The Visual Pathway in the Brain - Essay Example

The Visual Pathway in the Brain Abstract The processes involved in visualization are quite complex and involves the interaction of various parts of an organism’s eye and the brain. Visual perceptions move from the external environment to the internal environment through a series of processes and stages. The eye links with the retina, which ultimately links the perceptions to the brain regions and cells. Complex sensory systems are the basic features of the neural circuitry and comprises of numerous nerves as well as sensory fibers. The analysis of the working of these fibers in the cerebral cortex and the general principles through which communication by the sensory nerves in the brainwork reveals the complexity of the process of visualization. The study of the vision perception has had various inputs from different scholars among who developed visual theories to be used. They are instrumental in understanding the processes involved when objects are perceived and are understood by the brain. However, the theories are not holistically sufficient in describing the processes as they are and as such requires further analysis (Yantis, 2001). Such theories as the multi system theory, the continuity theory as well as the Wolford’s per-tabbed theory are such instrumental theories in understanding visual process. The multisystem theory of motion history dates far back with the three motion systems defined as the first order system, the second order system as well as the third order system. The first order system is responsible for moving luminance patterns; the second is responsible for modulation of feature types while the third system computes the motion in a neural representation of a visual space. In understanding the visual process, we note that the Retina is divided into two halves; ‘the nasal hemi retina and the temporal hemi retina’. The divisions further divide into dorsal as well as the ventral quadrants. Through these, the visual perceptions from the environment are coded. While the eyes can seen without having any motion with the head, this is referred to as the visual field. Light rays from the visual field goes through the Coptic cells and are further directed to the ganglion region where the fibers and the axons from the ganglion region further directs the stimulus to the retinal subdivisions and later to the brain sub-cortical regions. Superior colluculus form the final stage in perception where the different forms of stimulus through which the interpretation of the information is done (Anon, nd). Failure in feature extraction or the failure of proper feature extraction has been shown to be the main causes of errors in visual recognition in organism. Conjunction errors are those that are resultant of incorrectly joining of features. In a research study ‘Principles of feature integration in visual perception’, Prinzmetal conducted a test to understand what principles are used by the visual system to integrated observable features. He tested whether the likelihood that the visual system is usually likely to integrate closely located features within the visual space or otherwise. In contrast, the study tested whether the system would more likely integrate features of objects or stimulus coming from a common perceptual group. Feature analytic theories illustrate that the attributes of the stimulus activate feature detectors selectively when a subject is presented with a stimulus. Correct detection and report of a stimulus is ascribed to because of tactical abstraction of some features to discriminate against others. Inappropriate feature detection from accidental activation or the failure to correct enough abstract feature information to discriminate between the perceived stimuli would result to error in interpretation. The activation to inappropriate feature detector in visual process would result to interpretation of a ‘blue X’ as a ‘red X’, while on the other hand, the ability to see the letter ‘X’ without a color is because of the failure to abstract enough features to discriminate between the perceived stimuli. However, there is another type of an error, which is a resultant of the inability to combine correctly the perceived object’s abstracted features. For instance, if one has two objects, a green ‘O’ as well as a red ‘X’ then incorrect combination of the attributes would result to the observation of a red ‘O’ and a green ‘X’ and therefore this error is different from the feature errors and is called ‘conjunction error’. The theories that are consistent with the perceptual principles are relying on the similarities goodness of form of the objects and proximity of the group among others. They hold that illusory conjunctions often happen between objects sharing a perceptual group as against objects across perceptual groupings. According to the continuity theory by Fox, the early stage of visual information processing, ‘objects-tokens’ get created within the visual system on the framework of similarities, symmetry and texture among others. This theory therefore supports the principles that features of the objects from a like perceptual group are more likely to be joined. On the other hand, Wolford’s feature perturbation theory consents with other theories that assert that feature integration mediation arises from the perceived location of an object. According to this theory, features are perturbed and presented in a psychological space with isomorphic relationships to physical distances. This implies that features closely together in the physical space will, equally be closer within the psychological spaces and thus explaining the higher tendencies to pert-abate to overlapping positions within the psychological space. However, a more generalizing feature between the theories is that the two theories lead to a like prediction. This is because the common features to be abstracted from one visual space region often belong to a like perceptual unit or same object (Prinzmetal, 1981). The images as they form on the retina show an organized and systematic occurrence of events in the distal environment. The environment generates the visual stimuli whereas the brain is responsible for estimation as well as the accurate recognition of the input. Cognitive plans for a current time period as well as near future stems from the effective or ability to estimate the states in the prevailing time and then apply the estimation for future prediction. A common consensus between the neural scientists is that the brain has a capacity to learn and retain a model of the external world internally. In a vision research, Rao intended to establish the mathematical forms that internal perception adopts as well as how learned internal perceptions are useful during perceptions. Scientific studies have revealed that the cortex possess a similar ‘neuro-anatomical input – output’ structure as well as patterns of connections within varying cortical areas. However, the studies are yet to determine whether a specific approach to the cortical functioning would be suitably generalized and be uniformly applied in different cortical areas in overlooking the modality of inputs. Nevertheless, the optimal estimation models are independent of the type of stimuli or signal under estimation; it can therefore be used in visual stimuli alongside with the auditory as well as in olfactory motor signals (Rao, 1999). In sum therefore, the process of visual perception as described through perception of information and the ultimate interpretation by the brain is a complex system. The complexity arises from the processes involved; the visual systems used as well as the brain regions and processes responsible for interpretation of the information. Visual theories have been formed and are very instrumental in understanding the processes involved in visual perception. Such theories as the multi system theory, the continuity theory as well as the Wolford’s per-tabbed theory are such instrumental theories in understanding visual process. However, the various theories often fall short in explaining critical processes as they are. Visual perceptions move from the external environment to the internal environment through a series of processes and stages. The eye links with the retina, which ultimately links the perceptions to the brain regions and cells. References Anonymous. nd. Chapter 27:central visual pathways. Retrieved from on June 17, 2013 from http://www.bcs.rochester.edu/courses/crsinf/504/ARCHIVES/F05/ch27.pdf Prinzmetal W. (1981). Principles of feature integration in visual perception. Perception & Psyehophysics 30 (4), 330-339. Rao R. P. N. (1999). An optimal estimation approach to visual perception and Learning. Vision Research 39 1963-1987. Yantis, S. (2001). Visual Perceptions: Essential Readings. London: Psychology Press Read More