Neurobiology Theme 3 Flashcards
what are the types of sensory receptors in the skin
hair follicle receptors free nerve endings meissner corpuscle merkel cells pacinian corpuscle ruffini endings
what are hair follicle receptors
sense motion, direction
fibre type II (a beta)
small receptive field
uncapsulated
what are free nerve endings
nociception III ( adelta) & IV (cfibres)
what are meissner corpuscles
tap, flutter
fibre type II ( a beta)
small receptive field
encapsulated
what are merkel cells
touch, pressure
fibre type II (a beta)
small receptive field
unencapsulated
what are pacinian corpuscles
vibration
type II (a beta)
large receptive field
encapsulated
what are ruffini corpuscles
skin, stretch (slippage)
fibre type II (a delta)
large receptive field
encapsulated
what type of threshold do skin receptors usually have
low
except for nociceptors which have high
what is sensory transduction
conversion of a sensory stimulus from one form to another
describe signal transduction on the pacinian corpuscle
pressure on skin changes shape of pc stretching na channels so na influx.
depolarisation, more +ve inside cell.
only when threshold is reached AP is propagated (generator potential)
what type of action potential do sensory receptors generate
tonic- steady and constant firing
how can we tell between light and touch
changes in firing rate- increase in tonic firing
duration of time for AP
activation of different receptive fields
what is the difference between rapid and slow adapting receptors
rapid will respond to the application and removal of stimulus & fail to respond to a maintained stimulus
slow will increase firing rate if stimulus increased
what are some ex of rapid adapting receptors
meissner corpuscle
hair follicles receptors
pacinian corpuscle
what are some ex of slow adapting receptors
merkel cells
hair follicle receptors
ruffini corpuscles
what is the receptive field
space occupied by a sensory receptor that can elicit a response to a stimulus (may be overlap)
different receptors have different sized receptive fields
what would the receptive field be like on fingertips
small, numerous
more fields
highly discriminatory (can discriminate between 2 receptive fields)
what would the receptive field be like on the back
large, sparse
low discrimination
where is there a convergence of pathways in the body
rod of retina which signal to one bipolar neurone and one retinal ganglion cell can head to the brain
what happens in divergence
one neurone can make many divergent connections to a number of post synaptic neurones
what is the purpose of divergence and convergence
one sensory modality can alter the other like in the gated theory of pain
in sensitive areas what happens to receptive fields
they overlap
what is lateral inhibition
the ability of an excited neurone to reduce the activity of its neighbours
what happens when there is stimulation of the centre of the field
the lateral aspects can also be stimulated
what happens to the lateral neurones when the centre neurone is central neurone is stimulated
they are inhibited by interneurones from the middle neurone
what does the brain receive in lateral inhibtion
info from the middle neurone to provide a more accurate and discriminative input
what are the two motorneurones in the ventral horn that innervate skeletal muscle
alpha motor neurones
gamma motor neurones
specifically what the alpha motor neurones innervate
extrafusal muscle fibres
specifically what do gamma motor neurones innervate
intrafusal muscle fibres (within muscle spindle)
spindle measures the degree of stretch tension within the muscle
what does the myotactic (stretch) reflex involve
- 1A afferents bringing back info from muscle spindle relating to the degree of stretch
- excite the flexor/extensor muscle that it is coming from
- inhibitory inter neurones will inhibit the activity of the opposite muscle being excited
where do preganglionic sympathetic axons arise and where do they go
lateral horn of the thoracic spinal cord and enter the sympathetic chain and synapse in the sympathetic ganglia
what is flaccid paralysis caused by
damage to lower motor neurones due to no innervation of the muscle it supplies so muscle will not work
what is spastic paralysis caused by
damage to upper motor neurones (e.g stroke, lesion i spinal cord) , lower motor neurones still active and under reflex control
what signals change in length in muscle spindle
1a afferents- stimulate muscle contraction
what signals change in tension in golgi tendon organ
1b afferents - inhibit muscle contraction
what will an increase in muscle length causes
activation of stretch and tendon(dampen down stretch reflex) reflexes
what is the central pattern generator
generation of alternate flexion and stretching during routine movements e.g. walking (within the spinal cord or brainstem)
the primary somatosensory cortex is the site for the termination of what pathway
thalamocortical
what does the primary somatosensory cortex contain
a topographical map of senses proportionate to the amount of sensory info
what are Brodmans areas 1,2,3
in the post central gyrus, compartmentalisation based on different functions
what is area 3b
primary somatosensory cortex
what is area 3a
proprioception
what is area 3b and 1
cutaneous stimuli
what is area 2
tactile and proprioception, size and shape
how is the post central gyrus organised
columnar organisation
what does the columnar organisation of the post central gyrus allow for
