Consciousness (Physiological Point of View)

1. Consciousness (Physiological Point of View) by: Alvin Lee Jin Wen Ahmad SallehuddinMukhtarruddin

2. Introduction • Generally consciousness is the relation between the mind and the world it interact. • It is difficult to really define consciousness as it can be view from : 1. Philosophical point of view 2. Scientific (physiological point of view)

3. ` • The study of human consciousness was long considered outside the province of science , more appropriate as a subject for philosophy or religion. One reason for this view is consciousness is both broad-encompassing our awareness of ourselves and experiences- and subjective. • Over the past decade however neuroscientist began studying consciousness using MRI , PET scan etc. • It is now possible to compare activity in the human brain during different state of consciousness – e.g. before/ after seeing an object.

4. These studies does not pinpoint a “consciousness centre” in the brain rather they offer an increasingly detailed picture of how neuronal activity correlates with consciousness experience. • Physiologically, we opt to find Neuro-Correlates of Consciousness (NCC) to explain the consciousness phenomenon.

5. 1. Reticular Activating System (RAS) • “The system of cells of the reticular formation of the medulla oblongata that receives collaterals from the ascending sensory pathways and projects to higher centres ; they control the overall degree of CNS activity including wakefulness , attentiveness , and sleep” Saunders Comprehensive Veterinary Dictionary 3rd Ed.

6. It used to be thought that wakefulness depended only on the direct reception of afferent (sensory) stimuli at the cerebral cortex • Physiologists had proposed that some structure deep within the brain controlled mental wakefulness and alertness. • RAS Comprised of the • Motor system (reticulo-spinal system) • Sensory systems (RAS) • Vital centres

7. The RAS stimulates the whole brain to cause arousal (wakefulness) • It’s output is suppressed in sleep & coma Stimulated by : • Input from the cortex (corticofugal fibres) • OREXINS • Peptides released by hypothalamic neurons just before waking

9. 2. Medical Approach Assessing Consciousness •  Derives from a need to treat people whose brain function has been impaired as a result of disease, brain damage, toxins, or drugs. •  The medical approach focuses on the amount of consciousness a person has: in medicine, consciousness is assessed as a "level" ranging from coma and brain death at the low end, to full alertness and purposeful responsiveness at the high end

10. 2 ways of assessing consciousness in medicine: 1.Simple procedure that requires minimal training. • 1.1 Asking whether the patient is able to move and react to physical stimuli • 1.2 Asking whether the patient can respond in a meaningful way to questions and commands • 1.3 Asked for name, current location, and current day and time •  A patient who can answer all of these questions is said to be "oriented times three" (sometimes denoted "Ox3" on a medical chart), and is usually considered fully conscious.

11. 2.A more complex procedure that requires substantial expertise. • 2.1 Known as a neurological examination and is usually carried out by a neurologist in a hospital setting. • 2.2 Examination runs through a precisely delineated series of tests, beginning with tests for basic sensor motor reflexes, and culminating with tests for sophisticated use of language. • 2.3  Glasgow Coma Scale which yields a number in the range 3—15, with a score of 3 indicating brain death (the lowest defined level of consciousness), and 15 indicating full consciousness.

12. Impairment of conciousness Free Powerpoint Templates

13. How conciousness maybeimpaired? • brain’s ability to adjust its activity and consciousness levels can be impaired in several ways: • Severe sleep deprivation • After a seizure (Epilepsy) • both cerebral hemispheres are suddenly and severely damaged • the reticular activating system malfunctions • blood flow or the amount of nutrients (such as oxygen or sugar) going to the brain decrease • When toxic substances impair the brain (liver & kidney failure) • Drugs • -morphine • -diazepam • -antipsychotic drugs

14. Periods of impaired consciousness can be shortor long. The level of impairment can range from slight to severe: a)Lethargy- slight reduction in alertness or clouding of consciousness. People tend to be less aware of what is happening around them and to think more slowly. b)Obtundation- moderatereduction in alertness or clouding of consciousness. c)Stupor- excessively long or deep sleep-like state. A person can be aroused from it only briefly by vigorous stimulation, such as repeated shaking, loud calling, pinching, or sticking with a pin. d) Coma- state of complete unresponsiveness. A person cannot be aroused at all. A person in a deep coma lacks even the most basic responses, such as avoidance of pain. Reflexive behavior present

15. How conciousness maybeimpaired? • brain’s ability to adjust its activity and consciousness levels can be impaired in several ways: • Severe sleep deprivation • After a seizure (Epilepsy) • both cerebral hemispheres are suddenly and severely damaged • the reticular activating system malfunctions • blood flow or the amount of nutrients (such as oxygen or sugar) going to the brain decrease • When toxic substances impair the brain (liver & kidney failure) • Drugs • -morphine • -diazepam • -antipsychotic drugs

16. Periods of impaired consciousness can be shortor long. The level of impairment can range from slight to severe: a)Lethargy- slight reduction in alertness or clouding of consciousness. People tend to be less aware of what is happening around them and to think more slowly. b)Obtundation- moderatereduction in alertness or clouding of consciousness. c)Stupor- excessively long or deep sleep-like state. A person can be aroused from it only briefly by vigorous stimulation, such as repeated shaking, loud calling, pinching, or sticking with a pin. d) Coma- state of complete unresponsiveness. A person cannot be aroused at all. A person in a deep coma lacks even the most basic responses, such as avoidance of pain. Reflexive behavior present

17. Coma • -brain oxygen utilization is below normal resting levels • (in sleep, the brain is active and oxygen consumption is comparable to the waking state)

18. Coma • Caused by: • A)trauma • B)tumours • C)metabolic disorders • -hypoglycaemia (hyperosmolar coma) • -drug overdose • -liver and kidney failure • -fluids & electrolytes imbalance • -hypernatraemia (>Na+) • -hypokalaemia (<K+) • -water intoxication • -myxoedema (hyperthyroidism) • D)Depression of the reticular activating system (RAS) • Clinically assessed using Glasgow Coma Scale (GCS) • Four Score Coma Scale • eye & motor responses • brain stem reflexes • respiration. Total unresponsiveness to sensory stimuli for an extended period

19. Glasgow Coma Scale

20. Severe, with GCS ≤ 8 Moderate, GCS 9 - 12 Minor, GCS ≥ 13. FIN.