What Is Neuroscience?

Neuroscience is a highly interdisciplinary science that explores the relationship between the nervous system, behaviour, cognition, and disease. While the study of the nervous system dates to Egyptian times, modern neuroscience combines aspects of physiology, anatomy, psychology, biology, and mathematics to explore how the nervous system works at the cellular, molecular, cognitive, and societal level (Squire et al., 2012). Broadly, neuroscientists are interested in understanding how cells in the brain (primarily neurons and glia) communicate with one another, how they are organised to form circuits, how external and internal stimuli influence these circuits, and how they might go awry in the context of disease or trauma. Recent technological innovations in the 20th century regarding both molecular biological and neuroimaging techniques have led to significant advancements in our understanding of brain function. However, despite these advances, exactly how the brain combines external and internal signals to create a perceptual reality remains elusive.

The last 50 years have seen a massive increase in Neuroscience research, incorporating expertise from a wide range of scientific disciplines. To begin to understand the current state of neuroscience, it is useful to briefly review some of the major milestones across the history of research into the nervous system.

History of Neuroscience: Significant Scholarly Findings

Pre-18th Century

The study of the brain dates back millennia (see Kandel et al., 2013). The earliest written record referring to the brain dates from the 17th century BC, with an Ancient Egyptian medical text called the Edwin Smith Papyrus, which describes the symptoms associated with head injuries in two patients. Early descriptions of basic neuroanatomy have been found in Egyptian texts from the 3rd and 4th centuries BC, including reference to the cerebrum, cerebellum, and ventricles. The idea that the brain was the physical location of the mind was suggested as early as the 5th century BC by the Greek philosophers Alcmaeon of Croton and Hippocrates. This relationship between brain and mind was not universally accepted however, with Aristotle (4th century BC) believing that the brain acted to cool the blood, with intelligence instead located in the heart. The importance of the relationship between the brain and body was highlighted by the Roman physician Galen in the 2nd century AD, who correctly identified 7 of the 12 cranial nerves, proposing that these nerves carry fluid from the brain towards the rest of the body. While further detailed characterisation of the anatomy of the central nervous system would take place over the next 1500 years, including the contributions in 14th century by de Luzzi and da Vigevano, in the 15th-16th century by da Vinci, Vesalius and in the 17th century by Willis, substantial advancements in understanding the detailed functionality of nervous tissue would not be seen until the late 18th century.

18th to Mid-19th Century

Luigi Galvani (1737–1798) was an Italian physician who first discovered the link between electricity and the activity of the body. By applying static electricity to a nerve in the leg of a dissected frog he revealed that electrical stimulation could produce contraction of the leg muscles. These experiments represent the origin of the discipline of electrophysiology. Demonstration that the brain and not the heart was the physical location of the ‘mind’ was not achieved until the 19th century, in part through the work of the French physiologist Jean Pierre Flourens (1794-1867). Working with rabbits and pigeons, Flourens lesioned areas of the brain and found impairments in sensory and motor skills. His work however was consistent with the prevailing view at that time that the brain was a unitary and indivisible organ, and that specific functions were not localised to specific brain areas. This view was ultimately challenged by explorations of linguistic deficiencies in humans. In the mid-19th century, the French neurologist Paul Broca described a patient who had suffered stroke resulting in specific impairments in his ability to speak, although his ability to understand language was seemingly unaffected. Following the death of the patient, Broca undertook a post-mortem examination and identified a specific region of the left frontal lobe that was damaged. Further studies of a total of eight similar individuals with similar speech production impairments and similar patterns of damage led Broca to the conclusion that specific functions, such as language, are associated with specific areas of the brain. Around the same time as Broca’s findings, work conducted by the German neurologist Carl Wernicke identified a brain region particularly associated with language understanding, now known as Wernicke’s area. These findings helped to solidify the concept of brain specialisation and greatly influenced our understanding of cognitive functions.

Late 19th Century

A few decades later, work from the Italian biologist Camillo Golgi (1843-1926) would produce a watershed in our conceptualisation of the organisation of tissue in the brain. In the 1870s, Golgi invented a procedure for staining brain tissue with silver chromate salts. This technique, still widely used today, has the remarkable effect of completely staining a small subset (1-5%) of neurons in the brain. There is still no clear explanation for why some cells take up this stain while others do not. This technique was employed extensively by Santiago Ramón y Cajal beginning in 1887, allowing him to detail the shapes of hundreds of individual neurons across many different parts of the brain. This led Cajal to various conclusions including that brain tissue was a network of individual cells, with individual cells varying dramatically in their shapes and complexities depending on their location within the brain. Despite this morphological variability, neurons all seemed to have a cell body to which were connected two types of process, with many branching dendrites providing the input to the neuron, and a single axon providing the output from the neuron. These observations were used by Cajal to strongly support the neuron doctrine, that the neuron is the fundamental unit of signalling in nervous systems. Golgi and Cajal were awarded the Nobel Prize in Physiology or Medicine in 1906, for their pioneering contributions to understanding of the fine anatomy and organisation of neural tissue. The legacy of these early microscopic anatomical studies is still clearly visible in neuroscience textbooks today, most of which still carry drawings of cells made by Golgi or Cajal, and invariably include images of Golgi-stained cells.