exact info from body areas to be extracted & processing of all info from nearby modalities
where is the secondary somatosensory cortex located
towards the end of the post central gyrus
sup aspect is the lateral sulcus
what is the secondary somatosensory cortex involved in
higher order functions
- sensorimotor integration
- integration info from the 2 body halves
- attention, learning and memory
where is the association cortex for the primary somatosensory cortex located
posterior parietal cortex
what is the function of the posterior parietal cortex
integrate sensory info
recognition of objects by touch
what does the lateral corticospinal tract do
voluntary control of distal musculature- trunk and limbs
why are movements from one side of the body controlled by the opposite cerebral cortex
corticospinal & corticobulbar tract originate in the motor area are the cerebral cortex but decussate to the other side of the brainstem
what does the anterior corticospinal do
voluntary control of proximal musculature (either under voluntary or unvoluntary control) - trunk and limbs
what do the reticulospinal tracts do
from pontine and medullary reticular formation into the spinal cord
regulate flexor reflexed and initiate patterned activity e.g. locomotion, swallowing
what to rubrospinal tracts do
red nucleus
motor control, excitation of flexor muscles
which tract is the red nucleus apart of
rubrospinal
regulates ongoing movement
where does the tectospinal tract run from
sup & inf colliculus in the tectum to cervical region of spinal cord
what is the role of the tectospinal tracts
orientation to auditory and visual stimuli
control head movements in response to visual stimuli
where does the vestibulospinal tract run from
vestibular nucleus to the spinal cord
what do the lateral & med vestibulospinal tract do
lateral- controls antigravity muscles- balance
medial- regulates head movements
what are upper motor neurones
those found in the cerebral cortex
what are the 2 ways UMN can project to LMN
directly or indirectly
how can UMN project directly onto LMN
corticospinal or corticobulbar tracts
what can damage to direct pathways cause
babinski sign: paralysis, paresis (weakness) of fine skilled movements
why do segmental reflexes remain unaffected when there is damage to the direct pathways
local reflexes still present
only descending pathways damaged
what are the indirect pathways that UMN can project onto LMN
brainstem nuclei to LMN
- rubrospinal tract
- vestibulospinal tract
- tectospinal tract
- reticulospinal tract
what is the role of the indirect pathways of projection
integrate supporting musculature during voluntary movements & facilitate spinal reflexes involved with balance, posture eqm etc.
where does the lateral corticospinal tract decussate
medulla-spinal cord junction.
it innervates the LMN on the other side
where does the anterior corticospinal tract decussate
at the segmental level in the spinal cord
where is the internal capsule located
between basal ganglia and thalamus
what passes through the internal capsule
corticospinal and corticobulbar fibres
how is the internal capsule organised
segmented to receive fibres from different limbs and part of the face
what type of stroke affects the internal capsule
lacunar stroke- this can take out the corticobulbar/corticospinal fibres
what does the tectum consist of
sup and inf colliculi in the midbrain
what is the reticular formation
all the neurones in the pons/medulla that are not in a specific nuclei or axons not in a particular pathway
what does the reticular formation contain
many nuclei and fibres travelling to cortex that release neuromodulators such as AchCh, serotonin and nor adrenaline
what is the function of the reticular formation
regulate cranial nerve activity slow pain conduction and modulation voluntary movements autonomic nc activity distribution of monoaminergic and cholinergic pathways respiration sleep cerebral cortical arousal and wakefulness
where does the reticular formation spread from
pons to spinal cord
where do reticulospinal and vestibulospinal pathways originate from
brainstem
why does the vestibulospinal tract control the same side of the body
the cerebellum controls the same side of the body and the vestibular nucleus is linked to the cerebellum
what is the babinski sign
upper motor neurone lesion leading to damage to descending corticospinal pathways, stroking the sole of the foot causes an abnormal fanning of the toes and the extension of the big toe
what is the function of general somatic afferent fibres (GSA)
general sensation (from skin, skeletal muscle, joints and bone)
what is the function of special somatic afferent (SSA)
vision hearing and balance
what is the function of general visceral afferent (GVA)
visceral organs- info from visceral organs e.g in the vagus from the stomach
what is the function of special visceral afferent (SVA)
taste, visceral sense
what is the function of special visceral efferent (SVE)
skeletal muscle from branchial arches typically muscles of facial expression/mastication
what is the function of general somatic efferent (GSE)
skeletal muscle from somites (eyes and tongue
what is the function of general visceral efferent (autonomic) ? (GVE)
parasympathetic to smooth muscles and glands
which cranial nerves entirely sensory
I II and VIII
which cranial nerves are entirely motor
III, IV, VI, XI and XII
which cn are both sensory and motor
V, VII, IX and X
which 4 cranial nerves carry parasympathetic preganglionic fibres
