Neuro Physiology Flashcards
What are the 3 levels of functional hierarchy observed in motor control?
Strategy - basal ganglia
Tactics - motor cortex & cerebellum
Execution - brainstem & spinal cord
What do lateral spinal pathway control?
Voluntary movements of distal muscles
What do ventromedial spinal pathways control?
Control posture & locomotion
Where does the CS tract cross over?
Medulla
What does the right motor cortex control?
Left side (motor control)
Where do CST neurons synapse?
Ventral horn
Where does the Rubrospinal tract originate?
Red nucleus (midbrain)
If a lesion of CST or RST occurs what will be observed?
Fine movements of hands & arms lost
If the CST alone is lesioned what will be observed?
Some deficits seen however function will reappear after a few months
What is the Brodmanns area associated with motor control?
Area 4
What are the 2 ventromedial pathways called?
Vestibulospinal
Tectospinal tracts
Reticulospinal tract
What is the vestibulospinal tract responsible for?
Stabilises head & neck
What is the tectospinal tract responsible for?
Ensures eyes remain stable as body moves
Where do the reticulospinal tracts originate?
Brainstem
What is the function of the reticulospinal tracts?
Maintains balance & body posture
What muscles does the reticulospinal tract activate?
Trunk muscles
Antigravity muscles
Where are LMNs found?
Ventral horn of spinal cord
Medial motorneurones will control which muscles?
Axial & proximal limb muscles
Lateral motor neurones will control which muscles?
Distal limb muscles
What is another name for he primary motor cortex?
Pre-central gyrus
What lies in front of the primary motor cortex?
Pre-motor cortex (PMA)
Stimulating the right primary motor cortex will result in what?
Twitching of right limb
What inputs to the posterior parietal cortex allow knowledge of body in space?
Somatosensory
Proprioceptive
Visual
Axons from which 2 brain areas converge on Area 6?
Prefrontal cortex
Posterior Parietal cortex
If you only think about carrying out a movement, which are of the brain will become active?
Area 6 - pre-motor cortex
What is Area 6 responsible for?
Encodes decried actions and converts this int how to carry them out
Where will neuronal stimulation be identified just before a planned movement takes place?
PMA - Premotor cortex
In order to perform precise movements, what firing of Abs will be observed in Area 4?
Integrated activity of large population of neurones in M1 will produce precise movements
What symptoms/signs will be observed with cortical damage?
Contralateral flaccidity Hyperreflexia Babinski reflex - extension Spasticity Clonus
Describe the loop of information from cortex to basal ganglia
Inputs will move from cortex > thalamus > basal ganglia and back to SMA (AREA 6)
What is the corpus striatum? Role?
Caudate nucleus & putamen
Input zones of basal ganglia
What is the corticstriatal pathway?
Inputs running from the cortex to the basal ganglia
In Parkinsons disease, which area of the brain is affected?
Substantia niagra degeneration (dopaminergic neurons)
What are some of the classical signs of Parkinsons disease?
Slowness in voluntary movements
Increase muscle tone
Tremors in hands
What is observed in the brain of someone with Huntingtons disease?
Profound loss of caudate, putamen & globes pallidus (inhibitory basal ganglia)
What are some of the signs associated with Huntingtons disease?
Hyperkinesia - chorea
Dementia
Personality disorder
What is chorea?
Spontaneous, uncontrolled rapid flicks & movements
A lesion in the cerebellum will result in what?
Uncoordinated movements = Ataxia
Where do preganglionic sympathetic nerves synapse?
Sympathetic chain
What cranial nerves have parasympathetic innervation?
3,7,9,10
In the sympathetic system, the NT released from the preganglionic is ____ and acts on_____ receptors.
Ach
Nicotinic
In the parasympathetic system, the NT released from the preganglionic is ____ and acts on_____ receptors.
Ach
Nicotinic
In parasympathetic system, what NT is released from postganglionic fibres ____ and acts on _____ receptors.
Ach
Muscarinic
In sympathetic system, what NT is released from postganglionic fibres ____ and acts on _____ receptors.
Noradrenalin
Adrenergic
At the adrenal medulla, what stimulates release of adrenalin?
Sympathetic postganglionic fibres
In the eye, sympathetic activation causes what?
Contracts radial muscle = pupillary dilation
Relaxtion of ciliary body = focusses far away
B2 adrenergic receptors usually stimulate_____.
Relaxation
Alpha 1 adrenergic receptors usually stimulate ______.
Contraction
In parasympathetic activation, what happens to the eye?
