Class notes
PSY1005S Consciousness Notes
- Institution
- University Of Cape Town (UCT)
In-depth lecture notes on the consciousness section of the course, which helped me get 83% overall.
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ConsciousnessWhat is Consciousness
~ Your perception of the external world (what is happening around you and what your senses
pick up on) and how you make sense of that in your internal world (what you are thinking
and feeling in your mind). Consciousness is the merging of the external and internal.
Definitions of Consciousness
• Useful definition: is your awareness of everything that is going on around you and
inside your own head at any given moment, including your thoughts, sensations and
feelings, which you use to organise your behaviour
• Cognitive Neuroscience: consciousness is generated by a set of action potentials in the
communication amongst neurons just sufficient to produce a specific perception,
memory or experience in our awareness
• Global Workspace theory = consciousness is a spotlight of selective attention
[Important concepts from TED video:
• There is an important distinction between the brain’s processing of
information and our experience of that processing. That experience is what
we call consciousness. (we will look at the definition in the textbook in next
slide)
• We are conscious of both the external world and our internal selves— we
are aware of an image in much the same way we are aware of ourselves
looking at an image, or our inner thoughts and emotions.
• Where does consciousness come from? Good question. Hot topic at the
moment. We will discuss different aspects of consciousness. No agreed upon
area for it’s origins. Periaqueductal grey?
, • The brain has the ability to pay attention to specific objects and events. It
also controls that focus, shifting it from one thing to another, internal and
external, according to our needs. Without the ability to direct our focus, we
wouldn’t be able to assess threats, finish a meal, or function at all.]
Altered States of Consciousness
Consciousness exists on a spectrum, and there are varying states of consciousness.
Most of our lives are spent in waking consciousness.
But, as soon as your typical alertness changes, where the wavelength of neuron electrical
activity changes (measured by and EEG), you enter an altered state of consciousness.
- Sleep = altered state of consciousness (consciousness being supressed – unconscious)
~ Are animals conscious, and thus, is it ethical to test on them?
Circadian Rhythms (NB)
Sleep-wake cycle (circa – around and dia- day = 24 hours is one day to complete the cycle
and it repeats). A biological cycle that ensures you wake and sleep when needed.
Sleep is controlled by circadian rhythms
The melatonin cycle forms part of this.
Light/no light signal SCN (hypothalamus) pineal gland melatonin
Melatonin drugs
Influence of blue light screens
1. Your body is made up of biological innate cycles that regulate how you function.
2. It starts with your eyes, which register more light in the morning – retina carries info
to optic nerve where it is sent to SCN.
, 3. Sleep-wake cycle controlled by an area withing the hypothalamus (section of brain
that influences the glandular system)
4. The suprachiasmatic nucleus (SCN) (within hypothalamus – keeps body within
homeostasis) – the ‘internal clock’ – is influenced by light changes. It signals the
pineal gland to secrete melatonin. Melatonin makes us feel sleepy.
5. As daylight fades, the SCN signals the pineal gland to secrete melatonin. As
melatonin accumulates, one becomes drowsy.
6. As daylight increases, the SCN signals the pineal gland to stop secreting melatonin+
7. Impact of using light emitting technology before sleep… Blue screens confused blue
and natural light and therefore you will not secrete melatonin…
8. This is the natural cycle but it interacts with other factors like neuron activity and
physical fatigue
[Shift workers – melatonin…have black out curtains so you can sleep during the day and
while working at night they are given a large amount of blue light.]
SCN
• The Suprachiasmatic Nucleus is situated above the optical chiasma – which is part of
the optic nerve transmitting signals from the eye to the rest of the brain.
• In the eyes light is converted to electrical impulses that travels via the neurons (optical
nerve) to the brain
• i.e., the significance of its position in relation to it being influenced by light
• Not expected to be able to label
Why do we Sleep?
We spend a considerable amount of our lives in a state of sleep.
Sleep is found across species and classes of animals
- All mammals
- Aquatic animals such as dolphins and fish
, - Birds
- Reptiles
How much sleep is enough?
- It depends on a variety of factors
- Genetics, routine – you can train yourself to sleep less.
- Short and long sleepers exist
- Young adults need between 7 – 9 h of sleep per night
- Decreases as one ages (60 = 6 hours per night. Stop going into REM sleep as you age)
Sleep in Healthy Individuals
Sleep is comprised of NREM and REM sleep.
REM (Rapid Eye Movement) Sleep:
- Active type of sleep
- Most dreaming
- Voluntary muscles are inhibited
NREM (Non-Rapid Eye Movement) Sleep:
- Deeper
- More restful
- Free to move around
3 stages of NREM
N1-N3 (used to be N1-N4)
N1 = light sleep
• Brain wave activity slows down
• Some dreaming (hallucinations)
• Hypnic jerks
• Theta waves increase (alpha waves falls away)
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