CNS Lecture 5 Flashcards
The Cerebellum receives sensory input from the _______ and motor commands from the _____
The Cerebellum receives sensory input from the spinal cord and motor commands from the cerebral cortex
What are the four functional divisions of the Cerebellum?
- Vermis: posture, meck and axial (trunk) musculature)
- Intermediate zone: lovomotion
- Lateral zone: coordinating complex, skilled movements of arms, hands and fingers
- Flocculonodular lobe: balance
For each of the four functional divisions of the cerebellum, describe what they are concerned with:
- Vermis: _________
- Intermediate zone: _______
- Lateral zone: _________
- Flocculonodular lobe: _______
For each of the four functional divisions of the cerebellum, describe what they are concerned with:
Vermis: posture, neck and axial (trunk) musculature)
Intermediate zone: locomotion
Lateral zone: coordinating complex, skilled movements of arms, hands and fingers
Flocculonodular lobe: balance
There is a large nuclei deep within the cerebellum called the:
Basal Ganglia
The basal ganglia form which system?
Extrapyramidal system
What are the basal ganglia involved in?
Initiating movement and suppressing activity of muscles that would resist the intended movement (antagonist muscles)
What disorders can arise from lesions in basal ganglia?
- Parkinson’s disease
- Poverty of movement (bradykinesia - slow movement)
- Rigidity
- Tremor
-
Dyskinesia - Too much movement:
- Huntington’s chorea
- Tourette’s
- hemiballismus
What are four functions that the brainstem is involved in?
- Control of respiratory and cardiovascular musculature
- Control transmission in sensory, motor, reflex and pain pathways
- initiation of movement
- Supplying NT’s to different parts of the brain
What particular area of the brainstem is involved in the initiation of locomotion?
Midbrain locomotor area (MLA)
What does the EEG (electroencephalogram) monitor?
Electrical activity in the brain
What are the three stages of NREM sleep?
NREM (slow-wave) sleep:
- Stage N1
- Stage N2
- Stage N3
During this sleep stage:
- Light sleep
- Relatively easy to wake subject
Stage N1
What is Stage N2?
What would you see on the EEG?
- Second stage of NREM (slow-wave) sleep.
- Deeper sleep than N1 (ie harder to wake someone up)
- EEG:
- Alpha waves replaced by random waves of greater amplitude
What would you see on an EEG for the N1 stage?
Alpha waves reduced in frequency, amplitude and percentage of time present
Gaps in alpha rhythm filled with theta and delta activity
What is the N3 stage?
What would you see on the EEG?
- Third stage of NREM (slow wave sleep)
- Deep sleep - more difficult to wake
- EEG:
- Much theta and delta activity
- progressive increase in delta
What is REM sleep?
What does the EEG look like?
- aka paradoxical sleep
- stage associated with dreaming, rapid eye movement, relaxed muscles, active brain
- EEG:
- waves look like alert wakefulness - beta rhythm
What are the voltage fluctuations recorded by an EEG made up of?
Summed, synchronous, post-synaptic potentials of many neurons
Waveforms vary with behavioural states: attention, arousal, sleep, dreaming
In ______ _______ voltage fluctuations can become very large
In epileptic siezures voltage fluctuations can become very large
In the vicinity of brain tumours where neurons have died, what does the EEG look like?
EEG is small or absent
Before organs are removed what is used to verify brain death?
EEG
What are sleep spindles?
A burst of oscillatory brain activity visible on an EEG that occurs during stage 2 sleep
What is the Glasgow coma scale?
Important clinical scale to classify the level of consciousness of a person
What is the glasgow coma scale based on?
- eye movements
- responses to questions
- whether the person makes voluntary movements and can obey commands to move their limbs
What are three criteria for brain death?
- nature and duration of the coma must be known
- cerebral and brainstem function are absent
- supplementary criteria includes a flat EEG for 30 minutes
What is the Reticular Activating System?
set of nuclei in the brainstem and hypothalamus that controls sleep, wakefulness and arousal
What activates neurons in the RAS (reticular activating system) during wakefulness?
Visual and other sensory inputs
The activated neurons of the Brainstem RAS release _______ to the ______ and ______
The activated neurons of the Brainstem RAS release monoamines (norepinephrine, serotonin and histamine) to the hypothalamus and other brain areas
The hypothalamus supplies _______ to the _______ to maintain wakefulness
The hypothalamus supplies orexins to the thalamus to maintain wakefulness
What are orexins?
Neuropeptide hormone
(supplied by hypothalamus to thalamus to maintain wakefulness)
What activates orexin-producing neurons in the morning and secretes melatonin at dusk?
(sets circadian rhythm)
Suprachiasmatic nucleus activates orexin-producing neurons in the morning and secretes melatonin at dusk
What is the “sleep centre”?
Pre-optic nucleus in hypothalamus that delivers GABA-ergic inhibition of RAS - reducing orexin levels
What is the RAS inhibited by?
GABA agonist sedatives (eg valium, xanax, anti-histamines etc)
Small lesions in the RAS can produce:
A coma lasting for months or years
How is wakefulness maintained?
