PBSI 107 Study Notes: Consciousness and Altered States

Definition: Consciousness refers to our awareness of the external world and our internal self. There is currently no scientific consensus on its origin.
Brain's Role: The brain constructs an imperfect picture of its own activity by integrating sensory input to create models, which it uses to determine appropriate responses. It needs internal models of itself to control focus and direct attention toward different events based on our needs (e.g., a model of attention).
Impact of Brain Damage: Damage to the brain can severely impair consciousness, potentially leading to states like a persistent vegetative state.

Background: Terri Schiavo suffered from severe brain damage, leading to a persistent vegetative state (PVS). This case became a national debate regarding the right to die.
The Conflict:
- Her husband, Michael Schiavo, sought to remove life support, believing it honored her previously expressed wishes.
- Her parents argued for continued life support, believing she was still conscious or could recover.
Medical Condition:
- Percutaneous Endoscopic Gastronomy (PEG): A feeding tube was surgically placed to provide nourishment and hydration, as she was unable to eat or drink independently.
- Persistent Vegetative State (PVS): Diagnosed as only her brain stem functioning, with a complete absence of other cognitive functions or awareness.
Outcome: The feeding tube was eventually removed on March $18$ , $2005$ , leading to her death on March $31$ , $2005$ .
Broader Implications (End-of-Life Debate): This case sparked widespread national discourse on:
- The ethics of end-of-life decisions.
- The importance of living wills (advance directives).
- The role of government intervention in private medical matters.
- The philosophical and legal concept of the right to die.

Consciousness is not static; it fluctuates throughout the day, influenced by factors like hunger, pain, and sensory detection.
Waking State: Characterized by high alertness to both surroundings and internal sensations.
Sleep State: Involves reduced sensory awareness but is still a state of consciousness.
Altered States: These are states that deviate from normal waking consciousness. They are deeply subjective, and what is considered 'normal' can vary across time periods, geographical locations, and cultural contexts. Examples include states induced by drugs, meditation, or hypnosis.

Occurs when we are not fully paying attention to our surroundings. The brain attempts to