<p><strong>Short answer</strong><br>
Increasing neural complexity only increases processing times when neurons are serially linked together.</p>

<p><strong>Background</strong><br>
Neuronal conductance of action potentials takes time, as neuronal signals travel at a speed of 0.5 to 150 m/s through the axon <a href="https://www.ncbi.nlm.nih.gov/books/NBK10921/" rel="nofollow noreferrer">(Purves <em>et al</em>., 2001)</a>. Furthermore, synaptic transmission between neurons takes time. A chemical synaptic transmission takes approximately 0.5 ms <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1357674/?page=1" rel="nofollow noreferrer">(Katz &amp; Miledi, 1965)</a>. As a consequence, stringing neurons together increases processing time. </p>

<p>For example, if we look at the pain response, the reflex arc is very short, covering as little as two synapses (Fig. 1). The moment you touch a hot pan, you pretty much instantly draw away your hand. This process precedes even before you become consciously aware of the fact you touched something painful. This is because conscious awareness happens in the brain, involving a longer distance to be covered from your finger, and because it involves many more synapses including the brainstem, lower cortical areas and higher cortical areas (Fig. 2). </p>

<p>Processing time does not necessarily have to increase when processing complexity is increased, as long as the processing takes place in parallel. For example, multiple visual pathways in the human brain run in parallel, for example the 'what' and 'where' processing in the brain in the ventral and dorsal streams <a href="http://www.sciencedirect.com/science/article/pii/S0028393215300956" rel="nofollow noreferrer">(Van Polanen &amp; Davare, 2016)</a>, as depicted in Fig. 3.</p>

<p><a href="https://i.sstatic.net/r9cIX.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/r9cIX.jpg" alt="reflex arc"></a><br>
<sup>Fig. 1. Pain reflex arc. source: <a href="https://owlcation.com/stem/Here-is-what-happens-when-you-accidentally-touch-a-hot-pot" rel="nofollow noreferrer">Owlcation</a></sup></p>

<p><a href="https://i.sstatic.net/X8QAR.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/X8QAR.jpg" alt="painpathway"></a><br>
<sup>Fig. 2. Conscious pain pathway. source: <a href="http://www.neuwritewest.org/blog/pain-in-the-brain" rel="nofollow noreferrer">neuwritewest</a></sup></p>

<p><a href="https://i.sstatic.net/3ZoEl.png" rel="nofollow noreferrer"><img src="https://i.sstatic.net/3ZoEl.png" alt="ventral dorsal streams"></a><br>
<sup>Fig. 3. Parallel processing of 'what' and 'where' information in the visual system. source: <a href="https://www.brainscape.com/flashcards/visual-spatial-processes-2471552/packs/4358707" rel="nofollow noreferrer">Brainscape</a></sup></p>

<p><sub><strong>References</strong><br>
<strong>-</strong> <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1357674/?page=1" rel="nofollow noreferrer">Katz &amp; Miledi, <em>J Physiol</em> (1965); <strong>181</strong>(3): 656–70</a><br>
<strong>-</strong> <a href="https://www.ncbi.nlm.nih.gov/books/NBK10921/" rel="nofollow noreferrer">Purves <em>et al</em>. (eds), <em>Neuroscience</em>, 2nd ed. Sunderland (MA): Sinauer Associates</a><br>
<strong>-</strong> <a href="http://www.sciencedirect.com/science/article/pii/S0028393215300956" rel="nofollow noreferrer">Van Polanen &amp; Davare, <em>Neuropsychologia</em> (2015); <strong>79</strong>: 186–91</a></sub></p>

CC BY-SA 3.0
2017-08-15T09:15:04.380Z
2017-08-15T09:36:31.450Z
2017-08-15T09:36:31.450Z
AliceD
<p>If a sensory input is perceived, one needs to process this input from the sensory end organ (sensation) up to the brain (perception). Does a more more complex neural network consume more time than a simple one? For example, does a house fly process visual images faster than a human being? </p>

<neuroscience><perception><cognitive-neuroscience><neurophysiology><sensation>
Does increased neural complexity slows down brain operation speeds?
kurtkim
# Does increased neural complexity slows down brain operation speeds?

(Asked by: username_0 on 2017-08-15)

If a sensory input is perceived, one needs to process this input from the sensory end organ (sensation) up to the brain (perception). Does a more more complex neural network consume more time than a simple one? For example, does a house fly process visual images faster than a human being?

**Tags:** neuroscience, perception, cognitive-neuroscience, neurophysiology, sensation


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## 1 answers

### Answer by username_1 on 2017-08-15. Score: 2

**Short answer**  
Increasing neural complexity only increases processing times when neurons are serially linked together.

**Background**  
Neuronal conductance of action potentials takes time, as neuronal signals travel at a speed of 0.5 to 150 m/s through the axon [(Purves *et al*., 2001)](https://www.ncbi.nlm.nih.gov/books/NBK10921/). Furthermore, synaptic transmission between neurons takes time. A chemical synaptic transmission takes approximately 0.5 ms [(Katz & Miledi, 1965)](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1357674/?page=1). As a consequence, stringing neurons together increases processing time.

For example, if we look at the pain response, the reflex arc is very short, covering as little as two synapses (Fig. 1). The moment you touch a hot pan, you pretty much instantly draw away your hand. This process precedes even before you become consciously aware of the fact you touched something painful. This is because conscious awareness happens in the brain, involving a longer distance to be covered from your finger, and because it involves many more synapses including the brainstem, lower cortical areas and higher cortical areas (Fig. 2).

Processing time does not necessarily have to increase when processing complexity is increased, as long as the processing takes place in parallel. For example, multiple visual pathways in the human brain run in parallel, for example the 'what' and 'where' processing in the brain in the ventral and dorsal streams [(Van Polanen & Davare, 2016)](http://www.sciencedirect.com/science/article/pii/S0028393215300956), as depicted in Fig. 3.

[![reflex arc](https://i.sstatic.net/r9cIX.jpg)](https://i.sstatic.net/r9cIX.jpg)  
Fig. 1. Pain reflex arc. source: [Owlcation](https://owlcation.com/stem/Here-is-what-happens-when-you-accidentally-touch-a-hot-pot)

[![painpathway](https://i.sstatic.net/X8QAR.jpg)](https://i.sstatic.net/X8QAR.jpg)  
Fig. 2. Conscious pain pathway. source: [neuwritewest](http://www.neuwritewest.org/blog/pain-in-the-brain)

[![ventral dorsal streams](https://i.sstatic.net/3ZoEl.png)](https://i.sstatic.net/3ZoEl.png)  
Fig. 3. Parallel processing of 'what' and 'where' information in the visual system. source: [Brainscape](https://www.brainscape.com/flashcards/visual-spatial-processes-2471552/packs/4358707)

**References**  
**-** [Katz & Miledi, *J Physiol* (1965); **181**(3): 656–70](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1357674/?page=1)  
**-** [Purves *et al*. (eds), *Neuroscience*, 2nd ed. Sunderland (MA): Sinauer Associates](https://www.ncbi.nlm.nih.gov/books/NBK10921/)  
**-** [Van Polanen & Davare, *Neuropsychologia* (2015); **79**: 186–91](http://www.sciencedirect.com/science/article/pii/S0028393215300956)


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