Human Brain — The Warehouse of Universal Wisdom
William Ross Ashby, English and primarily a psychiatrist, in his work ‘Design for a Brain’, 1956, expounds at large an artificial model of the human brain. The analysis is thoroughly scientific, with the focus on adaptability. Adaptiveness in living beings is a mechanism that is constantly fueled by the learning capacity of the brain. While our machine learning models demonstrate intelligence and decision-making capabilities out of learned behaviors, they seldom are crafty enough to adapt to thrive. Adaptability is a central aspect in Thinking machines. Our future Steel Citizens of the world will have this feature sustaining their race, as with their biological counterparts. And this makes our understanding of the human brain essential.
The Brain is the single magnificent organ that lights up the world, awakens us, to and through the portal of Universal Truth.
Ashby however does not touch the sphere of conciliation between mind and matter in his book. Nevertheless, his work serves as a first little step from where we are, to where we may push our fences across to tame, the murky mires of the unknown. It always makes sense to model a system as interrelations of its internal and the (external) environmental variables, and thus deciding its behavior in the light of these interrelationships. We shall analyze the nervous system and more importantly the brain in a similar manner to start off. Ashby’s work will be a subject of our future discussions. Also, a knowledge of the biological construction of the brain and its function is imperative to understanding its cardinal stature in the process of evolution.
The Nervous System
The nervous system is what differentiates the higher animals from the lower, and which displays spontaneity of behavior in the organism. Our nervous system constitutes a highly complex system that controls, and coordinates our stimulatory senses and motor responses, in addition to autonomous activities like temperature regulation, heartbeat, etc. The nervous system is classified into two:
- The Peripheral Nervous System (PNS)
- The Central Nervous System (CNS)
The CNS is the power plant of the nervous system. It accepts, process-converts, and sends out electrical impulse signals that control and coordinate our activities. The PNS constitutes the transmission lines, that carry these impulses from and to the CNS and the various parts (organs and muscles) of our body.
The CNS is composed of the brain and the spinal cord. Yet otherwise, a labyrinth of complex neural circuitry, the CNS adds to itself the complications of 100 billion neurons in the biological organ that we know as the brain. The brain serves as the seat of perception, and imagination. It is the most important constituent in the biological and evolutionary bearing of the organism. It is what classifies the animal kingdom on intelligence capabilities — what makes its study indispensable to AI.
Thought
Thought, or imagination is a consequent behavior of the biological nervous system. The theories that point to this phenomenon are twofold — Reductionistic and holistic. Reductionism is where a complex phenomenon is broken down or reduced to its non-divisible building component, whereas holism supports a new behavior which emerges out of the unified whole, from its interconnections and interrelationships. Cognitive Science deals with the mental processes underlying our thoughts. Scientists from the Max Planck Institute for Human Cognitive and Brain Sciences (MPI CBS) in Leipzig, Germany, and the Kavli Institute for Systems Neuroscience in Trondheim, Norway, came up with a new proposal in 2018 — Humans think using their brain’s navigation system.
When we navigate our environment, two important cell types are active in our brain. Place cells in the hippocampus (refer to The Cerebral Cortex below for details) and grid cells in the neighboring entorhinal cortex form a circuit that allows orientation and navigation. The team of scientists propose that this system is also key to ‘thinking’, explaining why our knowledge seems to be organized in a spatial fashion.
“We believe that the brain stores information about our surroundings in so-called cognitive spaces. This concerns not only geographical data, but also relationships between objects and experience,” explains Christian Doeller, director at the MPI CBS.
Cognitive Spaces
The term ‘cognitive spaces’ refers to mental maps in which we arrange our experience. Everything that we encounter has physical properties, whether a person or an object, and can therefore be arranged along different dimensions. Depending on the dimensions of interest, individuals might be stored mentally closer together or further away. As per Doeller:
If I think about cars, I can order them based on their engine power and weight for example. We would have racing cars with strong engines and low weights as well as caravans with weak engines and high weight, as well as all combinations in between. We can think about our family and friends in a similar way; for example, based on their height, humor, or income, coding them as tall or short, humorous or humorless, or wealthy. These processes are especially useful for making inferences about new objects or situations, even if we have never experienced them.
Using existing maps of cognitive spaces, humans can anticipate how similar something new is to something they already know, by putting it in relation to existing dimensions. If they’ve already experienced tigers, lions, or panthers, but have never seen a leopard, we would place the leopard in a similar position as the other big cats in our cognitive space. Based on our knowledge about the concept ‘big cat’, already stored in a mental map, we can adequately react to the encounter with the leopard. “We can generalize to novel situations, which we constantly face, and infer how we should behave,” says Jacob Bellmund.
Coda
The following sections give a high-level overview of the various functional blocks in the brain, and their inter-dependencies and inter-relationships. At a much low level, it is the neurons that are the working hands at carrying out responsibilities collectively. The communication between neurons in the network is achieved via electrical impulses. This article is to give the sense of complexities in the human brain so that we can expect how a adaptive artificially intelligent machine would be, even with minimal capabilities compared to human beings. In future articles, we will refer to Neuroscience and other aspects of Human brain as required.
Next Week: Adaptive Intelligence
Previous Week: Neurons — The Nuts and Bolts of our Intelligence
First Week: Can Machines Think?
