Exam 4 - Thalamus and Cerebellum Flashcards
Shape of the Thalamus? Percent of diencephalon?
Oval shape cluster of nuclei. 80% of diencephalon.
Function of Thalamus? Where does the info come from? Exception?
Somatosensory input from spinal cord. Relays, modifies, and projects all sensory input to cortex, except for CN1.
Role of Relay Nuclei? Send to what?
Nuclei in Thalamus which send sensory input from body to cerebral cortex.
Gate Keeper role of Thalamus?
Decision maker for which type of info projected to cerebral cortex for processing.
Sensory input from body sent to which nuclei in the Thalamus then to the cerebral cortex?
Relay nuclei
Cortex/Limbic/Olfactory sensory info sent to which nuclei in thalamus? AKA? Then where to?
Thalamic Nuclei. AKA Association Nuclei. To cerebral cortex.
Basal Ganglia and Limbic System to cerebral cortex through which two nuclei?
Intralaminar and Midline nuclei
Role of Limbic System?
Survival, core levels, learning and experiences
Basal Ganglia involved in what?
Involved in motor output
Describe Central Pain. What causes it?
Sensation of pain (“nociception”) originating from CNS. No obvious injury. CNS pathology can cause central pain.
Describe Peripheral Pain. Cause?
Nociception originating in peripheral nerve. Due to actual injury.
Describe Thalamic Pain. Cause?
Nociception due to posterior thalamic damage. No or light somatosensory stimulus.
Describe Thalamic Pain Syndrome. Cause?
Pain and loss of sensation. D/T stroke in posterior thalamus.
Describe the Internal Capsule
Conduit and bundle of myelinated white matter between Thalamus/Caudate Nucleus and Lenticular Nucleus. Almost all neural connections to and from cortex go through Int Capsule.
What are the two limbs of the Internal Capsule? Jobs
Anterior Limb=diffuse sensory input to 3,1,2 Primary Somatosensory Area
Posterior Limb=Ascending (sensory) input, Descending (motor) output
What connects Thalamus to Cerebral Cortex?
Ascending and Descending tracts of the Posterior Limb of Int Capsule
What is the Genu?
“Transition” area between Anterior Limb and Posterior Limb of Internal Capsule
Job of the Retrolenticular and Sublenticular Parts of the Internal Capsule? Connect Thalamus to which lobes?
Retrolenticular=Optical Radiation. Thalamus to Parietal and Occipital lobes
Sublenticular=Auditory and Optical Radiation. Thalamus to auditory cortex on Temporal lobe
Stroke of the Internal Capsule called what? What is it not caused by?
“Lacunar Stroke”. Not an atherosclerotic stroke.
Describe Pure Motor Stroke of Int Capsule. Where lesion and what presentation?
Most common 50-60%. On Posterior Limb. Contralateral Hemiparesis/Hemiplegia on face/arms/hands/legs WITHOUT sensory deficits
Describe Ataxic Hemiparesis of Int Capsule. Where lesions and what presentation?
2nd most common type of Lacunar Stroke. Cerebellar/Motor symptoms. On Pons and Posterior Int Capsule.
Ipsilateral motor deficits. Clumsiness of leg.
Describe Mixed Motor and Sensory Input Lacunar Stroke of Int Capsule. Where lesions and what presentation?
On Posterior Limb and Thalamus. Contralateral hemiparesis and hemiparasthesia on face/arm/leg/trunk.
Describe Pure Sensory Stroke. Where lesions and what presentation?
Least common type 6-7%, lacunlar stroke in Thalamus, contralateral parasthesia in limbs (more) and trunk (less)
What and where are the Basal Ganglia?
Group of nuclei located bilaterally deep in the telencephalon, diencephalon, and midbrane.
What does the Basal Ganglia start and executes? Acts as what?
Starts and executes motor activity. Acts as governor switch to smooth out motor action.
The Basal Ganglia stimulates the Thalamus to do what?
Increase or decrease Thalamic Drive
Thalamic Drive is stimulated by what?
The Basal Ganglia
Increased Thalamic Drive due to what from motor cortex? Which pathway of Basal Ganglia? Inhibition?
Increased output from motor cortex stimulates Thalamus. Direct Pathway, reduced inhibition on Thalamus.