Contraction of sphincter muscle = pupillary constriction
Ciliary body contraction = lens focusses close up
Eye drops used to dilate the eye may contain ______ or ______.
Alpha 1 agonist
Muscarinic antagonist
In blood vessels, sympathetic innervation can cause _____ or _____
Vasconstriction (A1) or vasodilation (B2)
Where in the body can the sympathetic system cause vasodilation?
Skeletal muscle
Cardiac muscle
In the respiratory system, sympathetic stimulation will result in _____.
Relaxation of smooth muscle
What will happen in the Valsalva manoeuvre?
Sympathetic stimulation will increase HR & SV as a result of decrease in venous return during breath hold
What are the different types specific sensory receptor types which measure different modalities of sensation?
Nociceptors Chemoreceptors Mechanoreceptors Thermoreceptors Proprioceptors
When a stimulus is sensed, what is the name of the potential that is transduce?
Receptor (generator) potential
The size of the ______ encodes the intensity of stimulus.
Generator potential - graded potential
The frequency of _____ encodes the intensity of stimulus.
Action potential
What does the receptive field encode?
The location of the stimulus
Which test can be done to assess the size of receptive field?
2 point discrimination tests
What are the 3 primary afferent cutaneous sensory fibres?
Ab
Ao
C
Which is the fastest sensory afferent?
Ab (large myelinated fibres)
Which is the slowest sensory afferent?
C (unmyelinated fibres)
What types of sensation do Ab fibres carry?
Touch
Pressure
Vibration
What types of sensation do Ao fibres carry?
Fast pain
Cold
Pressure
What types of sensation do C fibres carry?
Slow pain
Warmth
What sensory afferents carry information about proprioception?
Ab
Aa
In which spinal column do Ab & Aa fibres go up?
Ipsilateral dorsal column (carrying mechanoreceptor/ proprioceptive info)
In which spinal column do C & Ao fibres ascend?
Contralateral spinothalamic tracts
How many neurones are present in ascending tract?
3
If damage occurs to dorsal column what will be observed?
Loss of pressure, touch, vibration of same side
If damage occurs to the anterolateral column of spinal cord what will be observed?
Loss of pain sensation on opposite side
Convergence will result in _____ acuity
Reduced
What allow for better definition of boundaries in a receptor field?
Lateral inhibition
What enables sensory receptors to alter firing in response to sustained stimulus?
Adaption
What are the different types of pain which can be perceived?
Sharp stabbing Dull, diffuse throbbing Visceral pain Referred main Phantom limb pain
What fibres would be responsible for fast stabbing pain?
Ao fibres
Which fibres would be responsible for slow dull pain?
C fibres
Which chemical mediators can activate nociceptive response at the nerve terminal?
Bradykinin
Prostaglandin
Histamine
Which channel do opiates mediate their action at the nerve terminal?
K channels - hyper polarise cell therefore inhibit signal transduction
Where do Ao/C fibres synapse?
Dorsal horn
What mediates Gate control theory?
Inhibitory interneuron
Descending inhibitory pathways
What 2 ways can the inhibitory interneuron be activated ?
By Ab fibres - rubbing it better (mechanoreceptors)
Descending pathways
How does the inhibitory interneuron close the gate at the dorsal horn?
Releases opiate peptides which inhibit synaptic release
What is another name for opiate peptides?
Endorphins
Where in the brain do descending pathways come from to close the gate?
PAG
NRM
What does prostaglandin do at the sensory nerve terminal?
PGN sensitises nociceptors to bradykinin
How do NSAIDs mediate their action?
Reduce PGN being produced therefore reduce the sensitisation of nerve terminal to bradykinin
How do TENS machines work?
Stimulate Ab fibres therefore activating inhibitory interneuron, reducing synaptic transmission
How does morphine mediate pain relief?
Reduces nociceptive sensitivity
Blocks synaptic transmission at dorsal horn (epidural)
Activates descending pathways
How do local anaeasthetics block pain transmission?
Block Na APs therefore all axonal transmission
Where do 2nd order neurons in the spinothalamic tract synapse?
Thalamus
Where do 3rd order neurons from the thalamus convey to?
Somatosensory cortex
Cingulate gyrus
Limbic system
Where does pain perception occur?
Somatosensory cortex
Descending pathways from the ____ radiate to the _____ which decrease pain signals.
Peri-aquaductal grey
Dorsal horn
What is hyperalgesia?
Exaggerated response to pain from normal stimuli
What is allodynia?
