A Neuroscience Short: Cat Brains and the Visual Cortex

cat brains

The Deep Waters of Neuroscience

Looking into neuroscience is a little bit like standing on the edge of a cliff at night while you peer down at the ocean below. Waves crashing against rocks; a roaring hum; black water that appears to be endlessly deep — a borderless expanse seeping into every edge of your vision. It is terribly complex and horrendously detailed. Simple concepts are merely an illusion when you realize that your foot is hovering near the steep drop-off to the depths below.

Neuroscience is currently in a rapid growth spurt. New advances are constantly being made; waters, once uncharted, are being mapped with great detail. New questions are constantly being asked and old ones are giving up their secrets.

I am currently drowning in the mass of information I have gathered for two neuroscience posts that will appear here in the near future. One, a terrifying dip into neurodegeneration and prion disease, the other is a three part on perception (as promised). While I sift through all this information to eventually cultivate (somewhat) coherent posts, let’s take a quick trip into the history of neuroscience and cats.

Visions of Cat Brains Dancing in their Heads

Today, mouse models are the most common animal model used for most research and neuroscience is a big consumer of mice and their little squishy brains. Mice, however, are not the only animals whose brains have been poked by the fingers of science.

Cats have a long history in neuroscience and it’s not cuddled on the laps of scientists while they review their research. (If the thought of animal experimentation makes you squeamish, wash this down by reading about the cat who co-authored a physics paper HERE.) Animals in research are crucial to advancement. We need them and their little biological systems to accurately assess how things function and interact as a whole –the test tube just doesn’t cut it. Small and large animals are helping to solve big problems in the health and disease of animals and humans alike.

Back to the cats. Cats were popular because they were cheap, easy to handle and large and hearty enough to withstand surgery and implantation of the old school bulky instruments.

In the 1950s, two scientists made a huge break through in visual perception by wiring up a cat’s brain, forcing its eyelids open and feeding its visual cortex (the part of the brain that “sees”) images projected on a screen. Perhaps an inspiration for Kubrick but certainly a huge leap for understanding how vision works. It was through these experiments that we began to understand that the interpreted world in front of us is not quite the way our brain first perceives it.

For example, the aptly named simple cells of the visual cortex perceive the lines or edges of objects. The neurons wired up in the cat’s brain had been silent for most of the images that flashed across the screen only to suddenly jump to life when the slide was being dragged across it. The slide’s glass edge caused a thin, faint line to appear on the cat’s retina making the neurons crackle like a vinyl record skipping.

There is a fairly recent study from 2010 that found something pretty interesting in the brain of deaf cats. They found that congenital deaf cats (cats who were born deaf) had better peripheral vision (side vision) and motion vision (they could track objects that zipped around better than others). Not really a surprising find but when they looked at how the cat’s brain worked they found that the increased visual acuity ( the ability to see better) was found to reside not in the “all seeing” visual cortex but in a specific portion of the auditory cortex — an area that should be silent in the deaf cat who received no auditory input from the outside world. The cat’s brain took a part that was underutilized and put that damn thing to work.

Feedback from a Human Brain

Cat brains and mice brains aren’t the only brains that we connect to wires to measure their response. Wiring up human brains can make neurosurgery a hell of a lot safer. One day, in my past life, I had the wonderful privilege of being allowed to observe a neurosurgery where the cranial nerves were wired to a machine. The machine was monitored by a neurophysiologist, a scientist who studies how the nervous system works. Every time the cranial nerves were stimulated by the surgeons – the machine beeped. Sometimes it let out a high pitch mechanical scream from the depths of hell. This was the brain giving feedback to the surgeons whenever they got too close for comfort and allowed the surgeons to avoid damaging precious nerves. The brain (and the person whose skull it resides in) had a more positive outcome because of it.

Shallow Swim

And thus ends the lap in the kiddie pool of neuroscience. Next time, we will be entering some pretty terrifying depths; and perhaps, next time, I will stop abusing water metaphors (but I promise nothing).

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Image: Erin Matthews
Cross-modal plasticity in specific auditory cortices underlies visual compensations in the deaf. Stephen G lomber. Nature Neuroscience. 2010
Animals in Neuroscience Research. Impact on Neuroscience Research: Workshop Summary. 2012
Watch an explanation of Hubel and Wiesel Cat Experiment HERE

 

 

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