Neuroscience Unveiled: Exploring Its Essence and Eccentric Beginnings
Behavioral neuroscience is a vast landscape that explores perception, movement, sleep and waking, reproductive behaviors, emotions, learning, and language. The primary goal of behavioral neuroscience is to explain behavior in terms of physiological processes, particularly those of the nervous system. The findings of basic research in behavioral neuroscience may be applied to improving the lives of both humans and animals. To study the structures (or mechanisms) involved in generating behavior, we must view the organism being studied as a machine made up of billions of neurons and ask: “How is this creature constructed to be able to do that?”
Structures — cells
Proteins, Receptors, Enzymes
Brain regions
Spinal cord
Peripheral Nervous system
Why Is Neuroscience So Important?
The study of neuroscience is essential due to the large number of neurological and psychiatric disorders. The prevalence of all disorders in the overall population is at an all-time high. Behavioral neuroscience involves many people working in various areas of specialization. A few professionals participating in neuroscience research are psychologists, biologists, physiologists, engineers, neurologists, and psychiatrists. A significant goal of behavioral neuroscience is to improve the health and well-being of humans and other animals. Conversely, knowledge gained from treating disorders can lead to new information that informs and aids basic research.
Five Major Viewpoints of Behavioral Neuroscience:
- Describing behavior
- Evolution of behavior: “Comparative Neuroscience,” as comparisons are often made between species to understand conserved characteristics, such as the presence of the same hormones in different animals.
- Development of behavior and its biological characteristics over the life span (Ontogeny)
- Mechanisms of behavior (Physiology)
- Applications of behavioral neuroscience
Studying differences among species highlights the ways in which neural mechanisms have been shaped by evolution to solve the particular problems that each species faces. For example, some bats use hearing to hunt and navigate, but others use vision. Each method seems to be an adaptation to the kind of food eaten by the particular species. Alternatively, studying similarities among species reveals the degree to which a feature is continuous, or conserved, presumably due to a common ancestry. For instance, some sex hormones are found in all mammals, suggesting that these evolved long ago. However, the data needs to be interpreted with care because some adaptations are so useful that they have evolved independently in numerous lines of species.
The process of change during the life span is formally called ontogeny. As behaviors emerge and decline during development and old age, parallel changes in the nervous system may be observed. For example, memory in monkeys improves over several years, suggesting that the circuits underlying memory are slow to mature. Learning ability emerges before the capacity to form long-term memories in rodents, suggesting that learning and memory involve different neural processes.
By exploring these various viewpoints, we can gain a deeper appreciation for how our current understanding of the brain and behavior arose.
The History of Research on the Brain and Behavior Begins in Antiquity
Early Egyptians and Greeks, including Aristotle, first thought the heart was the seat of mental capacities. When the ancient Egyptian Tutankhamen was mummified around 1300 BCE, his brain was discarded. The ancient Egyptians thought that the brain would be unneeded in the afterlife.
The Hebrew Bible and New Testament make no mention of the brain, but make hundreds of references to the heart and other organs, apparently ascribing wisdom to the heart. “Teach us… that we may gain a heart of wisdom” Psalm 90:12. This notion was still prominent by the time of the ancient Greek scholar Aristotle, according to whom the function of the brain was to the blood.
In dissecting human and animal bodies, the Greek physician Herophilus (350 BCE) noted the connection of separate nerves to each region of the body and also noted that the nerves arise from the spinal cord. During the second century, Galen noted the behavioral changes associated with brain injuries in gladiators.
Leonardo da Vinci’s drawings of the nervous system were especially remarkable because they provided cross-sectional views of structures. Examples of nervous system components that he studied include the nerves of the arm and the fluid-filled ventricles of the brain. Renaissance scientist Leonardo da Vinci pioneered anatomical drawings, including cross-sections, and anatomists emphasized the external surfaces of the brain.
The Mind-Body Problem
What is the relationship between the mind (soul) and the brain?
