Glossary of Neuro 3
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- What are the 2 main components of the cerebellum?
- Cerebellar cortex (cerebrocerebellum, vestibulocerebellum, spinocerebellum)
Deep cerebellar nuclei (dentate nucleus, fastigial nucleus, interposed nuclei)
- What is the primary function of the cerebellum?
- Detect the "motor error" between an intended movement adn the actual movement and to reduce the error.
- Describe the cerebrocerebellum aka PONTOCEREBELLUM
- Largest part of cerebellum.
Receives input from many areas of the cerebral cortex which go through the pontine nuclei (cortico-ponto-cerebellar projection)
Concerned with the regulation of highly skilled movements (including speech).
- Describe the vestibulocerebellum.
- Comprises the caudal lobes and includes the flocculus and nodulus.
Receives input from the vestibular nuclei in the brainstem. Concerned with regulation of movements underlying posture and equilibrium.
- Describe the spinocerebellum.
- Only part that receives input from the spinal cord.
Lateral part aka PARAVERMAL region: movements of distal muscles.
Central part aka VERMIS: movement of proximal muscle and regulates eye movements.
- What are the pontine nuclei?
- the cell bodies in the base of the pons that give rise to the pathway through the middle cerebellar peduncle.
- Describe the pathway through the MIDDLE cerebellar peduncle.
- Frontal/parietal cortex --> pontine nuclei in the pons --> cross the midline within the pons --> to cerebellum (cerebrocerebellum) via the middle cerebellar peduncle.
- Describe the pathway through the INFERIOR cerebellar peduncle.
- Axson from the inferior olive, spinal cord (Clarke's column), and vestibular nuclei enter the cerebellum via the inferior cerebellar peduncle. DO NOT CROSS THE MIDLINE = IPSILATERAL
**may alos include locus ceruleus, reticular formation, superior colliculus, and red nucleus?
- Which neurons project to the SPINOCEREBELLUM?
- Dorsal nucleus of Clarke and reticular formation (largely concerned with the activity of postural muscles)
- Which neurons project to the VESTIBULOCEREBELLUM?
- Vestibular axons from CN VIII terminate in the cortex of the flocculo-nodular lobe and axons from the vestibular nuclei project to the cortex of the flocculo-nodular lobe with collateral branches to the fastigiate nucleus.
- Describe the projections FROM the cerebellum to the cerebral cortex.
- Cerebellar cortex -->
deep cerebellar nuclei -->
CROSS THE MIDLINE (decussation of the superior cerebellar peduncle) THRU the superior cerebellar peduncle -->
Ventral lateral (VL) complex of thalamus -->
Primary motor and premotor cortex
- What is the exception to the fact that all projections from the cerebellar cortex go to the deep cerebellar nuclei?
- There is a direct projection from the vestibulocerebellum to the vestibular nuclei.
- The cerebrocerebellum, vestibulocerebellum, and spinocerebellum project to which deep nuclei?
- cerebro --> dentate
vestibulo --> fastigial nucleus
spino --> interposed nuclei
except for reticular formation afferents: fastigiate nucleus + spinocerebellum
- What are the output targets of the cerebellum?
- Motor cortex
- What are the 3 layers of the cerebellar cortex?
- molecular layer (outside)
Purkinje cell layer
granule cell layer (inside)
- What is found in the molecular layer of the cerebellar cortex?
- Stellate cells
Dendrites of Golgi cells
Dendrites of Purkinje cells
- What is found in the Purkinje cell layer?
- Cell body of the Purkinje cell only
- Mossy fibers (which come from all the afferents to the cerebellar cortex EXCEPT for inf olive) synapse on what?
- Granule cells in synaptic clusters called glomeruli in the granule cell layer.
- Climbing fibers
- arise in the inferior olive;
modifies the efficacy of the parallel fiber--Purkinje cell connection.
Synapses are strongly excitatory.
- difficulty performing rapid alternating movements such as heel-to-shin and/or finger-to-nose tests (damage to spinocerebellum)
- Over and underreaching (damage to spinocerebellum)
- Why do alcoholics develop ataxia?
- Degeneration in the anterior portion of the spinocerebellum. Specifically affects movement in the lower limbs = wide and staggering gait.
- What are the names of the interposed nuclei?
- Globose and emboliform
- Describe the pathway of the superior cerebellar peduncle.
- Primarily efferents from cerebellum to thalamus & red nucleus.
- Cerebellar afferents from below T-1
- Called the Posterior spinocerebellar pathway.
a. receptors - proprioceptors such as muscle spindles
b. Central processes of primary afferents which enter dorsal root of spinal cord from T-1 down synapse in a nucleus in the spinal cord called nucleus dorsalis for projections to cerebellum
c. Second order fibers from nucleus dorsalis ascend in ipsilateral posterior spinocerebellar tract and enter via the inferior cerebellar peduncle, send collateral branches into the globose/emboliform nuclei and terminate in the vermal and paravermal regions of the cerebellum.
