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175 Cards in this Set
- Front
- Back
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Where is the primary motor cortex located?
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frontal lobe
first gyrus anterior to sulcus |
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What is the somatotopic representation of the body muscles?
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Motor humunculus located in the primary motor cortex
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What % of the primary motor cortex is involved with controlling the hands and muscles of speech?
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50%
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Where is the premotor area located?
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immediately anterior to the primary motor cortex.
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What acts as the "programming area" for complex patterns of movement?
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premotor area
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Nerve signals from the programming area in the premotor area are directed where?
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to the primary motor cortex or the basal ganglia
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Broca's area
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necessary for production of speech, damage to this area can cause Broca's aphasia, or impaired ability to produce speech
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Where do mirror neurons exist?
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ventral premotor area
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Where do inputs to the motor cortex come from?
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1. somatic sensory, visual and auditory cortices
2. cerebelllum and basal ganglia, by way of motory relay nuclei in the thalamus 3. from the RAS & generalized thalamocortical system 4. interhemisphere communication via corpus collosum |
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Outputs from the motor cortex go where?
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1. corticospinal (pyramidal) tracts
2.Nerve fibers project from primary motor cortex to red nucleus in midbrain 3. Nerve fibers project from primary motor cortex to brainstem nuclei responsible for control of antigravity muscles 4.extensive connections between the motor cortex and the cerebellum(corticopontocerebellar tracts) 5. Nerve fibers project from the premotor area to the basal ganglia |
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Where do the corticopontocerebellar tracts pass through?
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The pons
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Where do the corticospinal (pyramidal) tracts originate?
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in the primary motor and premotor cortex, given rise to the medullary pyramids as they pass through the medulla
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Where do the corticospinal (pyramidal) fibers decussate and what to they descend into the spinal cord as?
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most pyramidal fibers decussate at the medulla and descend into the spinal cord as the lateral corticospinal tracts
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Where do the lateral corticospinal tracts terminate?
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mainly on spinal cord interneurons
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Where is the red nucleus located?
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midbrain; bilateral structure
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What does the red nucleus work closely with?
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the pyramidal tracts (and in parallel with)
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Where does the red nucleus receive input from?
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ipsilateral primary motor cortex and the contralateral cerebellum
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Where does the rubrospinal tract originate?
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This is an accessory pathway and origintes in the red nucleus, decussate ventral to nucleus, descend through midbrain, and parallel the pyramidal tracts in the lateral spinal cord white matter
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What are the primary influences of the red nucleus?
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shoulders and upper arms, with less important input to hands, fingers
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What in babies is primary controlled by the red nucleus?
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crawling
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What is the principal function of the brainstem in motor activity?
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to control background contractions of antigravity muscles in the neck, trunk and proximal portions of the limbs
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Inputs from what area largely control the level of contractile activity in the antigravity muscles?
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reticular nuclei
vestibular nuclei |
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The reticular nuclei include:
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The pontine reticular nuclei and
The medullary reticular nuclei |
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Describe the pontine reticular nuclei
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Located in the pons and lower midbrain
Highly excitable neurons, receive excitatory inputs from the vestibular nuclei and the cerebellum Transmit excitatory motor signals into spinal cord via the pontine (medial) reticulospinal tracts, nerve fibers terminate on the anterior motor neurons that control muscles of the vertebral column and extensor muscles of the limbs |
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Describe the Medullary reticular nuclei
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Extend length of the medulla, receive inputs from pyramidal and rubrospinal tracts, cerebellum and basal ganglia, inputs can be excitatory or inhibitory
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Where do the medullary reticular nuclei transmit inhibitory motor signals to?
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spinal cord via the medullary (lateral) reticulospinal tracts; nerve fibers terminate on the same anterior motor neurons that receive excitatory input from the potine reticular nuclei
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What demonstrates the importance of the medullary reticular system in controlling anterior motor neuron(expecially gamma) excitability?
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Clinical syndrome of decerebrate rigidity
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Where is the Vestibular nuclei located?
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in the lower pons and medulla
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What is the key role of the vestibular nuclei?
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maintenance of equilibrium
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Where does the vestibular nuclei receive excitatory input from?
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vestibular apparatus (inner ear) via vestibular nerves
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The vestibular nuclei also transmits signals into the spinal cord via what?