In the late 19th century, Emil du Bois-Reymond, Johannes Peter Müller, and Hermann von Helmholtz demonstrated that these neurons were electrically excitable and were therefore likely to be the cells carrying those signals that were first identified by Galvani. Furthermore, they found that electrically excited neurons were able to create changes in the electrical states of other nearby neurons.

20th to Early 21st Century

The question of exactly what caused the transmission of electrical activity from one neuron to another was finally answered in 1921 by the German pharmacologist Otto Loewi (1873-1961). In what has become a very famous experiment, Loewi took a frog heart which was bathed in a saline solution and electrically stimulated it via the vagus nerve, causing the heart to beat more slowly. He then took some of the surrounding solution and applied it to a second heart that had not been electrically stimulated and found that this caused the second heart to also beat more slowly. He concluded that electrical stimulation of the heart caused the release of a chemical into solution, and this chemical by itself was sufficient to stimulate the second heart to beat more slowly. The chemical was later identified as acetylcholine, which was the first of many neurotransmitters that would ultimately be identified. For this research, Loewi was awarded the Nobel Prize in Physiology or Medicine in 1936, together with Sir Henry Dale who was able to demonstrate that the active chemical from Leowi’s experiments was indeed acetylcholine. Subsequent work by Sherrington found that these chemical messengers were usually released at small, specialised structures called synapses, where chemical messages allowed one neuron to either excite or inhibit another; research for which Sherrington was awarded the Nobel in 1932.

By the 1930s, an emerging picture of the central nervous system had thus been established. The brain was the physical location of the mind, and controlled thought, sensation, and movement. Brain tissue was composed of individual neurons each of which had an input and an output. Information was transmitted along neurons in the form of electrical impulses, with intercellular communication mediated by chemical messengers which we now call neurotransmitters. The last century has built upon this foundation with extraordinarily rapid advances in our understanding of the nervous system. Any summary of these advances will by its nature be very incomplete. We have chosen to review progress by focusing exclusively on those neuroscientists whose research has been awarded the Nobel Prize in Physiology or Medicine. Names and dates of Nobel prize awards are indicated in parentheses below after “NP”.

The 20th century saw enormous advances in our understanding of neuronal communication, both in terms of how information is transmitted along an individual cell, and between different cells. New techniques that allowed visualisation and recording of electrical signals were developed in the 1920, and different neurons were shown to transmit electrical signals at different speeds, depending on the thickness of the neuron (NP: Erlanger & Gasser, 1944). These tools led to an elegant series of experiments by Hodgkin and Huxley that elucidated the molecular basis of electrical signaling. Using the giant axon of the squid they were able to record electrical potential across the neuronal membrane. By manipulating the ionic solution in which the neuron was bathed, and the electrical potential across the membrane, while recording the magnitude of current flowing across the membrane, they developed a model of how an electrical impulse is produced and propagated along neuronal axons, mediated by the flow of different types of charged ions both along and through the membrane. The Australian neurophysiologist John Eccles extended these findings by describing how electrical activity at the synapse could lead to excitation or inhibition of adjacent cells (NP: Eccles, Hodgkin & Huxley, 1963). Elucidation of the properties of individual ion channels that underlie changes in electrical currents across neuronal membranes was finally achieved through development of the patch-clamp technique, which allowed recording of electrical activity across microscopically small areas of cell membranes (NP: Neher & Sakmann, 1991). In parallel with the detailed characterisation of electrical properties of neurons, other neuroscientists were focused on understanding the basis of the chemical signals that mediated communication between neurons at the synapse. Building upon the earlier work of Loewi and Dale which identified acetylcholine as the first neurotransmitter, von Euler and Axelrood described a second neurotransmitter norepinephrine, which functioned (in part) to regulate blood pressure and made the important observation that some antidepressants acted by blocking the reuptake of the neurotransmitter at the synapse. Katz demonstrated that neurotransmitters were stored in small vesicles in one neuron, with vesicles released into the synapse following electrical stimulation, in a mechanism that required changes in intracellular calcium signalling (NP: Katz, von Euler, Axelrod, 1970). The complex process of vesicle release was carefully elucidated by Südhof, Rothman, and Schekman (NP: 2013). Many additional neurotransmitters were also identified by other researchers including dopamine, the deficiency of which was associated with Parkinson’s disease, leading to novel therapies for the disorder. Synaptic signalling was further refined with an understanding that while some neurotransmitters result in electrical changes in target cells, others change the chemical signalling environment of their targets, including mediating changes in synaptic strength as a form of learning and memory (NP: Carlsson, Greengard, & Kandel, 2000).

The above studies describe how signals move along neurons, and between closely adjacent neurons. However, signals can also be transmitted across much larger distances, in some cases by hormones that are released by the brain and that act on neuronal and non-neuronal targets throughout the body. Guillemin and Schally identified the specific factors that were released by the brain that cause the release of hormones from the pituitary gland at the base of the brain. To allow the effects of such hormones to be characterised, Rosalyn Yalow developed a technique that combined radioactive isotopes with highly specific antibodies to track levels of such hormones in the body (NP: Guillemin, Schally, & Yalow, 1977). In addition to hormones released by the brain acting on non-neuronal tissue, extensive work characterised the effect of other factors released by non-neuronal tissue on the brain. For example, Levi-Montalcini identified nerve growth factor (NGF) – a substance isolated from tumours in mice that would cause growth of the nervous system in chick embryos. This formed the basis of detailed characterisation of the role of various growth factors in the development and adaptation of the nervous system (NP: Cohen & Levi-Montalcini, 1986).