Decreased threshold for pain response
What are the 3 components of central sensitisation to pain?
Wind-up
Classical
Long term potentiation
How does wind-up central sensitisation mediate action?
Increases release of NT therefore increased response of neurons
How does CLASSICAL central sensitisation mediate action?
activates new synapses in the dorsal horn resulting in increased perceptive of noxious stimuli, lasts longer than original stimuli
How does long term potentiation central sensitisation mediate action?
Incorporates more receptors on post-synaptic side therefore increased response perceived
How long does acute pain last for?
1 month & resolves with healing of tissue damage
How long does chronic pain last?
> 3-6 months, lasting longer than duration of healing
Which type of pain is protective?
Acute
What type of pain is associated with acute pain?
Nociceptive pain
What type of pain is associated with poorly localised presentation?
Neuropathic
What is pain?
A sensory perception of the mind (not a stimulus)
What is cognition?
Highest brain function
Integration of all sensory information to make sense of situation
What are the 3 components of learning & memory?
Hippocampus
Thalamux
Cortex
What does the hippocampus do in memory?
Formation of memory
What part does the cortex have in memory formation?
Stores memory
What part does the thalamus play in memory formation?
Searches & accesses memory
What areas compose the limbic system?
Hypothalamus
Hippocampus
Cingulate gyrus
Amygdala
What areas in the limbic system are central to learning?
Punishment
Reward areas
If damage occurs to hippocampus, what will happen to memory?
Intact immediate & long term memory however unable to form new memories
What are the different types of memory?
Immediate (sensory) memory
Short-term memory
Immediate long term
Long term memory
Which type of memory is described as working memory?
Short term memory
Which the of memory is associated with electrical excitation of reverberating circuits?
Short term memory
If the memory in the reverberating circuit is deemed significant what will happen next?
Consolidated and stored in long term memory
If the reverberating circuit is disrupted eg head trauma and the hippo/thalamus is damaged what can occur?
Amnesia
What are the 2 forms of amnesia?
Anterograde
Retrograde
What will anterograde amnesia result in?
Inability to form new memories
What will retrograde amnesia result in?
Inability to retrieve old memories
What is intermediate long term memory dependant on?
Chemical changes at the presynaptic neuron
What is long term memory (LTM) dependant on?
Structural changes at the synapse
What structural changes occur at the synapse in formation of LTM?
Increase in NT release sites
Increase in vesicle & NT stored on pre-synpatic side
Increase in number of presynaptic terminals
What is another term for strengthening of the synapse observed in LTM?
Long term potentiation
What are the 2 types of LTM?
Declarative
Procedural
What is declarative LTM?
The ability to recall events (episodic) & language (semantic memory)
What is procedural LTM?
Often acquired through repetition, includes motor memory skills eg paying tennis, driving etc
How can short term memories be converted to LTM?
Consolidation (strengthening of synaptic connections by repetition)
What composes the Papez circuit?
Hippocampus
Mammillary bodies
Anterior thalamus
Cingulate gyrus
What is the definition of sleep?
A state of unconsciousness from which a person can be aroused by normal stimuli
What chemical is the precursor for melatonin?
Serotonin
If there is a deficiency in serotonin, what will be observed?
Inability to sleep
Where is melatonin produced?
Pineal glands
What structure in the hypothalamus is thought to contribute to sleep induction?
Suprachiasmatic nuclei (SCN)
What does activity of the SCN in the hypothalamus stimulate?
Release of melatonin
What is the name of the excitatory NT released from the hypothalamus which is required for wakefulness?
Orexin
If defective orexin signalling is present, what condition is observed?
Narcolepsy (inability to stay awake)
Where is the main sleep centre of the brain?
Reticular formation
What does EEG stand for?
ElectroEncepheloGram -assess neuronal activity
What are the 4 different types of wave pattern observed in EEG recordings?
Alpha
Beta
Theta
Delta
What EEG waves are associated with awake, relaxed?
alpha waves (^ are, ^ amplitude)
What EEG waves are associated with being awake & alert?
Beta waves (^ freq, low amplitude)
What EEG waves are associated with children and stress in adult?
Theta waves (Low freq)
What EEG waves are associated with deep sleep?
Delta waves (low freq, high amplitude)
How many stages of sleep are present in the sleep cycle?
5
What sleep stage is Theta waves observed?
Stage 1
What sleep stages are slo w wave stages?
1-4
What stages are delta waves observed?
Stage 3-4
Which stages of sleep are categorised as deep sleep?
3-4
What does EEG recording of REM sleep mirror?
