1. Lateral inhibition Domina Petric, MD

2. Lateral inhibition
refers to the inhibition that neighboring neurons in the brain pathways have on each other. 

3. In the visual system, neighboring pathways from the receptors to the optic nerve show lateral inhibition.
This means that neighboring visual neurons respond less if they are activated at the same time than if one is activated alone.
The fewer neighboring neurons stimulated, the more strongly a neuron responds.

4. Lateral inhibition
This process greatly increases the visual system's ability to respond to edges of a surface.
Neurons responding to the edge of a stimulus respond more strongly than do neurons responding to the middle.

5. Lateral inhibition
The edge neurons receive inhibition only from neighbors on one side: the side away from the edge.
Neurons stimulated from the middle of a surface get inhibition from all sides.

6. Intensity coding
The primary afferent fibre whose receptive field centre is closest to the point of stimulation will produce more action potentials than those on the periphery.

7. Stimulus intensity Population coding:
Frequency coding:
increase the firing rate of individual primary afferent fibres by increasing the size of the receptor potential
most common way to do this is by increasing the size of the receptive field stimulated
Population coding:
increase the number of primary afferent fibres responding
this process is called recruitment

8. Neurophysiology
The primary afferent neurons are connected to inhibitory interneurons as well as to second order neurons that continue to carry the information along the primary sensory pathway.
Dale´s law: primary afferent neurons release excitatory neurotransmitter at each synapse (positive response on inhibitory interneurons as well as on second order neurons).
The interneurons have a negative response on adjacent second order neurons.
Action potentials in the second order neurons whose receptive fields are toward the periphery of the stimulus field are more strongly inhibited and produce fewer action potentials, than the cell with its receptive field in the centre.

9. The result is that, within the CNS, the area of sensation is less than the area of receptor activation, due to the areas of inhibition that flank the centre of stimulus. Lateral inhibition increases contrast between strong and weak signals.

10. Literature: http://www.indiana.edu/~p1013447/dictionary/lat_i.htm
(2014 University of Minnesota Medical School Duluth)