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The vestibulospinal tracts
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Nerve fibers terminate on the anterior motor neurons that control antigravity muscles of the neck, shoulders, trunk and limbs; gamma motor neurons are particularly affected, What tract am I?
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Vestibulospinal tracts
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Is the vestibular apparatus(labyrinth) large or small?
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small
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What is the vestibular apparatus responsible for?
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sensation of equilibrium
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Where is the vestibular apparatus located?
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inner ear
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Contrast the pontine reticular nuclei and the medullary reticular nuclei
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The pontine RN excites antigravity muscles
The medullary RN relaxes antigravity muscles |
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So you could say that the pontine RN and the Medullary RN function antagonistically to each other, true or false?
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TRUE
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What is the sensory organ of the utricle and saccule(otoliths)?
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Macula
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What does the macula do?
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responds to changes, detects orientation of head in space, responds to linear acceleration(and deceleration) of the body
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Why are the macula hair cells oriented in different directions?
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so that some are activated when the head bends forward, others activated when head bends backward, yet others when head leans to one side
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Name the 3 ducts of the semicircular canals(ducts)
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anterior
posterior horizontal |
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What is the sensory organ of the semicircular canals?
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Crista ampullaris-hair cells detect when the head begins to rotate as well as when it stops rotating
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What are the semicircular canals filled with?
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endolymph
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What do the semicircular canals prevent?
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disequilibrium
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What response stabilizes the gaze of the eyes?
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output directed to the ocular muscles(through vestibular nuclei) in response to rotation of the head, info from semicircular canals causes eyes to rotate in a direction opposite to that of the head rotation
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Output of the vestibular apparatus is directed where?
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1. brainstem vestibular nuclei
2. brainstem reticular nuclei 3. cerebellum(flocculonodular lobe) |
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Why is the cerebellum called the "silent area"?
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electrical stimulation of the cerebellum DOES NOT cause sensation or motor activity
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However....injury to the cerebellum can produce severe motor dysfunction, in particular what?
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Ataxia and disruptions in equilibrium
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What does the cerebellum participate in?
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Planning of motor activities
It also compares actual, ongoing muscle activity with the "plan" and makes corrective adjustments as necessary by influencing the motor output of other brain areas such as the motor cortex and brainstem |
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What is the critical part of the cerebellum?
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planning the next movement
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What ensures smooth transition from one movement to the next?
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the cerebellum plans the next movement in advance while the present movement is still occuring
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Describe the anatomy of the cerebellum
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3 lobes
2 hemispheres Vermis |
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What is the oldert part of the cerebellum?
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flocculonodular lobe
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What does te flocculonodular lobe function together with?
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vestibular nuclei(two-way communication) in the control of equilibrium and eye movements
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What are the 2 cerebellar hemispheres divided in to?
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Intermediate zones
Lateral zones |
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What are the intermediate zones involved with?
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control of voluntary movements in the hands, fingers, feet, toes and face, somatotopic representation of body muscles in those areas
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Where do the intermediate zones receive information from?
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Somatic sensory feedback information from the same areas
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What zones DO NOT have somatotopic representation of the body?
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The lateral zones
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What permits the lateral zones to participate in the coordination of sequential motor activities?
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connections with association areas of the:
cerebral cortex premotor area somatic sensory cortex |
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what are the folds of the cerebellar cortex called?
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Folia
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Within the cerebellum are the deep nuclei...
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fastigial
interpositus dentate |
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Where do inputs to the cerebellum come from (via the cerebellar peduncles)?
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1.Corticopontocerebellar pathway
2.Olivocerebellar tract 3. Vestibulocerebellar fibers 4. Dorsal spinocerebellar tracts 5. Ventral spinocerebellar tracts |
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What tracts have the highest conduction velocities of any pathway in the CNS?
What is the consequence? |
Spinocerebellar tracts
immediate feedback |
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What is a very important input pathway to the cerebellum?
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Corticopontocerebellar pathway-originates in the primary motor cortex and premotor area(crossover)
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Where does the olivocerebellar tract originate and what excites it?
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originates in the inferior olive nucleus(medulla) and is directed to all parts of the cerebellum, excited by input from motor cortex, basal ganglia, reticular formation and spinal cord
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Where do vestibulocerebellar fibers originate and terminate?
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originate in the vestibular apparatus and vestibular nuclei
terminate in the flocculonodular lobe and fastigial nucleus |
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Dorsal spinocereballar tracts...