Decreased Thalamic Drive does what to motor cortex? Which pathway of Basal Ganglia? Inhibition?
Inhibits drive to motor cortex.
Indirect Pathway, increased inhibition on Thalamus.
Increase Thalamic drive does what to movement?
Excessive unwanted movement. Hyperkinetic.
Decreased Thalamic drive does what to movement?
Not enough movement. Hypokinetic.
Huntington is a disorder of which BG pathway and drive?
Direct Pathway, increased Thalamic Drive. Hyperkinetic.
Parkinson’s is a disorder of which BG pathway and drive?
Indirect Pathway, decreased Thalamic Drive. Hypokinetic.
Decreased thalamic drive to motor cortex from inhibitied direct pathway
Hyperkinetic disorders due to which BG pathway and Thalamic drive?
BG Direct Pathway. Decreased inhibition=Increased Thalamic Drive.
Hypokinetic disorders due to which BG pathway and Thalamic drive?
Increased inhibition=Decreased Thalamic Drive.
Parkinson etiology?
Reduced substantia nigra resulting in decreased dopamine production.
Causes decreased thalamic drive to motor cortex from inhibitied direct pathway
Huntington etiology?
Severe degeneration of striatum and frontal cortex.
Increased Thalamic Drive. Direct and Indirect Pathways involved.
Tardive Dyskinesia presentation and etiology?
Involuntary uncontrollable movements of mouth, tongue, and limbs from prolonged use of antipsychotics and dopamine antagonists. Continues after stopping meds.
Tics (Tourette’s Syndrome) presentation and etiology?
Rapid and repeated sterotyped involuntary movement. Motor and vocal tics more than 3 months. Onset under 18 y/o.
Unknown etiology. Not due to meds or other medical conditions.
Cerebellum percent of brain volume and percent of neurons total?
10% of volume, 50% of neurons
4 functions of the cerebellum?
- Maintain balance and posture
- Coordinate voluntary movement
- Motor learning
- Cognitive functions
The cerebellum integrates what two things?
Sensory perception with motor output
Cerebellar lesions affect which side? What happens to motor and sensory?
Ipsilateral (same side). No motor or sensory loss, but uncoordinated.
Are lesions on the cerebellum easy to pinpoint based on signs and symptoms?
Very difficult to pinpoint exact location.
Disequilibrium definition and due to lesion where?
Lesion on cerebellum. Loss of coordinated activity.
Dyssynergia definition and due to lesion where?
Lesion on cerebellum. Loss of coordinated activity.
Dysarthria definition and due to lesion where?
Slurring, slowing, “scanning” speech. Random volume, emphasis on wrong syllables. Lesion on cerebellum.
Dystaxia definition and due to lesion where?
Lack of coordination in execution of learned voluntary movement such as gait. Lesion on cerebellum.
Dysmetria definition and due to lesion where?
Overshooting target, inability to stop muscular movement at right space-time point. Finger to nose. Lesion on cerebellum.
Intention Tremor definition and due to lesion where?
Oscillating tremor that is worse with precise voluntary movement. Lesion on cerebellum.
Dysdiadocokinesia definition and due to lesion where?
Can’t perform rapid alternating or repetitive movement such as supination and pronation. Difficulty with timing and sequence. Lesion on cerebellum.
Nystagmus definition and due to lesion where?
Ocular dysmetria. Rhythmic oscillation of eyeballs. Lesion on cerebellum.
Decomposition of Movement definition and due to lesion where?
Breakdown of smooth muscle activity into jerky, awkward fragments w/poor timing. Lesion on cerebellum
Rebound definition and due to lesion where?
Inability to adjust to changes in muscle tension. Arm pull test hits self in chest. “Three stooges.” Lesion on cerebellum.
What separates the Right and Left Hemispheres of the Cerebellum? What is along the inferior surface?
Vermis.
Flocculondular Lobe.
Where are the cerebellar nuclei located?
Subcortical “deep” region of cerebellum
What are the three Cerebellular Peduncles and their input/output and connections?
Superior=Efferent from deep nuclei. Cerebellum to Midbrain
Middle=Afferent. Major motor input from cerebral cortex. Cerebellum to Pons.
Inferior=Both afferent and efferent. Cerebellum to Medulla.
