FMRI Traced Caffeine Intone Verbal Operating Storage Processes - Research Paper Example

Article Critical Review by The research conducted by the group of scientists, F. Koppelstaetter, T.D. Poeppel, C.M. Siedentopf, A. Ischebeck, M. Verius, I. Haala, F.M. Mottaghy, P. Rhomberg, S. Golaszewski, T. Gotwald, I.H. Lorenz, C. Kolbitsch, S. Felber, and B.J. Krause aimed to distinguish whether caffeine modulates verbal working memory processes and how this process can be traced with the help of fMRI. The oxygenation of the bilateral medial frontpolar cortex with caffeine and placebo consumption was examined with the help of MRI Scanner and BOLD approach. The research revealed that caffeine consumption alters MRI signal which means that the substance performs a modulating effect on brain activity and on tasks connected with memory in particular. The article was published in NeuroImage Journal in November 2008. The hypothesis of the authors consisted in that caffeine might modulate the fMRI signal in frontal cortical brain areas responsible for attention and executive functions. They based this assumption on the knowledge that caffeine acts as a stimulant improving cognitive abilities and increasing alertness. The Participants. The research was conducted in the form of experiment which involved 16 healthy moderately caffeine consuming males after consumption of caffeine and placebo. All the participants were Caucasian between 25 and 47 with no serious diseases preventing the conduct of the experiment. The men were recruited to the study upon personal written consent. The study was approved by local ethics committees. All participants were habitual to caffeine since they were regular moderate consumers of the substance. The participants were prepared for the study by abstaining from caffeine and nicotine for 12 hours and did not consume any food for 4 hours. In the course of the experiment the participants were dived in two groups and blinded. Each participant was given either 100mg of caffeine or a placebo in a random order. The dose was moderate as the researched did not want to cause significant heart rate and blood pressure increase. Two fMRI sessions were conducted: one prior to the experiment and the other in 20 minutes after the experiment. The results also included heart rate measurements, and blood pressure parameters. The Procedure The procedure consisted of performing a 2-back working memory task by participants. Participants were shown a succession of letters in a random order and they had to decide whether the letter was the shown two trials before. The subjects were instructed to give answers as fast as possible pressing “yes” button. The researchers used conventional fMRI block design as the basis of the experiment. Three randomizations runs were created and assigned to the participant each session lasting for about 10.7 minutes. Each participant underwent anatomical 3D scan prior to the experiment. Later the images obtained in the course of fMRi were coregistered into a mean image the results of which were taken for creation of the functional images. The whole experiment was run successfully since participants reported no awareness in the randomization groups. The Results The authors marked that results of the experiment were mostly predictable. Thus, the group of participants consuming caffeine had higher systolic blood pressure and heart rate after the experiment. There were also significant alternations in diastolic and arterial blood pressure. The images revealed considerable increase of activity in frontpolar cortex and ACC in participants consuming caffeine. The authors reminded that frontal brain areas along with anterior cingulate cortex (ACC) are the major neural zones responsible for attention. These areas are interlinked and controlled by each other, their work is interdependent with memory processes. PFC is also responsible for planning ad problems solving. The stimulation of the medial anterior pre-frontal and mediopolar prefrontal cortex was connected to the connection of these areas with planning tasks. Thus, it was possible to conclude that caffeine activates those brain areas responsible for attention. The authors` attention was attracted by the fact that caffeine did not show cognition stimulating properties unlike in the similar previous studies. This was explained by the low dose of caffeine chosen I order to prevent sharp changes I blood pressure and heart rate visible for the other. It is also possible that participants were habitual to caffeine and moderate dose did not affect them more than usually. The article published in NeuroImage by the experts of Radiology and Nuclear Medicine represents a coherent and serious study of the effects of caffeine on the brain work. The researchers were particularly interested in the distinguishing whether caffeine stimulates brain areas responsible for attention, however they connected the whole research to memory. Since attention is extremely important for effective encoding of information, it plays crucial role in ability to decode it on time.fMRI gives a perfect