Friday, December 29, 2017

The Human Brain and Human Mind



Dr Ruwan M Jayatunge 

The Human Brain
The human brain is a very complex organ. The human brain is largely interconnected. Brain controls all   mental   and physical functions. The human brain is primarily composed of neurons, glial cells, neural stem cells, and blood vessels. An average human brain contains about 100 billion neurons.  There are as many as 1,000 trillion synaptic connections in the brain.  Approximately 20% of the blood flowing from the heart is pumped to the brain. It uses 20% of all the oxygen we breathe. The brain is the central organ for adaptation to experiences (McEwen, 2016).

The brain is considered as the control center of the body. Human thought is controlled by the brain.  The brain is an electrochemical organ using electromagnetic energy to function (Beyo, 2011).

The largest part of the brain is the cerebrum which contains the cerebral cortex. The cerebrum directs the conscious or volitional motor functions of the body. Furthermore it controls planning, memory, and sensory integration.

The brain is divided into two hemispheres,-the left and right hemispheres.  The right hemisphere is known as the creative side of the brain, while the left hemisphere is the logical or analytical side of the brain.  Two hemispheres communicate with one another with corpus callosum. This bundle of nerve tissue contains over 200 million axons.

The lateralization of brain function is the tendency for some neural functions or cognitive processes to be more dominant in one hemisphere than the other. Language is considered to be one of the most lateralized human brain functions. Left hemisphere dominance for language has been consistently confirmed in clinical and experimental settings and constitutes one of the main axioms of neurology and neuroscience (Riès et al.,2016). 

Right hemisphere characteristics include creativity, the ability to see patterns, spatial awareness, and the understanding of how things relate to one another in different contexts. The absence of verbal and visual memories for early childhood and traumatic events relates to their right brain nonverbal retention and storage. The memories are unconscious, emotional, somatic behavioural and timeless. Right hemisphere damage can cause serious disruptions to verbal communication (Abusamra  et al, 2009).

The brain has four lobes. The brain’s frontal lobe is responsible for functions such as reasoning, problem solving, judgment, impulse control. The Parietal Lobe is involved in processing pain and touch sensation. The temporal lobe is involved in auditory sensation. The occipital lobe is located at the back portion of the brain and is associated with interpreting visual stimuli and information.

The human brain has three major components: the cerebrum, the cerebellum and the brain stem. The brainstem which includes the medulla, the pons and the midbrain, controls breathing, digestion, heart rate and other autonomic processes.The cerebrum is the largest portion of the brain. Cerebrum is associated with higher brain function such as thought and action.

The Cerebral Cortex is the outermost layer of the cerebral hemisphere which is composed of gray matter. The cerebral cortex is a complex structure   (Agirman,  2017). The mammalian cerebral cortex contains numerous anatomically and functionally distinct areas arrayed in a complex mosaic across the cortical sheet (Van Essen et al., 1998). The Cerebral cortex plays a key role in memory, attention, perception, cognition, awareness, thought, language, and consciousness (Kandel et al., 2000). 

The neocortex is the largest part of the cerebral cortex which is the outer layer of the cerebrum. The neocortex involved in higher-order brain functions such as sensory perception, cognition, generation of motor commands (Lodato,  2015).  Semantic memories appear to be stored in the neocortex, specifically the anterolateral temporal lobe of the neocortex (Carlson,  2013).

Among the other brain structures the amygdala helps the body responds to emotions, memories and fear. The amygdala plays an important role in the computation of internal reward signals (Mormann et al.,2017). Amygdala is the storage for the memories associated with emotional events. It is the center of the emotional memory. In addition amygdala is involved in the modulation of memory consolidation and social interaction. The ventromedial prefrontal cortex region of the brain  is responsible for regulating emotional responses triggered by the amygdala.

Many researchers believe that amygdala may be responsible for the emotional reactions of PTSD patients. Overstimulated amygdale can cause many PTSD symptoms. Psychological trauma usually increases activity in the amygdala. In severe anxiety the size and connectivity of the Amygdala changes drastically. Morey and colleagues (2012) found the association between a smaller amygdala volume and PTSD.

The hippocampus is vital for learning memory and spatial navigation. The hippocampus is critical for the formation of new memories and spatial orientation. According to Eichenbaum and Cohen (1993) hippocampus plays an important role in the experienced events (episodic or autobiographical memory).

PTSD patients have decreased gray matter volume in the hippocampus. In addition reduced hippocampal volume can be seen in PTSD. Following the reduced hippocampal volume patients loses the ability to discriminate between past and present experiences or correctly interpret environmental contexts.

The hypothalamus region of the brain controls mood, thirst, hunger and temperature. The neocortex or rational brain is important to develop language, abstract thought, consciousness and imagination. The hypothalamus has a central neuroendocrine function.

The reticular formation is a comprehensive network of nerves found in the central area of the brainstem. The reticular formation is important in somatic motor control, cardiovascular control, Pain modulation and Sleep and consciousness. The reticular formation regulates the shift between sleep and wakefulness.

The Cingulate Gyrus is located in the medial side of the brain between the cingulated sulcus and the corpus callosum. The region participates in the emotional reaction to pain and in the regulation of aggressive behavior. The anterior cingulate gyrus is important in self-regulation(Posner, 2007).

Insula is a vital human brain structure. It is a small region of the cerebral cortex located deep within the lateral sulcus, which is a large fissure that separates the frontal and parietal lobes from the temporal lobe (Craig 2009). Insula is important in awareness of our own body. The anterior insular cortex   is implicated in a wide range of conditions and behaviours, from bowel distension and orgasm, to cigarette craving and maternal love, to decision making and sudden insight (Craig 2009). Garavan (2010) believes that insula plays a key role in drug craving.


