Brain and Language
Download Brain and Language...
Brain and Language
(The Brain’s Language Centers, n.d.)
Laura Myers and Lyndsay O’Malley
Exercise 5 What are the arguments and evidence that have been put forth to support the notion that there are two separate parts of the brain?
Argument 1: Functions of the brain are localized. Evidence: (Wernicke’s Area, n.d.)
- Damage to Broca's area, the inferior frontal gyrus of the left hemisphere, results in the inability to follow the rules of syntax and the production of agrammatic language.
- Damage to Wernicke's area produces semantically incoherent language, for example trouble naming objects and producing lexical errors.
More Evidence - Deaf aphasics also show deficits in the same areas of the brain as hearing aphasics, even though they are signing rather than speaking. - Left hemisphere damaged Japanese are unable to understand Kana, the sound system-based language, and right hemisphere damaged Japanese are unable to read Kanji, the ideographic-based language. (Small Talk aphasia, n.d.)
Argument 2: Brain imaging technology allows us to identify parts of the brain and their correlation to cognitive tasks. Evidence: Magnetic encephalography (MEG) allows us to measure activity of the living brain and reaction to certain stimuli. Comparisons of fMRI of brain lesion patients and PET scans of normal patients showed that the lesions in fMRI patients, who had specific linguistic deficits, corresponded exactly to the functioning areas of the PET patients, who were able to perform the tasks that the fMRI patients could not.
Argument 3: The left hemisphere is predetermined to develop language in very young children. Evidence: - Babies expressing language-like sounds open the right side of their mouths more than the left side, indicating greater activity in the left hemisphere. - If the left brain has been removed the right brain will compensate for the missing brain functions, but a child undergoing a right hemispherectomy before the age of two generally does not develop language.
Argument 4: The corpus callosum is the connection between the left and right hemispheres of the brain. Evidence: When the brain is surgically split, the two hemispheres cannot communicate. For example, when a patient is given an object in the left hand he or she can sense the object but cannot describe it because the information cannot be sent from the right brain to the left, where the language cortex is located.
Argument 4 Evidence, Continued Split-brain operations show that the two hemispheres have different strengths. The right hemisphere is more visually oriented: it is superior in pattern matching tasks, recognizing faces, and in spatial tasks. The left brain is more abstract in orientation: it is stronger in language, rhythmic perception, temporal-order judgments, and arithmetic calculations.
Argument 5: There are several experimental evidences of brain organization. Evidence:
Dichotic listening allows researchers to study the effects of linguistic sounds and non-linguistic sounds on the brain and how the brain processes these sounds. Evidence shows that the left hemisphere processes linguistic sounds and the right hemisphere processes non-linguistic sounds, thus showing strong lateralization of the brain.
Argument 5 Evidence, Continued
Event-related brain potentials (ERP) allow scientists to study how quickly the brain processes language and the area it is being processed in. It also shows how strongly the brain responds to the stimulus and the variations in timing, pattern, and amplitude of the evoked potentials.
Questions about Exercise 5?
Research Article 1: Brain Connectivity: Gender Makes a Difference Neuroimaging has recently proven that male and female brains are different, therefore connectivity differs between genders. When an experiment or test is taking place on the brain, gender should be taken into consideration. However, it generally is not.
Research Article 2: Sex Differences in Dichotic Listening This meta-analysis examined the magnitude of difference in perceptual asymmetries between male and female subjects found in dichotic listening studies. Using statistical analysis of 595 effect sizes, it found a significant, homogeneous, but small difference in auditory specialization of tasks (lateralization) between sexes, in that men are slightly more lateralized than women. For both sexes, this laterality is greater for verbal than nonverbal tasks.
Pertinence to Chapter 2, Brain and Language This study provides confirmation that dichotic listening is a valid tool to investigate cerebral lateralization, so we can accept the section on dichotic listening. It also confirms that lateralization is considered a fact in the scientific community. Finding greater laterality in verbal than non-verbal tasks is interesting.
Additional Thoughts: LeftBrain/Right Brain Pseudo-Science Evidence of laterality in the brain has led to the idea that the right brain is more creative and the left brain is more logical. This idea is not supported by the scientific community at all. The evidence points to both sides having a role to play in cognitive tasks, but their roles differ. (Clark, 2007; Hemispheric dominance, n.d.; Taylor, 2009) Left-brain Right brain game
Discussion Questions 1. Could lateralization have an evolutionary purpose?
2. Is the brain differentiated between genders? If so, how? 3. Why is the brain more lateralized for verbal than non-verbal tasks? 4. How could one use the material covered in the chapter to combat the idea of right-brain/leftbrain hemispheric dominance?
References Clark, D. 2007. Left brain Right brain – a myth. Donald Clark Plan B. Retrieved from http://donaldclarkplanb.blogspot.com/2007/06/left-brain-right-brain-myth.html Gong, G., He, Y., & Evans, M. C. (2011). Brain connectivity: Gender makes a difference. The Neuroscientist, 17(5), 575-591. doi: 10.1177/1073858410386492 Hemispheric Dominance. n.d. Rational Wiki. Retrieved from http://rationalwiki.org/wiki/Hemispheric_dominance May 1, 2012 Small Talk aphasia. (n.d.). Retrieved from http://www.macworld.com/appguide/app.html?id=80138&expand=false April 30, 2012. Taylor, D. H. (2009). Modern myths of learning: the creative right brain. Donald H. Taylor. Retrieved from http://donaldhtaylor.wordpress.com/writing/modernmyths-of-learning-the-creative-right-brain May 1, 2012
References, Continued The Brain’s Language Centers. (n.d.). Retrieved from http://www.rhsmpsychology.com/Handouts/brain_and_language.htm April 30, 2012. Voyer, D. (2011). Sex differences in dichotic listening. Brain and Cognition, 76(2), 245-255. doi: 10.1016/j.bandc.2011.02.001 Wernicke’s Area. (n.d.). Wikipedia. Retrieved from http://en.wikipedia.org/wiki/Wernicke%27s_area April 30, 2012.