Appendix — The Brain
The brain is contained in the cranial cavity of the skull. It includes the cerebral cortex, limbic system, basal ganglia, thalamus, hypothalamus, and cerebellum. There are three different ways that a brain can be sectioned in order to view internal structures: a sagittal section cuts the brain left to right, a coronal section cuts the brain front to back, and a horizontal section cuts the brain top to bottom.
The Cerebral Cortex
The outermost part of the brain is a thick piece of nervous system tissue called the cerebral cortex, which is folded into hills called gyri and valleys called sulci. The cortex is made up of two hemispheres — right and left — which are separated by a large sulcus. A thick fiber bundle called the corpus callosum connects the two hemispheres and allows information to be passed from one side to the other. Although there are some brain functions that are localized more to one hemisphere than the other, the functions of the two hemispheres are largely redundant.
Each cortical hemisphere contains regions called lobes that are involved in different functions. Each hemisphere of the mammalian cerebral cortex can be broken down into four functionally and spatially defined lobes: frontal, parietal, temporal, and occipital. Figure illustrates these four lobes of the human cerebral cortex.
The frontal lobe is located at the front of the brain, over the eyes. This lobe contains the olfactory bulb, which processes smells. The frontal lobe also contains the motor cortex, which is important for planning and implementing movement. Areas within the motor cortex map to different muscle groups, and there is some organization to this map, as shown in Figure. For example, the neurons that control movement of the fingers are next to the neurons that control movement of the hand. Neurons in the frontal lobe also control cognitive functions like maintaining attention, speech, and decision-making.
The parietal lobe is located at the top of the brain. Neurons in the parietal lobe are involved in speech and reading. Two of the parietal lobe’s main functions are processing somatosensation — touch sensations like pressure, pain, heat, cold — and processing proprioception — the sense of how parts of the body are oriented in space. The parietal lobe contains a somatosensory map of the body like the motor cortex.
The occipital lobe is located at the back of the brain. It is primarily involved in vision — seeing, recognizing, and identifying the visual world.
The temporal lobe is located at the base of the brain by your ears and is primarily involved in processing and interpreting sounds. It also contains the hippocampus (Greek for “seahorse”) — a structure that processes memory formation. The hippocampus is illustrated in Figure. The role of the hippocampus in memory was partially determined by studying one famous epileptic patient, HM, who had both sides of his hippocampus removed to cure his epilepsy. His seizures went away, but he could no longer form new memories (although he could remember some facts from before his surgery and could learn new motor tasks).
The Basal Ganglia
Interconnected brain areas called the basal ganglia, play important roles in movement control and posture. Damage to the basal ganglia, as in Parkinson’s disease, leads to motor impairments like a shuffling gait when walking. The basal ganglia also regulate motivation. For example, when a wasp sting led to bilateral basal ganglia damage in a 25-year-old businessman, he began to spend all his days in bed and showed no interest in anything or anybody. But when he was externally stimulated — as when someone asked to play a card game with him — he was able to function normally. Interestingly, he and other similar patients do not report feeling bored or frustrated by their state.
The Thalamus
The thalamus (Greek for “inner chamber”), illustrated in Figure, acts as a gateway to and from the cortex. It receives sensory and motor inputs from the body and receives feedback from the cortex. This feedback mechanism can modulate conscious awareness of sensory and motor inputs depending on the attention and arousal state of the animal. The thalamus helps regulate consciousness, arousal, and sleep states. A rare genetic disorder called fatal familial insomnia causes the degeneration of thalamic neurons and glia. This disorder prevents affected patients from being able to sleep, among other symptoms, and is eventually fatal.
The Hypothalamus
Below the thalamus is the hypothalamus. It controls the endocrine system by sending signals to the pituitary gland, a pea-sized endocrine gland that releases several different hormones that affect other glands as well as other cells. This relationship means that the hypothalamus regulates important behaviors that are controlled by these hormones. The hypothalamus is the body’s thermostat — it makes sure key functions like food and water intake, energy expenditure, and body temperature are kept at appropriate levels. Neurons within the hypothalamus also regulate circadian rhythms, sometimes called sleep cycles.
The Limbic System
The limbic system is a connected set of structures that regulates emotion, as well as behaviors related to fear and motivation. It plays a role in memory formation and includes parts of the thalamus and hypothalamus as well as the hippocampus. One important structure within the limbic system is a temporal lobe structure called the amygdala (Greek for “almond”). The two Amygdala are important both for the sensation of fear and for recognizing fearful faces. The cingulate gyrus helps regulate emotions and pain.
The Cerebellum
The cerebellum (Latin for “little brain”), sits at the base of the brain on top of the brainstem. The cerebellum controls balance and aids in coordinating movement and learning new motor tasks. Ever got drunk and staggered to walk? The cerebellum is affected with the quantity of intake and under functioning.
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The Brainstem
The brainstem connects the rest of the brain with the spinal cord. It consists of the midbrain, medulla oblongata, and the pons. Motor and sensory neurons extend through the brainstem allowing for the relay of signals between the brain and spinal cord. Ascending neural pathways cross in this section of the brain allowing the left hemisphere of the cerebrum to control the right side of the body and vice versa. The brainstem coordinates motor control signals sent from the brain to the body. The brainstem controls several important functions of the body including alertness, arousal, breathing, blood pressure, digestion, heart rate, swallowing, walking, and sensory and motor information integration.
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Max Planck Institute for Human Cognitive and Brain Sciences. “Navigating our thoughts: Fundamental principles of thinking.”
