# Modelling the World

### Neurons

The human brain is composed of electrically excitable cells called Neurons, and these are the basic units of the central and peripheral nervous systems (CNS/PNS). The role of a neuron is **signal transmission**, and the cell has three main parts:

1. Dendrite – this part of the neuron _**receives**_ **signals**.
2. Soma/Cell body – houses the nucleus, is the site of protein synthesis, and much more.
3. Axon – this part of the neurons _**sends**_ **signals**.

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzPwR13e58KxhsW%2F9.gif?generation=1616010409255644\&alt=media)

#### What kind of electricity is this, and where is it coming from?

At the boundary between internal and external states – Sensations - lie sensory neurons that facilitate the sampling of the world through our five senses.

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzQ9uj61Z_IGHSA%2F10.png?generation=1616010409263205\&alt=media)

These sensory neurons are continuously processing incoming information; E.g. _even when we close our eyes, we see our eyelids which are black in the darkness (or red if you shine a light over them)_.&#x20;

{% hint style="info" %}
**Nothing exists in a vacuum**.
{% endhint %}

Sensory neurons in the retina, known as Photoreceptors, detect electromagnetic waves in the range of the visible light spectrum, convert them into electrical signals (called action potentials), and transmit them through the brain. **Vision**:

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzRdew98cqu2U0_%2F11.gif?generation=1616010409290437\&alt=media)

On the other hand, the sense of **Smell** is detected chemically. This is also true for **Taste**.

![Image result for smell olfactory receptors gif](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzS-4R8_XI9IC8a%2F12.gif?generation=1616010409546613\&alt=media)

**Sound** is detected mechanically when the tympanic membrane vibrates in response to audio waves transmitted through the electromagnetic spectrum. **Touch** is hybrid.

{% hint style="info" %}
Ultimately, **all signals are converted into electricity and propagated forward along neurons**.
{% endhint %}

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzTpM9bBljmpaL9%2F13.gif?generation=1616010409412242\&alt=media)

So, while electrons flow along hardware circuitry within our man-made computers, electricity is transmitted along neuronal pathways that form the “hardware” of our brains.&#x20;

{% hint style="info" %}
**The organic biological brain is our hardware, while our perception/**_**simulation**_**&#x20;of reality is our software (Model of the World).**
{% endhint %}

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzUxpebBZy4xi2h%2F14.gif?generation=1616010409527948\&alt=media)

There are **86 billion** such cells in the human brain.

Neurons are heavily inter-connected along junctions known as a **Synapse** – the human brain has over **4 quadrillion** such points of connection.

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzVHaQdGv5fcgXW%2F15.jpeg?generation=1616010409275578\&alt=media)

Furthermore, each synapse contains [varying numbers and types of receptors](https://en.wikipedia.org/wiki/Neurotransmitter#Types).

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzWbpej-_02KDOb%2F16.gif?generation=1616010409289312\&alt=media)

When 86 billion neurons are communicating at 4 quadrillion receptors with a seemingly infinite number of neurotransmitter and receptor combinations, a **tremendous degree of complexity emerges**. _For reference, we have only recently modeled the connectome of the nematode C. Elegans which as 302 neurons._

From this complexity, emerges Order.

![Hierarchical Organization of Brain Networks](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzXbG2D61O-C7-p%2F17.jpeg?generation=1616010409303348\&alt=media)

_Neurons at the Micro level coalesce into regions, and these regions also form networks as organization progressively approaches the Macro scale. Resultantly, this hierarchical organization structurally (and functionally) reverses entropy._

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzYcaZBQ9FKgNjU%2F18.jpeg?generation=1616010409262410\&alt=media)

### **Hierarchical Message Passing**&#x20;

Because they are electrically excitable information processing units, neurons can be conceptualized as computer **nodes** within a decentralized computing system. **Signal transmission** is the basic function of neurons, and they _**transmit information**_ to other neurons in a manner known as **hierarchical message passing** ([source](https://www.uab.edu/medicine/cinl/images/KFriston_FreeEnergy_BrainTheory.pdf)):

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzZSRow7ubrLCbG%2F19.png?generation=1616010409284158\&alt=media)

{% hint style="info" %}
_Like the game of Telephone, information entering the nervous system is relayed along neurons. In contrast to the one-way messaging resulting in the errors we enjoy while playing Telephone, neurons continuously try to_ _**mitigate forward prediction errors**_ _through_ _**backward predictions**_ _along each node in the chain of communication. To the extent possibl&#x65;**, information is verified along the communication chain**_ _all the way from lower cortical areas to higher cortical regions._&#x20;
{% endhint %}

This process is instrumental for the brain (and nervous system) to generate accurate Models of the World, done by maximizing model evidence and minimizing variational free energy.

Example:

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-MW0_lVVcWu8aAggonNE%2F-MW0jF6gPaiRZXgDa98-%2F-MW0k-Tewnq-K1Db9Sfi%2Fimage.png?alt=media\&token=204d21ee-fbd0-47cd-b71e-d017e6915c21)

_This silhouette would lead one to believe the shadow is formed by a person’s face. Phenomenologically, Prediction Error = I’m not sure how to explain this shadow; Backward Prediction = this shadow is probably formed by a person’s face._

![](https://3692130413-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2Fethereum-a-model-of-the-world%2F-MW0iAgZDJUnfzIs_6bW%2F-MW0iTzalJUsHsNljZv5%2F21.jpeg?generation=1616010409255597\&alt=media)

_In the presence of new information, prediction errors and backward predictions are updated, as is the Model of the World._

Of course, the process is far more nuanced. Uncovering the precise pathway from information to model of the world to experience of reality to consciousness (and the many other steps in between), would be the Holy Grail. _We don’t have these answers_.

{% hint style="info" %}
But we do have **insights**.
{% endhint %}

Next, we will highlight similarities between Ethereum and the human brain in the context of the Free Energy Principle – i.e. the understanding that self-organizing systems will do their best to model the world functionally and structurally. This is thermodynamically attained through _non-equilibrium steady states_.

Each of these topics can be unpacked in depth on many layers down the knowledge stack/hierarchy, but these concepts will be introduced only superficially for the sake of scope and brevity.
