The evocatively named “mirror neurons” have recently been attracting much discussion in the blogsphere. Mirror neurons seemed to be associated with hightened affective states and hyper-speculation in humans.
But they are not the only neurons with these properties. As early as 1993, two scientists found that a particular neuron in a cat’s brain responded to a wide range of auditory stimuli, but not when the cat’s eyes were closed or in the dark. After their work had been “interrupted by the inescapable late-night giddiness suffered (enjoyed?) by those who do electrophysiological experiments,” the scientists reached these conclusions:
we finally concluded that cats must be deaf at night. This, of course, began a string of other ridiculous conclusions: blind cats are probably deaf too; and on and on. [Stein and Meredith (1993) p. 108]
These are truly astonishing hypotheses!
Key images that mirror neurons evoke are probably biologically misleading. Mirrors produce representations of objects that have little relation to the physical form of the mirror. Mirrors do not adaptively tune to subjects of interests. Mirrors are typically part of a “one brain” circuit. Making sense of another like oneself is rather different from looking in a mirror.
The human brain evolved and develops in social circumstances – circumstances of living bodies communicating intensively with others like themselves. In game theory, the rules of the game are assumed to be common knowledge among the participants. In communication among conspecifics, the common structures of conspecifics’ bodies are rules of the game. The flesh-and-bone relations of whole living bodies are central to making sense of another like oneself.
Sensory tuning is an important feature of living bodies. One neuroscientist described this process thus:
every percept has two components intertwined, the sensory-induced re-cognition of a category of cognitive information in memory and the categorization of new sensory impressions in the light of that retrieved memory. Perception can thus be viewed as the interpretation of new experiences based on assumptions from prior experience — in other words, the continuous testing by the senses of educated hypotheses about the world around us. [Fuster (2003) pp. 84-5]
“Perceptual prediction” effects, such as representational momentum and the flash lag effect, suggest that the “sensory-induced re-cognition of a category of cognitive information in memory” can be highly decentralized and not dependent on traditionally defined cognitive and memory circuits.
Recently two scholars put forward a provocative proposal for motor involvement in perceiving conspecifics:
The various brain areas involved in translating perceived human movement into corresponding motor programs collectively act as an emulator, internally simulating the ongoing perceived movement. This emulator bypasses the delay of sensory transmission to provide immediate information about the ongoing course of the observed action as well as its probable immediate future. Such internal modeling allows the perceiver to rapidly interpret the perceptual signal, to react quickly, to disambiguate in situations of uncertainty, and to perceptually complete movements that are not perceived in their entirety. … Thus, what originally appeared to be a neurological extravagance – the activation of motor resources when no motor movement is intended – may instead be an elegant solution to a perceptual problem. [Wilson and Knoblich (2005) p. 468]
This proposal, while speculative, at least shifts attention from representations, meaning, and linguistic expression to presence, the real-time experience of making sense of another like oneself. The latter seems to me to connect more insightfully to developing biological knowledge about mirror neurons.
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Fuster, Joaquin M. (2003), Cortex and mind: unifying cognition (Oxford: Oxford University Press).
Stein, Barry E. and M. Alex Meredith (1993), The Merging of the Senses (Cambridge: MIT Press).
Wilson, Margaret and Günther Knoblich (2005), “The Case for Motor Involvement in Perceiving Conspecifics,” Psychological Bulletin, v. 131, n. 3 pp. 460-73.