Surround inhibition and its benefits in somatosensory system
Introduction
Somatosensory system is a complex sensory system that is made up of different types of sensory receptors. These sensory receptors include thermo-receptors (specialised heat receptors), mechanoreceptors (specialised cells that senses pressure and distortion), chemo- receptors (specialised receptors cells that converts chemical signals in action potential), and photo- rectors (specialised cells that converts light signals in to chemical signals) and so on. In this complex system there are lots of neural mechanisms or physiological mechanisms that regulate behaviour voluntary and involuntary system. In this essay one specific neural mechanism that focuses on neural activity in the central nervous system will be discussed. That is the surround inhibition (centre-surround inhibition). Its functions or rolls, its benefits and its involvements in different parts of the body will be discussed. In addition surround inhibition plays a major role in many disorders and two of them will be discussed in here. That its involvement in focal hand dystonia (FHD) and Schizophrenia disorders.
Surround inhibition
Surround inhibition receptive field is around the centre- surround organization ether in the retina of the eye or anywhere else. It was first discovered by Kuffler in 1953 and it has been studied widely in the retinal ganglion cell in vertebrates naming from fish to monkeys (mammals) to birds to amphibians (PATRICK K 2002). Surround inhibition works as a neural mechanism that sharpens the sensation and focuses neural activities in the central nervous system (PATRICK K 2002). This is well known in somatosensory system where central signals are made easy ...
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...round organization in bipolar cells: Symmetry for opposing contrasts, Visual Neuroscience 20 pp:, 1–10
• Queensland Government and Queensland Health (2011) What Is Schizophrenia? http://www.health.qld.gov.au/mentalhealth/abt_mental/facts_schizophrenia.asp • Suk Y.Kang, Mark Hallett, Young H. Sohan (2012), Synchronised finger exercise reduces surround inhibition, International Federation of Clinical Neurophysiology pp: 1388-2457
• Super .H, Romeo .A (2012), Masking of Figure-Ground Texture and Single Targets by Surround Inhibition: A Computational Spiking Model, PLoS ONE 7(2): e31773.
• Valentina R, Marc S. Tibber, Elaine J. Anderson, Tracy B, Patricia C, Sukhwinder S. Shergill, Steven C. Dakin, (2013) Reduced Crowding and Poor Contour Detection in Schizophrenia Are Consistent with Weak Surround Inhibition. PLoS ONE 8(4): e60951. doi:10.1371/journal.pone.0060951
Barlow (1953) first postulated the existence of feature-sensitive ganglion cells in a frog’s retina based on an inhibitory-surround structure of the receptive field. He maintained that the “on-off” units of these cells triggered by the presence of a particular stimulus corresponded to certain behaviour in the frog. For example, presenting a spot of light in the visual field would cause certain neurons to fire in a particular ganglion cell, and in a live frog, would cause the frog to snap at the stimulus. Barlow concluded that these cells must be “fly detectors”. Lettvin et al. (1959) further examined the visual mechanisms of the frog and discerned fo...
Rowland, Lewis P. (ed.): Merritt's Textbook of Neurology, eighth edition. Lea and Febiger. Philadelphia, 1959, pp. 630--631.
8Th edition, Chapter 15.3. Kentridge, B. (1995). S2 Psychopathology Lecture 3: Schizophrenia. Retrieved March 4, 2005. From Http://www.dur.ac.uk/robert.kentridge/ppath3.html Mann, R. (1996).
Vinogradov, S., Willis-Shore, J., Poole, J.H., Marten, E., Ober, B., & Shenaut, G. (1997). Clinical and neurocognitive aspects of source monitoring errors in schizophrenia. Am J Psychiatry, 154, 1530-1537.
The ‘where visual pathway’ is concerned with constructing three dimensional representations of the environment and helps our brain to navigate where things are, independently of what they are, in space in relation to itself (Mishkin & Ungerleider & Macko, 1983).... ... middle of paper ... ... The 'Standard' of the 'Standard'.
