There is a widespread assumption that the formation of new knowledge in the brain involves the creation of new synaptic connections. This certainly does occur, but acquiring new knowledge does not always necessarily mean forming new synapses. Learning often begins with the strengthening of already existing synaptic connections. When the same neural connection is repeatedly activated, glutamatergic transmission – and particularly mechanisms involving NMDA (N-methyl-D-aspartate) receptors – can lead to a long-lasting increase in synaptic transmission. This phenomenon is known as LTP (long-term potentiation) and is considered one of the key synaptic mechanisms underlying learning and memory.
Put simply, connections that are activated again and again can subsequently be reactivated more easily and efficiently. This is why it is often useful to repeat important information not only using the same words, but also through different formulations, examples, and contexts. This is particularly important in the psychoeducational component of psychotherapy: explaining something once does not necessarily mean that it has become part of the client’s stable knowledge and behavioral response.
I apply the same principle in my books. I deliberately return to some fundamental ideas using different formulations and placing them in different contexts. This repetition is not merely literary or stylistic redundancy; its purpose is to reactivate the same idea multiple times and connect it with other knowledge and experiences. Sapolsky discusses Hebbian learning, synaptic strengthening, glutamate, and NMDA-dependent processes within this broader context. The original English edition of his book was published by Penguin Press in 2017.
References
Bliss, T. V. P., & Collingridge, G. L. (1993). A synaptic model of memory: Long-term potentiation in the hippocampus. Nature, 361(6407), 31–39.
Malenka, R. C., & Bear, M. F. (2004). LTP and LTD: An embarrassment of riches. Neuron, 44(1), 5–21.
Sapolsky, R. M. (2017). Behave: The biology of humans at our best and worst. Penguin Press.