Chapter 6: Consciousness Flashcards
What is consciousness?
Your immediate awareness of our internal and external states.
Patients with unresponsive wakefulness syndrome:
For example, patients with unresponsive wakefulness syndrome (UWS), formerly known as
vegetative state (Laureys et al., 2010), “awaken” from a coma—that is, open their eyes—
but show only reflex behavior. They are not conscious!
Consciousness is our awareness for…
our external and internal environments at any given moment.
- Sensory awareness
- Selective attention
- Direct inner awareness
Consciousness involves:
- Attention
- Monitoring
- Remembering
- Planning
4 brain areas important for consciousness:
Reticular formation: Damage to reticular formation in hindbrain, one of factors contributes to cases
where individuals are “locked in” or paralyzed and in non-communicative state like a coma.
Hypothalamus: Relays signals from reticular formation to cortex to maintain awake and attentive state.
Damage to neurotransmitter system in hypothalamus, can lead to sleep disturbances such as narcolepsy.
Thalamus: Receives input from reticular formation. Relays sensory information from various parts of the
brain to the cerebral cortex. Damage leads to lack of conscious awareness of parts of body or surrounding
environments.
Cerebral cortex: Brain’s outer covering of cells. Contains areas that aid us to be aware that we are
attending to stimuli. RH-Nonverbal awareness, LH-Verbal awareness. Synchronized activity of temporal,
parietal and visual cortex lead to awareness of object.
Evidence for levels of conscious awareness: 1. Inattentional blindness
- Inattentional blindness — failure to notice things around us to which
we are not paying attention
- e.g., Unless you pay attention to appropriate aspects of a scene, you
miss the noticeable events around you. - Attention is a key part of consciousness as demonstrated by Daniel
Simons and Colleagues.
Conscious Awareness and the Cerebral Cortex: 2. Blindsight
Blindsight — being unaware of
what has reached our attention.
- Some people with damage to area V1
show a phenomenon called blindsight,
the ability to respond in limited ways to
visual information without perceiving it
consciously. - Say they can’t see table in environment,
yet when navigate or move through
environment, can go around the table. - Conscious visual perception requires
activity in area V1!
Split Brain Patients still have some degree of conscious awareness:
- When showed a word to patient’s left hemisphere, patient
was able to say and write the word. - When a word was flashed to the right hemisphere, the
individual could not name or write it. - Yet, when told to touch screwdriver behind the screen, on basis
of touch could select the screwdriver. - Right hemisphere responsible for non-verbal form
of conscious awareness or tactile awareness.
Conscious Awareness and the Thalamus
Different areas of the brain are responsible for attention and for one’s awareness of that
attention
Intralaminar nuclei and midline nuclei of the thalamus
* Damage bilaterally – Coma
* Damage unilaterally – loss of awareness of one half of the body
Conscious Awareness and Development:
- Conscious awareness —being aware of what has reached our attention
- Conscious awareness of self seems to develop around 18 months
- Full conscious awareness develops at around 22 months
Preconsciousness:
Level of awareness in which information can
become readily available to consciousness if necessary.
Unconscious state:
State in which information is not easily accessible
to conscious awareness.
Sigmund Freud’s differentiation of different levels of consciousness:
- Conscious: information that is part of our awareness
- Preconscious: material that is not currently in awareness but readily available
- Unconscious: material that is unavailable to awareness under most
circumstances - Repression: unconscious ejection from awareness of anxiety-provoking
ideas - Suppression: conscious ejection from awareness of unwanted mental
events - Nonconscious: bodily processes that cannot be experienced through sensory
awareness
Adaptive theory of sleep:
- Adaptive theory of sleep – theory that organisms sleep for the purpose of self-
preservation, to keep away from predators - There are also biological theories of sleep- Sleeps plays a role in growth
process, pituitary gland releases growth hormone during sleep. As we age, we
release fewer of these hormones, grow less, and sleep less.
Restoration theory:
holds that sleep restores our brains and bodies. Allows
the brain to restore depleted chemical resources, while eliminating chemical
wastes that have accumulated during waking day.
What is circadian rhythm?
- Circadian rhythm (biological clock) is a 24-hour cycle of which the
sleep/wake cycle is one. - The sleep/wake cycle is controlled by the suprachiasmatic nucleus
(SCN) of the hypothalamus
What factors can change circadian rhythms?
Changes in our body and environmental factors can cause our circadian
rhythms and the natural light-dark cycle to be out of sync.
For example:
*Mutations or changes in certain genes can affect our biological clocks.
*Jet lag or shift work causes changes in the light-dark cycle.
*Light from electronic devices at night can confuse our biological clocks.
These changes can cause sleep disorders, and may lead to other chronic
health conditions, such as obesity, diabetes, depression, bipolar disorder,
and seasonal affective disorder.
The Stages of Sleep:
- Sleep stages are distinguished by different brain waves.
- Brain waves differ in frequency (number of waves per second) and
amplitude (height of the wave).
*Electroencephalograph (EEG) measures brain waves. - High-frequency waves are associated with wakefulness.
- Typically, wave frequency decreases and amplitude increases as we
relax, fall asleep, and move deeper into sleep.
Sleep and levels of consciousness
- When we fall asleep, the brain passes through distinct brain states with typical patterns of EEG activity.
- We quickly pass through levels of sleep until we reach the deepest sleep
- When we are awake and drowsy, Alpha waves are present
- Stage 1 sleep is characterized by slower waves called Theta waves
- Stage 2 sleep our brainwaves slow further, and delta waves appear
- Very deep sleep: Stage 3 and stage 4 is non-rapid eye movement (NREM) sleep, where our brain wave
are less frequent and have a higher amplitude (i.e., More delta waves are present) - Then, throughout the night, we cycle between rapid eye movement (REM) sleep, which has low
amplitude, more frequent brain waves, and NREM sleep with high amplitude of low frequency. - NREM sleep cycles become progressively less deep the longer we sleep.
- Normally, when NREM sleep shifts into REM sleep, there is a loss of muscle tone, preventing motor
movement during REM sleep.
Stage 1 of Sleep
Stage 1 - transition into sleep (5 min)
- At sleep, alpha waves change to theta waves
- HR slows, BP decreases
- Hypnagogic state, hypnagogic hallucinations and myclonic jerks
Stage 2 of sleep
Stage 2 - harder to wake (15-20 min)
- More relaxed
- Sleep spindles (burst of rapid brain waves)
Stage 3 of Sleep:
Stage 3 - deeper sleep (5-15 min)
- Theta waves and appearance of delta waves
Stage 4 of sleep
Stage 4 - deepest sleep (20-30 min)
* Slow HR, brain and body in total relaxation (20-30 min)
* Deepest sleep
* Mostly delta waves
* Sleep walking and bed wetting are more likely
Rapid Eye Movement (REM) Sleep
A stage of sleep is associated with rapid and jagged brain
wave patterns, increased heart rate, rapid and irregular
breathing, rapid eye movements, and dreaming
Theories of dreaming:
- Dreams are imagery that occur without external stimulation.
- They may seem very real to the dreamer.
- Dreams are most likely to be vivid during REM sleep.
- People can dream in colour or black and white.
- Information Processing Theory of Dreaming
- Dreams involve processing information from the day (i.e.,
encoding memory and problem solving) - Dreams could be a mental realm where we can solve problems
and think creatively
