restriction in the number of cells. Another significant result of our paper is the control of the chaos on time scales. The presence of unstable periodic motions embedded in the chaotic attractor is evidenced by means of the Pyragas control technique [48, 49]. It is numerically demonstrated that the Pyragas method is appropriate for controlling chaos not only in discrete and continuous-time systems, but also in systems on time scales. The detection of chaotic behavior in neural networks is of great interest since it may provide the opportunity to understand how the brain and the rest of the nervous system works. We believe that the presented technique will shed light on the mathematical investigation of neural processes that work intermittently [69, 72, 82]. Moreover, our results can provide further research areas in neural activities that are achievable at certain time intervals. The problem of period-doubling route to chaos [83, 84] by neural networks on time scales can be considered in the future through the presented method. Our approach can also be useful for designing secure communication systems [63, 85, 86, 87], and it can be improved for other kinds of recurrent networks such as Hopfield and Cohen-Grossberg neural networks [88, 89]. This work is supported by the 2219 scholarship programme of TÜBİTAK, the Scientific and Technological Research Council of Turkey. 18 References Acknowledgments [1] L.O. Chua, L. Yang, Cellular neural networks: Theory, IEEE Trans. Circuits Syst. 35 (1988) 1257– 1272. [2] L.O. Chua, L. Yang, Cellular neural networks: Applications, IEEE Trans. Circuits Syst. 35 (1988) 1273–1290. [3] A. Bouzerdoum, R.B. Pinter, Shunting inhibitory cellular neural networks: derivation and stability analysis. IEEE Trans. Circuits Systems I Fund. Theory. and Appl. 40 (1993) 215–221. [4] A. Bouzerdoum, B. Nabet, R.B. Pinter, Analysis and analog implementation of directionally sensi- tive shunting inhibitory cellular neural networks, in: Visual Information Processing: From Neurons to Chips, Proc. SPIE 1473, 1991, pp. 29–38. [5] A. Bouzerdoum, R.B. Pinter, Nonlinear lateral inhibition applied to motion detection in the fly visual system, in: R.B. Pinter, B. Nabet (Eds.), Nonlinear Vision, CRC Press, Boca Raton, FL, 1992, pp. 423–450.