Flashcards in Neuro Physiology Deck (207)
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?
What does the right motor cortex control?
Left side (motor control)
Where do CST neurons synapse?
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?
What are the 2 ventromedial pathways called?
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?
What is the function of the reticulospinal tracts?
Maintains balance & body posture
What muscles does the reticulospinal tract activate?
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?
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?
Axons from which 2 brain areas converge on Area 6?
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?
Babinski reflex - extension
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
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?
What cranial nerves have parasympathetic innervation?
In the sympathetic system, the NT released from the preganglionic is ____ and acts on_____ receptors.
In the parasympathetic system, the NT released from the preganglionic is ____ and acts on_____ receptors.
In parasympathetic system, what NT is released from postganglionic fibres ____ and acts on _____ receptors.
In sympathetic system, what NT is released from postganglionic fibres ____ and acts on _____ receptors.
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_____.
Alpha 1 adrenergic receptors usually stimulate ______.
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
In blood vessels, sympathetic innervation can cause _____ or _____
Vasconstriction (A1) or vasodilation (B2)
Where in the body can the sympathetic system cause vasodilation?
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?
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.
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?
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?
What types of sensation do Ao fibres carry?
What types of sensation do C fibres carry?
What sensory afferents carry information about proprioception?
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?
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
What allow for better definition of boundaries in a receptor field?
What enables sensory receptors to alter firing in response to sustained stimulus?
What are the different types of pain which can be perceived?
Dull, diffuse throbbing
Phantom limb pain
What fibres would be responsible for fast stabbing pain?
Which fibres would be responsible for slow dull pain?
Which chemical mediators can activate nociceptive response at the nerve terminal?
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?
What mediates Gate control theory?
Descending inhibitory pathways
What 2 ways can the inhibitory interneuron be activated ?
By Ab fibres - rubbing it better (mechanoreceptors)
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?
Where in the brain do descending pathways come from to close the gate?
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?
Where do 3rd order neurons from the thalamus convey to?
Where does pain perception occur?
Descending pathways from the ____ radiate to the _____ which decrease pain signals.
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?
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?
What type of pain is associated with acute pain?
What type of pain is associated with poorly localised presentation?
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?
What does the hippocampus do in memory?
Formation of memory
What part does the cortex have in memory formation?
What part does the thalamus play in memory formation?
Searches & accesses memory
What areas compose the limbic system?
What areas in the limbic system are central to learning?
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
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?
What are the 2 forms of amnesia?
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?
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?
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?
If there is a deficiency in serotonin, what will be observed?
Inability to sleep
Where is melatonin produced?
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?
If defective orexin signalling is present, what condition is observed?
Narcolepsy (inability to stay awake)
Where is the main sleep centre of the brain?
What does EEG stand for?
ElectroEncepheloGram -assess neuronal activity
What are the 4 different types of wave pattern observed in EEG recordings?
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?
What sleep stage is Theta waves observed?
What sleep stages are slo w wave stages?
What stages are delta waves observed?
Which stages of sleep are categorised as deep sleep?
What does EEG recording of REM sleep mirror?
Wakefulness (fast waves)
What stage of sleep do dreams occur?
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?
Primary & secondary
In what stage of sleep do nightmares occur?
In what stage of sleep do night terrors occur?
Deep Delta sleep
What is somnambulism? When does it occur?
Stage 4 sleep
What sleep stage to patients with narcolepsy enter straight in to?
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)
Where are sensory hair cells found in the vestibular apparatus?
What is the name given to both the utricle & saccule combined?
What do the otolith organs detect?
Changes in linear acceleration
What does the saccule specifically sense?
What does the utricle specifically sense?
What do the semi-circular canals sense?
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?
What is the name of the flexible gelatinous structure found in the ampulla?
What is the name of the fluid which moves through the SCCs?
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?
What will happen is cilia are distorted away kinocilium?
What are the sensory receptors of the otolith organs called?
The maculae in the utricle are orientated in what plane?
The maculae in the saccule are orientated in what plane?
What is the gelatinous membrane called found at the maculae?
What is embedded in the otolith membrane?
What forces affect otoliths?
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?
Where does the vestibular nerve carry information to??
What is the name for the perception of movement & body position?
Name some of the vestibular system reflexes
Tonic labyrinthine reflex
Dynamic righting 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?
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?
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?
What is kinetosis?
What is labyrinthitis?
Infection of the vestibular system
What is Meniers disease caused by?
Increased endolymph resulting in increased pressure