Psychology of the Brain - Assignment Example

Psychology of the Brain and Section # of Psychology of the Brain Describe how Seidenberg andMcClelland’s (1989) model was trained to read words. Discuss how well this training imitates the process of a human learning to read Seidenberg and McClelland designed a dual route model to read words so they can study human reading ability (Ellis 1993). Their model was trained to read on two routes. One lexical route which includes irregular words, and the other non-lexical route - operating on basic grapheme-phoneme correspondence rules (Ellis 1999). They trained their model on a corpus designed by them including 2897 monosyllabic words (Steven Davis 1992). They used this model to study learning ability in a surface dyslexic patient. They studied the effect of word frequency in the patient and the model and found a characteristic pattern in their learning. This included a frequency-by-consistency interaction and a prevalent regularization error (Plaut 1993). The study also highlighted patient’s ability to read non-words which were pronounceable e.g. Heaf (Plaut 1993). The study concluded that surface dyslexia arise in the absence of semantics. Their model has provided a useful conformity within which to analyze the detailed patterns of behavior in normal and impaired word reading (Plaut 1993). The only problem with their model is that it is not able to pronounce the words as efficiently as the patient but they have successfully replicated the complex symptoms shown by dyslexic patients. Their model has contributed much in the field of cognitive psychology specifically in the area of learning. 2. Outline arguments for and against the notion that attention acts as a filter for unwanted stimuli. It is impossible for the brain to process all the information passed on to it by our senses. In human visual system alone the amount of information is estimated to be in the range of 108 - 109 bits per second (Koch 2004). In order to avoid this blockade, the human brain automatically filters the information it receives. This helps us to pay our attention to what is important without much effort. We usually focus on one or more selected stimuli while ignoring the rest. As far as sensory input is concerned, the incoming messages are stored in a sensory store for a very short time. One message is filtered in while the rest are discarded. The filtered messages are further processed when more information is received and associations are made and memory is formed. Treisman’s attenuation model argues that the ignored stimuli is not completely discarded and can be selected at a later stage to be processed (Fulcher 2003). According to Norman and Bobrow (1975), our ability to multi-task is confined by our limited attentional resources (Fulcher 2003). Studies suggest that attention is filtered out but not completely as the ignored stimuli may be stored unsonsciously. 3. Summarize the most salient changes found in the normal ageing brain with reference to their implications. Many aspects of sensory processing are altered by aging. These changes include coginitive pliability, processing speed, memory etc. More prominent changes take place in the medial network including the medial prefrontal cortex, dorsomedial thalamus, and the forebrain (NIH 2007). The decline in the medial network is correlated with the decline in cognitive functioning which are similar to the sumptoms of Alzheimers disease (NIH 2007). The impaired brain functioning due to normal aging is mainly due to the changes in the medial frontal lobe (NIH 2007). Studies also suggest that the ability to manage emotions either remains the same or improves but a decline seldom occurs (Carstensen 2009). According to a study conducted at Stanford University, older adults show high levels of interference and reduced cognitive control during unemotional tasks while they seem to be in complete control on emotional tasks (Carstensen 2009). A remarkable change in the dopamine system is also noticed. Studies have shown that there is a loss in the dopamine receptors and transpoters with age, but little is known about the consequences (Fowler 2008). Human brain is able to grow new neuron even in old age. Decline in cognitive activity usually results from a disease where as decline in memory is a result of lack of mental exercise and stimulation (FI 2004). 4. Describe and evaluate examples of plasticity in adult brains. Brain plasticity is defined as the change in neurons and their organization in brain. This abilitiy to change is life long and is also known as neuroplasticity. Brain is the most active organ in human body and is responsive to circumstances and the change in it is physical and and exhibited by the change in our abilities (Posit Science 2010). Genetic, enviornmental, as well as subjective factors play a crucial role in plasticity. Each time we learn something new it reflects the physical change in our brain. This is also true for each time we forget soemthing. Neuroplasticity is due to several different changes in our brain through out life. Different types of plasticity are dominant during different stages in life (Hoiland 2010). Reseach has shown that the brain never stops. Another example of brain plasticity is that when a person becomes an expert in a particular field, the are of the brain dealing with that specific skill will expand (Michelon 2008). Brain plasticity is also obvious in the brains of bilinguals as their left inferior parietal cortex is larger than in the brains monolinuals (Michelon 2008). 