File:HSE FD1-cirucits.jpg

Simplified wiring diagrams of neuronal circuits extracting different aspects of optic flow information. A Circuit for coherent wide-field motion. Input organization of the HSE-cell of the blowfly. The HSE-cell receives input from the eye ipsilateral to its main dendrite from many retinotopic motion-sensitive elements. As a consequence of this input, the HSE-cell is depolarized by front-to-back motion and hyperpolarized by back-to-front motion. The HSE-cell receives additional excitatory input on its main dendrite from the H1-cell or close to its axon terminal from the H2-cell. The spike activity of H1 and H2 is increased during back-to-front motion in the contralateral visual field. The cells are sketched only schematically. B Circuit for object motion. The FD1-cell is one output element of this circuit. It receives retinotopic input from the ipsilateral eye to its main dendrite. To prevent it from firing during wide-field motion, it is inhibited by the VCH-cell via GABAergic synapses. The VCH-cell responds best to wide-field motion as indicated by the inset. It receives input from the contralateral eye from both the H1- and the H2-cell. There is an additional inhibitory input during contralateral front-to-back motion not shown in the diagram. C Relationship of the two neuronal circuits sketched in A and B. The cells are indicated by boxes. Excitatory and inhibitory synapses are indicated by triangles and circles, respectively. Note the reciprocal recurrent inhibitory connections between neurons in both halves of the visual system.