opportunity to trace which brain areas are stimulated and to which extent. Strengths and Weaknesses of the Research The authors dedicated enough time to explaining the effects of caffeine on brain work giving the readers evidence of caffeine popularity as a substance. Moreover, big part of the article spoke about previous research of caffeine influence on cognition. The effects of caffeine were studied with the help of fMRI, its BOLD approach. It consists of tracing of hemodynamics to the active part of brain. The authors mentioned 5 different researches and proposed their conclusions to the readers. After the authors had analyzed all existing studies in these sphere they concluded that memory, and attention in particular was one of the least examined topics connected to caffeine. Moreover, as caffeine was already proven to stimulate vigilance, alertness, and attention, it must be traceable in the brain area responsible for attention- frontal cortical brain. Thus, the research turned out to be innovative and important for the whole understanding of memory work as well as for distinguishing exact impact of caffeine on the brain work. It helped to formulate precise and broad hypothesis. Among the other strengths of the study it is necessary to mention comprehensible and well-planned procedure. The participants of the study were described thoroughly and all precautions measures were taken to assure credibility of the experiment. The authors have chosen well-known methods of results analysis while they have divided the results into several categories. They also managed to represent the results in clear visible form using tables, graphs, and general MRI images. Graph was used to depict the frequency of accurate responses. Physiological data was analyzed accurately and was demonstrated as a table in the article. This means of information introduction allowed readers to compare the results of blood pressure, heart rate parameters in two groups. For behavioral patterns a repeated measures analysis of variance was chosen. Another strength of the experiment is authors` dedicated description of the equipment and the measurement s of MRI scanning. The images of the MRIs- the results for each condition (caffeine and placebo) were superimposed on the canonical SPM2 T1 image demonstrating the zones of cortical activation of working memory. The results achieved in the course of the experiment were similar to the results of the previous studies which allowed to conclude that the hypothesis was right. However, there were certain limitations to the study, which nevertheless were marked by the authors themselves. The experiment was supposed to stimulate certain cognitive processes in participants however due to a limited dose of caffeine no specific responses were observable. The authors also paid too much attention to the analysis of the results of other experiments and dedicated less space and attention to this experiment. So despite the fact that caffeine is often referred as BOLD booster meaning that it alters the signal due to its vasoconstrictive properties, this research proved that caffeine has modulating effect on frontal brain regions. These areas are responsible for short-term or working memory processes, and thus the results of the experiment allowed proving the hypothesis, however this sphere requires more profound research. References Koppelstaetter, F., Poeppel, T., Siedentopf, C., Ischebeck, A., Verius, M., Haala I., Mottaghy, F., Rhomberg, F., Golaszewski, S., Gotwald, T., Lorenz, I., Kolbitsch, C., Felber, S., & Krause, B. (2008). Does caffeine modulate verbal working memory processes? An fMRI study. NeuroImage, 39, 492-499. The authors first concentrate on the pharmacological properties of caffeine. Caffeine is a powerful excitatory neurostimulant widespread all over the planet. Its popularity can be explained by its abilities to evoke sense of well-being, energy, and increase attention. Caffeine enhances learning abilities, stimulates memory, and gives a sense of alertness to its consumers. It is often used in a form of beverages such as coffee and tea. The effect of caffeine is based on a nonselective antagonism on adenosine A1 and A2 receptors with the brain. Caffeine targets brain areas responsible for sleep, alertness, and concentration. Stimulation of these areas results in the increase of productivity. However, caffeine also has vasocostrictive effect reducing cerebral blood flow depending on a dose. Most studies devoted to this question aimed to reveal influence of caffeine on general cognitive activity not concentrating on minor tasks. The analysis of the previous studies allows concluding that caffeine plays a role of a “contrast booster” for fMRI experiments due to its ability to decrease resting perfusion. It leads to the changes of BOLD signal which is measured from that baseline. Other research suggests that the decrease of the BOLD signal can be attributed to the dose of the consumed substance. The authors further outline the information regarding the impact of a short-term memory on many cognitive operations. Read More