Electrical stimulation studies of emotion
Chapter 1 endnote 44, from Lisa Feldman Barrett.
Some context is:
[Emotion] fingerprints are also absent if you [...] stimulate individual neurons with electricity.
Electrical stimulation of individual neurons by and large does not allow us to localize emotions to specific sets of neurons. Over sixty years of this research has produced two general conclusions:
- Stimulating neurons in the same region of the brain in different people has variable consequences, not all of which are emotional
- When an emotion is evoked, it’s not always by stimulating neurons in so-called “emotional” parts of the brain
Even when (say) amygdala stimulation yields an emotional feeling, you can’t know if the emotion came from the amygdala or from some other distant brain region via the amygdala’s neural connections.
Many neurons do not appear to have a single, fixed function (or in neuroscience-speak, a single neuron has more than one "receptive field" — it codes for more than one feature). Beliefs to the contrary come from the fountain of essentialist thinking. The neuroscientist Eliot Valenstein, a pioneer in electrical stimulation methods, summed up the point very nicely:
“The impression exists that if electrodes are placed in a specific part of the brain, a particular behavior can inevitably be evoked. Those who have participated in this research know that this is definitely not the case. In a large percentage of cases, animals do not display any specific behavior in response to stimulation, even though great care may have been exerted to position the brain electrodes with as much precision as possible. Even in rats, where the behavior is more stereotyped than in monkeys and man, brain stimulation produces very variable results.”
Valenstein’s remarks are from the 1970s, but there’s nothing in later studies that violates his conclusion. In fact, Guillory & Bujarski (2014) conclude that emotions are not represented “by discrete, evolutionarily conserved anatomical systems in the brain (e.g., amygdala)” but by “widely distributed representations of emotions spanning the subcortical nuclei, the limbic/paralimbic regions and the neocortex,” i.e., the entire brain.
Notes on the Notes
- For a review of 64 experiments published since the 1950’s, see Guillory, Sean A., and Krzysztof A. Bujarski. 2014. "Exploring emotions using invasive methods: review of 60 years of human intracranial electrophysiology." Social Cognitive and Affective Neuroscience 9 (12): 1880-1889.
- Anderson, Michael L. 2014. After Phrenology: Neural Reuse and the Interactive Brain. Cambridge MA: MIT Press.
- Sillito, A. M. 1975. "The contribution of inhibitory mechanisms to the receptive field properties of neurones in the striate cortex of the cat." Journal of Neurophysiology 250 (2): 305-329.
- McIntosh, Anthony Randal. 2004. Contexts and catalysts: a resolution of the localization and integration of function in the brain. Neuroinformatics, 2 (2): 175-82.
- Halgren, Eric, Richard D. Walter, Diana G. Cherlow, and Paul H. Crandall. 1978. "Mental phenomena evoked by electrical stimulation of the human hippocampal formation and amygdala." Brain 101 (1): 83-115.
- Valenstein, Elliot S. 1973. Brain Control: A Critical Examination of Brain Stimulation and Psychosurgery. New York: John Wiley & Sons, p. 88.
- Guillory, Sean A., and Krzysztof A. Bujarski. 2014. "Exploring emotions using invasive methods: review of 60 years of human intracranial electrophysiology." Social Cognitive and Affective Neuroscience 9 (12): 1880-1889.
- For additional discussion, see Barrett, Lisa Feldman, Kristen A. Lindquist, Eliza Bliss-Moreau, Seth Duncan, Maria Gendron, Jennifer Mize, and Lauren Brennan. 2007. "Of mice and men: Natural kinds of emotion in the mammalian brain?" Perspectives on Psychological Science 2 (3): 297-312.