1. Biological Cybernetics By: Jay Barra Sean Cain

2. Biological Cybernetics An interdisciplinary medium for experimental, theoretical and application- oriented aspects of information processing in organisms. Sensory, motor, cognitive, and ecological phenomena Experimental studies of biological systems

3. Biological Cybernetics Topics Covered: Experimental studies of biological systems Quantitative modeling Computational, technical, or theoretical studies Understanding biological information processing Artificial implementation of biological information processing and self-organizing principles

4. Biological Cybernetics Performance and Function of systems: Communication between life sciences and technical or theoretical disciplines Neural Interactions a specific interest

5. Coupled Van der Pol Oscillators - A model of excitatory and inhibitory neural interactions Relate basic neural activities on the cellular level to: The various observed electroencephalograms (EEG) Potential differences in the cortex Interactions between and within excitatory and inhibitory neurons Modeled by Wilson and Cowan EEG phenomena studied in relation to such models Simple models explaining the rhythmicity of the EEG Based on Wilson and Cowan model A feedback loop through a third set of neurons – Lopes da Silva et al. Positive and negative feedback loops with two excitatory and one inhibitory subsets of neurons – Zetterberg et al.

6. Van der Pol Oscillators: Mutually coupled relaxation oscillators Done as a mathematical model for the electrical activity of the human and animal gastro-intestinal tract Reasonable to model EEG phenomena by a number of coupled oscillators Distribution of entrained oscillator frequencies can show the peak- dip shape of the EEG Phenomenological mathematical models: Explain EEG data Offer a guide for experiments on the EEG Coupled Van der Pol Oscillators

7. Biological Systems Biological clocks consist of: A group of interacting oscillators. Circadian rhythms, biochemical oscillators, pacemaker neurons, etc. May be related to biological oscillators Interesting subject in biological systems: The entrainment of oscillators under periodic forces The entrainment of a number of interacting oscillators

8. Biological Systems Apart from biological systems Nonlinear circuit theory Can be combined with biological systems for a better understanding of EEG phenomena Relation of physiological parameters to the coefficients in the circuits

9. Study Conclusions Hope to further the understanding of very generalized cortex-like tissue in conjunction with the EEG phenomena

10. System-Theoretical Analysis of the Clare Bishop Area (CBA) in the Cat Clare Bishop Area: Retinotypically organized cortical area of the cat brain Connected to a great variety of visual areas in a very complex way

11. Experimental Analysis Difficult because: The greater the distance from the retina, the more specific the signal combinations necessary to analyze the system become Feedback loops cannot be opened, unequivocal identification of CBA cell properties is impossible Nonlinear character has a great influence on signal processing

12. Experimental Analysis Circumvent Difficulties: Specific signal combinations have been developed, being restricted to: Deterministic and stochastic signals Determination of a number of cell properties Hypotheses on the function of the CBA are tested

13. Conclusions Only moving stimuli produce responses Reaction of Cells: Direction specific Prefer the extrafoveal direction Systems existent in the CBA: Have different behavior for: Space Time Amplitude

14. Study Conclusions CBA primary task: Orientation Exact localization of objects independent of velocity Treatment of objects in relation to background stimuli

15. Cybernetics of Limb Movement Determine stresses on joints during motion Neural planing involved in mapping spatial planning to move joint to new position Example, hand reaches for an apple Hand is the extension, upper arm and fore arm movements are automtically mapped

16. Computations in controlling movement Joint Torque Masses of individual segments Effects of gravity and momentum

17. Conclusions Normal straight line motion of joints involves –Compensation for dynamic interaction at each joint segment

18. Information Content of Texture Gradients Information gradients determine responses in stimuli sensory systems –Hairs on the back of the hand Touching one hair may not be felt, touching three will

19. Visual gradients Non-linear distribution gives interpretation of horizons in a 2D image –This is why perspective works in drawings

20. Visual Gradients Clear Horizon Horizon diminishes

21. Thresholds for activation Affected by regularity of the information gradient Global Uniformity Shape containing the pattern Foreshortening (perspective)

22. Pattern types Locally regular and globally uniform – Field of flowers, cars in parking lot Locally regular but globally varying – Waves on a lake Locally irregular but globally uniform – Field of rocks, boulders and pebbles Locally irregular and globally varying

23. Works Cited System-Theoretical Analysis of the Clare Bishop Area in the Cat. Jensen H.J. Springer-Verlag Biological Cybernetics 39 53-66 (1980). Coupled Van der Pol Oscillators – A model of Excitatory and Inhibitory Neural Interactions. Kawahara, Takuji. Springer-Verlag. Biological Cybernetics 39, 37-43 (1980). Dynamic Interactions between Limb Segments During Planar Arm Movement, S. Kemmerling, D. Varju, Biological Cybernetics 44 67-77 (1982) The Information Content of Texture Gradients, Steven, Kent, Biological Cybernetics 42 95-105(1981)