- Education and Science
How the Human Brain Works - A Simple Summary of Brain Segments
Flashing back through the different periods of human civilization, it is apparent how humans have progressed from their hunter-gatherer ways to today’s modern lifestyle. More notable is how we have consistently assumed a paramount status in the environment; compared to other species, we demonstrate considerable resourcefulness and expertise as we harvest food, resources and inspiration from nature undeterred to suffice our everyday demands. This very competitive behavior can be attributed to the deliberate design of our human brain – particularly the frontal lobes, which function as the brain’s “executive center” and contain the prefrontal cortex.
Space exploration is one activity whose success formula requires meticulous blueprints and precise calculations. Practically everything, to varying extents – whether designing financial budgets, or simply picking shoes to match our outfit – requires forethought and planning.
In the frontal lobe and the orbitofrontal and ventromedial region of the prefrontal cortices, rationalization occurs. It combines reasoning and decision-making processes to create systematic approaches instrumental to successful goal accomplishment.
These same regions, researchers believe, house the roots of empathy, compassion, disgrace and guilt. The limbic system, consisting of parts from the cerebral cortex and subcortex, is primarily responsible for emotions. Emotions develop from their matching neural patterns; coupled with rationalization, humans learn to navigate complex situations. These situations possess classical and operant conditioning effects, punishing or rewarding our actions, shaping our individual and social behaviors or behaviors-to-be.
The 1986 space shuttle Challenger tragedy illustrates this – until disaster struck on its 10th mission, the initial frictionless missions reinforced NASA’s catastrophic use of the mal-designed O-ring equipment. Since then however, recalling this disaster would stimulate the central nuclei of the amygdala deep inside the medial temporal lobes, inducing fear of future accidents. This type of learning engages the orbitofrontal cortex and insula.
Execution is the next important step to give life and tangibility to our plans, as musicians translate a composer’s imagination into music. Using this analogy, the premotor cortex activates readiness potential when the musician positions his fingers in preparation for performance, utilizing his supplementary motor cortex he breezes through strings of running notes and rhythmic passages, and the prefrontal cortex is responsible for these movement sequencings.
After execution, it is important to determine how far and long our desired results can be sustained. Incorporating elements of review, evaluation and monitoring, this peculiar ability to manipulate our outcomes to adapt them to suit our changing needs, improvise or compensate our shortcomings(or mistakes) is vital to our competitiveness. Using similar mechanisms to the planning stage this activity largely localizes in the prefrontal cortex. This is the process NASA underwent after the setback before bouncing back with Endeavor shuttle to replace the Challenger .
Indeed, learning and memory are closely intertwined. This continuous accumulation of knowledge and experiences influences the quality of our decisions. Long-term memories are typically emotionally-charged and lucid events like life or societal milestones, molding our identity and aspirations. An example of working memory at work is when a postman retains an address in between the short time he sees it and drops the letter into its mailbox. A cross between the two are intermediates, like finding the airconditioning control or recalling how much battery is left before your handphone needs charging. Structures like the anterior prefrontal cortex is involved in memory monitoring while the parietal lobes and lateral prefrontal cortex support working memory. Some researchers hypothesize that the dorsolateral areas of the prefrontal cortex is responsible for spatial working memory and the ventrolateral areas for the non-spatial. Undisputed is the importance of receiving, retaining, retrieving and revising information upon demand – abilities which when absent severely impede learning, confining our existence to the ‘present moment.’
Procedural learning is implicit, like when left-handers learn right-handed guitar. When Singaporeans drive in America; new habits form when the basal ganglia connects new stimulus (road signs) with our action of driving on the opposite side of the road. Hippocampal learning instead is declarative and explicit. Declarative memories are stored in the hippocampus, a subcortical structure that embeds these memories into long-term storage through a process of internal replay that occurs at later intervals. Sometimes, as students solving algebraic problems stumble upon ‘magic solutions’, learning catches us unaware. This ability to adapt and improvise upon our appraisal of immediate matters demonstrates our dynamicism in our environment.
Difficulties with working memory or focusing on tasks or sensations often stem from impairment in attention. In the frontal lobes, attention is a complex dance between concentrating, dividing, switching… localized in the right frontal, cingulate, orbitofrontal and dorsolateral cortices. Often underestimated, attention willfully draws fundamental objects, feelings or sensations into consciousness, preventing sensory neglect which results in disorganized perception and behaviors.
Our exceptional communicative abilities involve the possession of a unilateral cortical area handling linguistic functions(including broca’s and wernicke’s area in the frontal and temporal lobes respectively). Lateralized in the left hemisphere, such intricacy and vibrancy of overt language ability is not approached by other animals. Language is ‘productive’, presenting possibilities of using symbols to express creativity, facilitating the transmission, sharing of sophisticated concepts and ideas. The Safir-Whorf thesis proposes howlanguage colors our perception of the world, perhaps opening our eyes to complexities unseen by animals.
Evolutionary psychologists propose the Massive Modularity Hypothesis of the brain – essentially theorizing that the different segments of the brain have specific and specialized functions. Culmination of the millions of individual operations occurring simultaneously within the brain produces an overall response or set of instructions from the brain to the body.
Structurally, dendrites in the cerebral cortex have up to 16 times over dendritic spines as neurons in other cortical areas, explaining the high activity levels occurring here. The prefrontal cortex occupies a third of a primate’s entire cerebral cortex, and the human brain-to-body ratio is 0.02 – both values significantly larger than most species, explaining why our superior intelligence overrides animal instincts. In fact, the prefrontal cortex size is bigger today compared to our ancestors, suggesting that our enhanced competitiveness is not only unrivaled by other species but has historically reached unprecedented levels.