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Averaging is a convenient fiction of neuroscience

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Re: Averaging is a convenient fiction of neuroscience

#21

Post by dilawar »

robertclaus wrote: post #17

As a computer scientist, I was blown away the first time my friend explained to me that his research focused on the timing of neuron spikes, not their magnitude. After talking about it for a while I realized that machine learning neural networks are much closer to simple early models of how neuron's work (averages and all), not how neuron's actually signal. Makes sense when you consider how the latest LLM models have…

In many, perhaps most, signalling pathways, amplitude doesn't matter much (it does at log-scale). Given how well we control temperature and therefore rate of the reaction, it makes sense to use timing to fight off the noise.

Re: Averaging is a convenient fiction of neuroscience

#24

Post by Spooky23 »

bosma wrote: post #18
_yb2s wrote: post #7

I've become increasingly convinced that the idea of averaging is one of the biggest obstacles to understanding things... it contains the insidious trap of feeling/sounding "rigorous" and "quantitative" while making huge assumptions that are extremely inappropriate for most real world situations. Once I started noticing this I can't stop seeing this almost everywhere- almost every news article, scientific paper, etc.…

> In reality the modal life expectancy of adults (most common age of death other than 0) has been pretty stable in the 70s-80s range for most of human history- the low average was almost entirely due to infant mortality. This isn't true: https://ourworldindata.org/its-not-just-about-child-mortalit...

It mostly is. The biggest gains are in childhood. Aldo consider that you’re looking at figures for England and Wales, which isn’t necessarily representative.

The largest contribution to improving life expectancy is measured by reductions in child mortality. The factors that drove those improvements (infection control, improved hygienic practices, food quality, regulation of food and drug purity, medicine) benefited everyone, but had the biggest impact on the old and young. In the 1850s, 8,000 infants died annually from adulterated milk alone.

I think of my own journey. In 1824, 200 year ago Spooky23 would have died 20 years ago, a half blind cripple. 2024 Spooky23 is healthy with no back issues and god willing a few more decades.

Re: Averaging is a convenient fiction of neuroscience

#25

Post by ggm »

glial wrote: post #3

All models are convenient fictions. I heard a neuroscientist once describe averaging as a low-pass filter. People know it hides high-frequency dynamics. But unless you have a way to interpret the high-frequency signal, it looks an awful lot like noise.

> But unless you have a way to interpret the high-frequency signal, it looks an awful lot like noise.

In other words, they're looking for their lost keys under the lamp-post because it's easier there. If there is a signal in the HF, it's not yet understood. This feels like "junk DNA" -which is I believe receiving more attention than the name suggests.

Re: Averaging is a convenient fiction of neuroscience

#26

Post by richrichie »

There are even bigger problems. For example, the common “this region lights up more if this is done” type of fMRI studies are suspect because what the fMRI tool does may have no bearing to actual brain function. I read a book by a neuroscientist lamenting the abuses of fMRI in papers a while ago. Unfortunately, unable to locate the reference.

Re: Averaging is a convenient fiction of neuroscience

#27

Post by JumpCrisscross »

llm_trw wrote: post #19
_yb2s wrote: post #7

I've become increasingly convinced that the idea of averaging is one of the biggest obstacles to understanding things... it contains the insidious trap of feeling/sounding "rigorous" and "quantitative" while making huge assumptions that are extremely inappropriate for most real world situations. Once I started noticing this I can't stop seeing this almost everywhere- almost every news article, scientific paper, etc.…

>In reality the modal life expectancy of adults (most common age of death other than 0) has been pretty stable in the 70s-80s range for most of human history- the low average was almost entirely due to infant mortality. This is even wronger than what you critique. For every period in history that we have good data for people had a half-life - a period in which you'd expect half of all people to die: https://batinthea…

> if we ignore everyone under 10, half of all people left would still die before they are 40

Wouldn't it be 50 since the half-life is an interval?

Re: Averaging is a convenient fiction of neuroscience

#28

Post by llm_trw »

JumpCrisscross wrote: post #27
llm_trw wrote: post #19

Earlier quoted context omitted.

>In reality the modal life expectancy of adults (most common age of death other than 0) has been pretty stable in the 70s-80s range for most of human history- the low average was almost entirely due to infant mortality. This is even wronger than what you critique. For every period in history that we have good data for people had a half-life - a period in which you'd expect half of all people to die: https://batinthea…

> if we ignore everyone under 10, half of all people left would still die before they are 40 Wouldn't it be 50 since the half-life is an interval?

No, the half life for age 10-20 is much higher than that for 20-40 and the exponential function is non-linear.

Re: Averaging is a convenient fiction of neuroscience

#29

Post by JumpCrisscross »

hinkley wrote: post #16
_yb2s wrote: post #7

I've become increasingly convinced that the idea of averaging is one of the biggest obstacles to understanding things... it contains the insidious trap of feeling/sounding "rigorous" and "quantitative" while making huge assumptions that are extremely inappropriate for most real world situations. Once I started noticing this I can't stop seeing this almost everywhere- almost every news article, scientific paper, etc.…

Averages are very bad in bimodal distributions. And that includes issues of public policy, where going left sort of works, and going right sort of works, and going in the middle sucks for absolutely everyone.

> Averages are very bad in bimodal distributions

They're bad with multimodal distributions, generally, as well as any random process governed by a distribution with no mean, e.g. Cauchy [1].

(Neuronal firing appears to be non-Gaussian, possibly lognormal [2], which does have a mean [3], but it isn't equal to the simple average.)

[1] https://en.wikipedia.org/wiki/Cauchy_distribution#Properties

[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6633220/

[3] https://en.wikipedia.org/wiki/Log-normal_distribution

Re: Averaging is a convenient fiction of neuroscience

#30

Post by JumpCrisscross »

Spooky23 wrote: post #24
bosma wrote: post #18

Earlier quoted context omitted.

> In reality the modal life expectancy of adults (most common age of death other than 0) has been pretty stable in the 70s-80s range for most of human history- the low average was almost entirely due to infant mortality. This isn't true: https://ourworldindata.org/its-not-just-about-child-mortalit...

It mostly is. The biggest gains are in childhood. Aldo consider that you’re looking at figures for England and Wales, which isn’t necessarily representative. The largest contribution to improving life expectancy is measured by reductions in child mortality. The factors that drove those improvements (infection control, improved hygienic practices, food quality, regulation of food and drug purity, medicine) benefited e…

> It mostly is. The biggest gains are in childhood.

The life expectancy of a 60-year old going from 74.4 to 84, or a 70-year old from 79.1 to 85.9, is significant and meaningful. Not as much as a newborn's LE going from 41.6 to 81.1. But far from "pretty stable in the 70s-80s range for most of human history."

Also, recent life-expectancy increases have come from adult morality reductions [1].

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3000019/

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