Lecture 12 - Consciousness Flashcards
Why do we need consciousness?
In order to be able to process the world around us and the co-ordination of the body in external space
What are the two streams of consciousness?
Dorsal Path - Spatial Recognition
Ventral Path - Object Recognition
Where are ‘where?’ questions processed?
In the parietal cortex
Where are ‘when’ questions processed?
In the frontal region
Where are ‘what’ questions processed?
In the ventral path
Where are ‘how’ questions processed
In the frontal region
What is consciousness?
Observation of the internal mental representation
Outline the process of conscious perception
Visual stimulus –> Primary Processing –> Directing Attention –> Conscious Perception
What are the three main features which can be used to test cognitive abilities of comatose patients?
N100 - Primary processing
N200 - Attention
P300 - Memory functions
How strong is the p300 in comatose patients?
Very weak/ non-existent
Describe the word-matching test used to check cognitive abilities in comatose patients
Testing the N400 - which is the difference between words that match and words that don’t
The N400 is barely existent in comatose patients
Outline the semantic oddball test
Tests the N100 and P500
When words don’t fit in the sentence
Some comatose patients still had a significant P500/N100
How does N100 vary with comatization?
It is intact at high levels until non-responsive, pathological EEG
How does P300 vary with comatisation severity?
Decreases rapidly as consciousness decreases
How does the N400 vary with the severity of comatisation?
It is not even reliably detected in healthy controls
How is coma state detected?
Using the N100, p300 and N400 from EEGs
What are the states of consciousness?
Wakeful Vigilance - Resting, Concentration Somnolence/Drowsiness Sleep Dream Meditation Hypnotic Ecstatic
What are the different rhythms?
Delta - 1-4 Hz Theta - 4-8Hz Alpha - 8-12 Hz Beta - 15 - 30Hz Gamma - 30-40 Hz
What brain area controls the sleep/wake cycle?
Reticular formation
What function does melatonin have?
It is secreted by the pineal gland and regu;ates the sleep wake cycle