Beyond understanding the functionality of individual molecules and cells of the nervous system, other neuroscience pioneers explored various systems, including sensory systems by which the brain receives information from the outside world, and motor systems by which the brain acts on and interacts with the outside world. As an example of motor systems, early work on anesthetised cats revealed that weak electrical stimulation of the hypothalamic region of the brain could produce complex behavioural responses including both defensive and aggressive behaviours (NP: Hess & Moniz, 1949). For sensory systems, Nobel prizes have been awarded for the elucidation of both visual and olfactory systems. Collectively, Granit, Hartline and Wald pioneered research that enhanced our understanding of the operation of the retina, including characterising chemical changes that resulted from exposure to photons of light, the presence of different types of photosensitive cells resulting in colour vision, and how signals received by nearby retinal cells are compared within the retina to highlight contrasts in our visual fields (NP: Granit, Hartline, & Wald, 1967). In the following decades, Hubel and Wiesel explored how these retinal signals were then processed by the brain, with separate processing streams focused on different aspects of the visual input such as movement, contrast, and linear orientation (NP: Hubel & Wiesel, 1981). Research on the olfactory system was awarded the Nobel in 2004, for research demonstrating that the rich diversity of smells that are detectable are the result of the combined actions of hundreds of different chemical receptors called olfactory receptors, which in turn are the product of hundreds of different olfactory receptor genes. Individual smells are the result of the combined signalling of different odorants across a wide spectrum of different receptors (NP: Axel & Buck, 2004).

Other advances of the last century that led to receipt of the Nobel Prize include an understanding of functional differences between the left and right hemispheres of the brain (NP: Sperry, 1981), characterisation of prions as agents of infectious disease (NP: Blumberg & Gajdusek, 1976; NP: Prusiner, 1997), and an understanding of how specific cells (termed place cells and grid cells) in the hippocampus and nearby entorhinal cortex contribute to the brain developing an internal map of the surrounding environment, and one’s location within that environment (NP: O’Keefe, Moser, & Moser, 2014).

The above description of neuroscience advances represents the research of a small number of exceptionally talented and celebrated neuroscientists, and of course, represents a small fraction of the research output for the discipline. In Australia, the largest neuroscience conference – over 1,000 attendees – is organised by the Australasian Neuroscience Society. In addition, the Australasian Cognitive Neuroscience Society draws together people from a wide range of areas such as psychology, neuroscience, cognitive science, psychiatry, neurology, linguistics, and computer science to focus on the study of the brain, mental processes, and behaviour (www.acns.org.au). While much of the research in the field is not considered applied, basic research can lead to societal changes, both in the present and in the future. Abraham et al., (2022) report that the Australasian Neurosciences Society had its early origins the 1970s, becoming a formal society in the 1980s. These authors provide a brief history of the Society in A brief history of the Australian Neuroscience Society.

Branches of Neuroscience

Modern neuroscience can be broadly organised into several major branches:

• Cellular and Molecular neuroscience
• Systems Neuroscience
• Cognitive and Behavioural Neuroscience
• Social and Translational Neuroscience.

Cellular and Molecular Neuroscience

Cellular and Molecular neuroscientists are focused on understanding how cells of the nervous system express and respond to molecular signals. These scientists typically employ techniques and concepts of molecular biology to study how the brain develops, how cells communicate with one another, how genes and the environment might influence these processes, and how the brain can change and adapt (“neuroplasticity”) over the course of one’s lifetime.

Systems Neuroscience

Systems Neuroscience is a branch of neuroscience focused on understanding how different cell groups in the nervous system work together to create circuits, or pathways that have a functional outcome. For example, a systems neuroscientist might ask how specific anatomical regions and/or cell groups are involved in the higher order cognitive processes of learning and memory, or sensory functions such as vision. One branch of systems neuroscience is neuroethology, which involves the study of non-human model organisms to explore how certain sensory or cognitive functions exist in other species. By contrast, neuropsychologists explore how specific neural substrates may be implicated in human behaviour (and how damage to specific brain regions may yield unique deficits in cognition or behaviour).

Cognitive Neuroscience

Cognitive neuroscience is the third major Neuroscience branch and emerged from the fields of psychology, physiology, and computer science. Cognitive neuroscientists are interested in understanding how specific brain circuits relate to higher order psychological functions such as learning and memory, language, and thought. The field of cognitive neuroscience has benefited greatly from advances in neuroimaging techniques such as functional magnetic resonance imaging (fMRI), positron emission tomography (PET) and diffusion tensor imaging (DTI), in addition to electroencephalography (EEG). Behavioural neuroscientists, also known as physiological or biological psychologists, use basic techniques of physiology, chemistry, and computer science to study the function of the nervous system, with a specific application to how cells and cell circuits relate to all aspects of behaviour. Most of the experimental literature has employed model organisms such as rodents or non-human primates, with more recent research using molecular biological techniques to explore how genes and epigenetics may influence behaviour.