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transmit somatic sensory info from muscle spindles, golgi tendon organs and joint receptors to the cerebellum(proprioceptor feedback)
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Ventral spinocerebellar tracts...
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transmit a copy of motor signals (motor plan) delivered to the anterior motorneurons
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Describe the primary output from the cerebellum
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Flocculonodular lobe-vestibular nuclei-vermis-fastigial nucleus-brainstem reticular nuclei
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Output from the cerebellum is important to what?
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Control of posture and the maintenance of equilibrium
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What are the functions of the cerebellum in control of movement?
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Equilibrium and posture
Voluntary movement |
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OUTPUT from the flocculonodular lobe and vermis are important in maintenance of equilibrium much more so during rapid movement than when standing in place, true or false?
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TRUE
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INPUT from the vestibular apparatus and vistibular nuclei to the flocculonodular lobe is used to produce what?
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almost instantaneous corrections in postural motor activity necessary for the maintenance of equilibrium
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Does voluntary movement mean conscious movements?
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No
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What do the intermediate zones do?
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compare the plan of the motor cortex with the execution of the plan by the muscles
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What acts to "apply the brakes" in order to stop a voluntary movement at an intended point?
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The cerebellum
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If the cerebellar is dysfunctioning what can it cause?
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"overshoot" (dysmetria) or intentional tremor characterized by oscillating actions of antagonistic muscle groups
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What do the lateral zones of the cerebellum do?
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communicate with the premotor area for the planning and timing of sequential movements
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What are the predictable consequences of cerebellar lesions?
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Ataxia
Dysmetria Dysarthria Intention tremor Nystagmus |
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What is dysarthria?
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impaired coordination of muscle movements involved in speech, including movements of the larynx, mouth, and resp muscles
Impaired ability to predict the length of time a sound is produced, unable to stop the sound |
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What is dysmetria?
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"overshoot" impaired ability to predict how far a movement should proceed
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How does the basal ganglia contribute to motor function?
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work in concert with the motor cortex and pyramidal motor system
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What are the components of the basal ganglia?
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Striatum(caudate nucleus;putamen)
Globus pallidua(pallidum) |
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Structures that work with the basal ganglia
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Subthalamic nuclei
Substantia nigra-midbrain |
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Describe the putamen circuit
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Important in execution of complex, learned motor patterns(writing alphabet, vocalization, athletic activity)
Inputs from premotor and somatic sensory cortex Output to primary motor cortex Circuitry |
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Effects of lesions in the putamen circuit
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Globus pallidus-athetosis
Putamen-chorea |
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What is athetosis?
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Spontaneous writhing motions of hands, arms, neck, or face
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What is chorea?
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Involuntary flicking movements of the hands, limbs, or face
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Describe the Caudate circuit
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*important in cognitive control of motor activity
*Input from association areas of each of the lobes *Output directed to globus pallidus *Circuitry *cognitive input determines patterns of movement *important in timing and scaling of movements |
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Example of scaling...
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writing an a really big or small-scaling down
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Diseases of the basal ganglia
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Parkinsons
Huntington's Disease |
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Parkinsons disease
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Loss of dopaminergic fibers
motor dysfunction tremors rigidity akinesia-difficult initiation of movement Treatment: L-DOPA Surgical destruction of thalamic motor nuclei Transplant of fetal brain tissue:stem cells into basal ganglia pallidotomy-lesion in one or both globus pallidus Deep brain stimulation with "pacemaker"-newest approach |
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Huntingtons disease
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Hereditary disease
Motor dysfunction-chorea progressing to severe involuntary movements of entire body Dementia No treatment |
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In Huntingtons disease what is the dementia due to?
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Loss of ACh in the cerebral cortex
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Anatomy of cerebral cortex
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Thin layer of neurons(gray matter)
Contains 100 billion neurons |
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How many layers of the cerebral cortex?
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6 successive layers
Layer I is molecular layer Layers II-VI contain neurons |
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What are the principal cell types of the cerebral cortex?
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Granular(stellate) cells
Pyramidal cells Fusiform cells |
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Where are the granular (stellate) cells found and what is their function?
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Layers II and IV
Serve as cortical interneurons Excitatory (glutamate) Inhibitory(GABA) |
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Where are the pyramidal cells found and what is their function?
