Author: Donald Doherty

  • Wiggling Whiskers for a Living?

    At first glance it sounds like another pork barrel government waste of money. Research grants to wiggle rat and mouse whiskers?

    Connections from touch receptors that translate touch into brain signals to the brain are mapped in a precise reflection of the layout of your skin over your body. One thing different is that areas sensitive to touch like your fingertips and your lips have many more connections than relatively insensitive areas like your back.

    When you explore the environment with touch you probably reach out and grab something and then move it around in your hands. This is active touch carried out by a couple of your organs of touch; your hands. In particular, primarily the finger tips on your hands.

    As a brain scientist I ask what the signals are that the thousands of receptors are transmitting to the brain from those fingertips. How does the brain recognize an object and the object’s properties from those signals?

    The example of you exploring an object with your hands is surprisingly complex. How may a brain scientist control the stimulus to the fingers in such a precise manner that they’re able to come up with the precise, preferably mathematical, translation between stimulus and signal? This is where whiskers come in.

    Whiskers (technically vibrissae) are part of the sensory organs of touch that enable rodents like rats and mice to get around and explore their surroundings. Each whisker is attached at its root to a vibrissa follicle that contains the receptors that translate whisker movement into brain signals.

    Each follicle is located at a point on the rodent’s snout so that the group of more than 30 whiskers and each side of the rodent’s face forms an array that works as a unit for exploring the environment in much the same way as your fingers and thumb make up an array of five on each of your hands.

    The cool thing is that the scientist is able to very precisely control how a whisker is stimulated right down to about a one micron movement. And they may control other parameters like which direction the whisker is moved. Finally, the anatomy of the connections within the whisker system in rodents is very well defined. I will post more about this last very important point in the near future.

    In sum, wiggling whiskers enables us to learn a lot about the brain and touch. Expect future postings here on research in this area.

  • Brain Research Using Online Data Repositories: Predicting Alzheimer’s Disease II

    On August 8th when I posted my review of the February 10, 2010 Journal of Neuroscience article that used Alzheimer’s Disease Neuroimaging Initiative (ADNI) repository data to look for biological markers that would predict the onset of Alzheimer’s disease, I had no idea that the very next day the New York Times would post a sensational story about a new research article based on ADNI data.

    The last sentence in the results section of the article’s abstract states that in a set of 57 patients “with mild cognitive impairment followed up for 5 years, the model showed a sensitivity of 100% in patients progressing to Alzheimer’s disease.” This was the “100 percent accurate” cited by the New York Times and numerous posts over the Internet. “The model” that they refer to is their unique way of using a certain mixture of amyloid beta and tau proteins in the patient’s cerebrospinal fluid as the biomarker rather than each protein independently.

    It’s exciting to see papers pouring forth based on large online data repositories where scientists are able to analyze much more data than any one team could collect on their own. In the new article the authors seem to have applied an innovative approach to analyzing the data set.

    The new article was just published in the August 2010 issue of Archives of Neurology and I have not managed to get access to the full text yet. When I do I will post a review.

    Other related blog posts:

    Brain Research Using Online Data Repositories: Predicting Alzheimer’s Disease

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