Social and Translational Neuroscience

Social and translational neuroscience are the most recently developed fields of neuroscience. Social neuroscience borrows heavily from social psychology and seeks to understand how specific brain substrates, circuits, signals, and genes are related to behaviour, with an emphasis on domains of social behaviour. As humans are primarily a social species, this field has a focus on how higher order cognitive domains such as language and thought, as well as pathological conditions such as depression, may influence, and be influenced by, social behaviour. Related to social neuroscience, translational neuroscience is a field of study which translates study and knowledge of neuroscience to clinical applications. Translational neuroscientists are interested in applying technological advances in the field of neuroscience to address various societal needs, including novel treatments or therapies for neurological and psychiatric disease.

Methods in Neuroscience

Neuroscientists working within each of the major branches would typically apply a different set of techniques to answer questions about the brain (See Table 1 for a summary of some of the more common techniques). For example, while neuroscientists in general may be concerned with determining the neural basis for clinical depression, molecular-, systems-, cognitive-, and social-neuroscientists will employ differing techniques and methods to explore how proteins, cells, circuits, and brain regions may each be implicated in the aetiology of the disease.

Cellular and Molecular Neuroscience

A molecular neuroscientist may focus heavily on the application of molecular biology to the nervous system to answer questions regarding the pathophysiology of depression. For instance, they might be interested in identifying key changes in gene expression that are associated with depressive symptoms. This could be achieved by analysing expression levels of thousands of genes in various regions of the human brain using post-mortem tissues derived from individuals with and without depression. If the expression level of a specific gene was consistently higher or lower in the brains of people with depression compared to people without depression, it would suggest that the gene may have a functional role in depression. These genetic profiles can also give us hints as to which proteins may be increased or decreased, and in which specific area of the brain. Furthermore, finding a biomarker that strongly correlates with depression has high diagnostic value in research and in medicine – a biomarker is an easily detectable molecule in our body that is correlated with, and used to predict the presence of disease, infection, symptom, or toxic exposure. To be useful, the biomarker must be detectable in tissues that can be easily obtained from patients (typically saliva, urine, or blood). There are extensive interactions between the central nervous system and the periphery – our bodies can tell us numerous things about our brains. As such, a molecular neuroscientist might be interested in searching tissues outside of the central nervous system for candidate biomarkers for the diagnosis of depression.

A major component of molecular neuroscience involves the manipulation of genes within model organisms (rats, mice, zebrafish) to understand the function of that gene, including potential functions in the development of disease. Manipulations include changing the amount of gene product, changing the timing or location of gene expression, or changing the actual protein product that is generated by the gene. Molecular neuroscientists might therefore be interested in studying one of the differentially expressed genes identified through gene expression studies. Potential research questions might include, “What is the importance of this gene during development?”, “If we restore this gene back to ‘normal’ levels, what does it do to depressive-like symptoms?”, or “If we change gene expression levels in a similar manner to those that were observed in gene expression studies, does it induce depressive-like behaviours?”. Answering these questions requires the genetic engineering of non-human animals, a technique which has grown in prevalence over the last two decades as the technology becomes increasingly sophisticated, reliable, and affordable.

While genetic manipulations can alter the amount, location, or sequence of a protein, there are other methods for manipulating protein functions within cells. Pharmacological manipulations can include the use of competitive agonists (which activate proteins), competitive antagonists (which inactivate proteins), and neutralising antibodies that interfere with the ability of specific molecules to bind to their specific receptors. Whether by genetic-engineering, or pharmacological manipulation, molecular neuroscientists are concerned with the molecular and cellular changes that underpin diseases. Other techniques in the arsenal of the molecular neuroscientist include using radiolabelled tracers to visualise, in real-time, the movement of neurotransmitter-containing vesicles down an axon. Use of fluorescent or bioluminescent markers to visualise specific interactions between individual molecules (the fluorescence resonance energy transfer [FRET] or bioluminescence resonance energy transfer [BRET] techniques), such as for measuring the recruitment of receptors to the membrane, the coupling of a ligand to its receptor, the coupling of two or more receptors, and the change in conformation of an existing receptor. Researchers use microdialysis to measure the concentration of a specific molecule in the synapse between two neurons or use retrograde and anterograde tracers to determine the physical pathways linking one neuron to another. Ultimately, cellular and molecular neuroscientists interested in depression might employ a broad range of tools to understand how proteins and cells are implicated in disease, and whether these changes may represent either the cause or consequence of the disorder.

Systems Neuroscience

Questions about individual cells and molecules may also be of interest to a systems neuroscientist, but they would typically be exploring how cells and molecules modulate the function of brain regions, or circuits composed of multiple anatomical and functional components. One example to illustrate the systems neuroscience approach would be to investigate the hypothalamic-pituitary-adrenal (HPA) axis, which regulates the release of the stress hormone cortisol in humans (corticosterone in rodents) and has been heavily implicated in the aetiology of depression. Release of the stress hormone is mediated by a cascade of signalling factors released from various organs including the brain and is regulated in a manner that involves multiple different brain regions. As an example, a systems neuroscientist might explore signalling interactions between the hippocampus and the hypothalamus (the hippocampus senses levels of stress hormone and suppresses any further release of the hormone from the hypothalamus). To that end, they may manipulate hippocampal function in one of many possible ways (including through using a transgenic animal model, or ablation, or by stereotaxic delivery of a drug to the hippocampus, or through electrical stimulation; see table 1 for details) and measure subsequent changes in hypothalamic hormone release. This could be followed by post-mortem analyses of brain tissues by immunohistochemistry to determine whether patterns or levels of expression of specific proteins has altered in several interconnected brain regions. In the context of depressive disorders, any or all the above could be explored in the context of how these manipulations also impact depressive symptoms in model organisms.

