The Brain: A Systems Neuroscience Perspective

The lives of species are trapped within ‘cooperation and conflict’. They compete with each other to win the ‘survival of the fittest’. In cognitive neurosciences, action and perception are the most crucial. Perception guides action by selecting targets and correcting errors. This entire process is stored in the memory. It is an essential part of learning and creates the basis for new knowledge by association. Neural circuits that control metabolism and food intake are housed within the hypothalamus. It is small in size but plays a crucial role. Temperature, sleep, eating, and social interactions are its responsibility. Emotion and learning are related e.g., positive emotion (simply feeling good) motivates students to perform better. Emotion, as the present state of knowledge stands, is taken care of by the amygdala. Should we consider it the ‘heart of the brain’?

The purpose of this chapter is not to cover all systems or subsystems but to discuss only a select few. This decision has been taken to reduce the complexity of the brain’s neurovascular structure. Capillaries in the neurovascular structure hold back certain molecules, RNA viruses, and other disease-causing agents (ions, molecules, etc). The blood-brain barrier, cerebrospinal fluid, and blood-cerebrospinal fluid barrier are three key elements of the organizational structure of the brain.

Scientists at the European Molecular Biology Laboratory have investigated how embryonic stem cells become mature nerve cells. They assessed the complex interplay of molecules during the differentiation process. Consequently, new insights into the role of a protein called SOX2 in neurons emerged. This protein is expressed by a gene, SOX2, located on chromosome 3 in humans. This gene is a sex-determining Yrelated HMG box2 and serves as a marker for neural stem and progenitor cells [1]. Progenitor stem cells become neurons and glial cells. The ratio of glia to neurons in the human brain is 10:1. This suggests that glial cells play significant roles in cognitive functions. Glial cells of CNS are divided into microglia and macroglia. The microglia are macrophage-like cells, which function as a phagocyte. Macroglia consist of astrocytes and oligodendrocytes. Oligodendrocytes act as CNS equivalent to myelinating Schwann cells in the peripheral nervous system (PNS).

Neuroimaging is a branch of medical imaging that focuses on the brain. Among all imaging techniques, magnetic resonance imaging (MRIs) and MEGs (Magnetoencephalographs) are favorites of medical doctors. MRI has two variants: functional MRI and structural MRI. In this chapter, both of them are discussed. Detection and monitoring of the progression of neurodegenerative diseases are performed with MEG by analyzing neural complexity and the Grassberger-Procaccia correlation dimension. Lempel-Ziv complexity is a better option. Positron emission tomography (PET) is a useful procedure to measure the metabolic activity of the cells of body tissues. PET helps monitor biochemical changes in the body. Electroencephalography is used to characterize states of consciousness of the brain. EEG is not discussed in the present chapter since the aim of the chapter is not to present all neuroimaging techniques but to cover a select few depending on the author’s own background and experience.

In this chapter, theories of learning are not discussed at all. Numerous texts exist where they can be found. It would be enough to note that behavior has two aspects: 1) explorative and 2) exploitative in active inference. The former is sensitive to ambiguity, and the latter is sensitive to risk. In the absence of ambiguity, active inference reduces to a Bellman scheme [1]. Bayesian inference is integrated with active inference in free-energy formulation. Actions are guided by predictions and are refined by sensory feedback. The variational free energy is a function of observations and a probability density over their hidden causative agents. The time average of energy is action. Minimum variational free energy corresponds to a principle of least action. Perception can be regarded as a minimum of free energy with respect to inbound sensory information and action as a minimization of free energy with respect to outbound action.

Synaptic modification is a prerequisite for learning to occur. What one learns must be preserved for future use. Therefore, it needs to be stored. That storage is memory. Neural plasticity is the basis for memory formation. Information about biologically important events (Pavlovian conditional fear, Pavlovian conditioned eye-blink) reach centers in the amygdala and cerebellum through circuitry, which depends on the modality of stimulus and its complexity. In the present chapter, memory systems are introduced to the reader, starting from the Baddeley-Hitch model of working memory. Working memory is also known as short-term memory (STM). Certain information stored in short-term memory is transferred to a memory system known as Long-term memory (LTM). The brain makes decisions as to which information is to be transferred to LTM. The role of brain oscillations in memory formation is also discussed. 7±2 rule states that STM in humans can store only 5 pieces of information when it is complex; on the other hand, it can store 9 pieces when information is simple. A method to characterize the complexity of information is given. Information transport in the brain is thoroughly discussed. The chapter ends with a discussion on the discovery of engram cells, which participate in systems consolidation of memory.

