'Lectures in Neuroscience' by Rafael Yuste, a book review by Brenda Walker

21st May 2024

BNA associate member, Brenda Walker, shares her review of the book 'Lectures in Neuroscience', Columbia University Press - New York. 2023

RAFAEL YUSTE

These eighteen linked lectures highlight some of the ongoing work of this eminent American-Spanish neuroscientist, Rafael Yuste. The idea for this book arose from a collection of undergraduate class notes written for his Columbia University Neurobiology II course entitled ‘Development and Systems Neuroscience’ which he has been teaching and updating since 1996. In contrast to large text books which provide the student with ‘a molecular tsunami of exquisite but even more complex details...’, Yuste states in his preface that the purpose of his book is: ‘to answer, in simple language, two questions: what the brain does and how it does it’; his intention being to share his personal synthesis with undergraduates new to neuroscience or even with interested lay people.

If you follow Yuste’s career online you will discover that he is not only a distinguished professor of biological sciences, with an expertise in the function of the cerebral cortex, but also the director of the Neurotechnology Centre at Columbia University and in 2012 was named by the journal Nature as one of the five most influential scientists in the world. He is also a co-director of the Kavil Institute of Brain Science and led the beginnings of the international BRAIN initiative.  Currently chair of the HumanRights Foundation, he is an advocate for the protection of brain activity and recently, at a conference held at the Vatican in February 2024, pressed for the adoption of ethical rules for both neurotechnology and artificial intelligence, stressing the need for ‘Neuro-Rights’ to be added to the Universal Declaration of Human Rights.

Setting aside his international acclaim Rafael Yuste’s book, Lectures in Neuroscience reveals a great teacher who takes care to ensure his students understand the concepts involved. Starting with the basic principles of neuroscience: Ensembles/ Hierarchy/ Wiring/ Learning/ Maps/ Control/ Optimisation, this first chapter is the most important for any newcomer to the field as it provides the foundation for the rest of the course, as  these principles are still alluded to in the eighteen lectures detailed below:

Principles; Brains; Neurons; Circuits; Networks; Vision; Audition; Olfaction; Touch; Pain; Reflexes; Motor Planning; Motor Selection; Motor Control; Emotions; Speech; Memory; Thinking.

It is a heavy volume of over 450 pages and very costly. Yet, if you divide £50 by 18, the cost for attending such excellent lectures is well worth while! The acid-free shiny paper is great for the fine drawings of Ramón y Cajal and the simple but very effective illustrations by Gil Costa that support the text. However, if you are reading in artificial light, reflection can be a problem.

Each lecture has a similar format beginning with an interesting and relevant quotation, the first, LECTURE 1: PRINCIPLES, starts with C.S. Sherrington’s Man on His Nature (1942).  The other seventeen quotes reveal a rich variety of authors, some to be expected, such as Kant, Cajal, Plato, Proust and Goethe; but then there are some surprises like Buddah, Helen Keller, Winston Churchill, Martha Graham, Spinoza, and David Livingstone. Yuste then acknowledges the old-school rules: Say what you are going to say. Say it. Then say what you’ve said.

An OVERVIEW expresses the content:    

In this lecture, we’ll learn

• What the brain does
• How the brain does it     
• The basic principles of neuroscience

The full text follows, sectioned according to the subject matter and ending with a passage entitled RECAP, succinctly drawing together a conclusion that gathers all the key facts, looks towards the next lecture and throws out a few questions. I quote the end of LECTURE 1 in full so as to give you the flavour of the author’s friendly, conversational style and the essence of what has just been introduced:

‘One could argue that the brain does just one thing: predict the future using control algorithms to act intelligently. A few common principles of neuroscience explain how this is done beautifully and efficiently using neural hardware.  A model of the world is built with neuronal ensembles that are symbols of things.  Animals use these in all kinds of neural circuits for, effortlessly computing optimal strategies for future behaviour from an enormous number of possibilities.  They implement intelligence.  What an extraordinary job. Let’s dive into it.  Let’s find out how the brain is doing this. But first, in the next lecture, let’s take a closer look at the structures that make up the brain and how they develop.  What exactly IS the brain, what does it look like, and how does it assemble itself in the first place?’

The lecture having ended, a FURTHER READING list suggests titles that Yuste hopes will encourage students to explore further.

Every lecture guides the students’ knowledge on this exciting journey through the brain. The subjects become more sophisticated, but Yuste always reminds the reader of what has gone before such as Donald Hebb’s gem; ‘Neurons that fire together, wire together,’ or Sherrington’s discovery in the somatosensory system that applies to all sensory systems: ‘As you may remember, the skin area, or region in space, in which a stimulus can activate a neuron is called the neuron’s receptive field.’   Information handed on through the ages or in recent times is also recalled with catching enthusiasm.  He boosts the story with other stories; sometimes of research, sometimes personal, and sometimes even encouraging students to imagine themselves in certain situations.  As he builds a framework he sets it against an evolutionary time-scale that includes the development of the foetal brain and its organisation. The star role is given to the neuron and its operational tasks that enable neural circuits to form and then function as neural networks, whose part is to generate behaviour and states of the ‘mind’. To highlight this, when later discussing ‘mirror neurons’ that are linked to all our social actions, Yuste relates the Italian research that led to the use of the word ‘mirror’ in this context.  Their results revealed that such neurons are ‘encoding the abstract idea of movement regardless of who does it; they are conceptual neurons’, suggesting that mirror neurons help to build empathy for the feelings of others in humans – and logically also in animals. This is thought to be a stepping stone towards creating a theory of mind.

