How the Brain Works – What Psychology Students Need to Know

Chapter 1. Introduction (and some puzzles)

This chapter sets out some puzzles, such as why it should be that we forget what (say) the capital of Hungary is, but not that we’re afraid of spiders. From AI and robotics, we now know there are other ways that cognitive systems can work (e.g., store all the memories on the same hard drive, which doesn’t forget anything). Our minds have the peculiar properties they do because of how the brain works; the brain works the way it does because of biology; and biology is the way it is because of evolution. The chapter sets out the goal of the book: to give a gist of how the brain works, stressing an evolutionary context. And it highlights what the book is not about: learning lots of Latin names for parts of the brain and detailed explanations of how brain scanners work. Here are some notes that go with some of the points in the first chapter, including supporting evidence.

  • ‘The book originated from a moment of puzzlement for one of the authors, which he experienced while attending a neuroanatomy course‘ – The neuroanatomy course was taught by Paul Johns. Highly recommended. Here’s his book.
  • ‘We understand almost nothing about how the brain works‘. There are people who claim this, despite, apparently, hundreds of university degrees taught on the topic and shelves full of textbooks. Here’s one example of such a claim, this one in an article in the New York Times by James Gorman (November 10, 2014) “Learning how little we know about the brain”.
  • ‘We could tell you that each brain contains around 176,000 kilometres of wiring‘ – Marner, L., (2012). Communication among Neurons. Quantitative Measures in Aging and Disease. Dan Med J 2012;59(4): B4427. Page 13: “176,000 km of myelinated fibers at age 20 and 97,200 km at the age of 80 years. Women were found to have a total fiber length of 149,000 km at age 20 and 82,000 km at age of 80”
  • ‘I say, Carruthers, this piece looks like an almond.’ – The amygdala was first identified as looking ‘a bit like an almond’ by German physiologist Karl Friedrich Burdach in 1819, who gave it the slightly longer name of corpus amygdaloideum, the almond-like body. Burdach was born in Leipzig in 1776 and was a pioneer of neuroanatomy. He was the first to use the term “biology” in its modern sense.
  • We jested at the bizarre name of the retrosplenial cortex. Yes, but what is the retrosplenial cortex, you may ask? It’s the most caudal (rearmost) portion of the posterior cingulate cortex. The cingulate cortex here is a broker between the sensory information processed in the back lobes of the cortex and the emotion processing systems of the limbic system sitting inside the cortex. It therefore processes visuospatial information with emotional salience. It’s called ‘retrosplenial’ because it’s the bit of the cortex sitting behind (retro to) the splenium. The splenium is the thickest and rearmost portion of the corpus callosum, the bundle of fibres connecting the left and right hemispheres of the brain. Well, that’s just a taste of the naming craziness to come, which we will dodge where possible!
  • No, in fact, while we’re on Latin names, let’s get this off our chest: one part is even called the substantia innominata – the ‘substance without name’. So, the 19th century anatomists had pretty much run out of names by then. Might as well have called it ‘stuff’ or ‘thingy’. Perhaps Carruthers should have put his feet up for a bit and taken a whiskey before going with that name. For the aficionado, the substantia innominata is a series of layers lying below the anterior part of the thalamus and lentiform nucleus, consisting partly of grey and partly of white matter.
  • The brain has many working memory systems because working memory is an activity applied to different content in different specialised systems. Let’s pick a random example. You can keep in mind the meaning of a word. This would be semantic working memory, that is, the maintenance of information about word meanings during language comprehension and production. It’s separate to the working memory system that maintains the sound of a word, which would be phonological working memory. And separate to keeping in mind what you wandered into the kitchen to do, which is every easy to forget. See this paper to delve deeper into semantic working memory: Martin RC. (2021). The Critical Role of Semantic Working Memory in Language Comprehension and Production. Current Directions in Psychological Science. 2021;30(4):283-291. https://doi.org/10.1177/0963721421995178