Dr.
Ruwan M Jayatunge M.D. PhD
In
general terms, consciousness is defined as the state of awareness of self and
the environment. Consciousness can be defined as the subjective awareness of
the momentary experience interpreted in the context of personal memory and
present state (John, 2003). Consciousness is the ability to feel emotions and
have the ability to make decisions, plan, and generally respond in
non-automatic ways.
Consciousness
is not a single, monolithic entity; it’s a collection of interconnected
processes. Internal factors such as the activity of neural networks,
neurotransmitters, and neuroplasticity and external factors such as
sensorimotor experience, social interactions, and self-awareness help to form
consciousness. The development of consciousness is connected with evolutionary
progression. Biological, experiential, and evolutionary factors are linked with
consciousness.
Consciousness
develops as a memory system. Consciousness is a process (not a static entity)
with a continuous flow of experience. Consciousness encompasses ongoing,
dynamic interactions and transformations with a deeper connection to oneself
and the world.
The
first appearance of consciousness is linked to the Cambrian explosion around
520-560 million years ago. The Cambrian explosion represents a major
turning point in the history of life on Earth. With the Cambrian explosion,
complexifying nervous systems and new sensory capabilities arose. This period
saw the rapid diversification of animal life and the development of the first
complex brains, along with the emergence of simple reflexive behaviors and a
unified inner world of subjective experience.
When
does consciousness first begin in humans? is an age-old question. Research
suggests that some form of consciousness may be present in the late stages of
fetal development. Studies have shown that fetuses respond to stimuli and
exhibit signs of awareness. Although human fetuses may exhibit some rudimentary
forms of awareness, they don't possess the full capacity for consciousness. In
humans, the emergence of consciousness depends on the activation of the cortex
by thalamo-cortical connections around 24 weeks after conception (Padilla &
Lagercrantz, 2020). This means the emergence of consciousness occurs around 24
weeks of gestation.
Infants are born with a basic level of consciousness. Newborn infants are able
to differentiate between self and nonself touch, express emotions, and show
signs of shared feelings (Lagercrantz, 2009). They display basic or minimal
consciousness, and with age and maturation, they can reach a higher level of
consciousness. Gradually they possess self-awareness, subjective experience, or
the capacity to reflect on their own existence.
Consciousness and Its Components
Consciousness
consists of wakefulness (or arousal) and awareness. It provides a subjective
experience of the world and oneself. As described by Askenasy and Lehmann
(2013), subjectivity, intentionality, self-awareness, and will are major
components of consciousness in human beings. Carl Gustav Jung believed that
consciousness is composed of
four aspects: thinking, feeling, sensing, and intuiting.
Consciousness and the Human Brain
The
essence of the mind is consciousness. The brain plays a crucial role in the
formation of consciousness and arises from biological processes in the brain.
Consciousness is a result of complex neural activity and the neural structures
required for conscious experience. The intricate interplay of neurons and their
connections helps to form consciousness. The brain and its metabolism are
responsible for consciousness. The cerebral cortex, thalamus, and parts of the
brainstem are a crucial area for consciousness and work together to create the
conscious experience. The cerebral cortex deals with many conscious functions,
including awareness, perception, thought, and memory.
The Evolutionary Origin of Consciousness
Human
consciousness is thought to have evolved gradually through a complex interplay
during evolution (Padilla & Lagercrantz, 2020). Consciousness may have
arisen through natural selection and evolutionary processes. It may have begun
as an extension of very basic primitive or primordial emotional influences.
Consciousness presumably evolved as part of the evolution of the nervous
system. It took nearly 5 million years to form a fully developed brain cortex.
Experts believe that consciousness began with humans, Homo sapiens, around
200,000 years ago.
Conscious Experience
Conscious
experience refers to the subjective awareness and perception of emotions,
sensations, and thoughts that make up our individual experience of the world.
Chemicals, electrical stimulation, and sometimes brain trauma can alter
conscious experience. Head injuries, strokes, seizures, infections, and
issues related to blood sugar, blood pressure, and blood flow to the brain can
disrupt consciousness.
Neuroplasticity
and Consciousness
Neuroplasticity
is the brain's ability to change and adapt due to experience. Neuroplasticity
is deeply intertwined with consciousness. With neuroplasticity, the brain
adapts to new experiences, expands conscious awareness, and shapes the
content of consciousness. Furthermore, consciousness influences brain
neuroplasticity. Consciousness leads to neuroplastic adaptations.
Stream
of Consciousness
William
James, in his Principles of Psychology (1890), introduced the term,
and it mimics the continuous, free-flowing nature of human thought. It is the
unbroken flow of thoughts and awareness in the waking mind—the dynamic flow of
mental activity. William James argued that consciousness constantly changes
and evolves. Rational thoughts, sensations, perceptions, ideas, and emotions
form the content of human conscious experience. Every person's inner thought
process is distinct and personal, shaped by their individual experiences,
feelings, and viewpoints. According to Smallwood (2015), conscious experience
is fluid, and its dynamic nature is illustrated by the experience of mind
wandering.
Meta-Cognition and Consciousness
Metacognition
and consciousness are related concepts but distinct. Metacognition is the
ability to reflect on and regulate one's own thinking and cognitive processes.
It is a purposeful recognition, awareness, and even control of one's personal
thought processes. Metacognition, construed as a conscious, intentional
process, goes beyond simple awareness. Consciousness provides the foundation
for metacognition, and metacognition builds upon consciousness. Metacognition
involves monitoring and regulating consciousness processes.