Cognitive and Behavioural Neuroscience

In the study of depression, a cognitive neuroscientist could ask questions regarding how depression might affect activity levels of different regions of the brain, by for example, using imaging techniques to search for changes in metabolic processes of specific brain regions between people with depression and people without depression. Cognitive neuroscientists heavily rely on modern neuroimaging techniques such as functional magnetic resonance imaging (fMRI, to measure cerebral blood flow), or positron emission tomography (PET, to measure the metabolism of glucose within brain regions). While MRI technologies have been used in diagnostic medicine since the 1970s, novel analysis of MRI sequences using specialised software developed by computer scientists allows for alternative forms of MRI such as diffusion tensor imaging (DTI) which allows high resolution mapping of the major connections that link and allow communication between different regions of the brain.

Electroencephalography (EEG) is another technique that can be used to measure the electrical activity of the brain. EEGs are an inexpensive means of measuring brain activity in awake humans. A cognitive neuroscientist might use EEG to explore differences in the patterns of electrical activity between people with and without depression while they are engaged in specific cognitive tasks that are designed to assess processes such as attention, decision making, movement preparation, working memory, or cognitive flexibility.

Behavioural neuroscience, wherein researchers are concerned primarily with physiological, genetic, and developmental mechanisms of behaviour, investigates the influence depression has on behaviour, and often involves use of animal models (such as rodents or zebrafish). Animal models could be generated by various methods including selective breeding for a desired trait (such as anxiety or aggression), by genetic mutation (such as metabolic diseases), or conditioning an animal to elicit a desired behaviour (such as social defeat paradigms and the production of a socially anxious animal). Behavioural neuroscientists have developed a wide array of behavioural paradigms to explore different aspects of depressive-like behaviour including measures of learned helplessness (to model despair), sucrose preference (to model hedonic feeding), food intake, or locomotor activity.

A wealth of behavioural neuroscience research involves humans. For example, researchers have established that anxiety, depression, and stress play a role in the development and maintenance of pathological gambling (Coman et al., 1997).  In Melbourne, Australia, workshops were held to bring together neuroscientists, clinicians, and policy makers to improve outcomes for pathological gamblers.  These workshops, titled “Problem gambling: An interdisciplinary dialogue between neuroscientists, clinicians, and policy makers” are a prime example of how neuroscientists can contribute to important societal problems. Yucel et al. (2017) highlighted several key areas in which neuroscience may aid in the understanding of pathological gambling and how it may be treated.  For example, studies using techniques such as ECG and fMRI have shown that ‘near misses’ when gambling are arousing and may lead to continued gambling (Dixon et al., 2011), and that the brain responses to ‘near misses’ are greater in pathological gamblers than in a control group (Sescousse et al., 2016).  Building on these insights Yucel and colleagues (2017) suggested that neuroscience, when integrated with the social aspects of gambling, may help to identify problem gamblers, and provide targeted treatments.

Social and Translational Neuroscience

Social neuroscientists are fundamentally interested in how the brain mediates social interaction; behaviours that are meaningful, elicited by one’s individual agency, directed towards another’s individual agency, to receive a response. For example, social neuroscientists might be interested in how specific gene polymorphisms influence individual vulnerability to depression following exposure to bullying – both in humans and non-human animals. Translational neuroscientists apply basic neuroscientific research relating to the structure and function of the brain in a clinical setting. For example, basic research might indicate that cerebral stimulation has a significant positive effect on depression. A translational neuroscientist might then investigate the use of a transcranial magnetic stimulator (TMS) as a viable means for brain stimulation to decrease depressive symptoms, and determine the precise stimulation procedure (electrical frequency, duration, etc.) that generates the best results in people who have depression. In Australia, the Therapeutic Good Administration has approved the use of TMS for the treatment of major depression since 2007. Research exploring the use of neuroscientific techniques in treatment contexts is emerging. For example, Lawrence and colleagues (2018) used transcranial direct current stimulation (tDCS) alongside a computerised cognitive training program to investigate the treatment outcomes for people with Parkinson’s who have mild cognitive impairment. The tDCS only group showed significant improvements on the working memory and attention measures while the tDCS and cognitive training treatment groups showed improvements across a broader range of outcomes (i.e., executive functioning, attention, and memory). Corti et al., (2022) reported preliminary evidence that tDCS may reduce pain in people with chronic lower back pain; and Green et al., (2020) have published a protocol paper for the use of tDCS in the treatment of Obsessive-Compulsive Disorder. In addition, translational neuroscientists might explore new pharmaceutical drugs for the treatment of psychiatric or neurological disease, determining appropriate dose and duration of the drug to maximise efficacy. Neurorehabilitation is another area encompassed in translational neuroscience, wherein researchers develop, test, and optimise sensory prostheses for the implantation into humans experiencing sensory loss.

