Scientists show the evolution of the Amphitheatre

Scientists show the evolution of the Amphitheatre

This post was chosen as an Editor's Selection for ResearchBlogging.org

Back before the internet, twitter and megaphones it was a great deal more difficult to get your voice heard. However, those clever Greeks and Romans had a way of using the science of acoustics to get their message out.

They constructed great amphitheatres which seated thousands. An example of which is the image below I took when exploring an ancient Roman site in rural Turkey.

Click for High Def version

Scientists have continued to do research the way the acoustics worked to propel the voice of those ‘on stage’. A study by K. Chourmouziadou & J. Kang, published in the Journal of Applied Acoustics showed that amphitheatres evolved and changes in materials as well as design resulted in acoustic improvements. They simulated 6 different theatre types: Minoan, Pre-Aeschylean, Early Classic, Classic, Hellenistic and Roman.  Each of these had different characteristics (figure 1)

Figure 1: A breakdown of the different theatre types

Figure 2: Over time the amount of reverberation in an occupied theatre is seen to increase

The researchers then used acoustic simulation software to examine the theaters. They monitored the absorption and scattering conditions in each incarnation of the theatre. Their results indicated that there was increased reverberation time as the theatres evolved (figure 2) and the speech transmission increased in occupied theatres. They concluded that overall the evolution of the theatres brought about an improved listening experience.

ResearchBlogging.org
CHOURMOUZIADOU, K., & KANG, J. (2008). Acoustic evolution of ancient Greek and Roman theatres Applied Acoustics, 69 (6), 514-529 DOI: 10.1016/j.apacoust.2006.12.009

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Neuroscience Cases: Leborgne and Lelong

Neuroscience Cases: Leborgne and Lelong

The brain remains the most complex and unknown organ in the human body. The way that it malfunctions causes some of the most interesting phenomena science. In this feature each week I will attempt to look at a particular neurophysiological condition or case study.

Leborgne and Lelong

As with any story it is best to start at the beginning. Which is why for this first post, on Neuroscience cases, I will take a look at two of the oldest neuropsychology case studies.

Leborgne and Lelong were both patients of Paul Broca (1824-1880) a noted French physician and anatomist. Broca and his discovery shaped the

Paul Broca

knowledge of the science at a time when the consensus was divided. At the start of the 19th century the research of Jean Pierre Flourens in animals had stated that localisation of brain function did not exist and this was accepted by most researchers. However, there were those that challenged this idea. One in particular was Jean-Baptiste Bouillaud, who asserted that aphasias (language disorders) could only occur after lesions to the frontal lobes. His son-in-law and researcher Ernest Aubertin supported his views and challenged Broca to find an aphasic patient without a lesion in the frontal cortex. If he did, Aubertin vowed to renounce his views.

Broca was intrigued by this challenge. It was not long after this that he encountered a man named Leborgne. Leborgne appeared perfectly healthy, but unable to speak, except for one syllable, “Tan” (which became his nick name). He had been hospitalised due to this condition at the age of 21. However, after ten years paralysis had spread through his body leaving him bed ridden. 6 days after Broca met him he died. Following this Broca inspected his brain and found he found a lesion “capable of holding a chicken egg, and filled with serous fluid” in the frontal lobe of the left hemisphere. Broca’s presentation of this data was the first categorical proof of localisation of function in the brain, supporting Aubertin’s assertion.

After this Broca studied another individual with aphasia, Lelong. Lelong was an 84 year old man who had suffered a stroke and could only say 5 words, ‘oui’, ‘non’, ‘toi’, ‘toujours’ and ‘Lelo’ (meaning, ‘yes’, ‘no’, ‘always’, a mispronunciation of ‘trois’ or three used to represent any number, and a mispronunciation of his own name). After his death Broca found a region in the same region of the brain as Leborgne. Broca went on to become one of the main supporters of the localisation theory and the region where lesions were discovered in the brains of Leborgne and Lelong became Broca’s Area.

Whilst these studies may have occurred about 150 years ago the brains of Leborgne and Lelong  were preserved and studies with modern technology have given an intersting insight into what caused the plight of these two individuals. The following MRI images were taken of their brains in 2007:

High-resolution MRI of the preserved brain of Leborgne with representative slices throughout the brain. The first row shows photographs of the lateral and superior surfaces of the brain, with lines indicating the slices shown below. Row A shows axial slices, Row C coronal slices, and Row S sagittal slices through the left and intact right hemisphere for comparison with each other. In the axial and coronal planes, the left hemisphere appears on the left side of the images. The following structures are delineated: interhemispheric/longitudinal fissure (orange), central sulcus/Rolandic fissure (dark blue), sylvian/lateral fissure (aqua), inferior frontal sulcus (red), superior frontal sulcus (yellow), frontomarginal sulcus (pink), superior temporal sulcus (light green) and inferior temporal sulcus (brown). Sagittal slices S3 and S4 show the superior portion of the right hemisphere crossing over the midline due to extensive damage in the left hemisphere.

High-resolution magnetic resonance images of the preserved left hemisphere of the brain of Lelong with representative slices throughout the brain. The first row shows computerized 3D reconstructions of the lateral and superior surfaces of the brain with lines indicating the locations of the slices below. The widened sulci are easily visible and indicate severe atrophy. Row A depicts axial slices, Row C coronal slices and Row S sagittal slices through the left hemisphere. In these images, the colours have been reversed to enhance the contrast; cortex appears white and white matter appears dark. They have been flipped horizontally so that the lateral cortex of the left hemisphere is on the left side of the slice. Coloured lines again show the major sulci of the brain (see previous image for color codes)

Sources

Pierre Paul Broca (1861). Loss of Speech, Chronic Softening and Partial Destruction of the Anterior Left Lobe of the Brain. Bulletin de la Société Anthropologique2, 235-238

Dronkers et al (2007). Paul Broca’s historic cases: high resolution MR imaging of the brains of Leborgne and Lelong. Brain. 130 (5): 1432-1441