Understanding of cognition began with psychogenic theories derived from psychoanalysis — observation and study of mental associations made by patients during conversations with a psychological practitioner. It was found that maladaptive abnormalities in the psyche, what the medical field termed ‘neurosis’, could be linked to repression of thoughts and memories hidden under ordinary conditions, but evinced during therapeutic sessions as pauses, slips of the tongue, sudden or surprising personal insights, flare-ups of emotional disorders such as numbness and agitation, as well as dramatic descents into irrationality called ‘hysteria’. Under careful investigation, repression proved to be so common, even in healthy individuals, that it led to a foundational concept called the ‘unconscious’, referring to a portion of the psyche which stores memories of experiences below the threshold of a patient’s self-awareness. This inspired many techniques for drawing troubling memories to the doctor’s and patient’s attention so as to work towards coping, hopefully making patients more capable of normal relationships and in acute cases adequately caring for themselves.
While psychoanalysis provided major advancement, studying in depth human sexuality and psychological development, progress credited to the Freudian school, it was unable to help many patients either because of the severity of their symptoms or an inability to definitively establish whether supposed memory contents were real or induced by suggestion. Obviously a psychologist would have to be extremely competent bordering on genius to diffuse unconscious defenses without damaging the patient’s psyche, as well as dealing with all the idiosyncrasies of each patient’s mind and history. Psychoanalytic theory pushed on somewhat further, identifying in a preliminary way more details of the repressed psyche, such as the collective unconscious with its primordial mental images and behavioral inclinations linked to the cultural/psychical archetypes of prehistory, as well as personality types and their forms of expression and suppression in modern contexts, ascribable to the Jungian school.
It became apparent that social connections are vital to recovery from all kinds of psychological problems, and relationship-based treatments such as group meetings and paradigms of behavioral analysis with a strategy of more natural conversation style displaced the investigative, more invasive kind of therapy, though psychoanalytic history remains a positive impact on the training of mental health counselors, with potential to delve deeper into the psyche if at some point interest renews.
b. The rise of neuroscience
Formulation of biological evolution as a reputable theory revolutionized research, for it became evident that the hereditary relatedness of all species and an amplified potential to propose mechanisms of historical change made comprehension of the world in physical terms much more potent: deriving medications from chemistries of plants and animals based on similarities to humans, and describing the planet’s past with reference to the geological or fossil record had become simple common sense. Evolutionary theory also sparked interest in comparative anatomy, for it was clear that deeper explanations of biological function were possible, illuminating millions upon millions of years of interaction and transition within ecosystems. The growth of theoretical chemistry combined with explication of organic processes down to the microscopic level mobilized researchers to relate chemical structures and fluctuations to all sorts of bodily functions.
Since the organ most closely correlated with thought and personality is of course the brain, it has become the focal point of a wide variety of research efforts. Scientists implant electrodes in the heads of animals such as mice to observe how nerve cells called neurons transmit electrical current while organisms are performing activities such as learning, exercising motor coordination, or engaging in fear or pleasure responses to sundry stimuli. Effects of lesions to brains from surgery or injury are also studied for the purpose of pinpointing function.
Recent developments include methods of data collection that are noninvasive cognitively and behaviorally, such as fMRI (functional Magnetic Resonance Imaging), a vaulted machine tracking details of brain activation by imaging blood flow in real time using powerful magnets, or EEG (electroencephalogram), which places electrodes on the scalp to display electrical conduction in various portions of the brain, measured while the subject is in diverse mental states, like sleep stages as well as those involved in conversation, visual and aural attentiveness or remembering.
Neuroscience has reached a sizable understanding of neurochemistry and pioneered prescription drugs that work almost miraculously for many of the most severe types of psychological illness, helping incapacitated patients begin living normal lives, with jobs, families, personal interests and further involvements in the community. Drug-based treatments may soon be displaced by less invasive therapies such as neurofeedback, a several month treatment that recalibrates brain waves to more healthy synchronization using visual interaction with a digital interface. Newer techniques such as this may obviate the downside to medications — side effects, physical dependencies and stigma — but as newer drugs come out and mental health is advocated in campaigns which educate the public, some of these drawbacks tend to diminish, so that there is much hope for the most serious cases.
c. Brain structure and function
Research has mapped out brain structure and function in great detail, though much remains to be learned. The major human brain regions are the brainstem, midbrain, cerebellum, and cerebrum (cerebral cortex). The brain stem is the evolutionarily oldest part of the brain, found in mammals, birds, reptiles and amphibians. It is composed of subregions such as the pons and medulla oblongata that in combination with the rest of the brain regulate involuntary functions such as heart rate, breathing and digestion.