III, VII, IX and X
what are the general somatic efferent (GSE) nuclei- motor
oculomotor
trochlear
abducent
hypoglossal
generally, where are the general somatic efferent nuclei (GSE)
close to the midline
closest to the alpha motor neurones of the spinal cord
what do the oculomotor nerve innervate
superior, inferior & medial rectus, inf oblique & levator palpebrae superioris
what does the trochlear nerve innervate
sup oblique
what does abducent nerve innervate
lateral rectus
what does the hypoglossal nerve innervate
muscles of tongue
where is the oculomotor nuclei found
midbrain nearest midline
where is the trochlear nuclei found
midbrain nearest midline
where is the abducent nuclei found
pons nearest midline
where is the hypoglossal nuclei found
medulla nearest midline
what are the special visceral efferent nuclei (SVE) - motor
trigeminal
facial
nucleus ambiguous
what is nucleus ambiguous
the motor nuclei of IX, X, XI
all the fibres that run in these nerves originate from this single nucleus
what does the motor trigeminal supply
Muscles of mastication, tensor tympani, tensor palitini, mylohyoid, ant, belly of digastric
what does the motor facial supply
Muscles of facial expression, post. belly of digastric, stylohyoid and stapedius
what does the motor nucleus ambiguous supply
Skeletal m. of pharynx, larynx and soft palate
where is the motor trigeminal nucleus
pons
where is the motor facial nucleus
pons
what are the general visceral efferent (motor) nuclei - parasympathetic
edinger-westphal nucleus
super salivatory nucleus
inferior salivatory nucleus
dorsal nucleus of the vagus n
where is the edinger westphal nucleus
midbrain
where is the superior salivatory nucleus
pons
where is the inferior salivatory nucleus
medulla
where is the dorsal nucleus of the vagus
medulla
what does the edinger-westphal nucleus supply and via what cn
III
Sphincter pupillae and ciliary muscles
what does the Superior salivatory nucleus supply via what cn
VII
Submandibular, sublingual and lacrimal glands
what does the inferior salivatory nucleus supply via what cn
IX
Parotid gland
what does the dorsal nucleus of vagus n. supply
Many cervical, thoracic and abdominal viscera
where do all the parsympathetic fibres of the vagus originate
dorsal motor nuclues of the vagus
what are the general somatic afferent (GSA) nuclei
mesencephalic nucleus of V
chief sensory nucleus of V
spinal nucleus of V
which nuclei does proprioception muscle spindle relflex, spindle afferents enter
mesencephalic nucleus of V
which nucleus does fine touch (discriminative) enter
chief sensory nucleus of V
which nucleus does pain and temp from face enter
spinal nucleus of V
what are the special somatic afferent nuclei (SSA)
vestibular and cochlear nuclei
what is the General and special visceral afferent nucleus (SVA)
nucleus of solitary tract
what sensation does the nucleus of the solitary tract receive and from what cn
VII- taste from anterior 2/3 of tongue
IX- taste from posterior 1/3 of tongue
X- taste from epiglottis
what are the the 2 major places strokes can occur
cortical stroke- blood supply to the cortex from the carotid artery and middle cerebral (face and arms)
lacunar stroke- affects internal capsule area (more devastating)
what is the early neural tube surrounded by
alar and basal lamina
what does alar lamina develop into
dorsal horn- sensory - lateral
what does the basal lamina develop into
ventral horn- alpha
motor neurones- medial
Where do corticobulbar fibres run from ?
cortex to the cranial nerve nuclei
What is the innervation of lower motor neurones ?
cranial nerve nuclei
What is the innervation of V and VII ?
bilateral projections from the primary motor cortex - upper face
What is the innervation of VII - lower face ?
contralateral
What is the innervation of XI ?
ipsilateral from PMC
What is the innervation of II , IVand VI ?
contralateral innervation from frontal and parietal eye fields
What is the innervation of XII ?
bilateral from PMC except for genioglossus - contralteral
Where does the trigeminal carry pain afferent run from ?
face, nose , orbit , meninges and muscles of mastication
Where does the facial nerve carry pain afferents from ?
ear and the canal
Where does the vagus nerve carry pain afferents from ?
meninges , ear canal and the larynx
Where does the glossopharyngeal carry pain afferents from ?
posterior tongue and pharynx
Where do the cervical spinal nerves carry pain afferents from ?
neck , meninges in the psoterior cranial fossa
Where are the sensory neurone cell bodies of the trigeminal found ?
in the trigeminal ganglion
Where are the proprioception cell bodies of the trigeminal found ?
mesencephalic nucleus of V
What does the spinal nucleus of V receive information about ?
firm touch , pain and temperature from skin of the face , oral and nasal cavities and palate
What does the main nucleus of V receive information from ?
fine touch from skin of face , oral cavity and palate
What information does the mesencephalic nucleus of V receive ?
proprioception from muscles of head
Where are the sensory neurone cell bodies ?
geniculate ganglion
Where do the general somatic afferents in the facial nerve come from ?
skin of the ear , ext.auditory meatus to spinal nucleus of V in medulla
Where are the sensory neurone cell bodies of the vestibulocochlear nerve ?
vestibular and spiral ganglia
Where are the somatic sensory neurone cell bodies of the glossopharyngeal nerve ?
superior ganglion
Where are the visceral sensory neurone cell bodies ?