- Cerebellar afferents from above T-1
- Cuneocerebellar pathway
a. Fibers enter fasciculus cuneatus, ascend to the ipsilateral medulla where they synapse in a nucleus called the lateral (accessory) cuneatus nucleus and synapse.
b. From lateral (accessory) cuneatus nucleus - fibers enter via inferior cerebellar peduncle, send collateral branches into the globose/emboliform nuclei and terminate in the vermal and paravermal cerebellar cortex.
- Parkinson's Disease
- Loss of the nigrostriatal dopaminergic neurons so, facilitates the indirect route --> excites globus pallidus, inhibits thalamus, less activation of upper motor neurons in the motor cortex.
Hypokinetic movement disorder.
- Huntington's Disease
- Degeneration of the medium spiny neurons that project to the external segment of the globus pallidus.
Globus pallidus becomes abnormally active --> inhibits subthalamic nucleus so you don't get excitation of the globus pallidus internal so thalamus is activated --> upper motor neurons inappropriately activated.
Hyperkinetic movement disorder.
- What are the 4 types of cortical neurons?
- Pyramidal neurons
Cells of Marinotti
- Pyramidal neurons
- Contains an apical dendrite directed toward the cortical surface and the axon projects into the white matter.
- Spindle neurons
- axis-oriented perpendicular to the cortical surface.
Spindle-shaped soma present in deep cortical layers (VI).
- Granular interneurons
- Contains multiple short neurites.
- Cells of Marinotti (Marinotti neurons)
- Present in the DEEPEST layer of the cortex. Form SHORT branching dendrites and axon that BOTH project ot the superficial cortical layers.
- What are the layers of the cerebral cortex?
Molecular layer (primary synaptic layer)
External granular layer
External pyramidal layer
Internal granular layer
Internal pyramidal layer
Multiform layer (pyramidal, spindle, Marinotti)
- Describe the homotypical cortex and give an example.
- Granular cortex, so contains all 6 layers including the internal granular layer.
Ex: prefrontal association cortex (includes BA anterior to area 6)
- Describe the heterotypical cortex and give an example.
- Agranular cortex = no internal granular layer.
Ex: primary motor cortex (BA 4)
- Describe the Koniocortex and give an example.
- A type of GRANULAR CORTEX (homotypical) showing reduced internal PYRAMIDAL layer but exaggerated internal granular layer.
Ex: primary visual cortex (BA 17).
- Describe the cortical layers of the hippocampus.
- 3 cortical layers corresponding to layer I, V, VI of the neocortex.
- According to the FUNCTIONAL roles, the cortex can be divided into which areas?
Primary sensory areas
Sensory association areas
High order association areas
Primary motor regions
- Describe the (1) primary sensory areas.
- Visual: BA 17
Auditory: BA 41,42
Somatosensory: BA 1,2,3
- Describe the (2) sensory association areas.
- Visual association: BA 18,19,7,21,37,39
Auditory association: BA 21, 22
Somatosensory association: BA 5,7
- Describe the (3) high order association areas.
- Parieto-temporal: BA 39,40
Prefronal: anterior to area 6
Limbic: Areas 11, 23,24,28,38
- Describe the (4) motor association areas
- Areas 6 and 8
Responsible for construction of COMPLEX movements.
- Describe the (5) primary motor cortex.
- BA 4
Receives input from ventral anterior and ventral lateral (VA/VL) nuclei conveying motor information from the basal ganglia and cerebellum.
Responsible for execution of simple specific movements-displays somatotopic organization. Projects to the subcortical motor centers.
- The cortical limbic areas recive input from which fibers?
- From the limbic thalamic nuclei: anterior and lateral dorsal.
- The primary sensory areas (visual, auditory, somatosensory) receive input from which fibers?
- From sensory specific nuclei such as ventral posterior, lateral and medial geniculate nuclei conveying direct information from sensory organs.
- The association areas (sensory, high order, and motor) receive input from which fibers?
- Association thalamic nuclei convey multimodal sensory information to these areas.
These nuclei include: dorsomedial, pulvinar, and posterior nuclei [i guess these are the *specific* nuclei?]
- What are the NONSPECIFIC thalamic nuclei and what do they do?
- Reticular, intralaminar, midline
Project diffusely to all cortical layers and are involved in arousal and wakefulness.
- What is the difference between association input and commissural input?
What is their similarity?
- Association: input from cortical areas of the SAME hemisphere.
Commissural: input from cortex of the OTHER hemisphere.
Both synapse largely in layers I, II, & III.
- What are corticostriatal fibers?
- Fibers from the cortex to the BASAL GANGLIA.