As the book develops and more new terminology/vocabulary appear in the text, Yuste continues to help the reader by always explaining the meaning immediately afterwards, to avoid gaps in the slow and steady build of the students’ understanding of facts or hypotheses highlighted in the lecture. Information that is currently still debated among neuroscientists is openly expressed: (‘we are not sure what happens in the thalamus.’) and often the students are challenged to perhaps be future solvers of the mystery!  Yet they are reminded that ‘Nature is independent of our views.’  Yuste’s mission is to ‘capture the excitement that brought me to neuroscience in the first place.’ So he sets out to give a clear picture avoiding getting lost in Cajal’s ‘fearsome jungle’ and explains more complicated text with simple rather than complex illustrations. His mission is certainly accomplished.

Time and again, he refers to engineering and physics as correlating with brain functions, often using words like circuits, structure, measurement, and precision, which apply not only in the Central Nervous System but also in the Sensory and Motor systems. As more nomenclature is used the reader is introduced to the scientific abbreviations, e.g. nerve growth factor (NGF) and often these are repeated: ‘...repeating information in class makes it stick’. However, as use of such abbreviations increase and many are then repeated across the following chapters without a textual reference, it would have been most helpful to have a separate or even a pull-out, alphabetical reference of abbreviations in the final pages alongside the already inclusive Index, as the weight of the book inhibits quick reference seekers.

From the start, Rafael Yuste sets the scene where traditional viewpoints still resist the growing neuroscience renaissance that Louiz Pessoa mentions in his recently published volume, The Entangled Brain, (2022). This older traditional viewpoint, which Yuste refers to as ‘Sherrington’s neural doctrine’, describes the brain as an input/output system that reacts reflexively to sensory stimuli where the unit of structure and function is the individual neuron. However, other groups of neuroscientists, Yuste included, refute this, considering their idea of ‘neural spatiotemporal correlations to be the units of neural language’. The author acknowledges that the new paradigm indicates only a small change, but explains that it has important implications in that it answers the mystery of spontaneous activity and predicts that: ‘brains are intrinsically driven machines – machines that can learn and serve as universal computers.’ – in fact learning machines that continuously absorb stored information, so any plans that fail might subsequently be improved. It also enables us to use associative learning to achieve better results. In the following lectures Yuste examines the paradigm more fully and suggests it will ‘provide a common backbone that can help us put together a comprehensive view of what different parts of the brain do and how they do it’.  

Frequently, we are told there is still much to discover, but the author does attempt to guide the reader as far as is possible at the present time. In his preface, Yuste states that the study of emergent properties is at the frontier of science, that they are all around us but appear only when elements interact. He believes that if an inventor wanted to build a system to generate such emergent properties, described as ‘whatever cannot be measured by studying the elements of a system in isolation’, the human brain would be a fine choice. To explain, Yuste, following the laws of physics, gives magnetism as an example, where after breaking into the atoms of a magnet, its use disappears. Its function – magnetism – needed those atoms to interact in a stable state. Similarly with neurons: rather than each neuron having a special function, ‘ensembles of coactive neurons generate functional states’.  

As the reader follows the lectures, the correlation with what we know about deep artificial intelligence and what is being described about the functions of the brain is startling. Artificial neural networks are now closing the gap between theory and data. The notion that the brain is a predictive machine is not new. Anil Seth was a forerunner in print with his publication Being You (2021), which examines the mystery of consciousness. Yuste, concentrates on the brain building a model of the world, creating an internal map to aid anticipation of the future, thus enabling us to choose a successful outcome –  or one could say – ‘to act intelligently’. Within the author’s personal synthesis, the entire cortex appears to be working as one unit and the brain is viewed as a ‘gigantic neural network’.

 Technology, advanced modalities in medical imaging and deep learning AI are changing the world of neuroscience more rapidly than ever before. In today’s world we are surrounded daily by unfolding mysteries. Only today, an academic research article was published in SCIENCE, by the Neuro-Electronic Research Institute in Flanders (NERF). They have discovered that ‘two inhibitory neuronal classes govern acquisition and recall of spinal sensorimotor adaptation. Such findings identify a circuit basis involving two distinct populations of spinal inhibitory neurons, which enables lasting sensorimotor adaptation independently from the brain.’  Again, success for those neurons! If this can happen independent of the brain, and the NERF findings are said to ‘highlight the potential for rethinking how movement recovery is approached in patients with spinal damage’, one can’t help wondering how this will link to Yuste’s current interest in the on-going brain-computer interface research.

Lectures in Neuroscience ends with a personal message from the author to all those trying to understand the brain: ‘Yes Neuroscience is still young, with many opportunities for research and exploration. It’s a fascinating new continent waiting for all of us, waiting for you.’

 Brenda Walker, April 2024