Cerebellar (Afferent) Input to Cerebellar Cortex via what?
Via Climbing or Mossy Fibers, to Purkinje Fibers in Cerebellar Cortex.
Cerebellar Cortex to Deep Nuclei via what?
Purkinje Fibers
Deep Nuclei to Cerebellar (Efferent) Output via what?
Superior and Inferior Peduncles
Acute EtOH on Cerebellum?
Impaired signaling between Golgi Cells to Granule Cells, and Climbing Fibers to Purkinje Fibers
Chronic EtOH on Cerebellum?
Degeneration of Purkinje Fibers and Granule Cells. Apoptosis of Granule Cells, overall cerebellar atrophy/hypoplasia.
The Vestibulocerebellar (Archicerebellum), Spinocerebellum (Paleocerebellum), and Pontocerebellum/Cerebrocerebellum (Neocerebellum) make up what?
Phylogenic subdivisions of the cerebellum
Direction of newest to oldest in Phylogenic Subdivisions of Cerebellum?
Lateral (newest), Medial (oldest)
Vestibulocerebellum (Archicerebellum) age? Lobe? Reflex and control?
Oldest part. Flocculobar lobe. Visual reflexes and posture control.
Vestibulocerebellum (Archicerebellum) input and output? Which peduncle?
Inferior Peduncle.
Afferent input=CN 8 and vestibular nuclei.
Efferent output=to vestibular nuclei
Does the Vestibulocerebellum (Archicerebellum) have deep nuclei? What does lesion cause?
No deep cerebellular nuclei.
Lesion=Dysequilbrium, hypotonia, nystagmus, altered visual reflex
Spinocerebellum (Paleocerebellum) function? Which peduncles?
“Real time” correction and coordination of ipsilateral motor control on extremities and trunk. Inferior and Superior Peduncles.
Spinocerebellum (Paleocerebellum) Afferent Input and Efferent Output via?
Afferent Input=Inferior Peduncle
Efferent Output=Superior Peduncle to vermis and paravermis
Lesion of Spinocerebellum (Paleocerebellum)?
Rebound overshooting; ataxia of gait, trunk, leg, arm; hypotonia
Pontocerebellum aka Cerebrocerebellum (Neocerebellum) age and info?
Newest and largest functional subdivision of cerebellum
Pontocerebellum aka Cerebrocerebellum (Neocerebellum) peduncle and afferent/efferent connections?
Middle peduncle entering cerebellum.
Afferent Input=Via pontine nuclei
Efferent Output=via thalamus
Pontocerebellum aka Cerebrocerebellum (Neocerebellum) function and lesion?
Planning, learning, and timing of skilled voluntary movements; cognitive and emotional learning, congnitive speech.
Lesion=Dyssynergia, loss of coordinated movement
Dentate Nuclei is a deep cerebellar nuclei responsible for what?
Motor learning. Connection to motor cortex. Newest.
Interposed Nuclei is a deep cerebellar nuclei responsible for what?
Fine tuning motor coordination. Pick up coffee cup without spilling.
Fastigial Nuclei is a deep cerebellar nuclei responsible for what?
Oldest. Vestibular function. Stance, walk, antigravitational muscles.
Putamen, Caudate Nucleus, and Nucleus Accumbens makes up what?
Striatum
Putamen, Globus Padillus, and Caudate Nucleus make up what?
Corpus Striatum
Violent, flailing movements d/t damage from Subthalamic Nucleus and Basal Ganglia called what?
Ballismus (go ballistic!)
Parkinsons Disease inhibits which pathway and allows which pathway?
Inhibits direct, allows indirect.
Putamen and Globus Pallidus called what?
Lentiform nuclei
Rigidity vs Spacticity?
Rigidity not influenced by speed, Spacticity influenced by speed
Lead-pipe vs Cogwheel?
Lead-pipe=entire ROM
Cogwheel=portion of ROM
What is the role of the Basal Ganglia?
Stimulates Thalamus to increase or decrease Thalamic drive to motor cortex.
Increased Thalamic Drive leads to what?
Increased motor output from Motor Cortex. Too much=hyperkinesia
Decreased Thalamic Drive leads to what?
Decreased motor output from Motor Cortex. Hypokinesia=too little