Involved in sensorimotor, associative, and limbic activity.
- Modality specific and association thalamic nuclei project where?
- Largely to layer IV of the cortex (internal granular layer).
- Axons to subcortical regions except the thalamus originate where?
- Pyramidal cells in layer V.
- Axons to the thalamus originate where?
- Pyramidal and spindle cells of layer VI.
- Axons to the ipsilateral and contralateral cortex originate where?
- Pyramidal cells in layer II and III.
- Brodmanns's Areas 18 and 19
- Visual association cortex: occipital lobe.
Processing of spatial information.
- Brodmann Area 7
- Visual association cortex: parietal cortex.
Many cells respond to POSITION of th eimage within the visual field while some respond to both position and touching in the area of the face corresponding to this field.
Damage can result in simultagnosia, hemispatial agnosia, and contralateral agnosia.
- Results from bilateral damage to BA 7 (parietal cortex; visual association cortex).
Inability to see multiple objects.
- Hemispatial agnosia
- Damage to only 1 side of the area 7. Results in neglect of the 1/2 of the object observed contralateral to the damaged hemisphere independently of the position of the object in the visual field.
- Contralateral agnosia
- The object presented ot the eye contralateral to the damaged hemisphere is ignored.
Damage to 1 side of BA 7.
- Brodmann's Areas 18, 19, 21, 37
- 18 + 19 = occipital cortex
21 + 37 = temporal cortex
Recognition of images like faces.
Right hemisphere: processes the object as a whole and is involved in recognition of specific images.
Left hemisphere: processes the object as a sum of its parts; recognizes categories of images.
- Brodmann's Areas 39
- Recognition of COLOR.
Situated in a junction of occipital, parietal, and temporal lobes.
- Brodmann's Areas 21 & 22
- Auditory association cortex
Recognition of sounds and speech.
- Brodmann's Areas 39 & 40
- Parieto-temporal-occipital association cortex.
Intercalation between high order somatic, visual and auditory cortexes. Responsible for correlation of multisensory perception.
- Limbic association region
- BA 11, 23, 24 = regulation of emotional state.
BA 28, 38 = memory processing.
- Prefrontal association cortex
- BA areas anterior to 6.
Responsible for producting abstract ideas, appropriate judgment, and persistence.
Prefrontal lobe syndrome: impairment of decision making, ability to plan, social judgment, loss os spontaneity of motor and mental activities.
- Wernicke's Area
- Includes BA 22 and 39.
Recognition of SPOKEN LANGUAGE. Only in left hemisphere.
Connected to Broca's Area by arcuate fasciculus.
- Broca's Area
- BA 44.
Responsible for SPEAKING. Only in left hemisphere.
Connected to Wernicke's Area by arcuate fasciculus.
- Describe the cortices corresponding to Wernicke's and Broca's Areas in the RIGHT hemisphere.
- Wernickes --> recognizes tone of voice
Broca's --> rudimentary speech capability and responsible for tone to the voice of the speaker.
- Wernicke's Aphasia & Broca's Aphasia
- Inability to understand spoken words.
Inability to speak. Similar to Conduction aphsia (lesion of arcuate fasciculus).
- What is Alexia?
- Inability to comprehend written language -- lesion in area 39 in left hemisphere.
(Remember: Wernicke's is 22 and 39)
- Where is the temporo-spatial workign memory and where is the auditory-based working memory?
- Temporo-spatial: prefrontal cortex.
Auditory-based: parietal cortex.
- Procedural memories processed where?
- Striatum (basal ganglia) and cerebellum.
- Emotional memories processed where?
- Anterograde Amnesia
- New events are not transferred to long-term memory. Due to destruction of hippocampus.
- Retrograde amnesia
- Loss of memories acquired shortly before the damage. Due to destruction of hippocampus.
- Left hemisphere dominant for what?
The parietal association cortex mediates attention to the right part of the body only.
- Right hemisphere dominant for what?
- Visual-spatial skills
The parietal association cortex mediates attention to both right and left parts of the body.
- So the substantia nigra suppresses the indirect route by inhibiting which neurons?
- By inhibiting the gaba/enk neurons.
Facilitates the direct route by exciting the gaba/sp neurons.
- Which parts of the basal ganglia path are EXCITATORY?
- Cerebral cortex --> putamen (glutamate)
Thalamus (VLo) --> motor cortex
Pars compacta D1 --> putamen (dopamine)
Subthalamic nucleus --> globus pallidus internal (glutamate)
- Direct route: suppress or cause movement?
- Excites movement
- Indirect route: suppress or cause movement?
- Suppresses movement.
- What is hemiballismus?
- Damage to the subthalamic nucleus
Wayyy to much movement; violent, involuntary movements of the limbs.
Globus pallidus internal isn't excited so the thalamus has no inhibition.
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