Most members of these animal groupings also have a highly differentiated midbrain. In humans, the hypothalamus participates in regulating physiological arousal, such as the fight-or-flight response, as well as sexual arousal, processing input from many sources and then stimulating hormone secretion by the attached pituitary gland. The thalamus functions as a routing station for sensory stimuli that are processed in various parts of the brain. The hippocampus is the central apparatus for integration and routing of memory processing throughout the brain. The amygdala is involved with regulating reactions to novel stimuli, notably managing the experience of fear or ‘negative feedback’. The nucleus accumbens governs the reward or ‘positive feedback’ response, reacting downstream to release of the neurotransmitter dopamine and relaying that key event to control of activity in the rest of the brain. Happiness, sadness, anger, fear, all the basic emotions are heavily influenced by a well-developed midbrain, and are probably present to some degree in most bird and mammal species at the very least. The cerebellum is located at the back of the brain and is equally prevalent in the animal kingdom, tied to many aspects of motor coordination and implicated in a growing variety of additional functions. It contains a unique type of cell called the Perkinje neuron.
The cerebrum is a thin membrane with corrugated infoldings enveloping the top, front and sides of the brain, generally thicker and larger relative to body mass the more intelligent and thoughtful a species is, being about two millimeters thick in humans with an area of about one and a half square feet. It is tied to many behaviors influenced by higher thought, with a heftier mass in mammals and birds than reptiles and amphibians. In humans it has four main sections, the occipital, temporal, parietal and frontal lobes. The occipital lobe is located at the back of the cerebral cortex and is responsible for sight-related processes, the temporal lobes on either side of the head for hearing and memory, and the parietal lobe at the top of the head for many aspects of motor coordination. Much of memory retention and some elements of mathematical, spatial and linguistic thinking among many more functions are also distributed within these three structures, usually in areas where wiring together of adjacent neurons produces complex, hybrid behaviors, such as Wernicke’s area (located at the junction of the temporal and occipital lobes, important for reading and writing) or Broca’s area (located at the junction between motor coordination of the face, lips and tongue in the parietal lobe and sensation registering areas at the crest of the frontal lobe, important for speech production). The frontal lobe and especially its prefrontal cortex subregion are site of the highest level cognitive processing and key for some distinctly human characteristics like complex problem-solving, linguistic expression of the most technical concepts, social aptitude, long-term introspection, analytical decision-making and many more functions that seem unique to Homo sapiens.
The brain is divided into a left and right hemisphere connected by a thick bundle of neurons and additional fibers called the corpus callosum. Fairly consistent division of labor seems to exist between the two hemispheres, though there is of course variation between individuals, as well as overlap in function. For instance, the majority have primary language centers on the left side of the frontal lobe while a minority have these modules on the right or both sides, and it is even the case that a hemisphere can assume certain functions of its opposite when damage is sustained. The left hemisphere tends to be responsible for analytical operations such as logical thinking, the details of linguistic expression, everything involving minute symbolic analysis, while the right hemisphere tends to participate in spatial processing, generalization, awareness of flow in music tonality, and additional aspects of perception and conception that constitute the broad picture within which particulars inhere. Hemispheres of the brain are crosswired to the body, so a naturally left-handed individual is likely to be right hemisphere dominant and a right-handed individual left hemisphere dominant, but comprising a highly variable spectrum that produces an abundance of skill sets.
