Introduction

What is ‘The Biology of Thought’?

The human brain is the thinking organ, and neurons are its fundamental units. The myriad thoughts emanating from the magnificent human brain, minute after minute, are the products of the functioning neurons – and therefore we can say that neurons are the thinking machinery of the brain. However, it is still a puzzle how these neurons are designed to produce cascades of thoughts and can store them up in seemingly endless memory – all we know is that the sensations we receive from the outside world leave some sort of molecular signatures inside our brains that are imprinted in some form for future retrieval. What are these molecular signatures, and how are they made? How are these memory traces stored in the neurons? Our present science has no comprehensive answer – not yet.

The question of ‘what is thought’ is almost as ancient as human civilization. Thought is an abstract phenomenon occurring in the human brain. Thoughts underlie all human actions and interactions, and they make up the core of human mind and the background of human consciousness. The idea of ‘thought’ may mean so many different things to each of us. We have thoughts of material things such as flowers and mountains; or we may think of such abstract things such as the beauty of nature, solution to a problem, principle of a theory, etc.; or we have thoughts related to the past or future, and so on. These mental processes are so varied and diverse that it is impossible to group all these thoughts into a single definition. And all these thoughts are complex cerebral events requiring several areas of the brain operating together to produce coherent ideas. However, we are not concerned with such complex thoughts here in this work.

‘Thought’, in this book, means the most fundamental unit of mental processes happening in the brain. This work is concerned with the generation of the most basic unit of thought right at the level of neurons. There is no current theory in modern neuroscience as to how a stimulus from the external world is converted into a perception in the brain. Clearly, the human brain has some mechanism for this conversion. For example, we can perceive the color blue only when we are capable of converting the color blue we receive from the external world into internal thoughts of blue color in the brain. On the other hand, we fail to perceive ultraviolet light (or infrared rays, for that matter) because we do not possess the necessary mechanism to convert the UV light wavelengths into internal signals (as bats and butterflies do). Where is this mechanism located in the neurons? And how does this mechanism function? These questions are left unexplored and unanswered by modern science, and thus have remained a mystery until now.

This book, The Biology of Thought, is about the mechanism by which thought is generated and stored in the human brain. It describes a new molecular model by which thought is generated at the micro level in the human brain – right at the level of neurons. This work demonstrates how the biological electrochemical events occurring at the neuron interact with its molecular mechanisms to generate thoughts. In other words, here we have laid biological foundations for the generation of thought, hence the title of this book, The Biology of Thought. Thus, the hitherto abstract thought is shown to have a solid physical origin in the neuron, and this is showcased in a hypothesis called the ‘Molecular-grid Model’.

How is This Book Organized?

Now we can see that to study such a complex issue as the generation of thought in the brain, the reader must have an overall idea of the anatomical and functional aspects of the brain to assist him/her to fully understand the mechanism. For easy sailing, the book is presented in four parts.

Part I (Basic Concepts in Neurobiology). Part I of the book consists of three chapters which gives us some basic information on the structure of the brain and its functioning. Chapter 1 deals with the general plan of the human nervous system and the anatomy of the brain. Chapter 2 deals with the functioning of neurons – all the complicated electrochemical events occurring in a neuron are discussed in a simple and lucid way so that even a non-physiologist can grasp the electrical properties of neurons. Chapter 3 discusses the phenomenon of memory – the current concepts of the formation of memory along with the molecular basis of its storage are described briefly. Part I is obviously meant for those readers who want to brush up their knowledge on these basic concepts of the brain; however, this discussion may also interest a neuro-academic, because the presentation is a little out of the ordinary, to suit the purpose of the book.

Part II (The Molecular-Grid Model). This part of the book deals with the crux of the problem of the generation of thought by neurons. It consists of five chapters which attempt to answer the following three questions:

1. What is the fundamental unit of thought?

2. Where is it generated in the neurons?

3. How is it generated?

The sensory receptors sense various stimuli from the external world and send them up to the neurons in the brain, where they are converted into perceptions. This initial step generates the most fundamental units of thought in the neurons. Chapter 4 examines these fundamental units of thought (called the ‘primary thoughts’), and describes the properties of these primary thoughts. In Chapter 5 it is shown conclusively that only certain types of sensory neurons are designed to convert the external stimuli into primary thoughts (thus introducing the concept of ‘perceptual neurons’). In Chapter 6 it is shown that neurons have a certain molecular mechanism to receive the external stimuli and convert them into primary thoughts. A scientific discussion is undertaken to study the precise location of these molecular gadgets in the neurons. Chapter 7 examines the structure of these molecular gadgets (now called the molecular grids) and shows how they operate to generate primary thoughts. Chapters 4–7 take all the well-established concepts in neuroscience and show them in a new light, which helps us reach some far-reaching conclusions – and this can finally lead us to the concept of the molecular-grid model.

Having proposed a working model for the generation of thought by the neurons, we should now see how it works – now the molecular-grid model has to pass the acid test. As with any good scientific model, it must be able to explain at least a majority (if not all) of the concerned phenomena, and thus our new model must now explain the most obvious phenomenon of the brain, that is the phenomenon of memory. Therefore, Chapter 8 applies the molecular-grid model to explain the molecular basis of memory and its storage – and alongside, also explains other equally intriguing features of the brain, such as forgetfulness, intelligence, and such others. Part II is the work-book of a theoretical scientist – because it consists of all the new concepts in the field of neuroscience, which can open new vistas in the field of neuroscience.

Throughout Part II, thought is dealt with as an electrochemical process – i.e., a stimulus traveling to the neurons, exciting them electrochemically and generating primary thoughts. But it should be pointed out to the reader that the phenomenon of thought is far more elusive. We have seen, in the preceding chapters, only a physical mechanism by which thoughts are generated, but we have studied nothing about mind and consciousness or about the exact nature of thought itself.

Part III (The Evolution of Human Mind). The human mind is not a single entity but has many varied aspects – such as perceptions, cognition, memory, reasoning, emotions, desires, etc. Likewise, consciousness is also a vague phenomenon. Historically, mind and consciousness have eluded a precise definition, mostly because they cannot be examined by a strict scientific method. Part III consists of two chapters. Chapter 9 engages the reader in a scientific discussion of mind and consciousness, and arrives at important definitions. Alongside, we also examine intriguing aspects of the human mind, like intelligence and emotions.

Chapter 10 treats thought as a metaphysical entity (in contrast to the electrochemical process described in Part II). The ambiguous issues dealt with here are very complex; however, we will deal with them in a stepwise fashion to unravel the mystery of thought, and we approach these philosophical aspects of thought in a strictly scientific manner (or, at least, as strictly as abstract philosophical thought allows). At the end, we will examine the perplexing metaphysical conundrum that has bothered philosophers for ages – the mind-and-matter problem – and see how the molecular grids become relevant in this discussion.

The philosophical presentation in Chapter 10 may appear a little out-of-place to a student of biology, but even a pragmatic biologist who studies human thought dispassionately must be aware of these hard questions to remind him/her of the limitations of human knowledge. And biologists must also realize that there are a lot of loose ends in the fabric of our knowledge in the field of...