NC Exam 3

cerebral cortex

interpreting sensory information
perception of sensory information
active in voluntary movement
planning, execution, accuracy
making conscious decisions

brain injured

most knowledge of cortex and cerebellum activity is due to the study of _______ individuals

pyramidal and stellate

two types of cerebral cortex cells

molecular

axons and dendrites

external granular

small pyramidal and stellate cells

external pyramidal

pyramidal cells dominate

intracortial communication

the pyramidal cells in layers 2 and 3 project to other neurons within the same cortical areas as well as neurons in other cortical areas

internal granular

stellate and pyramidal cells
receives sensory info from thalamus

ganglionic

large pyramidal cells
major output from cortex

multiform

many different neurons that communicate within and leave the cortex

thalamus

most input to the cortex comes from the ____

thalamus

acts as a relay station, processing information from the peripheral afferents, cerebellum, and basal ganglia
make connections in layer 4

thalamus and cortex

pyramidal cells receive sensory info from _________

4 and 6

most important areas

area 4

primary motor area
contains giant output cells, motor map of the body
active during the excecution of voluntary movements
damage can cause paralysis and spasticity

area 6

premotor area
complex movements originate
premotor cortex and supplementary motor area

premotor cortex

mouth and hand movements
goal distracted actions such as reaching and grasping

supplementary motor area

involved in the planning generation and control of sequential motor actions

utilization behavior syndrome

impaired restraint of the potential motor acts elicited by objects

area 2

primary somatosensory area
responds to tactile info and joint movements
patients with lesions in this area unable to reach towards objects efficiently

parietal association cortex

sensory guidance of motor behavior and spatial awareness

temporal association cortex

recognition of sensory stimuli and storage of facts

frontal association cortex

organization of behavior and working memory

limbic association cortex

complex functions related to emotion and episodic memory

primary motor area

motor execution in cortical projections

supplementary motor area

prep, planning in cortical projections

premotor area

interpret clues or goal directed movements in cortical projections

parietal areas

proprioceptive info, speech, verbal expression

outputs

_____ of the motor cortex include projections to the basal ganglia, cerebellum, red nucleus, reticular formation, and spinal cord

medulla decussation

Corticospinal tracts from the left and right hemispheres change sites at the level of the _______

readiness potential

slowly rising negative potential prior to voluntary movement
ends up with a small positive potential
sometimes these potentials are seen in different locations

convergence

stimulating different cortical cells may activate the same group of motor units and result in similar motions

divergence

stimulating one cortical cell can activate different groups of motor units and move different body parts

cerebellum

consists of two hemispheres and a medial area (vermis)
connected to other structures by three pairs of peduncles
40:1 ratio inputs to outputs

cerebellum lobes

anterior, posterior, and flocculonodular

cerebellum disorders

result in disruptions of normal movement
different from paralysis

symptoms

hypotonia, astasia abasia, ataxia, and tremor

hypotonia

diminished resistance to passive limb displacements
muscle weakness
"dont let me push your arm down"

astasia abasia

inability to stand or walk

ataxia

lack of coordination

tremor

at the end of movement when attempting to stop

4

sensory info enters cerebral cortex in which layer?

2 and 3

intracortical communication occurs in which two layers of the cerebral cortex?

5

most info leaves the cerebral cortex from which layer?

6, supplementary

utilization behavior syndrome is caused by damage to what area?

4, PMA

upper motor neuron syndrome is caused by damage to what area?

basal ganglia, cerebellum spinal cord

info comes into the cerebral cortex from what 3 locations?

basal ganglia, cerebellum, spinal cord, red nucleus, reticular formation

motor info leaving the cerebral cortex goes to what five locations?

cerebellar cortex

consists of 3 layers and five types of neurons

mossy fibers and climbing

inputs to cerebellum carried by _____
excitatory

purkinje cells

only output system of the cerebellum is the axons of ______
inhibit

granular cells

parallel fibers
excitatory

golgi cells

excited by parallel fibers
inhibit granule cells

stellate and basket

interneurons within the cerebellum
inhibit purkinje cells

purkinje cells

only output of the cerebellum
inhibitory

cerebellar neurons

timing, learning, memory and modeling of motor actions

mossy

originate in spinocerebellar tract and brain stem nuclei
excite granule cells
any type of stimulus

climbing

originate in medulla
synapse on purkinje cells
obligatory

purkinje

stellate, basket, and golgi modulate the activity of _____

4 and 6

most info from the cerebellar thalamus projects to areas _____ of the cortex

cerebellum

eye movements, balance, posture, coordination, timing, motor learning, comparator