An antiquated procedure for curing severe epilepsy by severing the corpus callosum revealed some intriguing facts about left and right hemisphere interactions. A patient who had undergone this operation was shown a picture of a chicken to his right eye, wired to the left hemisphere, and a picture of a snowbank to his left eye, wired to the right hemisphere, then instructed to select the image most well-matched to what he had seen from a collection of pictures, with both his right and left hand separately. He chose the picture of a chicken claw with his right hand (left hemisphere) because a chicken claw obviously goes with the chicken, and a snow shovel with his left hand (right hemisphere) appropriate to the snow bank, but when asked why he chose the snow shovel he replied that the shovel goes with the chicken because you need it to clean the chicken shed. The left hemisphere was not aware of the right hemisphere’s processing because of their separation, but compulsively invented a story accounting for the left hand’s choice that rendered the total experience consistent to the patient’s analytical mind. This fascinating aberration was observed many times in mostly functional post-op patients (who often partially recovered from split-brained effects) and revealed that the left brain creates narratives integrating our experiences, often with a more subtle but nonetheless substantial infidelity responsible for flaws and inconsistencies of eyewitness testimony, the psychological power of suggestion, confirmation bias, and conducing the role of memory in supplementing consolidational processes of the introspective self.
d. Cells of the nervous system
Nerve cells can be divided into two general types, neurons and glia; the brain is about 90% glial cells and 10% neurons. In an inactivated state, neurons have an internal charge of about -70 mV (millivolts), but when activated conduct electrical signals throughout the body which stimulate all kinds of motion. Neurons are responsible for smooth and skeletal muscle movement, secretions of glands, and every task the brain performs including cognition, constituting the control center of an organism.
Neurons have three parts: axons, dendrites, and the soma (cell body). The axon is the midsection of the cell, which can be multiple feet long in some parts of the body. It conducts electricity, what is called an action potential, initiated by release of neurotransmitting molecules into synaptic clefts between neurons and chemical bonding of these substances to cell membrane receptors. Receptor biochemistry both propagates and responds to cascades of positively charged sodium ions that enter the axon through channels in its portion of the cell membrane, a current traveling in longitudinal sequence down its length. Nerve signals are inhibited when negatively charged chloride ions flow into the connected soma, located on the opposite side of an axon from the synaptic cleft. Strength of the electrical signal is determined by frequency of action potentials, with higher rate of turnover in ion diffusion/transport cycles stimulating more intense response from muscles or glands.
All of this neuronal activity is wired together in a gigantic, weblike bundle by neurotransmitter secreting structures called dendrites intertwined with axons and each other, long and thin protrusions from the soma. The soma serves as core support system for these cells, regulating their overall structure and function. More than ten thousand different types of neurons have been identified, including the two most common structural types — pyramidal and spindle neurons — and notably the VENS (von Economo neuronal system), key for self-awareness, primarily represented in the prefrontal cortex and to a lesser extent the insula and anterior cingulate which are both located on the underside of the frontal lobe. Interconnected plasticity of neurons at the cellular level is reminiscent of a rapidly morphing bacterial colony, though regulated by systemic chemistry and specialized mechanisms of intercellular recognition.
The role of glial cells is less understood, but seems at the very least to involve neuron maintenance and production of some of its auxiliary structures such as the myelin sheath, an insulating layer of fat encasing the axon. Glia may also have a crucial effect on migration and maturation of nervous system tissues during developmental stages. Connectivity of neurons in the human brain is astronomically huge, with more than a hundred trillion dendrite linkages.
The peripheral nervous system external to the brain, including the spinal cord, is composed of sensory and motor neurons. Sensory neurons send signals about environments to the brain, and motor neurons send signals from the brain to the rest of the body for purposes such as movement as well as coordination of organs and biochemistry. Some reflexive behaviors must be faster than signaling to and from the brain allows, and in these cases interneurons in the spinal cord interface sensation with movement. The chemistry of interneurons adjusts in proportion to frequency and extremity of the stimulus; habituation is the process reducing reactiveness to a sensation and sensitization is its increase, with these mechanisms of conditioning present in even simple species lacking much cephalization. The more developed the central nervous system is in an organism, the more subtle and diverse its habituation and sensitization, so that the human brain can be thought of as in part a colossally large and variegated system of interneuronal function mediating between sensation and behavior via complex perception, long-term memories and conception.