René Descartes was a 17th-century dualist who viewed animal behavior as mechanistic (like a machine) regarding reflexes elicited by environmental stimuli. He also wrestled with how the mind could control the body and proposed an interface in the pineal gland. He selected this structure because unlike most brain structures, which are doubled with one in each hemisphere, the pineal gland is unitary, like consciousness. He also believed the gland to exist only in humans, and we now know this is untrue.
Dualism is the belief that mind and body are two separate entities — a thought substance and a physical substance that interact. Dualism, the assertion that an immaterial soul exists in parallel with and exerts control over the material body, permitted early scientists to study the body without being obviously guilty of heresy. Dualism is rejected in behavioral neuroscience, which asserts that all facets of behavior can be understood as purely physical processes of the nervous system.
Conversely, monism is the belief that the universe consists of only one kind of existence. There are different categories of monism. Let’s start with materialism, the belief that everything is material; purely mental events don’t exist; thoughts result from physical properties. The second category of monism is mentalism, the belief that only the mind exists; the physical world only exists in our imagination.
Which one do you think 99% of neuroscientists ascribe to?
If you answered materialism, you’re right.
Monism, particularly materialism, aligns with the core goal of behavioral neuroscience: to explain behavior through the workings of the physical nervous system.
Most scientists agree that consciousness, the state of awareness of one’s own existence and experience, is connected to brain activity. Consciousness allows us to do important things like planning and reaching conclusions. However, some brain activity is unconscious. The deep parts of our brain are important for arousal; topmost parts are responsible for current experience. Our understanding of consciousness is still in its infancy; we still have difficulty explaining higher cognitive function.
Close, but not quite: Phrenology
By the end of the 1600s, the English physician Thomas Willis had convinced the people of the Western world that the brain is the organ that coordinates and controls behavior. A popular nineteenth-century idea called phrenology held that the behavior of individuals can be predicted from the pattern of lumps and bumps on the skull. Other investigators rejected this notion, arguing that the brain operates as a whole, without any localization of functions to specific regions. We know now that although the whole brain is active in most behavior, peaks of activity are seen in different locations depending on the task being performed.
Galton was disappointed in his search for a consistent relationship between head size and intelligence due to two methodological problems: lack of a direct measure of brain size and lack of a systematic way of measuring a person’s intelligence. Three ways in which brain size has been measured, from the nineteenth century to today, are (1) overall head; (2) skull volume; and (3) MRI measurements of living brains.
Making Advancements
Broca advanced the localizationist position when he presented an analysis of a patient who had lost the ability to talk; this patient had suffered brain damage limited to the left frontal region of the brain, which came to be known as Broca’s area. The dawning of behavioral neuroscience was signaled by the publication of Principles of Psychology by William James, which viewed human experience as intimately related to the function of the nervous system. Workers in the early twentieth century developed systematic methods for measuring learning and memory, first in humans and then in animals.
Pavlov described the process of conditioning, which opened up many new avenues for research. In other early work, Lashley’s “search for the engram” was undertaken, using a combination of training and brain lesions to try to discover the physical basis of memory traces.
In The Organization of Behavior, D. O. Hebb describes two theoretical mechanisms that could, in principle, provide the necessary processing to accomplish complex cognitive tasks. The first of these is the concept of cell assemblies, which describes how brain cells that are initially connected in a somewhat random fashion can become organized into circuits as a consequence of activation. The second mechanism, now known as the Hebbian synapse, describes how synaptic connections can become strengthened through use. By the 1970s, a number of studies correlating estimated brain size and IQ, as measured by standardized tests, had reported correlation coefficients ranging from +0.08 to +0.22. A more recent study, using brain-imaging technology, found that, after correction for body size, the correlation between brain size and IQ scores is 0.38, a modest but significant correlation.
Neuroscience has a long and fascinating history, with our understanding of the brain constantly evolving. Today, the field is thriving, with a massive community of researchers delving ever deeper into the mysteries of the nervous system. In 2018, over 25,000 neuroscientists attend the annual Society of Neuroscience meeting, and over 40,000 neuroscience articles were published. As we continue to explore the intricate workings of the brain, we can expect even more remarkable discoveries that will help us understand ourselves and the world around us.
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