The Human Mind
There is a popular notion that states - As humans we live in our Minds. The mind is the organized totality of an organism's mental and psychological processes, conscious and unconscious. Mind does not end in the brain and brain is the liaison between mind and body (Tan, 2007). Mind is not a physical object but the mind is infinite. According to some scholars the mind is a set of cognitive faculties. The British evolutionary biologist, Sir Julian Huxley expressed that brain alone is not responsible for mind.   The mind is also portrayed as the stream of consciousness where sense impressions and mental phenomena are constantly changing (Karunamuni &Weerasekera , 2017).   
Theory of mind is the ability to attribute mental states to self and others in order to understand and predict behavior. It involves the distinction between the real world and mental representations of the world (Duverger  et al.,2007). The mind is a set of cognitive faculties including consciousness, perception, thinking, judgment, and memory.  Human mind is the result of the brain activities and has a conscious as well as a subconscious side. The human mind is   built on the physical scaffolding of the brain. Human mind is shaped by natural selection and sexual selection (Pinker, 1997). According to the psychomotor theory, the human mind may be an emergent property of the motor system, expressed by human language (Tan, 2007).

Our mind is our own creation. John Milton emphasized that the   mind is its own place and in itself can make a hell of heaven or a heaven of hell. If we view the mind as software, and the brain is obviously the hardware.

The Buddha explained that the mind is exceedingly subtle and is difficult to be seen. It attaches on whatever target it wishes. The mind moves about so fast it is difficult to get hold of it fully. It is swift. It has a way of focusing upon whatever it likes. The mind is capable of travelling vast distances - up or down, north or south, east or west - in any direction. It can travel to the past or the future. It roams about all alone. The Buddha viewed mind as a non-physical phenomenon which perceives, thinks, recognizes, experiences and reacts to the environment. The Buddha further stated that mind is the ultimate cause of everything in this world.

Sigmund Freud developed a topographical model of the mind, whereby he described the features of the mind’s structure and function. Freud used the analogy of an iceberg to describe the three levels of the mind. Furthermore Freud analyzed the human psyche in terms of three elements, which he calls, the Id, Ego, and Super Ego. 

Carl Jung believed that the human psyche was composed of three components: the ego, the personal unconscious, and the collective unconscious. Jung concluded that the collective unconscious is formed by instincts and archetypes that are symbols, signs, patterns of behavior, and thinking and experiencing, that are physically inherited from our ancestors. 

The American, logician, mathematician, and philosopher Kurt Gödel argued that human mind is a Turing machine. For Kurt Gödel human mind was fully algorithmic.
The Cognitive Psychologist Steven Pinker expressed that human mind is a naturally selected system of organs of computation. Steven Pinker states that cognitive psychology has shown that the mind best understands facts when they are woven into a conceptual fabric, such as a narrative, mental map, or intuitive theory. Disconnected facts in the mind are like unlinked pages on the Web: They might as well not exist. 
The spiritual author Eckhart Tolle affirms that boredom, anger, sadness, or fears are   conditions of the human mind.  He further states that the mind is a superb instrument if used rightly. Used wrongly, however, it becomes very destructive. 


Mind -Brain Connection
The mind vs. brain debate has been going on since before Aristotle ( Sarich, 2013). Brain" refers to the "machine" made of neurons and glia; "mind" refers to the products of that machine including conscious thought, as well as emotions, perceptions and unconscious thought (William Harris). The mind is the manifestations of thought, perception, emotion, determination, memory and imagination that take place within the brain. The mind is where experiences are collected and then expressed in other words the mind is a storehouse of information. Mind is that it is the space and time in which thought and feeling exists. Some consider mind as pure vibrating energy. The Nobel prize laureate Neils Bohr’ once stated; there is “an indivisible wholeness, an unanalyzable wholeness.  It is assumed that large-scale quantum coherence is necessary to understanding the brain and mind (   Sarich, 2013).  The concept of mind shows that a human being has a corporeal body and a mind, that is, a range of psychological capacities (Bennett, 2007).

According to western medical science there is no anatomical entity known as mind. However Sigmund Freud used the term "psyche” to describe the mental process. It is suggested that the history of the concept of mind shows that a human being has a corporeal body and a mind (Bennett, 2007). According to Pandya (2011) mind is responsible for one’s thoughts and feelings, the seat of the faculty of reason or the aspect of intellect and consciousness experienced as combinations of thought, perception, memory, emotion, will and imagination, including all unconscious cognitive processes. Pinker (2003) hypothesized that the mind is a complex system composed of many interacting parts. The Indian Philosopher E.S Krishnamoorthy states that mind is a virtual entity.  The British Neurologist John Hughlings Jackson called the prefrontal cortex as the organ of mind.

In his famous book , “ The Tell-Tale Brain: A Neuroscientist's Quest for What Makes Us Human” the Neuroscientist V.S. Ramachandran writes :How can a three-pound mass of jelly that you can hold in your palm imagine angels, contemplate the meaning of infinity, and even question its own place in the cosmos? Especially awe inspiring is the fact that any single brain, including yours, is made up of atoms that were forged in the hearts of countless; far-flung stars billions of years ago. These particles drifted for eons and light-years until gravity and change brought them together here, now. These atoms now form a conglomerate- your brain- that can not only ponder the very stars that gave it birth but can also think about its own ability to think and wonder about its own ability to wonder. With the arrival of humans, it has been said, the universe has suddenly become conscious of itself. This, truly, it the greatest mystery of all.

2 comments:

  1. Good article Ruwan.How the brain changes when we meditate?

    ReplyDelete
    Replies
    1. Lalith when we meditate brain's gray matter level increases

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