e. Chemistry of the neuron
Communication between neurons happens within the synaptic cleft and occurs when one or more of four classes of molecule bind to receptor sites. Neuromodulators such as acetylcholine, epinephrine and norepinephrine regulate motor-related functions: muscle contraction, arousal of the fight-or-flight response, and its suppression, respectively. Neurotransmitters are involved in the generation of emotional states: for example, dopamine initiates the pleasure of positive reinforcement, serotonin elevates mood and deficiency can induce obsession, oxytocin participates in relational bonding of couples and families, and melatonin concentrations govern the sleep cycle. Neuropeptides such as cytokines are vital in managing hormone release within the endocrine system via the pituitary gland. Enkephalins are opioids that act like morphine, functioning in the palliation of pain.
Various molecules transmit signals from surface membrane receptors of the soma, initiating biochemical pathways in its cytoplasm. An enzyme called Adenylate Cyclase converts ATP (adenosine triphosphate) into cAMP, a ‘second messenger’ molecule activating enzymes such as CaM Kinases, continually stimulating and modifying biochemical cycles upstream of neurotransmitter release by dendrites. Calcium ions (Ca2+) can also act as second messengers; this is true of heart contraction, as their influx through the cell membrane into the soma speeds heart rate. Biochemical pathways intermediate between cell membrane receptors of the soma and gene expression in the nucleus link intercellular activity to the rate and form of mRNA synthesis, influencing concentrations of cell body proteins and by extension the general structure and functioning of neurons. Properties of channels in a neuron’s outer membranes are continually modified by feedback loops that increase or decrease their porousness as functional need dictates, regulating the exquisite intricacy of synapsing.
f. Recent developments in neuroscience
Neuroscience is starting to move away from models of the brain as a set of distinct modules with static functions neatly correlated to traditional understandings of the mind as divisible into experiences like emotion, reasoning, memory, and towards a revamped set of categories reflecting what has been discovered to be the brain’s more actual structure. Regions like the amygdala were formerly considered responsible for single affective states such as fear, but it grows apparent that organs of the brain are in complex cooperation extending throughout its mass during production of any experience that has definite, expressible identity to the individual.
For instance, the amygdala has been found in advanced research to be associated with many different forms of response to novel stimuli running the whole gamut of emotion and cognition, not just fear. Commitment to linking the amygdala with fear arose from early experiments that removed whole temporal lobes of rhesus monkeys and observed extinguishment of avoidance response to snakes. More finely grained investigations recording neuronal activity down to the cellular level or watching the flux of brain region activation in real time with techniques such as fMRI reveals a more interesting picture, with pervasive sharing of labor between distant structures and a general lack of clear localization for any subjective experience identified by a human patient. Subregions of the brain are much more integrated, variegated and versatile than had traditionally been assumed.
Researchers found that simple correlation between mental states as they are experienced by human subjects and overall patterns in brain activity does not exist. Thoughts and emotions as we know them are largely cultural constructs added on to the phenomenon of mind by experience, physiologically narrow conventions modulating how we understand each other and ourselves in social contexts, but very minimally a hard-wired innateness. Even basic thoughts and emotions are the product of an individual’s cognitive and physiological history, varying by region of the world and in reaction to all kinds of conditions such as one’s surroundings, appetite, health and general homeostasis.
Dynamics of the brain are functionally deeper, more subtle and deceptive than folk psychology and most Western epistemology supposed. Educating individuals about the growing knowledge of our often illusion-inducing complexities seems essential to progressively fashioning an empowered, responsible public and all future social planning. Disconnect between ourselves and many traditional interpretations of ourselves can perhaps explain the constant disintegration and corruption of institutions. Mechanistic modeling of our fallibilities and most civically maladaptive behaviors might help remedy with better intuition their persistent recurrence, diverting society away from perpetual discord and thus altering the course of history in a positive manner.
A free download of the book Standards for Behavioral Commitments: Philosophy of Humanism, also available for preview below. Topics covered include chemistry, biology, genetics, neuroscience, epistemology, the history of Western philosophy, cultural evolution, theory of cognition, ethics and much more.