petrosal ganglion
Where does the glossopharyngeal bring general somatic afferents from ?
firm touch , pain and temperature from posterior third of the tongue , oropharynx , nasal cavity and paranasal sinuses to the spinal nucleus of V
Where are the somatic sensory neurone cell bodies of the vagus ?
jugualr ganglion
Where are the visceral sensory neurone cell bodies of the Vagus ?
nodose ganglion
Where does the vagus carry general somatic afferentss from ?
firm touch , pain and temperature from the ear and external auditory meatus and mucous membrane of the larynx to the spinal nucleus of the V
What is the plexus of Raschkow ?
a central plexus in the pulp of the tooth - pain from teeth is mediated through this
What type of pain do A-fibres transmit ?
rapid and sharp pain
belong to the myelinated group
What can A-fibres end branches to ?
odontoblastic processes located on the periphery of the pulp and dnetinal tubules
Where are A-fibres located ?
on the periphery of the pulp
What may trigger pain sensation in the teeth ?
fluid movement in the dentinal tubules
What type of pain is conducted by C-fibres ?
dull aching pain
Are C-fibres myelinated or unmyelinated ?
unmyelinated
Where do C-fibres terminate ?
in the pulp proper as free nerve endings or branches around blood vessels
What is the route of A and C fibres ?
run in the branches of V2 and V3 and then terminate in the spinal nucleus of V - passing to the thalamus and cortex
Where is pain associated with emotional distress processed ?
anterior cingulate cortex
Where is the periaqueductal grey matter located ?
around the cerebral aqueduct in the tegmentum of the midbrain
What does the periaqueductal grey matter do ?
plays a role in the descending modulation of pain
What neurones are found in the periaqueductal grey ?
enkephalin releasing neurones
What do enkephalin releasing neurones do ?
suppress pain
What is released from the raphe nuclei ?
serotonin
What does serotonin do ?
descends to the dorsal horn of the spinal chord where it forms excitatory connections with inhibitory interneurones in laminae II
When activated what do the interneurones do ?
release enkephalin
binds to opioid receptros - descending pain modualtion
What is the corneal reflex ?
touch cornea with a cotton wisp which elicits the bilateral blink reflex
What is the pathway of the corneal reflex ?
sensory input from V1 - spinal nucleus of V - facial motor nucleus - orbicualris oculi
What is the gag reflex ?
touching the back of the oropharynx elicits brief elevation of the paate and brief constriction of the pharyngeal constrictors
What is the pathway of the gag reflex ?
sensory input from the glossopharyngeal - nucleus of solitary tract - nucleus ambiguus - vagus to the pharyngeal constrictors
What is the jaw jerk reflex ?
tapping on the chin leads to contraction of masseter and jaw closing
What type of reflex is the jaw-jerk reflex ?
monosynaptic
What is the pathway of the jaw-jerk reflex ?
chewing against resistance builds up tension in the PDL
unloading of stretch inhibits masseter
golgi tendon organ detects level of stretch in PDL , pressure is released and inihbits contraction of masseter
Which 3 cortices can pain pathways synapse in ?
nsular cortex
somatosensory cortex
anterior cingulate cortex
What is the spinal nucleus of V continuous with ?
dorsal horn of the spinal chord
Where is the primary visual cortex ?
occipital lobe - either side of the calcarine sulcus
Where does light first hit ?
retinal ganglion cells
How do impulses tavel from the retina to the bvrain ?
sensory neurones
What does the retina consist of ?
pigmented epithelium
rods and cones
Where are the cones situated ?
fovea
Where are the rods sitted ?
peripheries
How do the rods synapse ?
many rods synapse on one bipolar sensory neurone - more sensitive to lower light
How do cones synapse ?
cones synapse on one bipolar neurone providing higher resolution
What are the membraneous discs ?
thye contain proteins that respond to light - rods contain rhodopsin and cones contain photopsin
What is the disinhibition of bipolar neuroness ?
light hits photoreceptors leading to hyperpolarisation which stops the release of neurotransmitter
Where does the optic nerve travel ?
through the optic canal
What is the pathway of the optic nerve ?
passes through the optic tract and the optic chiasm to the thalamus
Where in the thalamus does the optic nerve pass to ?
lateral geniculate nucleus
Alternatively where does the optic nerve pass to ?
superior calliculus
What are the 4 cranial nerve nuclei that control the movements of the eye ?
edinger- westphal nucleus
oculomotor nucleus
abducens nucleus
trochlear nucleus
What does the edinger westphal nucleus supply ?
ciliary muscle and the iris muscle
What is the papillary light reflex ?
light shone in one eye - contraction of both pupils - direct light reflex
contraction if the pupil oppsote leads to consensual light reflex
What is the accomodation relfex ?
focus on the incoming object leads to pupillary constriction- convergence of eyes as eyes focus on the near object
What is the pathway of the pupillary light reflex ?
