Exploration of Brain Processes in Reading

Exploration of Brain Processes in Reading

Studies into the human cognition of reading tend to use Experimental Cognitive Psychology and Cognitive Neuroscience and Cognitive Neuropsychology approaches for developing further knowledge of the processes involved in the reading of language.
The experimental cognitive psychology approach designs laboratory experiments to reveal the processes which are involved in the human cognition being researched. The experiments are considered to be a scientific way of researching, as they are highly controlled. (Eysenck and Keane 2010) Using this approach in understanding the processes of reading, involves the use of certain tasks in order to study these processes.

The cognitive neuroscience approach involves intensive studying of the brain and behaviour. Due to advances in technology, there are now many different techniques available for studying the brain. These techniques obtain detailed information about the way the brain functions and the structure of it. From these techniques researchers can work out where and when in the brain specific cognitive processes occur, as well as determine the order in which parts of the brain become active when a person performs a task. Researchers can also find out whether tasks involve the same parts of the brain in the same way, and establish if there are any important differences in the parts of the brain used. (Eysenck and Keane 2010)
Cognitive Neuropsychology looks at the patterns of cognitive performance shown by brain – damaged patients, as this can tell us a lot about human cognition. For example, Epelbaum et al (2008 as cited by Cummine, Dai, Borowsky, Gould, Rollans and Boliek 2013) observed a patient who had developed pure alexia; this is the ability to perform letter by letter reading, but not whole word reading. The patient developed alexia following a small surgical lesion which damaged the left interior longitudinal fasciculus (ILF) just behind the putative visual word form area (VWFA). Hanley and McDonnel (1997 as cited by Eysenck and Keane 2010) studied Patient PS, who understood the meaning of words when reading, but could not pronounce them. From this research it was suggested that phonological processing is accessed after word meaning when reading. However, there are issues with using this approach to explaining reading and the processes which are involved, as sometimes the impact of brain damage on cognitive performances may be camouflaged because patients can develop compensatory strategies.
Reicher (1969 as cited by Eysenck and Keane 2010) studied the word superiority effect, by briefly presenting a letter string followed by a pattern mask, participants then had to decide which letter was in a particular position. Reciher found that participant’s performance was better when the letter string formed a word.

Rayner and Sereno (1994 as cited by Eysenck and Keane 2010) studied word recognition to assess whether this was automatic or not, they found the Stroop effect, this is when a colour e.g. ‘Orange’ is printed in a different colour e.g. Red, they found participants took more time to answer than when the colour was printed in either the same colour font or just in black, suggesting that we are not consciously aware of word recognition.
Rastle and Brysbaert (2006 as cited by Eysenck and Keane 2010) carried out a meta-analysis of various studies of participants completing lexical decision and naming tasks. From the analysis it was found that when words were preceded by primes similar to them in terms of phonology they were processed faster than those words similar to them in terms of spelling. These findings suggest that phonological processing occurs automatically and rapidly.

Yates (2005 as cited by Eysenck and Keane 2010) used both lexical decision making and naming tasks within their research, to support the assumption that phonological processing is used in visual processing. Yates’s research found that within both of these tasks, when words which have many phonological neighbours (words which differ in one syllable from each other) are fixated on for less time than those with fewer phonological neighbours.

There are a number of issues and limitations within the experimental cognitive psychology approach. Often, the cognitive tasks involve the use of a complex mixture of different processes and it is hard to interpret the findings, for example, the Stroop Effect mentioned above, it is difficult to interpret what processes are actively involved in interpreting the colour of the word and reading it.

Often the way the studies are controlled can limit how ecologically valid they are, for example in the lexical decision tasks participants have to decide if a string of letters forms a word and in the naming tasks they have to as quickly as possible pronounce visually presented words. Within these tasks normal reading times of participants are disrupted by the requirement to respond to the task, therefore can the results be generalised to real life and the wider population? Also, as both of the tasks, are not tasks we often engage in when reading normally, this can also impact on how true to real life the results are.
There are also issues when interpreting the task performance results, as it provides us with indirect evidence about the internal processes involved in the cognition of reading, and it is difficult to decide at what time processes occur, whether they are at the same time, with some overlap, or at different times. For example, in Rastle and Brysbaert’s study it is unsure from the results whether phonological processing occurs before word meaning is accessed. However, this can often be clarified by using brain imaging techniques.
Khateb and Annoni et al (1999) recorded event related potentials (ERP’s) during a semantic and a phonological reading task to determine the time period when semantic and phonological processing start to differently activate the neuronal language network in the brain. From the results the researchers found that these differences did not significantly occur.

Event related potentials are linked to the use of EEG which is based on recordings of electrical brain activity measured at the surface of the scalp; ERP is a way of resolving one of the limitations of the EEG technique. ERP involves presenting the same stimulus to participants several times, as this resolves any spontaneous or background brain activity from obscuring the impact of the processing of the stimulus on the recording. ERP’s have a number of strengths in terms of their contributions towards research. They provide good temporal resolution, can indicate when a given process occurred to within a few milliseconds, e.g. in Khateb, Annoni et al’s study the difference between activation of semantic and phonological processing was only for 100 milliseconds. This technique also provides detailed information about the time course of brain activity, compared to a lot of other techniques. However, the technique does not precisely indicate which regions of the brain are most involved in processing.
Cao, Bitan and Booth (2008) used dynamic casual modelling (DCM) and MRI to examine the effective connectivity between three regions in the left hemisphere of the brain in children with and without reading difficulties when completing a rhyming judgement task. The researchers found that the modulatory effect from the left fusiform gyrus to the left inferior parietal lobule was weaker in children with reading difficulties when completing the conflicting trials of the rhyming judgement task (where the words had either similar orthography but different phonology, or had different orthography and phonology). Another finding is that the modulatory effect from the left fusiform gyrus to the inferior frontal gyrus was significantly greater in conflicting trials than non – conflicting trials in the children in the control group; however, this was not apparent in the children with reading difficulties. The final finding was that the modulatory effect from the left inferior frontal gyrus to the left inferior parietal lobe and the bidirectional modulatory effects between the left inferior parietal lobule and medial frontal gyrus were positively correlated with reading skills in the control group of children only.
MRI tells us about the structure of the brain by using radio waves to excite atoms in the brain, which produces magnetic changes which are detected by a large magnet; these changes are then interpreted by a computer and changed into a very precise 3d image. However, as most cognitive psychologists wish to look at the functions of the brain rather than the structure, MRI can be a limited technique to use when studying human cognitions. This can be resolved though by using the fMRI technique which looks at the functions of the brain.

