A Neural Computation Model Based on nCRF and Reverse Control Mechanism - Developing Concepts in Applied Intelligence - page 47

cell (AC) connects many of the nearby ganglion cells (GCs) in the horizontal
direction through its extensive dendritic branches. Amacrine cells (ACs) also
interconnect with each other. The breadth of AC's connection goes far beyond GC's
CRF surround, So AC is properly related to the formation of nCRF with a wide range.
Thus, HC and AC play the role of information integration in the outer and inner
plexiform layer respectively. Retinal GC receive inputs from many neurons in the
outer and inner plexiform layer, hence HC and AC are connected with the formation
of nCRF of retinal GC.
2.2 Reverse Control Mechanism of Retina
The IPC sends messages to HC and BC in the outer plexiform [10]. The works of
Yang et al. [11] show that IPC ceasing activity in light enhances HC activity. After a
long period of dark adaptation, IPC accelerates activity, inhibits HC and decreases the
peripheral antagonist. In addition, some fibers from mesencephalic center (MC) are
found into the centrifugal fibers of the retina through optic nerves in all vertebrates.
The fibers from MC control AC and IC. Electrical stimulation to centrifugal fibers
can increase response of GC to lights. It is possibly caused by the disinhibition of IPC
and AC. This shows that IPC takes backward control of HC and BC to change the size
of CRF surround, and MC takes backward control of IPC and AC to change the size
of CRF center through centrifugal fibers.
3 Calculation Model
3.1 Neural Circuit for Dynamically Adjusting of RF
Based on the above neurophysiological mechanism of retinal ganglion cell nCRF, the
reverse control mechanism and fixation eye movement, the neural circuit showed in
Fig. 1 is designed to adjust RF dynamically. The details of retinal micronetwork are
very complex and partly unclear. So we simplify the RF mode appropriately
simplification by omitting the contribution of HC to the formation of nCRF.
In Fig. 1, the axons of several RCs form synaptic connections with the dendrites of
a BC. The RCs compose the CRF center of the BC. HC connects many of the nearby
RCs in the horizontal direction through its dendritic branches. Horizontal cells (HCs)
also interconnect with each other. The HCs integrate the responses of the RFs,
transfer them to the BC, and inhibit BC's CRF center, and form BC's CRF surround.
BCs with antagonistic center-surround CRF transfer their responses into GC and form
the GC's CRF with antagonistic center-surround structure. AC connects many of the
nearby GCs in the horizontal direction through its extensive dendritic branches. ACs
also interconnect with each other. The ACs integrate the responses of the BFs,
transfer them to the GC, and inhibit BC's CRF surround, thus forming GC's nCRF.
IPC takes feedback control of HC and BC and changes the size of CRF surround and
MC takes feedback control of IPC and AC and changes the size of CRF center
through centrifugal fibers.