Animal Ethics in Neuroscience Research

The use of animals in experimental research has always been a point of controversy. However, the use of animals in research is highly regulated, with use most carefully controlled for animals with higher sentience (primates, then other mammals, then other vertebrates and certain molluscs). As such, research that induces suffering in any capacity (e.g., pain, adverse changes in psychological states, stress) must be stringently justified, and will often not be approved. That is, the expected benefits from the proposed research must outweigh the potential suffering of the animal. Governing the subjective nature of such decision-making is an institutional animal care committee comprised of both scientists and members of the non-scientific community who decide whether the research merits the use of animals. In Australia, the state and territory governments have regulatory responsibility for animal welfare which includes the care and use of animals in research (see the Australian Code for the Care and Use of Animals for Scientific Purposes.). Developed and overseen by the National Health and Medical Research Council (NHMRC) the code has been adopted into legislation in all states and territories in Australia. All research involving animals must be approved by an Animal Ethics Committee and adhere to the framework of “Replacement, Reduction, and Refinement” (NHMRC, 2019).

The above techniques were often developed in the context of academic research and remain used in that setting. However, neuroscientists use these and other techniques while working in a range of different settings and careers.

Neuroscience and Careers

What Do Neuroscientists Do?

Neuroscientists are scientists who are engaged in activities that seek to improve our understanding of the nervous system and its relationship to behaviour and/or disease. Neuroscientists who are principal investigators (and who therefore determine their own research directions) have typically followed a training path consisting of an undergraduate degree in Science (B.Sc.) or Arts (B.A.), usually followed by a Master’s degree, then a Ph.D. in Neuroscience or a related discipline. For those wishing to pursue an academic career, it is common to complete one or more post-doctoral positions, typically at an internationally reputed laboratory. Postdoctoral positions (commonly referred to as postdocs) involve working in the research laboratory of a principal investigator and leading individual research projects. Post-doctoral fellows also typically take on supervisory responsibilities for other members of the research laboratory, including undergraduate and postgraduate students. However, unlike undergraduate or postgraduate studies, post-doctoral positions do not involve any course work. Instead, the focus is on developing research skills, acquiring skills in new techniques, and publishing research. An academic appointment at a university is the typical desired outcome for people who have pursued each step of this pathway. However, these jobs have been relatively scarce in the past decade. In a university environment, neuroscientists may be spread across many different academic units or in departments fully dedicated to the discipline of Neuroscience.  For example, neuroscientists may be housed in a department of Psychology, Biology, Pharmacology, Medicine, Cognitive, or Computer Science. From a program perspective, this can be challenging, as students who wish to obtain a degree in Neuroscience often may find that their degree has no ‘home base’, and instead consists of courses that may have a focus on neuroscience, but are housed in multiple, related units. Further compounding this issue is that neuroscience is not commonly taught in high school but may sometimes be included as part of a biology curriculum. As such, many students graduate from high school not being aware that neuroscience does exist as a discipline of study. That said, neuroscience has been growing over the last few decades, and is becoming more defined as a stand-alone discipline.  There are now more than 10 universities in Australia offering a Bachelor of Neuroscience which is the most direct pathway to this career.  However, people with a bachelor’s degree in a related field (e.g., biology, physiology, psychology) are eligible to apply to study a Masters of Neuroscience.  In addition, people can pursue a PhD in a neuroscience-related area after completing a degree in another field (e.g., psychology).

Common Misconceptions About What Neuroscientists Do

There are several common misconceptions regarding what neuroscientists do. For example, it is common to confuse a doctoral (PhD) degree with a medical (MD) degree. However, neuroscientists (who have earned a PhD) are not trained to deliver therapy and they do not treat patients with medicine (as would someone with an MD). Neurologists are specialised medical practitioners who have earned an MD followed by residency training in neurology. Neurologists treat individuals with neurological disorders such as stroke, epilepsy, and Parkinson’s disease. Neurosurgeons have earned a medical degree followed by residency training in neurosurgery; as a surgical profession, neurosurgeons would operate on patients with any damage or trauma to their nervous systems (e.g., tumor excision).

Similarly, there are branches of psychological practice that often are confused with neuroscience. Clinical Neuropsychologists are individuals who have completed an APAC (Australian Psychology Accreditation Council) accredited Master of Psychology (Clinical Neuropsychology) and who have been endorsed as a Clinical Neuropsychologist by the Psychology Board of Australia. These individuals have the training to do both research and clinical practice, though they do not have training in medicine. Moreover, they are specialised to assess, diagnose, and treat clients with either congenital or acquired brain injury. Although a fundamental understanding of how the nervous system works is a key component of each of these above-mentioned disciplines, it is important to emphasise that research neuroscientists do not treat or provide therapy to patients.