Wakefulness (fast waves)
What stage of sleep do dreams occur?
REM sleep
How often does REM sleep cycle/last for?
Occurs every 90 mins and lasts 5-30 mins
What is the name of a specific sleep disorder & what are the different types?
Insomnia
Primary & secondary
In what stage of sleep do nightmares occur?
REM sleep
In what stage of sleep do night terrors occur?
Deep Delta sleep
What is somnambulism? When does it occur?
Sleep walking
Stage 4 sleep
What sleep stage to patients with narcolepsy enter straight in to?
REM sleep
Where is the “master clock” which regulates the circadian rhythm?
Suprachiasmatic nuclei in hypothalamus
What is the function of the vestibular system?
Sensation of balance & posture
Where is the vestibular system found?
Inner ear (temporal bone)
What is the vestibular system composed of?
Membranous fluid filled canals (labyrinths)
What is the vestibular apparatus composed of?
3 semi-circular canals (superior, posterior & horizontal)
Utricle
Saccule
Where are sensory hair cells found in the vestibular apparatus?
Ampulla
Utricle
Saccule
What is the name given to both the utricle & saccule combined?
Otolith organs
What do the otolith organs detect?
Changes in linear acceleration
What does the saccule specifically sense?
Vertical movement
What does the utricle specifically sense?
Back/front movement
What do the semi-circular canals sense?
Rotational acceleration
Where are the sensory receptors in the SCCs found?
Swellings at the base of canals called Ampulla
What is the name of the sensory receptors in the SCCs?
Cristae
What is the name of the flexible gelatinous structure found in the ampulla?
Cupula
What is the name of the fluid which moves through the SCCs?
Endolymph
What is embedded within the gelantinous cupula?
Cilia of hair cells
What way will endolymph move in side the SCCs?
Opposite direction to movement
What accounts for dizziness?
Suddenly stopping following rotational acceleration will result in continued motion of endolymph = dizziness
What are the 2 types of cilia called at the hair cells?
Kinocilium (1 large)
Stereocilia (multiple small)
What will happen is cilia are distorted towards kinocilium?
Depolarisation
Increased APs
What will happen is cilia are distorted away kinocilium?
Hyperpolarisation
Decreased Abs
What are the sensory receptors of the otolith organs called?
Maculae
The maculae in the utricle are orientated in what plane?
Horizontal
The maculae in the saccule are orientated in what plane?
Vertical
What is the gelatinous membrane called found at the maculae?
Otolith membrane
What is embedded in the otolith membrane?
Otolith crystals
What forces affect otoliths?
Gravitional
Moving the head back/forward with result in what happening at maculae?
Gravitational movement of otolith & membrane, thus moving cilia and causes firing of APs
If the head is tilted backwards, what will happen to no. of APs?
Cilia will move towards the kinocilium and cause depolarisation (inc. APs)
If the head is tilted FORWARDS, what will happen to no. of APs?
Cilia will move away from kinocilium and cause hyperpolarisation (decreased Aps)
Which nerve carries information from the 2 maculae & 3 cristae of SCCs?
Vestibular nerve
Where does the vestibular nerve carry information to??
Cerebellum
What is the name for the perception of movement & body position?
Kinaesthesia
Name some of the vestibular system reflexes
Tonic labyrinthine reflex
Dynamic righting reflex
Vestibule-Ocular reflex
What does the tonic labyrinthine reflex do?
Keeps the axis of the head in relationship with the rest of the body
What does the dynamic righting reflex do?
It keeps you upright if you trip, rapid postural changes
What are the different reflex tests of the vestibulo-ocular reflex?
Static
Dynamic Vestibular Nystagmus
What is the static reflex testing?
Movement of the head results in involuntary eye movements in order to maintain upright image
What is the dynamic vestibular nystagmus?
Saccidic movements of the eye which rotate against the direction of movement
If there is R nystagmus, which direction will the rapid eye movement be observed?
Right sided eye flick
What ways can nystagmus be tested?
Post-rotational nystagmus Caloric stimulation (cold/hot water)
If hot water is injected into outer ear, which way will nystagmus be observed?
Same side as ear injected
What is the mnemonic used to remember the side to which nystagmus occurs with cold/hot water?
COWS
What is kinetosis?
Motion sickness
What is labyrinthitis?
Infection of the vestibular system
What is Meniers disease caused by?
Increased endolymph resulting in increased pressure
What symptoms are observed with Menieres disease?
Nausea
Tinnitus
Vertigo
Nystagmus