Meyler and Keller et al (2007) used fMRI to examine brain activity during a visual sentence comprehension task among poor and high ability readers. Meyler and Keller et al used a higher level comprehension task in order to expand on previous research which found a reduced or absent activation in the left parietotemporal and occipitotemporal cortices in individuals who suffer from dyslexia or have a low reading ability. The results form Meyer et al’s research found that poor reading ability was associated with reduced activation in those areas compared to those of higher reading ability. There was also a positive linear relationship between reading ability and cortical activation in Wernicke’s area, the right inferior parietal lobule, and the left post central gyrus.

Mechelli and Crinion et al (2005) using fMRI wanted to build on the theory that readers employ word specific knowledge and general information about how a combination of words corresponds to phonological representations by exploring how neuronal interactions within the reading system are influenced by word type. The pars triangularis showed increased activation for exception words compared to pseudo words, however, in the dorsal premotor cortex, increased activation was found for pseudowords compared to exception words, and finally the pars occercularis showed increased activation in exception words compared to regular words, and for pseudo words compared to regular words.

Bavelier et al (1997 as cited by Pinel 2011) used fMRI to measure the brain activity of participants whilst they read silently. The fMRI used in this study was particularly sensitive meaning that the researchers could identify areas of activity more accurately than in previous studies. The researchers recorded brain activity during the reading of sentences. The participants completed in periods of silent reading followed by a control period where they were presented with strings of consonants, which served as a basis for determining those areas of cortical activity associated with reading. Bavelier at al found in the lateral cortical surfaces which were monitored that there was a difference in the cortical activity. The results showed tiny areas of activity separated by areas of inactivity, these patches of activity were variable, and differed between participants, and from trial to trial on the same participant. Although some of the activity was observed in the classic Wernicke – geschwind area, it was widespread over the lateral surface of the brain. It was found that there was significant activity in the right hemisphere, however considerably more activity was detected in the left hemisphere.

FMRI assesses distortions in the local magnetic field and provides a measure of the concentration of deoxyhaemoglobin in the blood. This technique shows temporal and spatial resolution at a higher level than PET. However, there are flaws with this technique as it provides an indirect measure of underlying neural activity. Also, as this technique involves the participants being encased into a scanner, some participants can feel uncomfortable, find it upsetting and experience side effects (Cooke, Peel, Shaw, Senior 2007 as cited by Eysenck and Keane 2010).

The use of the experimental cognitive psychology approach provides a good basis for cognitive neuroscience research to study further, as although it can provide some explanation for what processes may be involved in reading, it cannot provide specific information on what part of the brain these processes occur in, or in what order and so forth. By combining both the experimental cognitive psychology and cognitive neuroscience approaches, more in depth research can be conducted. For example, Cao, Bitan and Booth’s study with combines the use of DCM, MRI and a rhyming judgement task provides more information and explanations for poorer reading abilities. Or Mechelli and Crinion et al’s research combined the use of fMRI and a phonological task finding that there are distinct regions within the left prefrontal cortex activated differently depending on the word type being read.

Finally, the use of cognitive neuropsychology provides explanations for the processes involved in reading by studying patients with brain damage who have issues in certain cognitions presumed to be involved in reading, and examining which parts of the brain are damaged.

References:
Cao, F., Bitan, T. and Booth, J. (2008) ‘Effective brain connectivity with reading difficulties during phonological processing’ Brain and Language Vol. 107 pp. 91 – 101 [online]
Cummine, J., Dai, W., Borowsky, R., Gould, L., Rollans, C. and Boliek, C. (2013) ‘Investigating the ventral – lexical, dorsal – sublexical model of basic reading processes using diffusion tensor imaging’ Brain Structure and Function Vol. 218, No.6 [online]
Eysenck, M. and Keane, M (2010) Cognitive Psychology A Student’s Handbook 6th ed. New York: Psychology Press
Khateb, A., Annoni, J-M., Landis, T., Pegna, A., Custodi, M-C., Fonteneau, E., Morand, S. and Michel, C. (1999) ‘Spatio-temporal analysis of electric brain activity during semantic and phonological word processing’ International Journal of Psychophysiology Vol.32 pp. 215-231 [online]
Mechelli, A., Crinion, J., Long, S., Friston, K., Lambon Ralph, M., Patterson, K., McClelland, J. and Price, C. (2005) ‘Dissociating Reading Processes on the Basis of Neuronal Interactions’, Journal of Cognitive Neuroscience, Vol17. No.11, pp 1753 – 1765 [online]
Meyler, A., Keller, T., Cherkassky, V., Lee, D., Hoeft, F., Whitfield-Gabrielli, S., Gabrielle, J. and Just., M (2007) ‘Brain Activation during Sentence Comprehension among Good and Poor Readers’, Cerebal Cortex, Vol 17. No.12, pp. 2780 – 2787 [online]
Pinel, J. (2011) Biopsychology 8th ed. Boston: Pearson Education