Common Careers in Neuroscience

Undergraduate Degrees

Students graduating with an undergraduate degree in Neuroscience will have developed a range of technical and analytical skills, and the ability to synthesise and communicate research findings in an effective manner. For example, they have developed investigative and research skills in the collection, organisation, analysis, and interpretation of data, use of appropriate laboratory techniques, application of logical reasoning and critical/analytical thinking, proficiency in computing skills, familiarity with a wide range of scientific/lab equipment, and extensive oral and written communication skills. They are creative thinkers, can work effectively both as individuals and as part of a team, and they have advanced time-management skills. As with many university degrees, neuroscience does not lead directly into a specific and defined career. Instead, training received as an undergraduate provides students with an excellent foundation for a range of possible careers.  Based on our experience over the last decade, over half of the students who graduated with an undergraduate degree in Neuroscience have secured employment in either a scientific research setting, in health care, or are in continuing education. Common research paths for Neuroscience graduates include coordinating clinical research trials or working as research scientists and research technicians in the government, academia, or industry. While many graduates are therefore directly employed in a scientific environment, other students chose to pursue postgraduate degrees in neuroscience or a related discipline (including psychology, biology, biochemistry, pharmacology, ethics).

Postgraduate Degrees

Postgraduate degrees can lead towards careers within academia or increase a student’s opportunities of employment and higher salaries in non-academic environments. Health care professions are very popular with Neuroscience graduates. Neuroscience graduates have successfully pursued continuing education to train in a variety of professions including as psychologists, speech pathologists, occupational therapists, medical assistants, nurses, or polysomnographic technicians. While science, healthcare, and future education are the main career paths pursued by neuroscience graduates, almost as many of our graduates have followed alternative routes including training as schoolteachers, working for government funding agencies, regulatory agencies, or the civil service, working in knowledge brokerage, law, or following careers as emergency responders (police, ambulance, firefighters).

Some of the areas into which neuroscience graduates work include basic research (in government and clinical laboratories), drug development and evaluation, education, audiology, behavioural research, brain imaging, policy development in the private or public sector, and many more.

While it is impossible to predict the major growth areas in terms of neuroscience career paths, some of the more promising areas for future expansion are described in the following section.

Applications of Neuroscience in Society

Medical

Over 1000 neurological and neurodegenerative diseases affect the lives of approximately 10.6 million people in Australia alone (Productivity Commission, 2019), and neuroscience research has led to a diversity of therapeutic approaches to the treatment of diseases including mood disorders, chronic pain, neurodegeneration, stroke, and addiction. Many of these treatments are pharmacological, with widespread use of drugs including antidepressants, anti-anxiety medication, attention deficit hyperactivity disorder medication, though non-pharmacological treatments have also been supported by neuroscientific research, including behavioural/lifestyle modification or non-invasive brain stimulation.

Unfortunately, many of the pharmacological interventions have been successful in only a subset of patients, with individuals often having to try several different treatment paths before finding one that is successful. This may be due to many disorders being commonly diagnosed through somewhat imperfect tests, often including self-report measures. A specific disease, defined by a collection of symptoms, may not be a unitary condition but instead a spectrum of related disorders, which collectively have a diversity of different potential origins and associated cellular and molecular signatures. While symptoms may be similar across individuals, the best route for treatment may be very different. An example of this is Parkinson’s disease where it is now accepted that many combinations of factors (such as environmental and genetic) manifest uniquely in the individual disease trajectories of people who have been diagnosed (Farrow et al., 2022).  In fact, the Michael J Fox Foundations (n.d.) states “…when you’ve met one person with Parksinon’s, you’ve met one person with Parkinson’s”.   Current research attempts to better define subsets of patients for various diseases, to facilitate more efficient targeting of specific treatment to the individual. Understanding the specific cellular and molecular deficits in an individual may be informative as to which molecules would be the best targets for pharmacological treatment.

Public Health: Recreational Drugs

Outside of drug development for medical purposes, there is a need for still more neuroscience research on recreational drugs. Use of legislation to control the misuse of recreational drugs (i.e., the ‘war on drugs’) has been of limited success, with a growing interest towards tolerance and education. In Australia, the national framework underpinning the government drug strategy proposes three pillars of action: Demand Reduction, Supply Reduction, and Harm Reduction (Commonwealth of Australia [Department of Health], 2017). We are continually exposed to the use of drugs that alter brain activity including drugs that are common and largely accepted (e.g., nicotine, caffeine, alcohol), drugs prescribed to patients but for which dependency develops (e.g., the current opioid crisis), classical illegal drugs that stimulate our reward systems (e.g., cocaine, heroin) or alter consciousness (e.g., amphetamine, MDMA), drugs used to improve performance (e.g., Ritalin and Adderall for exam performance), or drugs that have been weaponised and used widely (including the date-rape drugs GHB or Rohypnol). An important part of any strategy to deal with drug use and misuse is to understand the biological effects (both in the short and long terms) of these various drugs, for which additional neuroscience research and outreach to the community is required.

Public Health: Neurological and Psychiatric Illness

On a related topic, one of the most compelling (and difficult to measure directly) applications of neuroscience on public health has been the impact of increased understanding of the role of the nervous system in psychiatric and neurological disease. Indeed, over the last 50 years, we have made great strides in our understanding of how key neural circuits and signals are disrupted in several disorders, including (but not limited to) depression, anxiety, schizophrenia, substance use disorders, attention deficit hyperactivity disorder, dementias (such as Alzheimer’s) and neurodegenerative disorders (such as Parkinson’s Disease), among others. These advances have led to the development of pharmacotherapeutics for the treatment of these disorders, but also, crucially, the destigmatisation of mental health. More specifically, when we educate the public around the role of brain (dys)function underlying psychiatric disorders, it can lead to increased awareness and knowledge, and reduced blame for mental illness (Corrigan & Watson, 2004).

