<p>It is generally thought that thalamic input comes in layer 4, feed back from higher areas come through layer 1 to layer 2/3 and feed forward is sent from the deeper layers.  </p>

<p>see Canonical Microcircuits for Predictive Coding<br>
Andre Bastos, W. Martin Usrey, Rick Adams, George Mangun, Pascal Fries, and Karl Friston<br>
<a href="http://psych.nyu.edu/clash/poeppellab/JournalClubPapers/BastosFristonNeuron12.pdf" rel="nofollow">http://psych.nyu.edu/clash/poeppellab/JournalClubPapers/BastosFristonNeuron12.pdf</a></p>

<p>who cite Douglas, R.J., and Martin, K.A. (1991). A functional microcircuit for cat visual cortex. J. Physiol. 440, 735–769.</p>

CC BY-SA 3.0
2015-11-18T17:47:02.350Z
what do you mean by higher areas?
ceillac
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2015-11-18T17:52:00.577Z
"top-down processing" would be equivalent to "feedback from higher areas"
honi
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2015-11-18T18:53:26.013Z
what are higher areas?
ceillac
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2015-11-18T19:14:08.950Z
what is top-down processing?
honi
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2015-11-18T23:34:23.940Z
Correct me if I'm wrong, but don't top-down predictions (feedback) arise from deep layers of agranular cortex, and prediction error neurons (feedforward) in the superficial layers?
mrt
CC BY-SA 3.0
2015-11-19T02:33:48.393Z
yeah, that's the bastos friston version, but it's not clear to me that its universally accepted (see the diagram that bruce smitherson linked in their comment on the original post).  but i dont know for sure myself.
honi
CC BY-SA 3.0
2015-11-19T04:09:48.923Z
Interesting. I think it depends on the model of corticocortical connections that you use (but I'm not really sure).
mrt
CC BY-SA 3.0
2015-11-19T19:20:11.883Z
the other thing is that these studies have only been done on a few cortical areas, and we just assume that the rest of the brain will be similar, even though the few we've looked at have pretty clear differences.
honi
CC BY-SA 3.0
2015-11-18T14:45:07.563Z
2015-11-18T19:16:59.340Z
2015-11-18T19:16:59.340Z
honi
<p>What are the relations between top-down and bottom-up processings and the flows of information in the brain? For example, does top-down processing start from some layers and go to lower layers? 
If so does the information remain in the same area of the brain or can it travel from a layer of one area down to lower layers of an others areas? 
Also how are feedforward (feedback) pathways related to bottom-up (top-down)?</p>

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2015-11-18T19:03:45.733Z
http://www.nature.com/nature/journal/v503/n7474/box/nature12654_BX1.html
Wolphram jonny
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2015-11-18T19:15:02.100Z
@brucesmitherson, make that an answer!
honi
CC BY-SA 3.0
2015-11-18T19:33:30.960Z
@bruce smitherson , thanks for the link. I am still confused by the use of the vocabulary. And that was part of my original question in fact. What do they mean by "higher order cortex"? is it the "higher order association" that we see here for example http://www.indiana.edu/~p1013447/dictionary/brocwern.htm ?
ceillac
CC BY-SA 3.0
2015-11-18T19:46:44.170Z
yes, that would be an example. In general a higher area is any area that received forward input for additional processing or is upstream in this sense, as opposed to areas lower in the hierarchy that are closer to the sensory input. Thus, green arrow are forward connections, and purple ones are feedback connections (to and from higher areas relative to the one you are looking).
Wolphram jonny
CC BY-SA 3.0
2015-11-18T19:57:49.747Z
it shows that some feedback informations are coming from the thalamus then? or the thalamus is just a lap (or relay) on the way from a higher order  to   lower order areas?
ceillac
CC BY-SA 3.0
2015-11-18T21:13:45.867Z
yes, in addition to direct feedback connections many areas have their feedback connections pass first through the thalamus. It is not clear yet what function these loops have, but they are not thought to be just a relay.
Wolphram jonny
CC BY-SA 3.0
2015-11-19T02:42:03.147Z
also, it is important that feed-forward information also comes through the thalamus.  most well known is the feed-forward projection from the retina to the first cortical visual area, V1, which passes through the LGN of the thalamus.
honi
<neuroscience><cognitive-modeling><theoretical-neuroscience><computational-modeling><neural-network>
link between top-down (bottom-up) processing and cortex layers
ceillac
# link between top-down (bottom-up) processing and cortex layers