light comes into the retina and the retinal gnaglion cells
travel via the optic tract to the lateral geniculate nucleus and the superior colliculi
bilateral innervation of the edinger westphal nucleus
output to the pupil and ciliary nucleus - contraction of the pupils
What is the pathway of the accomodation relfex ?
information travels tothe primary visual cortex
bilateral innervation of the oculomtor (eye muscles) and edinger westphal nucleus (eye focus)
Where is the primary auditory cortex located ?
in the superior tempora; gyrus
How are action potentials triggered in the ear ?
pressure waves in the ear are conducted through the inner and middle ear
vibrations are caused in the tympanic membrane
generates waves of fluid on the cochlear
triggers hair cells to move
opens mechanically gated ion channels
triggers action potentials
What does the cochlear consist of ?
semi circular canals utricle sacculae ampullae cochlea nerve
What is the organ of corti ?
between the scala vestibuli and the scala tympani
has a tectoriul and basilar membrane
What does the sensory ganglion contain ?
sensory cell bodies of the cochlea nerve
What does the sound on the tympanic membrane cause ?
sound hits the ossicles and causes vibration of the endolymph in the cochlea
generates vibrations in the basilar membrane
rubs in the tectorial membrane
moves the hair cells on the organ of corti
opens up channels and triggers APs.
What is the action of stapees ?
vibrates on the oval window
What is the helicotrema ?
a gap at the end of the unravelled cochlea allows fluid to move constantly
High frequency sounds are picked up by what ?
proximal end of the cochlea
Low frequency sounds are picked up by what ?
distal end of the cochlea
Which hair cells are sensory ?
95% of inner hair cells
What is the role of the outer hair cells ?
receive efferents from the superior olive
modulate basilar membrane motions
What are sterocilia ?
organ of corti hair cells
What are present on hair cells ?
potassium ion channels - linked mechanically
Moving hair cells side to side causes what ?
physically opens the potassium channels and triggetrs voltage sensitive calcium channels - calcium cascade - vesicle movement and fusion with the presynaptic membrane
Desribe the auditory pathway ?
1st order neurones from receptors in the organ of corti , fibres synapse in the cochlear nuclei
2nd order neurones travel to the medial geniculate nucleus of the thalamus via the superior olivary nucleus and the inferior colliculus
3rd order neurones travel to the superior temporal gyrus in a bilateral pathway
Describe the auditory stream ?
primary auditory cortex association auditory cortex wernickes area arcuate fasciculus brocas area motor cortices
What are the roles of the auditory cortrex
processing of sound
receives information from the medial geniculate nucleus
tonotopic representation of frequencies- different parts of the cortex pick up different f requencies
What is the vestibular system concerned with ?
balance
What is the vestibular system ?
semi circular canals are fluid filled - bulges are called ampullae
hair cells are located at the ampullae
endolymph inside the semi circular canals moves via inertia
triggers hair cell movement
nerve cells are triggered
What are otolith organs ?
ear stones
What are the ear stones ?
utricle and the saccule
What is the sensory epithelium of the ear stones called ?
macula
What do the ear stones do ?
sense tilt and linear head motions
respond to gravity and linear acceleration
Where are the otolith organs ?
in a gelatinous mucous on top of hair cells
What are the otolith organs made of ?
CaCo3 deposits
What is the effect on the otolith organs of moving backwards ?
gravity pulls stones backwards and this pulls on the hair cells triggering a response
Describe the vestibuLar pathway ?
information from the ampullae , utricle and saccule goes to the vestibualr nucleus
from here pathways go to the cortex (III, IC,VI) , spinal chord (vestibulospinal tract and cerebelllum (balance)
to enter the cortices the pathway is the medial longitudinal fasciculus
performance of voluntary movements requires ?
job/task identification
planning for the activity
performance
What are the 3 levels of motor control ?
motor areas of thee cerebral cortex
brainsntem
spinal chord
What are the roles of the motor areas of the cerebral cortex ?
issue sequential and parallel commands
change intensities of different patterns
modify timing
What are the roles of the brainstem ?
maintain axial tone for standing
What are the roles of the spinal chord ?
programmed , local pattern of muscle movement
location of complex pattern of rhythmical and reciprocal motion
What are the cortices of the brain related to motor control ?
posterior parietal cortex
primary motor cortex
What is the role of the posterior parietal cortex /
association and representation
initiation , planning and thought of activities
What is the role of the primary motor cortex ?
corticospinal and corticobulbar fibres arise from here
What are the 2 loops from the posterior parietal cortrex ?