Quantum Theory of Consciousness
Physical
laws Neurobiology alone cannot explain consciousness. Some quantum physicists
suggest that consciousness
is a manifestation of quantum processes in the brain. They describe consciousness
as a computational process. Georgiev (2023) states that the evolution of brain
cortical networks contributes to increased computational power, memory
capacity, and cognitive intelligence of the living organisms. According to the quantum
theories of consciousness, quantum mechanical phenomena, like superposition and
entanglement, play a role in how the brain generates consciousness. Quantum
entanglement theorized different parts of the brain could be connected in
conscious experience. Hameroff and colleagues (2014) hypothesized that
consciousness depends on biologically 'orchestrated' coherent quantum processes
in collections of microtubules within brain neurons.
The Cultural Shaping of Consciousness
Culture
has a powerful influence on human perceptions and behavior. Therefore, culture
has played a notable role in human consciousness. Culture profoundly shapes
consciousness by influencing how individuals perceive themselves, others, and
the world around them. Cultural identity and heritage shape neurocognitive
processes. Both conscious and unconscious images are shaped by the cultural
environment. Pérez-Arce (1999) indicates that cultural factors have a
determining influence on an individual's behavior regardless of the
neurophysiological status of the brain.
According
to the evolution of human consciousness psychologist Merlin Donald, humans have
developed such a deep dependency on collective storage systems. Merlin Donald
states that the
evolution of consciousness has gone through a number of stages: episodic,
mimetic, mythic, and theoretic. Episodic con-consciousness,
characterized by episodic event perceptions and self-awareness
The Relationship Between Consciousness and Language
Conscious
capacity provides the biological basis for symbolic thought and language.
Consciousness exists prior to language development. Language and consciousness
are not separate entities but rather influence each other in a dynamic and
reciprocal way. Language helps to organize thoughts. Language shapes a
dimension of consciousness. Basic forms of consciousness can exist without
language; however, language shapes consciousness. Language is built upon
pre-existing consciousness.
Disorders of Consciousness
Disorders
of consciousness (DOC) are conditions where wakefulness and awareness are
significantly impaired. These conditions can inhibit consciousness. Brain
injuries can cause a range of disorders of consciousness. Coma, vegetative
state, and minimally conscious state are the consequences of a severe brain
injury that disrupts the brain's ability to generate consciousness (Bagnato,
2022). There is no consciousness in brain death (brain death is
the permanent, irreversible, and complete loss of brain function). A
brain-dead person is not aware and responsive to his surroundings. In a
brain-dead person, all conscious processes cease to exist.
Can Consciousness Extend Beyond the Physical Brain?
The
existence of a consciousness independent of the brain is a crucial question.
Some have argued that consciousness can exist independently of the physical
brain. The patients who encountered near-death experiences have described some
forms of out-of-body experiences. However, these experiences could be hallucinations
following brain ischemia. There is no conclusive scientific evidence to prove
that consciousness can reside outside the body.
References
Askenasy J & Lehmann J. Consciousness,
brain, neuroplasticity. Front Psychol 2013; 10(4):412.
Bagnato,S. (2022) Chapter 26 - The role of plasticity in the
recovery of consciousness, Editor(s): Angelo Quartarone, Maria Felice Ghilardi,
François Boller, Handbook of Clinical Neurology, Elsevier, Volume 184, 2022,
Pages 375-395, ISSN 0072-9752, ISBN 9780128194102.
Changeux J-P, Dehaene S 2008 The neuronal
workspace model: conscious processing and learning. In: Menzel R (ed) Learning
Theory and Behavior, Vol 1. J Byrne (ed) Learning and Memory: A Comprehensive
Reference. Elsevier, Oxford, pp 729–758.
Georgiev DD. Evolution of Consciousness. Life
(Basel). 2023 Dec 27;14(1):48. doi: 10.3390/life14010048. PMID: 38255663;
PMCID: PMC10817314.
Hameroff S, Penrose R. Consciousness in the
universe: a review of the 'Orch OR' theory. Phys Life Rev. 2014
Mar;11(1):39-78. doi: 10.1016/j.plrev.2013.08.002. Epub 2013 Aug 20. PMID:
24070914.
Lagercrantz H. The birth of consciousness.
Early Hum Dev. 2009 Oct;85(10 Suppl):S57-8. doi:
10.1016/j.earlhumdev.2009.08.017. Epub 2009 Sep 17. PMID: 19762170.
Lagercrantz H, Changeux JP. The emergence of
human consciousness: from fetal to neonatal life. Pediatr Res. 2009
Mar;65(3):255-60. doi: 10.1203/PDR.0b013e3181973b0d. PMID: 19092726.
Padilla N, Lagercrantz H. Making of the mind.
Acta Paediatr. 2020 May;109(5):883-892. doi: 10.1111/apa.15167. Epub 2020 Jan
31. PMID: 31922622.
Pérez-Arce, P. (1999). The Influence of Culture
on Cognition, Archives of Clinical Neuropsychology, Volume 14, Issue 7, 1999,
Pages 581-592.
Smallwood J, Schooler JW. The science of mind
wandering: empirically navigating the stream of consciousness. Annu Rev
Psychol. 2015 Jan 3;66:487-518. doi: 10.1146/annurev-psych-010814-015331. Epub 2014
Sep 29. PMID: 25293689.