(Asked by: username_0 on 2015-11-18)

What are the relations between top-down and bottom-up processings and the flows of information in the brain? For example, does top-down processing start from some layers and go to lower layers?
If so does the information remain in the same area of the brain or can it travel from a layer of one area down to lower layers of an others areas?
Also how are feedforward (feedback) pathways related to bottom-up (top-down)?

**Tags:** neuroscience, cognitive-modeling, theoretical-neuroscience, computational-modeling, neural-network

> **Comments:**
> **username_1**: http://www.nature.com/nature/journal/v503/n7474/box/nature12654_BX1.html  
> **username_2**: @brucesmitherson, make that an answer!  
> **username_0**: @bruce smitherson , thanks for the link. I am still confused by the use of the vocabulary. And that was part of my original question in fact. What do they mean by "higher order cortex"? is it the "higher order association" that we see here for example http://www.indiana.edu/~p1013447/dictionary/brocwern.htm ?  
> **username_1**: yes, that would be an example. In general a higher area is any area that received forward input for additional processing or is upstream in this sense, as opposed to areas lower in the hierarchy that are closer to the sensory input. Thus, green arrow are forward connections, and purple ones are feedback connections (to and from higher areas relative to the one you are looking).  
> **username_0**: it shows that some feedback informations are coming from the thalamus then? or the thalamus is just a lap (or relay) on the way from a higher order  to   lower order areas?  
> **username_1**: yes, in addition to direct feedback connections many areas have their feedback connections pass first through the thalamus. It is not clear yet what function these loops have, but they are not thought to be just a relay.  
> **username_2**: also, it is important that feed-forward information also comes through the thalamus.  most well known is the feed-forward projection from the retina to the first cortical visual area, V1, which passes through the LGN of the thalamus.  

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## 1 answers

### Answer by username_2 on 2015-11-18. Score: 2

It is generally thought that thalamic input comes in layer 4, feed back from higher areas come through layer 1 to layer 2/3 and feed forward is sent from the deeper layers.

see Canonical Microcircuits for Predictive Coding  
Andre Bastos, W. Martin Usrey, Rick Adams, George Mangun, Pascal Fries, and Karl Friston  
<http://psych.nyu.edu/clash/poeppellab/JournalClubPapers/BastosFristonNeuron12.pdf>

who cite Douglas, R.J., and Martin, K.A. (1991). A functional microcircuit for cat visual cortex. J. Physiol. 440, 735–769.

> **Comments:**
> **username_0**: what do you mean by higher areas?  
> **username_2**: "top-down processing" would be equivalent to "feedback from higher areas"  
> **username_0**: what are higher areas?  
> **username_2**: what is top-down processing?  
> **username_3**: Correct me if I'm wrong, but don't top-down predictions (feedback) arise from deep layers of agranular cortex, and prediction error neurons (feedforward) in the superficial layers?  
> **username_2**: yeah, that's the bastos friston version, but it's not clear to me that its universally accepted (see the diagram that bruce smitherson linked in their comment on the original post).  but i dont know for sure myself.  
> **username_3**: Interesting. I think it depends on the model of corticocortical connections that you use (but I'm not really sure).  
> **username_2**: the other thing is that these studies have only been done on a few cortical areas, and we just assume that the rest of the brain will be similar, even though the few we've looked at have pretty clear differences.  

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