# Signal Substance Dependence

Signal Substance Dependence is a game mechanic avaliable in some Cell Types that make that specific mode programmable with certain functions or responses that take, or depend of, Signal Substances as input and change its behavior accordingly.

## Signal Substance

Signal substances are the output of Neuron Cells, those being the Neurocytes, Senseocytes and Stereocytes. Secrocytes produce signal outputs too, but since they cannot be programmed with how much or in what conditions to produce it, it's not considered a neuron cell.

These signals, the output of neuron cells, go through adhesin connections and reach other cells that, if they are programmed, can behave differently from when this output is not present. This effectively generates a relation between the receptor cells (cells with signal substance dependence) and the cells that produce these signals where the latter determines the behavior of the former. These signals are crucial to generate sentient ('smart') behavior.

There're 4 different signal substances, which are just called S1, S2, S3 and S4. These substances behave exactly the same and the only difference is that any mode can only be programmed to depend on one signal substance, meaning that if other type is present inside of it, it won't have an effect. This allows organisms to have different channels of signals inside of it that perform without altering each other.

Signal substances travel only inside of the cells (with the exception of Secrocytes), meaning that two unconnected cells cannot transmit signals between them. Signals also diffuse over time (if they aren't produced continuously) and through cells. This means that a strong signal will become weaker and weaker the more cells it travels through until it fades completely. This means that a signal has to start relatively close to its objective cell in order to reach it.

Secrocytes secrete signals in the nearby enviroment, which are picked up by cells if they enter this enviroment. This is the only exception to the rule of signal transmitions.

Signal Substances can't travel through Lipocytes, which have the ability to diffuse completely any signal that goes inside of it.

In every case, cells that have avaliable this game mechanic will activate it after pressing the [...] button. This will open the Signal Substance Dependence window:

This are the settings from this window:

• Fixed Value:

This corresponds to the direct, fixed, value of the setting without extra functions. This setting means that no signal will have an effect in the mode. It has the same function as the usual value without using the [...] button, so if the value of the setting outside is 0.5, this setting will be on 0.5 and viceversa. It also has the same max and min values as the setting that depends on has. So if it's the [...] of the Flagellocyte, it will range from 0 to 1.

This setting is the one selected by default.

This setting is a way to 'deactivate' the signal dependence.

• Use signal substance:

This activates the signal dependence. There are 2 ways (functions) to build this dependence, specified in the value setting.

• Substance: This defines the channel that will be picked up by this mode (or depend on). Any signal substance of a different type will have no effect on this mode. For example if a Flagellocyte is programmed to depend on S1, and there's a Neurocyte that produces only S2; this Neurocyte won't affect the Flagellocyte.
• Cell mass / 3,6 ng: This will activate the signal subtance that depends from the "Mass" of the cell. For example, the signal will stronger or more low as the mass increases.
• Cell age / 240 h: This will activate the signal subtance that depends from the "Age" of the cell. For example, the signal will stronger or more low as the age increases. Note: Age of a cell will reset after it has split.
• Value: This sets the function that the dependence will execute. There are two functions:

### Linear Function

Expresed as:

a x concentration + b
Or alternatively
$\qquad f(x)=ax+b$

Where $x = concentration$ is the amount of Substance Signal that has reached from the Neuron cell, and $a,b$ are the settings from a and b options from this window. This two values can alter the input/output relation quite strongly. a=-1, for example, will produce the opposite result from the Input. a=-2 will give the opposite of the double of the input as output. b sets a fix value that gets added to the one relation $ax$. If a=0, b behaves almost as the normal fixed value of the setting, and so there's alot of posible settings.

This type of function doesn't have the c option available.

### Conditional Function

Also called If-then Function, expresed as:

a if concentration < c and b if concentrationc
Or alternatively
$\qquad f(x) = \begin{cases} a, & if \ \ x \lt c \\ b, & if \ \ x ≥ c \end{cases}$

Similar as the other function, it has $x = concentration$ as the amount of Substance Signal that has reached from the Neuron cell, which is used as input. As output it will switch between the a and b values depending if the value of the input is greater lower than the c value.