Your Senses Awe Scientists

The ear, the eye, the nose, and the mind itself continue to display wondrous capabilities.

The Ear

In a paper meant to argue for evolution, Science described the phenomenal capabilities of the human ear, likening it to a piano:

In mammals, the chain of auditory biophysical events starts with the transformation of airborne acoustic energy into the mechanical vibrations of an eardrum. The lever action of delicate middle ear bones passes these eardrum vibrations to the oval window (Fig. 1), generating force gain via surface area ratio. This is the critically important step of impedance conversion that enables the efficient transfer of acoustic energy from airborne vibrations to the liquid-immersed mechanosensory hair cells in the cochlea. A second salient feature of many auditory systems is their capacity to analyze the frequency content of incoming sound waves. This process makes use of the mechanical anisotropy of the fluid-bathed basilar membrane to spatially decompose the acoustic signal into its frequency components, a biological form of the Fourier transform. Cochlear hair cells receive mechanical inputs at specific frequencies, depending on their position along the stiffness gradient of the basilar membrane. This “piano keyboard” mapping, or tonotopic organization, is the canonical mechanism for frequency selectivity in mammals.

The authors found a similar chain of acoustic-mechanical-fluid energy transfers leading to frequency selectivity in a katydid ear, leading them to claim it was an extreme case of “convergent evolution.”  Ronald R. Hoy in his summary of the paper in Science actually used an illustration of a piano keyboard to portray the frequency selectivity mechanism.  See also the 11/15/2012 entry.

The Nose

A short article on Science Daily described a new finding about the sense of smell.  How are odors mapped to the brain? In “How Cells in the Nose Detect Odors: Braking Mechanism in Olfactory Neurons Helps Generate Amazing Diversity of Sensors,” the article introduced some of the complexity involved:

The human nose has millions of olfactory neurons grouped into hundreds of different neuron types. Each of these neuron types expresses only one odorant receptor, and all neurons expressing the same odorant receptor plug into one region in the brain, an organization that allows for specific odors to be sensed.

Scientists at UC Riverside studied the olfactory mechanisms in insects, and found another convergence: both insects and mammals – far removed from any possible evolutionary relationship – use a similar and very complex “braking” mechanism to repress genes until they should be expressed.  The article compared the mechanism to another human device: a typewriter –

Ray explained that one way to understand the mechanism in operation is to consider a typewriter. When none of the keys are pressed, a spring mechanism or “brake” can be imagined to hold the type bars away from the paper. When a key is pressed, however, the brake on that key is overcome and the appropriate letter is typed onto the paper. And just as typing only one letter in one spot is important for each letter to be recognized, expressing one receptor in one neuron lets different sensor types to be generated in the nose.

“If this were not the case, a single cell would express several receptors and there would be no diversity in sensor types,” Ray said. “Our study then attempts to answer a fundamental question in neurobiology: How do we generate so much cellular diversity in the nervous system?”

But the nose’s “typewriter” is much more elaborate, because it can modulate the response level of the inputs.

The Eye

Imitation is the sincerest form of flattery.  That’s why scientists at Case Western Reserve University are working to imitate the human eye’s lens, reported Science Daily.  A crucial trait of the lens’s effectiveness is its graduated index of refraction (GRIN), a property difficult to replicate in glass.  The researchers at Case Western have now achieved the fabrication of GRIN lenses by stacking thousands of nanoscale layers.  This “visionary design” promises a “new, more natural lens technology” that can begin to duplicate some of the benefits of biological lenses for those needing lens replacement surgery.  And that’s not all:

Drawing heavily upon nature for inspiration, a team of researchers has created a new artificial lens that is nearly identical to the natural lens of the human eye. This innovative lens, which is made up of thousands of nanoscale polymer layers, may one day provide a more natural performance in implantable lenses to replace damaged or diseased human eye lenses, as well as consumer vision products; it also may lead to superior ground and aerial surveillance technology.

It’s good they said “nearly identical” instead of identical, because polymer-based lenses only duplicate the graduated index of refraction.  They are not capable of self-repair and genetic self-replication.  It is, though, an important step in trying to replicate something natural that many of us take for granted as we read articles like this one.  “The human eye is a GRIN lens,” Michael Ponting, who is applying the research to a spinoff industry. “It’s a very efficient means of controlling the pathway of light without relying on complicated optics, and one that we attempted to mimic.”

The Brain

A remarkable story was posted on Medical Xpress: doctors in Canada have apparently succeeded in communicating with a man thought to be in a “vegetative state” for 12 years following an accident (a vegetative state is defined as inability to communicate or respond, even though an EEG shows brain activity).  Though Scott Routley is incapable of body movement, his brain and hearing are still apparently responsive.  Using functional MRI (fMRI), the scientists found an ingenious way to make contact:

To try to communicate with Routley, doctors asked him to try to visualize himself playing tennis and recorded the way his brain responded using fMRI. They then asked him next to try to visualize himself walking around in his house and recorded the way his brain responded to that exercise as well. Then, they asked Routley to use the visualizations as a means of responding to questions – to visualize the tennis match as a means of answering yes to a question, for example…. team lead Prof Adrian Owen, said tests were run multiple times using the same question and answer process and he reports that the results indicate that Routley was definitely communicating with him and his team.

Some are not yet convinced, doubting the interpretation of the scans.  If confirmed, though, serious ethical issues arise: “such research raises the possibility that science will discover that some people have been left to lie immobile for years under the assumption that they are unaware of the reality of their situation – a situation that would have to be addressed if it’s determined that they are and have been, capable of conscious thought.”  The BBC is making a documentary about it.  This is definitely a story to watch.  Doctors may have found a key to communicating with patients once thought to be out of touch with reality, giving them a way to reach out and express their pains and pleasures simply by thinking about them.

Wonderful stories that speak for themselves.  Darwinism is useless to all this.  It’s like ugly fat that clogs the arteries of science.  Let’s put science on a fitness program.  The future could be bright for open minds running a lean, mean, well-designed machine.