Higher Cortical Function / The Reticular Formation and Consciousness Flashcards
Which hemisphere of the brain deals with language and mathematical processing in 95% of people?
Left hemisphere
Define “arousal”
The emotional state associated with some kind of goal or avoidance of something noxious
Define “consciousness”
This is difficult, but something to do with “awareness” of both external and internal states
How do Wernicke’s aphasia and Broca’s aphasia differ?
Wernicke’s aphasia- Broca’s area is working so fluent speech is produced, but the speech doesn’t make sense
Broca’s aphasia- Wernicke’s area is working so they are understanding and making sense, but unable to articulate what they are wanting to say
Which two basic ingredients required for consciousness?
Cerebral cortex
Reticular formation
What is the reticular formation?
A population of specialised interneurones in the brainstem
What are the inputs of the reticular formation?
The cortex
The somatosensory system
What are the outputs of the reticular formation?
Thalamus
Hypothalamus
Basal forebrain nuclei
Spinal cord
Which neurotransmitter is released at the basal forebrain nuclei during arousal?
Acetylcholine
Which neurotransmitter is released at the hypothalamus during arousal?
Histamine
Which neurotransmitter is released at the thalamus during arousal?
Glutamate
The cortex and reticular formation for a _________ feedback loop
Positive
What can we use clinically to assess consciousness?
What are the value ranges?
The Glasgow Coma Scale
3 (bad)—->15 (good)
How can we clinically measure consciousness?
The electroencephalogram (EEG)
If the neurones in the brain are deprived of sensory input, what do they tend to do?
Fire synchronously
During the night, you typically pass through how many cycles of sleep?
6
What are the 6 stages of sleep?
Awake Stage 1 Stage 2 Stage 3 Stage 4 Stage 5 REM sleep
What is the wave form shown on an EEG during the awake period?
Describe the wave pattern & speed.
Beta waves
Irregular and complex
Around 50Hz
What is the wave form shown on an EEG during the period when eyes are closed (not yet asleep)?
Describe the wave pattern & speed.
Alpha waves
Slower than beta waves, regular-loss of external input
Around 10Hz
What is the wave form shown on an EEG during stage 1 of the sleep cycle?
Alpha waves + Theta waves
Delta waves are around 5 Hz
What is the wave form shown on an EEG during stage 2/3 of the sleep cycle?
Theta waves + Sleep spindle + K- complex
Sleep spindle - the thalamus trying to wake the cortex up
K-complex - intrinsic rate of the cortex as most input is taken away “complete brain block”
What is the wave form shown on an EEG during stage 4 of the sleep cycle?
Describe the wave pattern & speed.
Delta waves - intrinsic cortical activity
Neurones firing all together
Slow and synchronous
What is the wave form shown on an EEG during REM sleep?
Describe the wave pattern & speed.
REM sleep looks like beta waves - as if eyes were open but the stimulation instead comes from the cortex
Around 50 Hz
The frontal lobes are responsible for what functions?
Motor Expression of speech Behavioural regulation Cognition Continence Eye movements
The parietal lobes are responsible for what functions?
Sensory Comprehension of speech Body image Awareness of external environment Calculation & writing (visual pathways projecting through the white matter)
The temporal lobes are responsible for what functions?
Hearing Olfaction Memory Emotion (visual pathways projecting through the white matter)
What is the role of the corpus callosum?
It connects the two cerebral hemispheres
