Lateral inhibition in a recurrent network

Adding Lateral Inhibition to a Simple Feedforward Network Enables It to Perform Exclusive-Or

Neural Computation ◽

10.1162/089976698300017755 ◽

1998 ◽

Vol 10 (2) ◽

pp. 277-280

Author(s):

Leslie S. Smith

Keyword(s):

Lateral Inhibition ◽

Recurrent Network ◽

External Input ◽

Output Function ◽

Output Unit ◽

Feedforward Network ◽

Point Attractor ◽

Exclusive Or

A simple laterally inhibited recurrent network that implementse xclusive-or is demonstrated. The network consists of two mutually inhibitory units with logistic output function, each receiving one external input and each connected to a simple threshold output unit. The mutually inhibitory units settle into a point attractor. We investigate the range of steepness of the logistic and the range of inhibitory weights for which the network can perform exclusive-or.

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The Cockroach DCMD Neurone: I. Lateral Inhibition and the Effects of Light- and Dark-adaptation

Journal of Experimental Biology ◽

10.1242/jeb.99.1.61 ◽

1982 ◽

Vol 99 (1) ◽

pp. 61-90 ◽

Cited By ~ 1

Author(s):

DONALD H. EDWARDS

Keyword(s):

Lateral Inhibition ◽

Dark Adaptation ◽

Light Adaptation ◽

Absolute Intensity ◽

Recurrent Network ◽

Light Spot ◽

Movement Detector ◽

Threshold Response ◽

Inhibitory Network ◽

Local Background

1. The responses of the cockroach descending contralateral movement detector (DCMD) neurone to moving light stimuli were studied under both light- and dark-adapted conditions. 2. With light-adaptation the response of the DCMD to two moving 2° (diam.) spots of white light is less than the response to a single spot when the two spots are separated by less than 10° (Fig. 2). 3. With light-adaptation the response of the DCMD to a single moving light spot is a sigmoidally shaped function of the logarithm of the light intensity (Fig. 3a). With dark-adaptation the response of a DCMD to a single moving light spot is a bell-shaped function of the logarithm of the stimulus intensity (Fig. 3b). The absolute intensity that evokes a threshold response is about one-and-a-half log units less in the dark-adapted eye than in the light-adapted eye. 4. The decrease in the DCMD's response that occurs when two stimuli are closer than 10°, and when a single bright stimulus is made brighter, indicates that lateral inhibition operates among the afferents to the DCMD. 5. It is shown that this inhibition cannot be produced by a recurrent lateral inhibitory network. A model of the afferent path that contains a non-recurrent lateral inhibitory network can account for the response/intensity plots of the DCMD recorded under both light-adapted and dark-adapted conditions. 6. The threshold intensity of the DCMD is increased if a stationary pattern of light is present near the path of the moving spot stimulus. This is shown to be due to a peripheral tonic lateral inhibition that is distinct from the non-recurrent lateral inhibition described earlier. 7. It is suggested that the peripheral lateral inhibition acts to adjust the threshold of afferents to local background light levels, while the proximal non-recurrent network acts to enhance the acuity of the eye to small objects in the visual field, and to filter out whole-field stimuli.

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