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Layers III and V
Major output cells of the cerebral cortex to intracortical targets, subcortical areas and spinal area |
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Where are the fusiforms cells found and what is their function?
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Layer VI
Output cells-to the thalamus |
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What is the function of layers I, II and III?
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Responsible for association functions(integration)
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Layer IV
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Receives most sensory input
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Layer V
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output from pyramidal cells, eg, from the primary motor cortex to the spinal cord
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Layer VI
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output from fusiform cells to the thalamus
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What is the function of the association areas of the cerebral cortex?
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Integrate information from multiple cortical and subcortical regions
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Name the 3 major association areas
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Parieto-occiptotemporal association area
Prefrontal association area Limbic association area |
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What is the function of the Parieto-occiptotemporal lobe ?
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Receives sensory info
Analysis of "self in the environment Wernicke's Area |
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Where is Wernicke's area what is it responsible for?
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Posterior portion of the superior temporal lobe, highly developed in dominant hemisphere
Receives input from surrounding association cortex Critical area for language comprehension-the "form and meaning" area for language Output directed to Broca's area in frontal lobe |
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What is the function of the prefrontal association area?
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Works in association with the motor cortex in the planning of complex movements
Important for: problem solving judgement and foresight establishing strategies monitor behavior Role in memory |
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Where does the prefrontal area receive and deliver info?
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Receives input from the parieto-occipitotemporal association area
Output directed to basal ganglia |
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Where is the limbic association area and what is its function?
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Anterior portions of temporal lobes, ventral portions of frontal lobes and the cingulate gyri
Functions together with other limbic structures in producing emotions and motiviation |
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What is involved in learning?
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Some change in behavior as a result of experience either cognitive or sensory
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How do we learn through sensory and cognitive experience?
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experience=chemical and physical changes in the brain(learning)=knowledge (memory); behavior
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Long-term potentiation (LTP) is developed how?
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Basic mechanism of learning involves long-term strengthening of synaptic connections between neurons that are responsible for holding information
Occurs in the hippocampus and in some other areas of the brain |
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What is Ca++ role in learning?
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increased Ca++ concentration followed by additional synaptic connections then no longer need Ca++ to access info
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What brain regions are involved in learning and memory?
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Cerebellum
Hippocampus Cerebral cortex |
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What is the cerebellums role in learning and memory?
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Recall
Simple learning Conditioned learning:Pavolv dogs |
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What is the hippocampus role in learning and memory?
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CRITICAL for the development of new memories
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What difficulties may you see if damage is done to the hippocampi?
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1. learning difficulties
2. Proplems with storage of declarative information(facts about the world) 3. Memories of events that occured prior to brain damage are typically not impaired-long term memory remains intact |
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What is the cerebral cortex role in learning and memory?
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Complex learning:
problem solving analysis language Pre-frontal cortex Medial temporal lobe-entorhinal cortex-works with hippocampus |
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What are the stages of memory?
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Short-term memory
Lont-term memory Consolidation |
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What is consolidation?
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transfer of information from short-term memory to lont-term memory
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What does consolidation require?
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Hippocampi and medial temporal lobes
Rehearsal Time |
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What does rehearsal do?
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facilitates memory consolidation, trying to fortify synaptic connections
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Consolidation takes time and what is necessary before it is completed?
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the hippocampi and medial temporal lobes are necessary to retrieve the information
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What are the memory systems?
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Declarative(explicit) memory
Non-declarative(procedural, implicit) memory |
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What are the two components of declaritive memory?
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Semantic memory
Episodic memory |
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What is semantic memory?
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an individuals collection of facts, vocabulary and general knowledge
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What is episodic(context rich) memory?
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memory of when or where something was learned
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What is nondeclarative (procedural, implicit ) memory?
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Knowledge of how to do something
Does not involve conscious awareness Does NOT require the hippocampi and medial temporal lobes Examples: using tools riding a bike writing the alphabet |
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Wakefullness is regulated how?
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Neural regulation
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Clusters of cholinergic neurons in the pons(RAS) and basal forebrain(GTS) are connected, true or false?
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True, connected, project and release acetylcholine
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What are the adrenergic(release norepinephrine) neurons of the locus coeruleus(pons) responsible for?
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increased vigilance; activated during stress
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Serotoninergic neurons of the raphe nuclei(pons, medulla) release serotonin and project to the cortex and contribute to what?