Neuroscience and Technology: Neural Interface Devices

In addition to pharmacological interventions, neuroscience research is likely to result in growth in the number, efficacy, and complexity of neural interface devices. Devices are being developed that both enhance existing sensory inputs (including replacing deficiencies in inputs) or enhance/replace motor outputs. The range of applications is diverse, from the purely medical, to military, to recreational. Neurobionics, a rapidly advancing subfield of neuroscience, explores bionic therapies for sensory and motor impairments.

One example of bionic therapy is for blindness, which affects millions of people worldwide, with a subset of that population suffering from complete retinal degeneration. Among potential treatment options is sensory substitution, wherein an inoperable sensory organ is replaced with an artificial sensor. Most recently, cortical prostheses have taken a leap forward, featuring arrays that are upwards of 192 electrodes in size that are molded to the occipital lobe of experimental participants. Miniaturised computers connecting the electrode plates to light-sensing glasses worn by the participant can simulate a small, but promising, degree of vision (Maghbami, Sodagar, Lashay, Riazi-Esfahani, & Riazi-Esfahani, 2014). There are currently several groups of researchers actively engineering and developing visual prosthetics to better the quality of life for those suffering from blindness, Groups such as the Centre for Eye Research Australia (CERA), the Monash Vision Group, and Bionic Vision Technologies, among others, are progressing research in this area. Many of these projects combine an external visual processing source (i.e., a camera attached to the frames of glasses), a processor that breaks down visual images into similar bits of information that the brain uses to construct visual images, and a transducer that turns such bits of information into patterns of activation on the microarray of electrodes which then stimulates the visual cortex. Other prostheses exist that are also integrating neural interfaces, such as prosthetic hands that give amputees a functional hand, or cochlear implants that restore function back to the deaf and hearing-impaired.

Neuroscience and The Law

The legal and ethical ramifications of current and future research in neuroscience are likely to be diverse, from which a few examples will be introduced. In criminology, identification of structural and/or functional correlates of criminal behaviour will lead to questions of free will and determinism, and debates about the concept of criminal responsibility. Remaining with the judicial system, neuroscientific research of memory has clear implications for reliability and accuracy of eye-witness testimony. Within pharmacology, there is limited and contentious evidence to support the efficacy of current brain-enhancing drugs (termed “nootropics”) such as Ritalin and Adderall, yet such drugs are widely used in college campuses to improve performance. If the efficacy of these, or other drugs, was clearly demonstrated, it may lead to the need for drug testing analogous to that employed in competitive sport, especially in the context of examinations that are viewed as a component of competitive entry to certain career or funding opportunities.

The last decade has seen dramatic proliferation of wearable biometric technology. Most of our mobile phones are quietly collecting information about our daily activity. Some phones can sense when you are looking directly at the screen. Our watches may be constantly collecting data on our heart rate, while we may be inputting data on our sleep patterns, our meditation routines, and/or our patterns of eating and drinking, to name a few. There are important ongoing conversations around the ownership, privacy, and security of these data. The coming decades are likely to see growth of biometric inputs to incorporate limited neural data – data that, as with heart rate, we are often unaware of inputting to our devices.

Future Considerations for The Disciplines of Neuroscience and Psychology

The discipline of neuroscience has clearly grown and thrived over recent decades. International and national funding opportunities related to neuroscience and brain health suggest that the study of the nervous system and its application to other disciplines, like psychology, will continue to grow. For example, the Australian NHMRC (National Health and Medical Research Council) is providing up to $3 million to support Australian-based researchers who are participating as partners in applications for the Network of European Funding for Neuroscience Research (NEURON).

The combination of neuroscience and psychology as distinct yet complementary disciplines cannot be understated, reflecting the strong ongoing interest in the brain and behaviour relationship. There are now some psychology degrees offered in Australia that have a “cognitive neuroscience” specialty; and new areas of research are continuing to emerge in which psychology and (cognitive) neuroscience are well placed to have impact. New opportunities harnessing the collective insights of neuroscience and psychology such as in the realms of artificial intelligence and technology are clearly on the rise. For example, the development, utilisation, and ethical implications of Generative AI products using large language model algorithms (e.g., ChatGPT) draw upon principles from both disciplines. These efforts can help us create and benefit from human-like algorithms safely as well as opening doors for further exploration and innovation.

Despite the dramatic advances in our understanding of the nervous system over the last century, we are just starting to make sense of the enormous complexity that underlies the structure and function of the human brain and how it underlies all thought, behaviour, and perception. Further information on the synergies between psychology and neuroscience can be found o the Australasian Cognitive Neuroscience Society (ACNS) website.

This chapter has been adapted by Natalie Gasson and Welber Marinovic from Scool of Population Health, Curtin Unviersity. It has been adapted from Stead, J., Wiseman, A., & Hellemans, K. (2019). Neuroscience and careers. In M. E. Norris (Ed.), The Canadian handbook for careers in psychological science. eCampusOntario. https://ecampusontario.pressbooks.pub/psychologycareers/chapter/neuroscience-and-careers/

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