers to answer."

Comment: I'm sure the brain has more tricks up its sleeve. Bit by bit the deep complexity of our brain is yielding its secrets, in the most complex living organ in the universe. It originated in the Cambrian Explosion without precursors and evolved to our form. By far it is the strongest argument for a designer.