Chapter 4 endnote 4, from Lisa Feldman Barrett.
Some context is:
Your brain’s 86 billion neurons, which are connected into massive networks, never lie dormant awaiting a jump-start.
The firing of a single neuron (or a small population of neurons) represents the presence or absence of some feature. The feature can be simple, like a line; or a complex summary of multiple simple features, like a face, or the sight, sounds, and tastes of an apple. However, a given neuron (or group of neurons) represents different features from moment to moment; Its receptive field (the feature it represents) is not fixed. Many different neurons synapse onto one neuron (many-to-one connectivity), so that a neuron’s receptive field depends on the information it receives at a given moment in time. Most of these neurons excite each other (speed each other’s firing rates) but some inhibit each other (slow each other’s firing rate); i.e., all neurons have a neural context in the moment that determines their receptive field. Conversely, one neuron also synapses on many other neurons (one-to-many connectivity). Each neuron is connected to over a thousand other neurons, by many thousands of synapses, although on average, a change in one neuron’s firing rate will cause changes in about 15,000 to 17,500 synapses. This is just an estimate, however, because neurons at the front of the brain are more densely connected to each other than those at the back by a systematic factor of five to tenfold from occipital to frontal.
Notes on the Notes
- Spillmann, Lothar, Birgitta Dresp-Langley, and Chia-huei Tseng. 2015. "Beyond the classical receptive field: the effect of contextual stimuli." Journal of Vision 15 (9): 7.
- Stokes, Mark G., Makoto Kusunoki, Natasha Sigala, Hamed Nili, David Gaffan, and John Duncan. 2013. "Dynamic coding for cognitive control in prefrontal cortex." Neuron 78 (2): 364-375.
- Rigotti, Mattia, Omri Barak, Melissa R. Warden, Xiao-Jing Wang, Nathaniel D. Daw, Earl K. Miller, and Stefano Fusi. 2013. "The importance of mixed selectivity in complex cognitive tasks." Nature 497 (7451): 585-590.
- Basole, Amit, Leonard E. White, and David Fitzpatrick. 2003. "Mapping multiple features in the population response of visual cortex." Nature 423 (6943): 986-990.
- 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 Physiology 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): 175-182
- Sporns, Olaf. 2011. Networks of the Brain. Cambridge, MA: MIT Press..
- Peters, Alan. 2002. "Examining neocortical circuits: Some background and facts." Journal of Neurocytology 31: 183-193.
- Lennie, Peter. 2003. "The cost of cortical computation." Current Biology 13 (6): 493-497.
- Charvet, Christine J., and Barbara L. Finlay. 2014. "Evo-devo and the primate isocortex: the central organizing role of intrinsic gradients of neurogenesis." Brain, Behavior and Evolution 84 (2): 81-92.