A Lesion in the Motor Cortex - Essay Example

?Brain and Mind work If a patient has a lesion in the motor cortex and is unable to speak as a consequence, why is this condition NOT calledaphasia? A patient having a lesion in the motor cortex and is unable to speak as a consequence would not have aphasia but dysarthria. First of all, aphasia usually refers to lesions of affectations of the frontal, temporal, and parietal lobes of the brain which are areas concerned with the ability to produce and comprehend language (Masdeu, 2000). Aphasia also refers to difficulties of a person in remembering words, as well as their inability to speak, read, and write (Masdeu, 2000). For dysarthria however, the person can remember the words and how to speak, how to read, or how to write the words, but due to motor affectations in his motor-speech system, he cannot speak the words (Duffy, 2005). Where dysarthria refers to the improper or poor articulation of words or phonemes, aphasia refers to the disorder in the content of the language. Cognitive language is not affected, but the difficulty in speaking the words is based on motor muscles neurologically impaired (Duffy, 2005). Due to lesions in the motor cortex, there would also likely be impairment in respirations, resonance, as well as phonation, and articulation causing issues in the patients’ intelligibility, audibility, and vocal communication (Duffy, 2005). 2. Why was lobotomy administered on a wide scale between 1950 and 1970? Lobotomy was administered on a wide scale between 1950 and 1970 because at that time, mental health and the neurological functions were not adequately understood (McManamy, 2011). Although lobotomies were first performed on humans in the 1890s, it was considered a strong and effective remedy for many years after (McManamy, 2011). It reached widespread use in the 1940s and 1950s simply because there were no alternative forms of treatment at that time. Lobotomies were also considered an effective remedy in order to eliminate many social issues linked to mental health issues, including the overcrowding of mental health institutions and the rising cost of mental health care (Tartakovsky, 2011). There were about 40,000 to 50,000 lobotomies carried out from 1936 and on to the late 1950s. They became popular interventions because Freeman, the Father of lobotomy believed that these lobotomies were effective forms of treatment. He explained that this procedure cut of connections between the frontal lobes and the thalamus, thought to control human emotions which mental health professionals, at that time, believed to be in abundance among the mentally ill (McManamy, 2011). By the 1970s, these beliefs were discredited and when other forms of treatment were made available, lobotomies were soon banned from the mental health practice. 3. You are in the MRI scanner room and on the control room console you see activations of the hand region of the motor cortex in a participant's being scanned. Does it automatically mean that the participant is moving? Justify your answer. This does not automatically mean that the participant is moving. In instances where a patient mentally stimulates an activity, the corresponding area stimulated would also indicate a response (Mao, et.al., 1998). This is often seen in paralyzed patients where electrodes would be implanted in some regions in the brain in order to detect responses, stimulate communication, and yes or no responses. A yes/no communication can be triggered based on brain activity by detecting electrical responses from the electrode implants in the brain (Mao, et.al., 1998). As the patient mentally makes yes or no responses, the corresponding areas of the brain would manifest some activity (Mao, et.al., 1998). For a patient having an MRI, the patient mentally thinking of moving his hand would likely trigger some form of activation in the hand region, even without the hand actually moving. The activation of the motor cortex would indicate that even if patients are not moving, they still have motor control. Moreover, motor imagery and actual motor movement seem to share a similar nerve network (Mao, et.al., 1998). 4. Do you expect a right-handed split-brain patient to have difficulties talking about his/her emotions? Explain why. A right-handed split-brain patient is expected to have difficulty in expressing his feelings, very much like being unavailable for discussion (MacAlester College, n.d). It would be likened to patients having two different minds. Usually split brain patients have a superior right hemisphere in relation to spatial tasks like arranging blocks. Where patients were asked to draw what they saw from either hemisphere, left-handed drawings usually looked better (MacAlester College, n.d). The right side of the brain which controls the left side of the body has less understanding of language and therefore the perception of one side would be different from the other side. Where a word is flashed to the right hemisphere for interpretation with a response to be written by the left hand, the correct word would usually be written (Zaidel, 1994). However, when the patient would be asked what he wrote, he would not know it. The split would be on the relay of the information from the right to the left half of the brain. Where an experiment was carried out to elicit response from either side of the brain, it was discovered that the left hemisphere usually expressed little or no anger about past incidents, whereas, the right hemisphere still expressed some anger about past incidents (Vasiliadis, 2000). Where the link is broken between these two hemispheres, the emotions felt on the left side (right handed) would not be felt by the right side. 5. What symptoms can be associated with a lesion in the orbitofrontal cortex? Lesions in the orbitofrontal cortex have been known to be disinhibited and to