- Orexin-producing neurons are activated by:
- the ________ of the hypothalamus
- a ______ balance (eg low blood glucose causing hunger)
- Activity of the _______ system
- _______- concerned with memory and motion triggers the drive to explore and move
- Orexin neurons then release ______ which have what effect on the sleep centre?
- Orexin-producing neurons are activated by:
- the suprachiasmatic nucleus of the hypothalamus
- a negative energy balance (eg low blood glucose causing hunger)
- Activity of the limbic system
- Limbic system- concerned with memory and motion triggers the drive to explore and move
- Orexin neurons then release monoamines (serotonin and noradrenaline) which inhibit the sleep centre and, via the thalamus, activate large parts of the cerebral cortex
How is the transition from wake to sleep carried out?
- Sleep centre is activated by a gradual increase in the blood concentration of ________
- Increase in ^ inhibits activation of the _______ in the suprachiasmatic nucleus
- Result in inhibition of activation in the _________ neurons in the RAS which results in a reduced drive to the thalamus and cerebral cortex
How is the transition from wake to sleep carried out?
- Sleep centre is activated by a gradual increase in the blood concentration of adenosine
- Increase in ^ inhibits activation of the orexin-producing neurons in the suprachiasmatic nucleus
- Result in inhibition of activation in the monoaminergic neurons in the RAS which results in a reduced drive to the thalamus and cerebral cortex
What are the 3 characteristics of consciousness?
- Awareness of the passage of time
- Awareness of external sensory inputs
- Awareness of internal states such as fatigue, thirst, happiness memories, reasoning, ideas
What are two main aspects of Conscious experiences?
- Selective attention
- Conscious perception
What is selective attention?
- Attention shifts from one focus or attractor to another
What are coincident attractors?
Visual and auditory inputs coming from the same direction
-more likely to trigger a shift in attention than separate attractors
What is conscious perception?
- Specific sets of neurons in different parts of the brain temporarily function together to generate the consciousness experience
- A central brain area selects and illuminates a temporary set of neurons in different separated brain areas (spotlight affect)
What is hemi-neglect and how might it occur?
- After a stroke affecting parietal lobe
- person is unaware of half of their visual field
- Destruction of specific brain areas that abolishes selective parts of consciously perceived inputs
What are the two divisions of motivation?
Primary and Secondary motivated behaviours
What are primary motivated behaviours?
Relate to homeostasis
- eg maintaining water balance, nutrition, body temperature
What are secondary motivated behaviours?
Behaviours resulting in pleasure
- can be disadvantageous (eg over-eating, taking recreational drugs)
What is the concept of “reward” and how does it explain motivation?
“mesolimbic dopamine pathway”
The idea is that there is a pathway in the brainstem nuclei that releases dopamine within the frontal lobe of the brain which elicits pleasure (reward)
What are emotions
Internal attitudes toward events and the environment
-external responded (emotional behaviour)
What can elicit rage responses?
Electrical stimulation in lateral hypothalamus elicits rage responses
Lesions in which region results in absence of fear?
Amygdala
How do antidepressants manage depression?
- act by maintaining levels of serotonin and norepinephrine at synapses in the CNS
- Thought that act via neurogenesis (generation of new neurons)
How is substance dependence diagnosed?
When 3+ of the 7 specified criteria occur within a twelve-month period
What are the two divisions of Memory?
- Working Memory (Short-term memory)
- episodic
- visuospatial
- phonological
- Long-term Memory
- Declarative
- Procedural
What is Working memory and what does Working memory (short term memory) include?
- Easily acquired, quickly lost
- Episodic
- recent events/ places
- Visuospatial
- recent sights, locations
- Phonological
- recent words, sounds
- Episodic
What is Long term memory and what are it’s divisions?
- Slower period of acquisition, last for much longer, even a lifetime
-
Declarative (involves consciousness)
- Semantic
- facts
- Episodic
- personal experience
- Semantic
-
Procedural (mainly subconscious)
- Stimulus-response behaviours
- motor skills
What is memory consolidation and where does it (most-likely) occur?
- Transfer from short-term to long-term memory
- occurs in the temporal lobe
- probably involves reward systems involving the hypothalamus
The _______ is implicated in consolidating stimulus-response associations taught during operant conditioning and in solving sequence tasks
The caudate nucleus is implicated in consolidating stimulus-response associations taught during operant conditioning and in solving sequence tasks
What is amnesia?
absence of memory
- retrograde
- anterograde
Loss of memory in events prior to the injury is considered:
Retrograde amnesia
Loss of memory of events after the injury is called:
Anterograde amnesia
What is a concussion measured by?
Type and duration of amnesia
What is korsakoff’s syndrome?
Complete anterograde amnesia
-often occurs in chronic alcoholism
What causes Korsakoff’s Syndrome?
Damage to hippocampus
- complete anterograde amnesia
- can be caused by chronic alcoholism
What is Alzheimers caused by?
Degeneration of memory-holding neurons
- perhaps due to proteins called amyloid precursor proteins that cause excitotoxicity
- Neurons are damaged by over-excitation