40:1

ratio of inputs to outputs in cerebellum

basal ganglia

motor, emotion, reward, executive, function, and mood
diseases cause complex behavioral and neuropsychiatric disturbances
globus pallidus, subthalamic nucleus, substania nigra, putamen, caudate nucleus

disorders of basal ganglia

excessive involuntary movement
movement poverty
slowness
without paralysis

striatum

are the sites of almost all afferent inputs to the basal ganglia

direct pathway

projections onto the GPi and substania nigra directly onto thalamus and back to cortex
net excitatory effect
play a major role in control of limb movements

indirect pathway

projects onto the GPe then to subthalamic nuclei
net inhibitory loop
play a role in oculomotor control (eye movements)

functions of basal ganglia

sequencing voluntary movements
force control, controlling antagonist group
prevent unwanted movements

ascending

from the periphery to the center

descending

from the center to the periphery

pathways

presence of synaptic relays
information can be amplified or attenuated
integration of information
topographic organization

thalamus and cerebral cortex

info comes into the basal ganglia from the _______

caudate nucleus and putamen

where within the basal ganglia does the info enter

first order neurons

primary afferent neurons
bring info into the spinal cord

second order neurons

relays between first order neurons and brain centers
typically in the spinal cord and brain stem

third order neurons

commonly in thalamic nuclei

afferent

fibers enter the spinal cord through the dorsal columns

spinal ganglion-medulla-thalamus-cortex

dorsal columns of spinal cord carry info from sensory neurons in spinal ganglia to brain
ascending fibers of the dorsal column pathway terminate in cuneate and gracile nuclei in medulla
from medulla, info goes to medial lemniscus to thalamus then to cerebral cortex

spinothalamic

consists of axons of neurons whose bodies lie in the dorsal and intermediate parts of the gray matter
axons cross the midline and travel along the contralateral side of the spinal cord in the ventrolateral funiculus
this tract conveys the sensations of touch, pressure, temp, and pain

spinocerebellar

cerebellum receives info from peripheral sensory receptors by means of the dorsal, ventral, and rostral tracts; cuneocerebellar tract; spino-olivary-cerevellar tract

DSCT (dorsal)

ascends in clark's column
carries information from proprioceptors in the lower extremities
also has projections to nucleus z and thalamus

Cuneocerebellar

carries info from upper extremities

VSCT (ventral)

ascends laterally in the central horn
carries FRA info from the lower extremities and afferent signals
only in active movement

RSCT (rostral)

carries FRA info from upper extremities
also carries afferent signals

spinoreticular

ascends in the ventrolateral fasciculus directly to the reticular formation
plays a role in controlling the sense of pain

pyramidal

consists of two major groups of axons
axons of the first group go down to the spinal cord (corticospinal)
some fibers leave and innervate the motor nuclei or cranial nerves
from M1, premotor and supplementary, and somatosensory

Lateral CST

contains most of the fibers that decussate at the brain stem
has direct projections to both INs and MNs at all levels of the spinal cord

ventral CST

contains most of the fibers that do not decussate
mostly controls axial trunk muscles
damage can disrupt voluntary movement

corticobulbar

exits at the pyramids
controls cranial nerves

rubrospinal

originates in red nucleus
receives input from the motor cortex, cerebellum, and olives
decussates at midbrains and descends to lateral CST and olives
suspected of being major importance for motor coordination
damage disturbs voluntary movement

vestibulospinal

vestibular nuclei receive main inputs from the cerebellum and labyrinth
lesions cause ataxia and postural instability
lateral and medial side

Lateral VST

comes from the lateral vestibular nucleus
descends ipsilaterally to the lumbar level
makes connections with IN
plays a role in the control of posture

medial VST

comes from the medial vestibular nucleus
descends ipsilaterally to the mid-thoracic level
makes connections with INs
plays a role in control of posture through control of head position

Medial RST

to spinal INs ipsilaterally
its effects are mostly inhibitory

lateral RST

to INs in the ventral parts of the spinal cord
postural control of proximal extensor muscles

Reticulospinal tract

suspected of bringing about the startle reaction
lesions to these tracts also can cause ataxia and postural instability

tectospinal

comes from neurons in superior colliculus
decussates and plays a role in motor reactions to visual stimuli

interstitiospinal

comes from neurons in the midbrain
function is a mystery

rubrospinal

which pathway descends from the red nucleus and plays a role in motor coordination?

spinothalamic

which pathway ascends to the thalamus and carries info related to touch, temp, pressure, and pain?