Donald Doherty's blog

Category: Brain Science

  • Conscious Effort Influences Brain Activity

    It’s been more than twenty years since the first time scientists showed that brain cell (neuron) activity may be influenced by conscious effort. For example, research by Dr. Apostolos Georgopoulos’ team showed neurons in the motor cortex follow the mental rotation of a handle to a particular location (“Mental rotation of the neuronal population vector” published January 13, 1989 in Science.

    A new paper takes the conscious influence of neural activity a step further. The paper “On-line, voluntary control of human temporal lobe neurons” published October 28, 2010 in Nature describes the affect of attention on neural activity in the medial temporal lobe. (The medial temporal lobe is involved in learning, memory, and emotions and includes the hippocampus, parahippocampal cortex, entorhinal cortex, and amygdala.)

    For this research, electrodes were used to record neural activity to images of people or things familiar to the subject. Twelve patients who already had electrodes implanted in their medial temporal lobes for clinical reasons volunteered to be subjects in the experiment.

    The team isolated activity from two neurons. One neuron responded best to the presentation of an image of Josh Brolin, for instance, and the other responded best to the image of Marilyn Monroe. (They isolated activity from two additional neurons for technical reasons we won’t go into here.) The two images were superimposed and the subject was asked to attend to just one of them. The subjects of the experiment received real-time feedback of the activity of their medial temporal lobe neurons on an external display.

    When a person focused on one of the images, the activity of the neuron best driven by that image would increase while the activity of the neuron driven by the other image decreased. The research shows that conscious effort exerted to attend one thing at the expense of another was able to control the spiking (action potential) activity of neurons in the medial temporal lobes of their brain.

  • Bio-Commons a Global Challenge

    Science has always been an international endeavor and challenges have always stemmed from this fact including national differences in freedom of travel and speech, national secrecy and competitiveness, and national security to name a few. Changes in information technology and the state of the life sciences in particular are creating new challenges and perhaps heightening old ones.

    The policy forum paper “Research Funding: Sustaining the Data and Bioresource Commons” published today (October 29, 2010) in Science has some welcome viewpoints on these developments although I’m uncertain what they mean by the “globalization of scientific research” since, as stated above, science has always been global.

    Simply stated, the global public needs information repositories that are globally accessible. At one time it was the library at Alexandria. Recently the large repositories have been national libraries like the U.S.A.’s Library of Congress. Most recently the Internet has become a major, if not the main, repository of global knowledge.

    The issue of global access to life sciences data is particularly important right now. The project to understand life, including brain function, is producing vast amounts of data on mechanisms active at multiple scales of time and space.

    We must create a virtual biomedical library for everyone. The data will be too vast for any mortal to read. The library will need to present its data visually and actively. That is, users will need to get into the data intuitively by working with a virtual brain, for instance, and actively investigating its various functions through simulations.

    The way we share knowledge is going through radical shifts in the life sciences. Journal articles as we’ve known them have already changed and will change far more in the future. Humanity is on the cusp of perhaps its greatest project ever. By meeting the global challenge of a bio-commons we will attain levels of biological knowledge and medical practice far beyond what is currently possible.

  • Blind People Perceive Touch Faster than Those with Sight

    The brain’s visual system and, in particular, its visual cortex is activated in people that are blind since early in life. Studies have shown that blind people are better at detecting things touching their skin close together than are people with sight. People that are blind seem to have a particularly acute sense of touch. Are they faster at perceiving touch?

    Dr. Daniel Goldreich’s team just published the paper “Vibrotactile Masking Experiments Reveal Accelerated Somatosensory Processing in Congenitally Blind Braille Readers” (October 27, 2010 in The Journal of Neuroscience) that suggests the answer is yes.

    Fast Braille readers encounter a raised dot about every 50 millisecond. Sighted people would not be able to perceive a raised dot encountered so rapidly. They’d either simply not perceive the first or second raised dot they encountered or they would perceive the two dots as one dot. These phenomena are known as perceptual interference.

    The research team set up a series of experiments to test blind and sighted people on detection and discrimination tasks. They showed that all of their sighted and blind participants performed equally well on simple detection and discrimination tasks. However, on the tasks that included perceptual interference, people blind since early in life differed significantly from those with sight.

    In fact, those blind since early in life were the fastest Braille readers and were able to perceive individual touch stimuli faster than any other group. They concluded that early onset blindness leads to accelerated perceptual processing, which in turn enables rapid Braille reading.