Tag Archives: neuroplasticity

A Day Just for Music

Posted on June 22, 2015 by | 4 comments

Dear family and friends,

Imagine a day in Paris dedicated to music – voilà, Fête de la Musique!

My friends and I decided to first explore the music scene in the Saint Michel-Notre Dame area, one of our favorite parts of Paris (see map below). As soon as we emerged from the underground metro station near the Saint Michel Fountain, we heard a lively cacophony of sounds from every direction. Immediately, my appreciation for jazz music pulled me towards a jazzy trio on Rue Serpente. After they concluded their piece, I felt compelled to keep moving and enjoying as much music as possible. Further along, at the intersection of Rue Serpente with Rue Hautefeuille, we bumped into a crowd of spectators swaying to a soft rock band and our faces instantly brightened with auditory pleasure. Earlier in the day, I felt stressed by schoolwork and my upcoming departure from Paris, but I was beginning to notably relax upon joining the musical festivities.

Fete de la Musique Map

While I was absorbed in the drum rhythms of another music group – I even watched a dance-off between a young girl and a grown man! – I considered the ways in which music was positively impacting my mental state (see image below). But the neuroscientist in me also wondered, what happens at the neurobiological level?

danceoff                                                                        Dance-off

After some internet research, I chose a study by Sheikhi and Saboory examining the impact of musical stimuli on the rat brain, because the study was uniquely conducted during the fetal period. Isn’t that incredible? Previous studies have identified the connection between environmental factors and prenatal development, demonstrating how sensory and motor stimuli entering the central nervous system can lead to neuroplasticity changes in neurons (Mathies et al., 2013). Neuroplasticity refers to changes in neural pathways and synapses. Specifically, stimuli can cause an increase in synaptic connections in the brain (Pirulli et al., 2013). In the fetal brain, other studies have examined the fetal response to music (Gerhardt et al., 2000). In this particular study, Sheikhi and Saboory examined neuroplasticity and neuronal cell density in the parietal cortex (see image below) of the fetal rat brain that was exposed to music as part of a prenatal model.

As part of the methodology, the researchers utilized twelve female Wistar rats (see image below) and followed ethical guidelines established by the Medical Ethics Committee of Iran. (Ethics boards encourage researchers to use the lowest number of rats and cause the least amount of pain possible!) At twelve weeks, the researchers mated the female rats and then divided pregnant rats into a control group and a musical group. Thus, each group included six pregnant rats. Twice per day, from day 2-20 of gestation, researchers exposed the musical group to classical music. However, they did not expose the control group to music. Before labor could occur on the 21st day of gestation, the researchers anesthetized the pregnant rats and collected blood samples from them. Sheikhi and Saboory removed the fetuses and randomly chose one fetus from each mother for brain dissection. Then, the researchers horizontally sliced the parietal cortex and examined the slices via an electron microscope. Returning to the blood samples collected from the pregnant rats, Sheikhi and Saboory measured corticosterone (COS) levels in each blood sample. Corticosterone refers to a hormone secreted by the adrenal cortex in rodents (see image below). COS protects against stress, in a similar way to cortisol in humans.

Wistar rat                                                                        Wistar rat

parietal_lobe                        The parietal cortex is located in the yellow region of this brain.

rat body

                             The adrenal cortex is the outer part of the adrenal gland.

Sheikhi and Saboory found that control rats exhibited simpler and smoother cells, while the music-treated group exhibited a more complex cell membrane and cytoplasmic organelles, which are the specialized structures inside of cells. Alternatively, the intercellular space, or the space between cells, displayed a greater density of structures in music-treated rats than in control rats. To determine the effect of prenatal music on the density of parietal cortical cells, researchers counted the number of nuclei in one electron microscope field, since each cell should theoretically have one nucleus. As expected, researchers found a greater cell density in the parietal cortex of music-treated rats than in control rats. Additionally, prenatal music helped to reduce COS blood levels in pregnant rats. Aha! I bet that a decrease in my cortisol levels is one of the reasons why I felt so relaxed during Fête de la Musique.