 A cognitive map guides spatial navigation in mammals. Pyramidal neurons in the hippocampus become active only in a particular region of the environment. These regions are called ‘place fields’, and these neurons are called place cells. Many brain regions are involved in the cognitive mapping of the environment. Grid cells in the medial entorhinal cortex organize themselves on a regular grid of triangles covering the entire surface of the environment. The firing pattern of grid cells represents the distance between spatial locations. These distances provide spatial metrics for the cognitive map. Other neurons that participate in spatial navigation are head direction cells, border cells, speed cells, goal cells, reward cells, etc.

Hippocampus-entorhinal circuit provides a ‘coordinate system’ for on-line measurement of distance and direction of landmarks defining a path leading to a goal. Navigation of an animal toward a goal depends on synaptic plasticity. Functional synapses are chosen from a set of anatomical synapses based on the interaction of Hebbian learning rules, sensory feedback, attractor dynamics, and neuromodulation. Artificial neural networks, which emulate biological neural networks, can be derived from complete connectomes of an organism. Design and control principles underlying intelligent autonomous control systems can be understood based on an analysis of these ANNs. 

Causative agents of Alzheimer’s disease are 1) amyloid β foldings, 2) neurofibrillary tangles, and 3) reactive gliosis. Interaction of Aβ with the prion protein within neurons has recently been suggested to be the basis for drug discovery. Prion protein is a membrane protein found on cell surfaces of diverse types [1]. The accumulation of misfolded and unfolded proteins (UP) generates stress in the endoplasmic reticulum. This stress worsens the health of the regular function of neuronal cells. The role of unfolded protein response in T cell development and function has also been acknowledged [2]. The induction of Femto particles (Fps) is proposed inside G protein-coupled receptors at an appropriate point in time to monitor the accumulation of unfolded proteins and to control the misfolding of amyloid β. These new particles of 10-15m are proposed to be produced in neurons of the bloodbrain barrier (BBB). Protons released by hemoglobin can be glued to their antiparticle, i.e., antiproton, in the conformational space of partially folded amyloid β polypeptides. Portable Penning antiproton traps are now available at CERN. Gluing of protons and antiprotons to form a femto particle is mediated by dopamine, a neurotransmitter in the excitatory synapses.

Intraneuronal oxygen homeostasis also contributes to the control of the progression of the disease. Quantum entanglement between two fps (cf. Fig. 8), one in the neurons of the neurovascular system (NVU) and the other in cerebrospinal fluid (CSF), may be used to assess the efficiency of the process in a patient with AD. Our approach to the discovery of a drug for AD is based on monitoring and controlling the misfolding of amyloid β and the initiation of folding of unfolded proteins by the intervention of femto particles. 

The meaning of the word “romantic”, according to Oxford Dictionary, is having a quality that motivates emotions. It makes you think about love. One would find the meaning of love either in the poetry of Ravindra Nath Tagore or in the poems of Rumi. W. B. Eats defined beauty as a thing of eternal joy, which keeps on increasing. It has no upper bound. The branch of neurosciences that connects us to the study of literature, paintings, and movies is cognitive neuroscience. Cognition is the process by which knowledge and understanding are developed in the mind, i.e., how does the brain enable the mind? Now, what is mind? Mind is reflected in occurrences such as sensations, perceptions, emotions, memories, desires, and many more. The aim of this chapter is to elucidate the link between neuroscience and romanticism.

Language plays a central role in cognition. The effects of language on visual perception were explored by Lupyan et al. [1]. Our ability to recognize perceptual stimuli is dependent on the physical features of the stimuli and our prior experiences. Language influences visual processing both offline and online. These effects are the result of a predictive processing approach to perception. The history of English (both British and American) literature is discussed. Poets from South Asia and the Middle East are also covered. The chapter impresses upon the reader that poets such as Rumi, Khalid Gibran, Mirza Ghalib and others guide us to the path of eternality. The reader will find a few stanzas from their poems in this chapter.

Theories of action and perception are discussed in Chapter 1 under the heading ‘Reward’. Sensations, emotions, desires and empathy are the subject matter of this chapter. This chapter will attempt to establish a link between the occurrences and the quality, which is known as empathy. A piece of literature devoid of this quality does not qualify to be literature. Some recent developments in neurosciences are reviewed. Free-energy formulation of inference and learning schemas based on generative models of the world is given. The free-energy principle provides a useful framework to investigate neural computation and probabilistic world models.