5. Describe changes in sleep structure from birth to adolescence with special reference to total sleep time, distribution of day and night time sleep, and relative representation of REM and NREM sleep Sleep duration varies from individual to individual depending on their age and personality. There is a chage in the pattern of sleep with age. A new born baby requires 16 or more hours of sleep per day where as adults only require 7- 8 hours of sleep per day. There is a lot of difference in the sleep pattern of infants and adults. New born babies dont sleep for 16 hours at a stretch but take 3-4 hour long naps through out the day (Nemours 2010). As children mature they adopt the pattern of adults and require less sleep and often take their sleep in stretch at night. School going children require 10-11 hours of sleep in 24 hour period (Medscape 2005). Adolescents require 9-9.25 hours of sleep but studies have shown that they are getting less than 8 hours (Medscape 2005). Adults require 7-8 hours of sleep over a persiod of 24 hours but most are only getting 6 hours or less (Medscape 2005). Along with sleep pattern, the slep structure also changesas the person grows old. The phases of sleep in babies include “drowsiness, REM (rapid eye movement) sleep, light sleep, deep sleep, and very deep sleep” (Nemours 2010). As the person grows old, the amount of REM sleep decreases down to 50% in early childhood and 25%-30% in adulthood (Medscape) 6. Outline the effects of Transcranial Magnetic Stimulation (TMS). Indicate how TMS might be used in cognitive neuroscience research. Transcranial Magnetic Stimulation (TMS) is used to activate certain parts of the brain to get the desired result. It has different effects on different parts of the brain. TMS can be divided into two types: Single and repetitive TMS (rTMS). Studies have shown that repetitive TMS in the left dorsolateral prefrontal cortex has a posotive affect on mood and a lower rate of depression but has no affect on the cognitive function (American Journal of Physical Medicine & Rehabilitation 2010). TMS in the superior parietal lobule (SPL) and premotor cortex (PM) has an effect on movement (Plosone 2010). A study concludes that the repetitive TMS in right lateral prefrontal, a left lateral prefrontal, and a midoccipital reduces obsessive compulsive behavior for at least 8 hours. It also has a positive effect on the mood. TMS is an important tool for the neuroscientists because it helps them study each area of the brain in detail experimentally. TMS is also used to study human behavior. Performance of the subject before and after TMS is compared which helps understand which reagion of the brain is responsible for which task (University of Glasgow). TMS is an essential tool for studying the functioning of human brain under normal and therapeutic conditions. 7. Describe the contribution of different areas of the brain to the perception of pain. The sense of pain is essential for survival and its ignorance would lead to the point of death. Many studies suggest that pain can be controlled. Different areas of brain contribute to the perception of pain. There are special transmitters, called the nociceptors, which sense the damage done to the tissues. They transmit pain messeges to the spinal cord whch sends the message to the thalamus after processing the incoming information. The thalamus then sends the message to the somatosensory cortex, the limbic system, and the frontal cortex which respectively locates the region, the feeling, and then assigns meaning to it. Researchers believe that chrronic pain is the result of sensitization (NIH 2003). It makes the nociceptors react more intensely than they normally would. Experiments have shown that the nervous system can regulate the severity of pain (Reiness 2005). If the mind can consciously alter the nervious system, the perception of pain can also be altered. People often report little or no pain when they are not aware of the severity of their injuries e.g on the battlefield. Innocuous drugs decrease pain in 25%-33% of people (Reiness). This is known as the placebo effect. Studies have shown that certain parts of the brain are more active during painful experiences. List of References American Journal of Physical Medicine & Rehabilitation( 2010). Effect of Repetitive Transcranial Magnetic Stimulation on Cognition and Mood in Stroke Patients. [online] Available from [Accessed on 18 May 2010] Carstensen, L. Laura (2009). Selective Attention to Emotion in the Aging Brain. [online] Available from [Accessed on 18 May 2010] Ellis, Rob (1999). Connectionist psychology. East Sussex: Psycholoy Press Publisher, 687. FI (The Franklin Institute) (2004). The Human Brain. . [online] Available from [Accessed on 18 May 2010]. Fowler, S. Joanna(25 June 2008). Age-related changes in midbrain dopaminergic regulation of the human reward system. [online] Available from [Accessed on 18 May 2010]. Fulcher, Eamon (2003). Cognitive Psychology. . [online] Available from [Accessed on 18 May 2010]. Hoiland, Erin (2010). Brain Plasticity. [online] Available from [Accessed on 18 May 2010]. Koch, Christo (24 February 2004). Selective Visual Attention and Computational Models.. [online] Available from< http://www.klab.caltech.edu/cns186/PS/attention-koch.pdf > [Accessed on 18 May 2010]. Medscape (25 August 2005). The Normal Duration of Daily Sleep for Different Age Groups. [online] Available from [Accessed on 18 May 2010]. Michelon, Pascale (26 February 2008). Brain Plasticity. [online] Available from [Accessed on 18 May 2010]. Nemours (2010). Kids Health. [online] Available from [Accessed on 18 May 2010]. NIH (13 May 2003). Panel on Pain Research. [online] Available from [Accessed on 18 May 2010]. NIH (2007). Where the Brain Grows Old. [online] Available from [Accessed on 18 May 2010]. Plaut, C. David (November 1993). Impaired Oral Reading in Surface Dyslexia. [online] Available from [Accessed on 18 May 2010]. Plosone (2010). Effect of Transcranial Magnetic Stimulation (TMS). [online] Available from [Accessed on 18 May 2010]. Posit Science (2010). About Brain Plasticity. [online] Available from [Accessed on 18 May 2010]. Reiness, Gary (14 March 2005). Pain Perception. [online] Available from [Accessed on 18 May 2010]. Steven Davis (1992). Connectionism: theory and practice. New York: Oxford University Press, 322. University of Glasgow (2010). Centre for Cognitive Neuroimaging. [online] Available from [Accessed on 18 May 2010]. Read More