I believe the prenatal music model is a unique strength in study design and the findings can be related to an intra-uterine musical effect. However, I would like to offer a few of my own criticisms and suggestions for future experiments. According to the methodology, researchers only collected blood samples on the 21st day of gestation, and then claimed to see a reduction in COS blood levels. However, in order to draw comparisons, the researchers should have collected at least one other blood sample on the 1st day of gestation. Preferably, Sheikhi and Saboory should also have drawn blood from the pregnant rats at various, controlled time points throughout the experiment for stronger comparisons. In this research study, researchers exposed pregnant rats to only classical music, but I wonder if results would change with exposure to different types of music, such as jazz or soft rock. In a future experiment, Sheikhi and Saboory could also test the effect of music on rat infants immediately following birth. Additionally, the researchers only examined the fetal parietal cortex, but should examine other cortical areas as well.

– Beatrice

References

Gerhardt KJ, Abrams RM (2000) The Fetus Fetal Exposures to Sound and Vibroacoustic Stimulation. Journal of Perinatology 20:S20-S29 Available at: http://www.ncbi.nlm.nih.gov/pubmed/11190697 [Accessed June 22, 2015].

Matthies U, Balog J, Lehmann K (2013) Temporally coherent visual stimuli boost ocular dominance plasticity. J Neurosci 33:11774–11778 Available at: http://www.ncbi.nlm.nih.gov/pubmed/23864666 [Accessed June 22, 2015].

Pirulli C, Fertonani A, Miniussi C (2013) The role of timing in the induction of neuromodulation in perceptual learning by transcranial electric stimulation. Brain Stimul 6:683–689 Available at: http://www.ncbi.nlm.nih.gov/pubmed/23369505 [Accessed June 22, 2015].

Sheikhi S, Ph D, Saboory E, Ph D (2015) Neuroplasticity Changes of Rat Brain by Musical Stimuli during Fetal Period. 16:448–455 [Accessed June 22, 2015].

*I photographed the rock band and drum group, and found the other images through Google Maps and Images.

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Why put so much effort into learning a second language?

Posted on June 22, 2015 by | 6 comments

I have loved the study of French language since the day I started classes in 9th grade. Even though Neuroscience is my primary major, my French second major has always been a passion and an outlet from core sciences. While this is my 3rd time in Paris, I’ve (finally) noticed that fluency is coming more naturally, even when I’m flipping between conversations and homework in French to texts and Skype sessions in English. As a double major in French and Neuroscience, (naturally) I was interested in finding out how language development and the brain’s response are interconnected.

I have stayed with 3 homestays and lived in the Cité Universitaire over the past 5 years. [image souce: Google maps]

Over the past 5 years, I have stayed with 3 homestays and lived in the Cité Universitaire. [image souce: Google maps]

Paris is an ideal place to begin an inquiry into language and speech. The earliest roots can be attributed to the work pioneered here by Paul Broca, the French physician and anatomist, who studied the speech production centers of the brain – now termed Broca’s area.

The brain Broca studied at Musée Dupuytren [image source: google images]

I visited the brain Broca studied at Musée Dupuytren [image source: Google images]

Advances in technology not available to Broca in the 1800s allow us to use neuroimaging methods to reveal specific functional brain patterns in learning a second language. After doing some research on the effect of bilingualism on the brain, I think that what I’ve been experiencing in my studies abroad is likely an actual change in brain structure. A property known as plasticity is the ability of the brain to physically and functionally change in response to factors such as environmental stimuli or cognitive demand (Stein et al., 2010). This process occurs in everyone who learns or speaks a second language, which turns out to be over half the global population (Bialystok and Barac, 2013). Learning a language in addition to your native tongue induces these changes in the brain (Stein et al., 2010). While this process occurs regardless of age, the speed of plasticity directly correlates to the long-term proficiency of an individual (Stein et al., 2010). So, relative to the time I started learning French in 9th grade, my immersion experience these last six months has allowed my brain to greatly pick up speed in making physical and functional changes compared to my 15-year-old self.

