Sequential pictorial presentation of neural interaction in the retina. 1. The synaptic ribbon complex.
The analysis of circuits in the retina revealed by three-dimensional reconstructions (Sjöstrand, 1958, 1974, 1976,1978, 1990) is presented in a simplified way by series of schematic drawings illustrating each individual step in the sequence of synaptic transmission between the neurones. In addition, the analysis has been extended further compared to earlier presentation (Sjöstrand, 1998a). The circuit of the synaptic ribbon complex controls transmission between cones and bipolar cells by the inhibitory input from horizontal cells being controlled by the cone. At low light intensity, horizontal cell inhibition blocks transmission between cones and bipolar cells because of high concentration of transmitter at the critical synapse, explaining fading of cone vision. The requirement for maintaining a low transmitter concentration at the synapses to secure proportionality between input and output signals is established by horizontal cell inhibitory input both at the cone-bipolar cell and the cone-horizontal cell synapses. How one bipolar cell can transmit information regarding average light intensity over a large area of the retina is discussed in detail.
Sjöstrand
F S
FS
University of California, Los Angeles, USA. fsjostra@ucla.edu
D000818:Animals; D021621:Imaging, Three-Dimensional; D008954:Models, Biological; D009474:Neurons / Q000166:cytology / Q000502:physiology; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology*; D017949:Retinal Cone Photoreceptor Cells / Q000033:anatomy & histology / Q000502:physiology; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D009435:Synaptic Transmission / Q000502:physiology*; D014785:Vision, Ocular / Q000502:physiology