engage in socially inappropriate behaviour as well as to manifest with various emotional changes (Berlin, et.al., 2003). These changes may involve difficulties in responding appropriately to rewards and punishments. In this case, patients have trouble learning how to manage their choices in visual stimulus when not associated with some form of reward (Berlin, et.al., 2003). They are known to be impulsive and usually did not perform well on stimulus-reinforcement association reversal activities. They often expressed subjective anger more often than normal individuals. They also had faster subjective sense of time (Berlin, et.al., 2003). These patients usually swear excessively, have poor social interactions, and are involved in compulsive gambling, promiscuity, excessive drug use, alcohol abuse, and usually have poor empathy. Some are also hypersexual (Snowden, et.al., 2001). Affectations in the orbitofrontal cortex have been known to affect decision-making, regulation of emotions, and expectation of rewards. Issues in substance dependence often emerge with these patients, mostly because their striato-thalamo-orbitofrontal cortex is affected. Some cases of Attention Deficit Hyperactivity Disorder (ADHD) have also been associated with orbitofrontal cortex lesions (Snowden, et.al., 2001). 6. Describe likely symptoms of a patient with extended lesions in the superior temporal cortex (Wernicke's area) and the left calcarine fissure (left primary visual cortex). Lesions in the superior temporal cortex would likely cause issues in speech perception, along with issues in discriminating speech and in the temporal order of sounds (Milner, 2005). These lesions also affect the rhythm of the speech and can cause issues in the perception of music, as well as the inability to discriminate melodies (Milner, 2005). Lesions in the Wernicke’s area would also lead to receptive aphasia. In this type of aphasia, the person is able to hear and read words, however, he may not be able to understand it. Many of these patients often take language literally and their speech may be impaired because they do not know how and what words to use (WebMD, 2011). Lesions in the left primary visual cortex would experience alexia without agraphia where there is a loss of sight in the right visual field of each eye (Murdoch, 2010). Patients are however able to see in the left visual field. Patients would be able to write fluently, however they may not be able to read what is written (Barton and Goodwin, 2001). Reading for these patients would likely be one word or even one letter at a time. 7. Provide one piece of evidence in favour of the existence of a module in the brain dedicated to the processing of the human face. The study by Kanwisher, McDermott, and Chun (1997) provides evidence in favour of the existence of a module in the brain dedicated to the processing of the human face. The authors used functional MRI in their study and were able to establish an area in the fusiform gyrus in 12 (out of 15) respondents which was significantly more active when subjects were looking at faces in contrast to when they were looking at other common objects. The face activation was utilised in order to identify a specific area of interest for each subject; several new tests of face specificity were then carried out. In the five subjects, the candidate face area also reacted well to passive viewing of intact rather than scrambled two-tone faces, as well as full front view face photos from front-view photos of houses. Based on these experiments, the researchers were able to detect that the fusiform face area appealed selectively to the perception of faces. References Barton, J. and Goodwin, J. (2001). Alexia without agraphia. Vancouver has no relevant financial relationships to disclose. Medlink. Retrieved from http://www.medlink.com/medlinkcontent.asp Berlin, H., Rolls, E., and Kischka, U. (2004). Impulsivity, time perception, emotion and reinforcement sensitivity in patients with orbitofrontal cortex lesions. Brain, vol. 127, no. 5, pp. 1108-26. Duffy, J. (2005). Motor speech disorders: substrates, differential diagnosis, and management. Saint Louis: C.V. Mosby. Kanwisher, N., McDermott, J., and Chun, M. (1997). The fusiform face area: a module in Human extrastriate cortex specialized for face perception. The Journal of Neuroscience, vol. 17, no. 11, pp. 4302-4311. MacAlester College. (n.d). Behavior of split brain patients. Retrieved from http://www.macalester.edu/psychology/whathap/ubnrp/split_brain/Behavior.html Mao, H. Muthupillai, M., Kennedy, P., Popp, A., Song, A. (1998). Clinical application of fMRI: Motor cortex activation in a paralysed patient. Medica Mundi, vol. 42, no. 3, 19-22. Masdeu, J. (2000). Aphasia. Archives of Neurology, vol. 57, no. 6. McManamy, J. (2011). Walter Freeman - Father of the lobotomy. Retrieved from http://www.mcmanweb.com/lobotomy.html Milner, B. (2005). The medial temporal-lobe amnesic syndrome. Psychiatr Clin North Am., vol. 28, no. 3, pp. 599-611, 609. Murdoch, B. (2010). Acquired speech and language disorders. London: John Wiley and Sons. Snowden, J., Bathgate, D., Varma, A., Blackshaw, A., and Gibbons, Z. (2001). Distinct behavioural profiles in frontotemporal dementia and semantic dementia. J Neurol Neurosurg Psychiatry, vol. 70: 323-332. Tartakovsky, M. (2011). The surprising history of the lobotomy. PsychCentral. Retrieved from http://psychcentral.com/blog/archives/2011/03/21/the-surprising-history-of-the-lobotomy/ Vasiliadis, M. (2000). Split- brain behavior. Biology. Retrieved from http://serendip.brynmawr.edu/bb/neuro/neuro00/web1/Vasiliadis.html WebMd. (2011). An overview of aphasia. Retrieved from http://www.webmd.com/brain/aphasia-causes-symptoms-types-treatments Zaidel, D. (1994). A view of the world from a split-brain perspective. Retrieved from http://cogprints.org/920/3/critchelyf.pdf Read More