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Activation of the cerebral cortex, through raphe activity is not enhanced during stress
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Histaminergic(histamine-releasing) neurons of the tuberomammillary nucleus (TMN) of the hypothalamus do what?
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directly activate the cortex and enhance arousal activity of cholinergic neurons in the pons and basal forebrain; some antihistamines cause drowsiness by inhibiting the effect of histamine to activate the cortex
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Orexinergix(orexin-releasing) neurons of the hypothalamus-axons project to where?
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cortex,pons, basal forebrain, and TMN
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What do the orexinergic neurons do?
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facilitate wakefulness, degenerations of these neurons is thought to cause narcolepsy
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Is wakefullness a self-perpetuating process?
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Yes
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What is sleep?
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a state from which a person CAN be aroused by an appropriate stimulus
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Is the change from the waking state to sleep (and vice versa) instantaneous?
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Yes
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Can different stages of sleep/wakefulness be identified by electrical activity on the EEG?
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Yes
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What waves are present on EEG when a person is awake?
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Beta waves, high frequency, low amplitude
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What waves are present of EEG when a person becomes drowsy?
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Alpha waves
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How many nonREM sleep stages are there?
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4
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What waves are present in NonREM stage 1?
Light sleep(dozing) |
Theta waves
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What will the EEG show in stage 2 of NonREM sleep?
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theta waves interrupted by brief bursts of sleep spindles and K complexes
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What % of total sleep time is spent in stage 2 NonREM sleep?
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50%
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In NonREM stage 3 sleep what waves are present on EEG?
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Delta waves(slow waves)
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Stage 4, deep sleep also shows delta waves, true or false?
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True
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What is sleep deprivation associated with?
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cognitive impairment
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What is another name for REM sleep?
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paradoxical sleep
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During REM sleep the EEG pattern resembles the waking state more than sleep, what waves are present?
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beta waves-low voltage
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What does the bete wave during REM sleep tell us?
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that during REM sleep the cortex is very active but activity is not directed to awareness of surroundings as in wakefulness(hence, "paradoxical" sleep)
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How much time is spent in REM sleep?
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20%
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What stage is associated with dreams?
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REM sleep (dream sleep)
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Why is it called REM sleep?
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because we have entire body muscle relaxation with exception to the eyes-rapid eye movement
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What increase during REM sleep?
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Heart rate
Respiration Blood pressure |
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Purpose of REM sleep?
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precise functions unknown
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What % of newborns sleep is in REM?
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70% and declines to 30% at 6 months and less than 25% by age 8
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What is slow-wave(nonREM) sleep caused by?
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neurons in the ventrolateral preoptic area-GABAergic neurons project axons to pons, locus coeruleus, raphe nuclei and TMN
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What permits rapid transition between wakefulness and nonREM sleep?
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A "flip-flop", or on-off arrangement
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During wakefulness, the wakefulness areas of the brain are inhibiting what?
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ventrolateral preoptic area(vIOPA)
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During sleep the vIOPA inhinbits what?
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wakefulness-promoting areas
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Stability of the "flip-flop" is provided by what?
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orexinergic neurons of the hypothalamus
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What is activation of the vIPOA possible a resut of?
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Adenosine in the brain during the period of wakefulness, adenosine is a product of neuron metabolic activity(remember that ATP is adenosine triphosphate)
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What does caffeine inhibit?
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adenosine receptors
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REM sleep is controlled by another flip-flop mechanism know as?
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REM-ON
REM-OFF |
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Where are REM-ON neurons located?
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PONS
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Where are the REM-OFF neurons located?
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MIDBRAIN
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What are the PONS and MIDBRAIN connected by?
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GABAergic neurons, so when one area is active, the other area is simultaneously inhibited
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During wakefulness, the REM-OFF neurons are stimulated by input from what?
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orexinergic neurons
adrenergic neurons serotoninergic neurons |
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where are orexinergic neurons located?
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hypothalamus
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where are adrenergic neurons located?
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locus coeruleus
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where are setotoninergic neurons located?
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Raphe nuclei
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With the onset of nonREM sleep, activity in the orexinergic neurons ceases, activity in the locus coeruleus and raphe nuclei declines slowly until the flip-flop switches to activate what?
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REM-ON neurons; REM sleep then proceeds until some signal(a biological clock?) activates the REM-OFF neurons and individual returns to nonREM sleep or awakens
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