Computational Model of Neural Networks on Layer IV or Primary Visual Cortex

There is perfect correspondence between the retinal image and the cellular encoding in V1 (striate cortex), which is completed in terms of contrast and orientation. From there, information from the retinal image is sent forward to distinct regions of the occipital lobe for more complex encoding, called extra striate cortex, including V2 (discrimination, orientation, and color), V4 (shape), and V5 (motion) “(Stevens PH.D., livestong.com)

The primate visual system is usually separated in two partially independent pathways; the dorsal pathway subserves mostly motion perception, while the ventral one subserves object feature recognition. The primary visual cortex (V1) receives most of its retinal input through the lateral geniculate nucleus (LGN). Anatomical and functional segregation of visual perception starts at the level of the retina, where parvocellular (P) ganglion cells have small receptive fields and have sustained colour-sensitive synaptic response to light, whereas magnocellular (M) ganglion cells have larger receptive fields and a faster adapting achromatic response to light [Livingston et al., 1992]. Both types of cells project to the layers 3-6 and 1-2 of the LGN, respectively, which in turn send most of their outputs to layers 4Cβ and 4Cα of V1, forming what is known as the P and M pathways [Refs].

According to current research there are about 800,000 ganglion cells in the human optic nerve (J.R. Anderson, 2009,pg. 35). The ganglion cells are where the first encoding of the visual information happens. Encoding is the process of recognizing the information and changing it into something one’s brains can understand and store. Each ganglion cell is dedicated to encoding information from a specific part of the retina. The optic nerve goes then to the visual cortex and the information enters the brain cells. There are two types of cells that are subcortical, or below the cortex; the lateral geniculate nucleus and the superior colliculus. The lateral geniculate nucleus is responsible for understanding details and recognizing objects. The superior colliculus is responsible for understanding where objects are located spatially. This collection of cells working together is called the “what-where” distinction. The division of labor continues, as the information is further processes. The “what” information travels to the temporal cortex, the “where” information travels to the parietal regions of the brain.

Also, there are some Martinotti(triangular or polygonal shaped multipolar neurons) and granular neurons. Afferent fibers projecting from the thalamus, corticocortical connections come to here and IV layer. These synapses both efferent cortical neurons and intercortical( granular, Martinotti and horizontal types)neurons.

a. multipolar neurons: Multipolar neurons are the most common type of neurons in the human body.(1) It usually has three or more processes, one of the process is axon and the rest of the processes are dendrites. Multipolar neurons are found in the central nervous system.(1)

class of cognitive functions could be achieved include those long-range connections within and between cortical regions that activate

The experiment’s hypothesis was whether IT cortical neurones respond to shapes specified by the Kanizsa type. The experimenters were also testing how neurones’ respond if the stimulus they have previously been responding to is present only in short time frame.

Bentin answers the discrepancies by hypothesizing that the anterior-posterior region is sensitive to eyes and is in the mid-fusiform region. His research concentrated on the ERP component N170, which is linked to perceiving faces. Moreover, Bentin questioned the correlation of the N170 to spatial rearrangement of faces, specific face components, and the process of face recognition.

Sensory tissue, introduce in both the CNS and PNS, contains two essential sorts of cells: neurons and glial cells. A glial cellis one of an assortment of cells that give a structure of tissue that backings the neurons and their exercises. The neuronis the all the more practically essential of the two, regarding the informative capacity of the sensory system. To depict the utilitarian divisions of the sensory system, it is critical to comprehend the structure of a neuron. Neurons are cells and along these lines have a soma, or cell body, however they likewise have augmentations of the cell; every expansion is by and large alluded to as a procedure. There is one imperative process that each neuron has called an axon,

Pyramidal cells(PC) are the source of excitatory input to the cortex, similarly the granule cell in the cerebellum, core and matrix thalamocortical cells in the thalamus, and by STN in the basal ganglia. GABA is responsible for keeping a tab on excitatory activity in the brain and prevent the occurrence of a seizure (9).

The travelling-wave fMRI measurement clearly reveal the human visual areas i.e. V1, V2 and V3 in the occipital lobe (Engel et al., 1997; Sereno et al., 1995). The visual areas in the left hemisphere contains a topographic map of the right half of the visual field, with the fovea being represented at the back of the occipital lobe, increasingly eccentric retinal regions being represented at more forward locations within the calcarine sulcus. Moreover, the lower visual field projects to the upper bank of the calcarine sulcus, and the upper visual field to the lower bank, to provide a full topographic map of the right visual field. These maps are repeated, with variants, in areas V2 and V3. Primary visual cortex (V1), which receives direct input from retinogeniculate pathways, occupies calcarine cortex and represents as a hemifield of visual space.

particular cortical regions) (Mitchell et al., 2008), or they can also select the cortex that makes

However, the LGN does not solely receive signals just from the retina, but from the thalamus and cortex also. There are six layers that make up the lateral geniculate nucleus. Layers 1 and 2 are called the magnocellular LGN while layers 3 through 6 make up the parvocellular LGN. The visual cortex is also organized into layers. The first layer is the striate cortex (V1 or primary visual cortex), which both the magnocellular LGN and parvocellular LGN send signals to. The function of V1 is to recognize which area in the lateral geniculate nucleus a signal is coming from and determine the pathway that will encode that

The connection between neurons is essential for neurological function. Interaction between two neurons is called the synapse. In order for the synapse to operate, an action potential must first happen. If one does not work, then the whole neurological function will not, which will eventually lead to humans not working at all as a whole. This paper will look into the two following subjects in Neurological Functioning:

Periodic spontaneous activity is found in many parts of the developing central nervous system including the spinal cord, cortex, hippocampus and retina, and evidence suggests that this activity could underlie aspects of development such as axon guidance, local circuit formation and establishment of sensory maps (Feller, 1999). In the retina, this phenomenon has been studied in detail because its circuitry is stereotypic and its activity can be manipulated easily in development. Before eye opening, retinal circuits undergo a great deal of maturation and refinement. The immature circuits spontaneously generate propagating bursts of action potentials called retinal waves. Retinal waves correlate the firing of retinal ganglion cells (RGCs) and play a role in establishing and refining circuits in the visual system, but there is a great deal of controversy about whether waves play an "instructive" or a "permissive" role in neuronal development. The term instructive implies that retinal activity contains information that affects the formation of synaptic connections, while the term permissive implies that activity is necessary at some minimum level in order for the refinement to occur. This review will focus on the role of retinal waves on three aspects of visual system development – eye-specific segregation in the thalamus, retinotopic refinement in the superior colliculus, and establishment of cortical columns – and summarize the existing arguments for the role of retinal waves