Not only is the study of French language a passion, being bilingual (or as close as I’ll ever get) advances cognitive control meaning that bilinguals develop better decision making and conflict mediation skills than monolinguals, according to the bilingual cognitive advantage hypothesis (Bialystok and Barac, 2013). This development results from a bilingual’s ability to better monitor life-long experience, cultural sensitivity, and mentally separate and switch between two languages (Stein et al., 2010).

A study in 2011 tested the impact of bilingualism on conflict monitoring and found that bilinguals not only resolve cognitive conflicts more efficiently (meaning with less neural input), but that their brain also better sorts and makes sense of conflicting input (Abutelabi et al, 2011). Using a group of 17 highly proficient German-Italian bilinguals and 14 Italian monolinguals, researchers studied the anterior cingulate cortex (ACC), the brain center involved with language control and monitoring conflicting information, through blood flow measurements in a functional magnetic resonance imaging (fMRI) scanner. Participants were then asked to perform language and non-language switching tasks. For the language-switching task, monolinguals were presented with a set of 32 different pictures and asked to produce a noun or a verb associated with the picture based on a color-coded system (red for nouns and green for verbs). Bilinguals were then shown these same pictures, but asked to describe the picture in either German or Italian, per another color-coded system (green for German and blue for Italian). Researchers found that ACC activity was significantly increased in bilinguals. For the non-language switching task, the participants were presented with a cross in the middle of the screen to fixate their line of sight during the entire trial. Five arrows then appeared in randomized order and direction and the participants were asked to identify the direction of the center arrow only.

A schematic of the visual task presented (Albutelabi et al., 2011).

A schematic of the visual task presented (Albutelabi et al., 2011).

Here, the bilinguals required less ACC activity while still outperforming monolinguals in accuracy. These results show that bilinguals are more efficitvely and efficiently able to distinguish the direction of the center arrow surrounded by the swtiching stimuli.

I loved that this study incorporated both a language switching task and a non-verbal task, which shows that the two tasks were carried out by the brain in the same region and thereby lends credit to the idea that development of the ACC in the study of a second language has positive effects in other parts of our daily lives. However, I wish that Albutelabi et al. had used participants of varying degrees of proficiency to see if the bilingual advantage spans across any second language learner.

Independent of my improved ability to find the best pastry in Paris due to increased language proficiency, I hope that I will have gained a life-long advantage to greater health and mental acuity. Not only have Paris and my French studies given me a greater awareness and appreciation of the world, increased neuroplasticity will allow me to use these now more refined areas, giving me confidence to switch between subjects and focus in on information relevant to the task at hand. This will come in particularly useful in my pre-dental studies along with other future endeavors, as lifelong bilingual experience may serve as a major deterrent to the onset of age-related cognitive decline (Grogan et al., 2012).

I shadowed a French general dentist in the 11th arrondissement.

This semester, I shadowed a French general dentist in the 11th arrondissement.

As I end my time in this beautiful city, I will keep my experiences (and brand new brain) pour toujours.

~ Amy Yeh

References

Abutalebi J, Della Rosa PA, Green DW, Hernandez M, Scifo P, Keim R, Cappa SF, Costa A (2011) Bilingualism Tunes the Anterior Cingulate Cortex for Conflict Monitoring. Cerebral Cortex 22:2076–2086.

Bialystok, E., & Barac, R. (2013). The psycholinguistics of bilingualism. New York, NY: John Wiley & Sons, Inc.

Grogan A, Jones OP, Ali N, Crinion J, Orabona S, Mechias ML, Ramsden S, Green DW, Price CJ (2012). Structural correlates for lexical efficiency and number of languages in non-native speakers of English. Neuropsychologia 50(7): 1347-1352.

Stein M, Federspiel A, Koenig T, Wirth M, Strik W, Wiest R, Brandeis D, Dierks T (2010) Structural plasticity in the language system related to increased second language proficiency. Cortex 48:458-465.

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