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. 2013 Nov:2013:835-838.
doi: 10.1109/ner.2013.6696064. Epub 2014 Jan 2.

Simulating lesions in multi-layer, multi-columnar model of neocortex

Beata Strack  1 , Kimberle M Jacobs  2 , Krzysztof J Cios  3
Affiliations

Simulating lesions in multi-layer, multi-columnar model of neocortex

Beata Strack et al. Int IEEE EMBS Conf Neural Eng. 2013 Nov.

Abstract

The paper presents results of modeling global and focal loss of layers in a multi-columnar model of neocortex. Specifically, the spread of activity across columns in conditions of inhibitory blockade is compared. With very low inhibition activity spreads through all layers, however, deep layers are critical for spread of activity when inhibition is only moderately blocked.

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Figures

Fig. 1.
Fig. 1.
Example of connectivity. (a) RS neurons (light green triangle) in layer VI connect with different probabilities to IB neurons in layer V (blue-green triangle), FS neurons (blue circle) in layer VI within the same and adjacent columns, LTS cells (red ellipse) in layer VI, and other RS cells in layers V and VI. For each layer, the number in parenthesis is the total number of neurons in this layer per column. Percentages of each neuron type within given layer are also listed. (b) Selected cells (as shown) within each column receive input from a thalamic cell.
Fig. 2.
Fig. 2.
Spread of activity in the intact network. (a) Peak negativity vs. level of inhibitory blockade in different columns. Results averaged from two simulations. (b) Local field potentials in stimulated column (column 2), one column away (column 3), and two columns away (column 4) in conditions of 70% inhibitory blockade.
Fig. 3.
Fig. 3.
Horizontal spread of activity through individual layers after removal of other layers in all columns (global lesion). (a-b) Peak evoked negativity from computed LFP after stimulation of column 2 under various levels of inhibitory blockade. Cortical strips of only layer III (a) or layer V (b) were modeled as created experimentally from biological tissue after cut of coronal slices (Telfeian). Average of 2 simulations shown. (c-d) Local field potentials produced after stimulation of column 2 under condition of 70% inhibitory blockade for layer III (c, black) and layer V (d, blue). Activity in columns 3 and 4 is a result of propagation across the laminar strip. Propagation to columns 3 and 4 occurs for both layer III and layer V strips.
Fig. 4.
Fig. 4.
Propagation through superficial versus deep cortex measured by creating bridges of tissue within column 3 (focal lesions). (a-b) Peak evoked negativity from computed LFP after stimulation of column 2 under various levels of inhibitory blockade when only superficial (a) or deep (b) layers remain within column 3. Average of 2 simulations shown. Larger LFPs are produced from propagation across the deep layer bridge. (c-d) Local field potentials produced after stimulation of column 2 under condition of 60% inhibitory blockade for the superficial (c, black) and deep(d, blue) layer bridge. A greater amount of propagation occurs with the deep layer bridge.
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