1 to basal ganglia
1 to pontine nuclei and the cerebellum
Describe the basal ganglia loop for planning , carrying out and modulating activities ?
from the posterior parietal cortex to the basla ganglia
back through the thalamus to the pre motor cortex to the supplementary motor cortex and to the primary motor cortex
What do the basal ganglia store ?
patterned movements are stored , responsible for initiation and planning of movement
Describe the pontine nuclei loop for planning , carrying out and modulating movement ?
fibres from the posterior parietal cortex to the pontine nuclei to the cerebellar hemispheres through the deep cerebellar nuclei to the thalamus
from the thalamus to the pre motor cprtex , supplemnetary motor cortex and the primary motor cortexx
What does the cerebellum do in modifying movements ?
it looks at intended movement and the current position of the muscles and decides which muscles to move
What does the cerebellum receive input from ?
the inferior olive- proprioception information from muscles
What arises from the primary motor cortex ?
corticospinal and corticobulbar fibres that travel in the internal capsule
What does the paramedian midbrain reticular formation do ?
regulates walking
What do the pontine reticulospinal pathways do ?
control extensor lower motoneurones
What does the posterior parietal cortex produce ?
produces internal models of movement prior to the involvement of the premotor and motor cortices
What do the prefrontal areas do ?
decisions here are made about what action to take
integrates info
concerned with personality , reasoning and conscience
`What does the premotor area do ?
controls axial and proximal limb muscles in the initial phases of orientating the body and arm to a target
wha does the supplemnetary motro area do ?
execute stages of complex movements based on past experiences
What side of the body does the cerebellum control
ipsilateral side
What does the cerebellum consist of ?
vermis - central
folia - folds
flocularnodular lobe
deep cerebellar nuclie
What are the 4 deep cerebellar nuc,ei from lateral to medial ?
dentate nucleus emboliform nucleus globose nucleus fastigial nucleus interposed nucleus - some individuals have this - emboliform and globose
What are the 3 functional parts of the cerebellum ?
vestibulocerebellum
spinocerebellum
neocerebellum
What is the vestibulocerebellum ?
flocculo-nodular lobe and part of the vermis
What is the function of the vestibulocerebellum ?
posture and balance
input from the vestibular nucleus and the dorsal spinocerebellar tract
output to the vestibular nucleus
What is the spinocerebellum ?
vermis and the fastigial nucleus and the intermidiate part or cerebellar hemisphere , globose and emoboliform nuclei
What is the function of the spinocerebellum ?
updating ongoing movements
input from the primary motor cortex via pontine nuclei, DSCT, ASCT and olivary nucleus
output to red nucleus
What is the neocerebellum ?
lateral part of the hemisphere and the dnetate nucleus
What is the role of the neocerebellum ?
initiation and planning of movements , motor learning
inout from the posterior parietal cortex , inferioe olivary nuclue s
output to the premotor cortedx , supplemnetary moor area via the thalamus
What is the route for planning and prediction in the cerebellum ?
from the cerebral cortex to the dentate nucleus via corticopontine fibres back to the thalamus to the cerebral cortex
What is the route for modification of ongoing movement ?
from the inferior olivary nucleus to the interposed nucleus to the red nucleus and the rubrospinal tract
What is the input and output of the olivary nucleus ?
output as climbing fibres to opposite cerebellum
input from cortex and spinal chord
What is the role of the olivary nucleus ?
plays a role in movement inititation and motor learning
How is a lesion in the vestibulocerebellum presented ?
staggering gat
How is a lesion in the spinocerebellum presented ?
ataxia
How is a lesion in the corticocerebellum presented ?
slow movement onset
What are the basal ganglia ?
caudate nucleus putamen globus pallidus subthalamic nucleus substantia nigra
What is the circuit of the basal ganglia ?
output from cortical areas involved in planning and execution of movement to the basal ganglia
output from the basal ganglia to motorrelay areas of the thalamus (ventral anterior and ventral lateral nuclei of the thalamus)
How do the basal ganglia act ?
act ispilaterally
What do basal ganglia tend to do ?
inhibit movements therefore lesions produce unwanted movements
What are the 2 circuits through the basal ganaglia ?
putamen ciruit- putamen - globus pallidus to the thalamus and the cortex
What is the role of the putamen circuit ?
subconscious execution of learned patterns of movement
What is the caudate circuit ?
cognitive planning of movement - feedback to cortex
What does the substamtia nigra do ?
releases dopamine into the putamen circuit which acts on D1 and D2 receptors
Describe the direct pathway ?
cells with D1 receptors are excited by dopamine released from the substantia nigra
release of dopamine increases inhibition of the globus pallidus
releases tonic inhibiion of the thalamus causing cortical excitation
increases movement and cortical activity
Which pathway is normally inhibited ?
indirect pathway
Describe the indirect pathway ?
cells with D2 receptors are inhibited by dopamine
increases inhibition of the globus pallidus
decreases inhibition of the sub thalamic nucleus
increases excitation of globus pallidus
increases inhibition of thalamus
reduces thalamic excitation of cortex
reduces cortical motor activity
What are hypokinetic disorders ?
insufficient direct pathway output
excess indirect pathway output
What are hyperkinetic disorders ?
excess directly pathway output
insuufficient indirect pathway output
How is chewing iniitated ?
by voluntary movement
followed by a period of reflex activity
What do CPGS do in mastication ?
generate masticatory rhythms - alternative action of jaw openers and closers
Where are the CPGs for mastication ?
in the pontine reticular nucleus
Describe the process of mastication ?
food is taken in and rhythmic mastication is imitiated
receptors in the oral cavity monitor hardness
assess whether the food is fir for swallowing
adjust the activity if muscles by feedback to motor neurones , CPG and cerebllum
when bolus is appropriate swallowing is initiated
Describe the control of mastication ?
