Stimulus-response view of the brain

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Chapter 4 endnote 3, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

So scientists assumed that neurons in the brain operated [like muscle neurons, by stimulus and response].

The roots of this stimulus-response analogy run very deep. The historian of science Kurt Danziger writes that when psychology, as a young science, imported methods of physiology to study the physical basis of the mind, the scientists imported stimulus-response assumptions for free.[1] Mental events were were thought to be like internal motor events that had to be triggered. A person was mindless until stimulated by the outside world.

This belief that the brain is mindless until stimulated by events in the world--although it sound preposterous to most of us today--probably accounts for a delay in one of the most important scientific discoveries in modern neuroscience: that the brain is made up of networked neurons that are intrinsically active. The neuroscientist Randy Buckner wrote an interesting and entertaining paper detailing how it took scientists more than a decade to realize this, even though the evidence was present in study after study.[2] The changes in fMRI signal, however, were coming from moments during brain scanning when subjects were not being probed with an external stimulus, and so scientists did not recognize it as meaningful brain activity, because their assumption was, more or less, that the brain was in an “off” mode.

A single neuron, alone, does lie dormant until stimulated. For example, the neuroscientists Hodgkin and Huxley studied an isolated giant squid neuron to understand how it conveyed information down its axon (called an action potential).[3] Studying an individual cell, however, does not tell us how it actually functions in a network, where neurons are continually passing information back and forth to one another. Neurons must be studied holistically to understand this.

Stimulus-response assumptions have been criticized in psychology for as long as they have been around.[4]


Notes on the Notes

  1. Danziger, Kurt. 1997. Naming the Mind: How Psychology Found Its Language. London: Sage.
  2. Buckner, Randy L. 2012. "The serendipitous discovery of the brain's default network." Neuroimage 62 (2): 1137-1145.
  3. Hodgkin, Alan L., and Andrew F. Huxley. 1952. "A quantitative description of membrane current and its application to conduction and excitation in nerve." The Journal of physiology 117 (4): 500–544.
  4. E.g., Dewey, John. 1896. "The reflex arc concept in psychology." Psychological Review 3 (4): 357-370.