The basal ganglia are part of the extrapyramidal system and work in conjunction with the motor cortex in providing movement and serve as the relay center. Damage to this area results in Athetoid Cerebral Palsy, the second most common form of cerebral palsy. Involuntary purposeless movements, particularly in the arms, hands, and facial muscles, characterize Athetosis. In addition, the individual can become “stuck” in abnormal positions or postures and require specific positioning to maintain more normal tome and
Firstly, there is various of sensing activities as in seeing and hearing as in a sense of understanding of what is seen and heard. Secondly the sense of feeling in numerous parts of the body from the head to the toes. The ability to recall past events, the sophisticated emotions and the thinking process. The cerebellum acts as a physiological microcomputer which intercepts various sensory and motor nerves to smooth out what would otherwise be jerky muscle motions. The medulla controls the elementary functions responsible for life, such as breathing, cardiac rate and kidney functions. The medulla contains numerous of timing mechanisms as well as other interconnections that control swallowing and salivations.
Kandel, E. R., J. H. Schwarz, and T. M. Jessel. Principles of Neural Science. 3rd ed. Elsevier. New York: 1991.
Kanske, P., Heissler, J., Schönfelder, S., Forneck, J., & Wessa, M. (2013). Neural correlates of
National Library of Medicine, National Institute of Health. Schizophrenia. 31 Jan 2013. Web. 15 May 2014
In this lab we apply the technique known as a two point discrimination test. This test will allow us to determine which regions of the skin are best able to discriminate between two simultaneous sensory impulses. According to (Haggard et al. 2007), tactile discrimination depends on the size of the receptive fields located on the somatosensory neurons. However receptive fields for other types of sensations are located elsewhere. For vision we find that the receptive fields are located inside the visual cortex, and for hearing we find receptive fields in the auditory cortex. The ability for the body to discriminate two points depends on how well that area of the body is innervated with neurons; and thus conferring to the size of the receptive fields (Haggard et al. 2007). It is important to note that the size of the receptive field generally decreases in correlation to higher innervations. As was seen in the retinal receptive fields, the peripheries of tissue had contained larger receptive fields (Hartline, 1940). In our test we hypothesized that the finger region will be able to discriminate better than the forearm. This means that they will be much more innervated with neurons than the forearm, and likewise contain smaller receptive fields. This also means that convergence is closer to a 1:1 ratio, and is less the case the farther from the fingers we go. We also think that the amount of convergence is varied with each individual. We will test to see if two people will have different interpretations of these results.
Schizophrenia is a devastating and costly mental disorder that affects 1% of population worldwide. Patients manifest clusters of positive, negative and cognitive symptoms in early twenties and are often left with life-long severe mental disability and social stigma. Cognitive deficits in patients with schizophrenia are considered core symptoms of this disorder, and can manifest at the initial stage (Elvevåg and Goldberg, 2000). Atypical antipsychotics ameliorate positive symptoms but may only modestly improve cognitive symptoms (Richelson, 2010). In addition to this, some of the typical antipsychotics are even have deteriorative effects on cognitive symptoms (Heaton and Crowley 1981). To find the appropriate treatments for cognitive deficits of schizophrenia, it is important to know the underlying pathophysiology.
M.M. Merzenich, J. K. (1983). Topographical reorganization of somatosensory cortial areas 3b and 1 in adult monkeys following restrictive deafferentation. Neuroscience, 33-55.
The five senses of sight, hearing, touch, taste and smell are all sensations throughout the human body. Sensation is the involvement of sensory receptors as well as the central nervous system in order to allow us to experience outside stimuli. The system that allows us to experience sensation is the sensory system.
This arc belongs to the autonomic nervous system (ANS). The ANS is the part of the peripheral nervous system that is responsible for controlling involuntary body functions. This system helps us maintain a steady heartbeat while we are sleeping, and anything else that is necessary to keep us alive during low levels of consciousness. This system affects the body functions that are not consciously managed, such as breathing, digestion, heart rate, pupillary dilation, and urination. However, there are some ANS actions that we are able to control with our mind to a certain extent, such as swallowing.