CPG in the pontine RF
activate s the pre motro neurones and the trigmeinal motro nucleus
sneds rhythmical signals to the maticatory muscles
sensroy signals feedback about the bolus to the RF and the trigeminal motro neucleus
Which receptors control masticatory force ?
periodontal ligament receptors
What do periodontal ligament receptors do ?
inhibit neurones in the trigmeinal motro nucleus via inihbitory interneurones
What is the limbic system ?
neuronal cicitry that controls emotional behabviour and motivational drivees
What does the anteiror conguakte gyrus do ?
emotional aspect of pain
Where is the hippocampus and what does it do ?
medial aspect of the temporal lobe and is involved in memory formation
What is the hypothalamus and what does it do ?
major part of the limbic system and controls internal body conditions - vegetative behavior and endocrine fucntions
What are the outputs of the thalamus ?
to the braisntem RF
anterior thalamus and the limbic portion of teh cerebral cortex
hypothalamic infindibulum - pituitary glands
What are the functions of the thalamus ?
sexual behaviour
endocrine function
homeostasis
What does the hypothalamus do in terms of endocrine function ?
neuroendocrine cells reelase hormones that act in the pituitary gland and this releases more hormones
Which part of teh hypothalamus is to do with sexdual behaviour in fmelaes ?
ventromedial hypothalamus
Which part of the hypothalamus is to do with sexual behaviour in males ?
preoptic region
How does the hypothtlmaus carry out temperature reguaktion ?
temeprature sensitive neurones in the preoptic area measure the core body temeprature of teh blood
reduced brain/blood barrier in the hypothalamus
repsonse- horemone production
activation of teh ANS
behavioural response
Which area of the hypothalmaus creates a thirst sensation ?
laterla hypothalamic area
Which nucleus of the hypothalamus controsl the excretion fo water into urine ?
supraoptic nucleus
Which ara regualtes hunger in the hypothalamus ?
lateral hypothalamic area
Which area of the hypothalamus creates a desire for food ?
satiety centre in the ventromedial nucleus
What area of the hypothalamus carries out GI activity ?
mammillary bodies
What is the orexigenic response ?
response to low glucose and the need to eat more food
What is the anorexigenic response ?
high nutrients - stop eating food like GI stretch , circadian rhythms
What does GI stretch do ?
inihibits te orexigenic response and excites the anorexigenic response
What are circadain rhythms ?
endodogenous entrainsble 24 hour rhythmicity
What nucleus are circadian rhythms controlled by ?
suprachiasmatic nuclei
Where is the amygdala located ?
below the hypothakmaus and i the inferior portion of the laterla ventricvle
What ae the fucntions of teh amygdala ?
emotional letrning and memeorty
fear and fear cinditioning
reward
What does activation of the amygdala lead to ?
indices fea anxiety and violence
What does deactivation of the amygdala lead to ?
incapable pof fear
How is the amygdala involved in emotional learning and memory ?
amygdala assesses the emotional significance of inputs
much more likely to remember something with emotional significance
How is thye amygdala involved in fear and fear conditioning ?
amygdala and the medial temporal lobe are invollved in the mediating , acquisition and storage of fear and memory
What is the reward system for ?
liking and positive reinforcement
What are the important structures in the reward system ?
ventral tegmental area - origin amygdala nucleus accumbens hippocampus prefrontal cortex
What is the reticular formation ?
a complex group of neurones and nuclei in the brainstem
What are the afferent inouts to the RF ?
spinal chord
cranial nerves
cerebellum
forebrain
What are the efferent ouputs of the RF ?
spinal chord and cortex
What are the fucntiomns of the RF ?
sleep and consciousness somatic motor cintrol - CPGs cardiovascular control pain modulation habituation
What are the 4 nuclei of the reticualr acting syste, ?
locus coereleus
raphe nucleus
ventral tegmental area
basal forebrain - nucleus of meynert
Where are the dopaminergic pathways of the RF ?
Ventral Tegmental Area - mesocorticolimbic pathway
and substantia nigra - dopamine to basal ganglia
Where are the serotonergic pathways ?
raphe nuclei and the nucleus raphe magnus
ascending pathways to the cortex
descending pathways to the spinal chiord - pain modulation
Where are the noradrenergic pathways ?
locus coereleus
Where are the cholinergic pathways ?
basal forebrain and nucleus of meynert
to the hippocampus
When does rapid eye movement sleep occur ?
JUST BEFORE WE WAKE UP
Wehre is rapid eye movement sleep regulated ?
pontine RF
What is needed to prevent the acting out of ndreams ?
connections between the pontine RF and the spinal chord
What nuclei are involved in sleep ?
