Donald Doherty's blog

Author: Donald Doherty

  • Emotional Response Best Predicted by Response of Others

    If I’m told about a future event I may take part in, I feel that I’m the best estimator of what my own emotional response will be to that event. Experimental psychology results described in “The Surprising Power of Neighborly Advice” (published March 20, 2009 in Science) show that not only is this what we all typically think but also that it’s false.

    Each participant in the experiments was either given information about an event that they’d take part in or was provided the opinion of another participant on how much they thought the individual would enjoy (or not) the future event. Each participant was then asked to rate how much they were likely to enjoy (or not) the future event. After providing a rating the participant was exposed to the other set of information (the opinion of another participant or information about the future event) so that, by the time of the event, all participants were exposed to the same set of information. After the event, each participant stated how much they enjoyed (or not) the event.

    The researchers then compared the emotional response each individual predicted with the response they reported at the end of the event. The results showed that those who heard the opinion of another participant on how they may respond to an event were significantly more accurate in predicting their final response than those who simply knew details about the upcoming event.

    The results are intriguing. Nevertheless, I wonder if unconscious influence (priming) may be at work here even in those who did not get the neighborly advice before estimating their future emotional response (see my blog post “Is the Conscious Decision an Illusion? Pursuing Goals Unconsciously“). That is, not only is the input from another participant influencing the individual’s estimate of their emotional response to a future event but it’s influencing their perception of the event itself (while it happens). In this case, the influenced perception of the event itself would happen to both those who got advice before and those who received advice after they predicted their future emotional response. That would explain the good predictions of the former and the poor predictions made by the latter.

    Other related blog posts:

    Is the Conscious Decision an Illusion? Pursuing Goals Unconsciously

  • Electric Stimulation of Spinal Cord for Treating Parkinson’s Disease

    People with Parkinson’s disease suffer from the inability to move in the typical, apparently effortless, way. Initiating movement can become difficult and, once initiated, movement may be clumsy and require a great deal of effort.

    A prominent feature of Parkinson’s disease is the death of brain cells (neurons) in a brain nucleus known as the substantia nigra (substantia is Latin for substance and nigra is Latin for black; the nucleus in the brain looks black). These neurons produce dopamine, which they use to communicate with other neurons in the brain. Replacing the dopamine lost when these cells die by taking L-dopa has been the treatment of choice for many decades. L-dopa therapy decreases the severity of the patient’s movement problems but does not cure the disease. Worse, L-dopa therapy decreases in effectiveness over the long term.

    The electrical stimulation of deep brain structures (the basal ganglia) has been shown to be effective in reducing the dose of L-dopa needed by patients to maintain their ability to move. However, placing electrodes deep in the brain is a very serious matter. Exposing the brain during surgery should be avoided if possible. A research team has provided evidence that stimulating the spinal cord dorsal columns from outside the nervous system’s protective covering (the dura mater) may provide the same benefits without the dangers of open brain surgery. The research was described in the paper “Spinal Cord Stimulation Restores Locomotion in Animal Models of Parkinson’s Disease” published March 20, 2009 in Science.

    This was the first paper on treating Parkinson’s disease by stimulating the spinal cord dorsal columns so we’re probably a long way off from using this therapy in humans (the experiments were performed in mice). The next step should be to try the procedure on non-human primates.

  • Watching Brain Cells Track Location

    The description of a technical tour de force was published this month. The experimental setup enables us to watch a mouse’s brain cells track the mouse’s location in a virtual environment while the mouse is actually exploring that environment .

    The paper “Functional imaging of hippocampal place cells at cellular resolution during virtual navigation” was published November 2010 in Nature Neuroscience.

    A mouse navigating a virtual maze. The mouse runs in place on a ball within a computer-generated visual environment that provides the sensation of running through an actual maze. From “Intracellular dynamics of hippocampal place cells during virtual navigation.” By Christopher D. Harvey, Forrest Collman, Daniel A. Dombeck & David W. Tank. Nature, Vol. 461 No. 7266, October 14, 2009.

    The team’s virtual maze setup was introduced last year (see video above). In this paper they introduced a custom two-photon microscopy setup that integrates with their virtual maze to enable them to image brain cell (neuron) activity at a high spatial resolution while a mouse is running the maze. Using the setup they record place cell activity in the hippocampus of living and behaving mice.

    This technique holds huge potential for resolving questions about brain function. Optical imaging of neuronal activity at a high spatial resolution can

    • display the precise anatomical position of functionally identified neurons within the microcircuitry
    • record from genetically labeled neuronal subtypes
    • enable functional recording from subcellular compartments like dendritic branches and spines
    • identify all neurons (even silent cells)
    • enable the unambiguous identification and recording of the same neurons over many weeks.

    It’s with great anticipation that I await further data to flow from the laboratory of Dr. David Tank and colleagues.

    Other related blog posts:

    Do You Know Where You Are? Place Memory

    Nature versus Nurture and Place Memory Development

    Spikelets and Place Cells