Arpahe nuclei
dorsolaterla pontine RF
What are the motor effects if the reticular formation ?
meduallry reticulospinal tract - laterla
pontine reticulospinal tract- medial
What is the function of the pontine RT ?
enhances antigravity muscles and reflexes of the soinal chord
helps maintain a standing posture by resisting the effects of gravity
What is the function of the medullary RT ?
liberates the antigravity muscles from reflex control
What is the collective fucntion of the reticulospinal fibres ?
modualte muscle tone
regualte psoture
participate in automatic reflexes involving extensor musculature
What are CPG s?
trigger the correct enets at the right time
2 processes occur and they interact sequentially
What are the repsiratory CPGs ?.
pontine respiratory group
medullary respiratory group - DRG and VRG and the pre botzinger complex
What is the paccemaker theory of CPGs ?
self activating fibres that trigger events
What is the network theory of CPGs ?
VRG made of inspiratory and expiratory neurones
reciprocal imnhibition
Main output from the basal ganglia is from where ?
globus pallidus
What are the receptor organs responsdibl;e for detecting vibrations in the basialr membrane ?
organ of corti and the ampullae
What are sensory projections on the hair cells known as ?
sterocilia
What are the receptor organs responsible ofr snesing baalnnce ?
ampullae
Where are the ampullae located ?
in the semi circular canals of the cochlea
Which nuclei in the brainstem does the ouput from the vestibular nucleus go to ?
nucleus of oculomotr , trochlear and abducens
What are the outputs of the supplementary motor cortex ?
primary motor cortex
reticular formation
cortocspinal and corticobulbar
Which area of the brain is responsible for making an internal model of move,ent when assessing movements ?
posterior parietal cortex
Which nuclei are responsible for adaptation of movement in response to external stimuli ?
red nucleus
olivary nucleus
In huntingtons disease which of the basal ganglia are effected /
globus pallidus
Which of the nuceli are responsible for conbtrol of water excretion ?
supra optic nuclei
Where is the satiety centre which controls hunger ?
ventromedial nuclei
What are the 5 structures responsible for the reward system ?
ventral tegmental area nucleus accumbens hippocampus amygdala pre frontal cortex
What are thee nuclei of the reticular formation and what do thy release ?
nucleus of meynert- acetylcholine
nucleus raphe magnus/raphe nuckeus- serotonin
ventral tegmental area- dopmaine
locus coerleus- noradrenaline
What happens during rapid eye movement sleep ?
paralysis of voluntary mucle and active brain
What happens during non rapid eye movemnt sleppe ?
lowering of body temeratir
movement of muscles
lowering of heartr rate
How can you identify a ruffini corpuscle ?
highly branched
How can you identify a pacinian corpuscle ?
round
How can you identify a pacinian corpuscle ?
round
How can you identify merkel cells ?
individual cells
How can you identify a meissner corpuscle ?
bunch of cells
How can you identify hair follicle receptors ?
around the hair
What are the structural components of the cerebellum ?
vermis
intermdiate zone
cerebellar hemispheres
floculonodular lobe
What are the functional components of cerebellum ?
spinocerebellum
vestibulocerebellum
neocerebellum
What is the vestibulocerebellum ?
floculonodular lobe
posture and balance
What is the neocerebellum ?
posterior lobe
planning of movement
What is the spinocerebellum ?
anterior lobe
monitoring of ongoing movements
brain stem nuclei pathway- reticular nuclei
sensory, premotor, sup motor –> reticular nuclei -> reticulospinal -> coordianted movement muscle e.g. running
brain stem nuclei pathway- vestibular nuclei
vestibular nerve, cerebellum -> vestibular nuclei -> vestibulospinal -> maintenance of upright posture
brain stem nuclei pathway- cortex
cortex -> potine nuclei -> cerebellum -> Precision and efficiecny
brain stem nuclei pathway- inferior olive
cortex, spinal cortex -> inferior olive -> cerebellum, spinal cord -> coordination learned movement
what are the the 3 routes of pathways in the folia via
deep cerebellar nucleus
pontine nucleus
olivary nucleus
what are the descending fibres that enter the pontine nuclei
corticopontine/bulbar/spinal
where do axons from pontine nucleus go
send mossy fibres to cerebellum and into opposite cerebellar cortex
where does olivary nucleus send climbing fibres from inputs of proprioception
to opposite cerebellar cortex
what and where are purkinje cells
in folia- they are highly branches dendritic cells
what fibres run through dendritic trees of purkinje cell
parallel fibres- (each one is info from a point in the cortex
what permits the purkinje cells to allow or not allow movement to happen
collisions of proprioceptive info in purkinhe cells wiht sampling from hte cortex
where do purkinje cells send output axons
deep cerebellar cortex
where does deep cerebellar nucleus send its axons
back across midline to thalamus(hemisphere) or red nucleus (vermis)
