8. Brain tracts, neurotransmitters, neuronal circuits, “connectomics” Structure of the cerebral cortex Flashcards
Composition of CNS
cortical lamination + nucleus
Composition of PNS
ganglion
What type of cells are included in Nervous system?
principal cells (pyramidal neuron in the cerebral cortex); and interneurons/local circuit cells
Types of neurotransmitters
- colocalisation / coexpression
- co-release OR co-transmission
What does gray (grey) matter include?
neurons and supporting cells within the CNS
What does cortex include?
laminar structure composed of gray matter, covering the surface of the cerebrum and the cerebellum
What does nucleus include?
deep gray matter within the CNS
What does white matter include?
axonal masses within the CNS (arising from neurons)
What is tract (pathway)?
a specific collection of axons running together aiming often for the „same” target
What is SYNAPSE?
Communication between neurons - SYNAPSE
What is volume transmission?
Non-synaptic transmission
What are the 5 types of neurotransmitters?
- Excitatory amino acids (EAA)
- Cholinergic system
- Biogenic amines
- Inhibitory amino acids
- Neuropeptides
Name 8 majors neurotransmitters
What is allocortex?
Gray matter with less than 6 layers
What does allocortex include?
- Paleopallium (rhinencephalon)
- Archipalleum (archiotex)
Name 6 layers of neocortex
What are the 2 neuronal cell types of the cerebral cortex?
- Principal cells (80%)
- Interneurons (20%)
NEURONAL CELL TYPES OF THE CEREBRAL CORTEX
Describe principal cells
- Pyramidal cells (excitatory, GLU)
- Projection neurons
- Carry dendritic spines
Describe interneurons
- Local circuit cells
- Different subgroups (morphology, cotransmitters, function)
- Most of them are inhibitory
- Control neocortical network interactions
2 types of interneurons?
- Stellate (spiny neurons)
- Inhibitory interneurons
What are the 4 examples of inhibitory interneurons
- neuroglioform cells
- basket cell
- chandelier cell
- columnar arborization is apparent
3 types of glia
- Astrocytes
- Oligodendroglia
- Microglia
Myelin sheath of axons is produced by ___ (which type of glia?)
oligodendrocytes
What are oligodendrocytes?
Small cells with processes
When is microglia activated?
In case of CNS injury
This is PYRAMIDAL NEURON
-> Identify
What is the true interneuron?
Neuroglioform neuron
Describe Neuroglioform neuron
- Rich, local axonal arbor
- Many presnaptic terminal boutons
- Small cell body
- „volume transmission”
Descrobe basket neuron (a type of inhibitory interneurons)
- Long horizontal axon collaterals;
- Rich basketlike terminals around the body of the pyramidal cells ;
- Perisomatic inhibition (synchronous)
Describe Chandelier neuron
- Vertically oriented (candle like) terminals;
- Terminate on the axon hillock of pyramidal neurons;
- Perisomatic inhibition of several pyramidal neurons to exclude overexcitation.
Describe Cells with columnar axon arborization
- Long, vertically oriented (horsetail-like) axon;
- Disinhibition: the axon terminates on further inhibitory interneurons ;
- Located on the edge of cortical columns – controls the activity pattern
Describe polarized cell that you can see in pyramidal neron
- Apical dendrite (dendritic spines)
- Perikaryon
- Basal dendrites
- Axon (axon hillock)
- Axon collaterals
3 types of projections of pyramidal neurons
- Commissural projections
- Association projections
- Long projections
Identify
Stellate neuron is frequently occuring interneuron
-> T or F?
Stellate neuron
Stellate neuron is frequently occuring interneuron
-> T or F?
Stellate neuron
Where can you find stellate neuron with excitatory or inhibitory functions?
- Excitatory (somatosensory cortex)
- Inhibitory (cerebellum)
3 layers that are main efferent projections of the cortex?
III. Outer pyramidal cell layer
V. Inner pyramidal cell layer
VI. Plexiform layer
What is the output of layer III. Outer pyramidal cell layer?
Cortico-cortical projections innverating layers 1 - 6
What is the output of layer V. Inner pyramidal cell layer?
- Subcortical projections
- Pyramidal tracts to motor neurons: spinal cord, cranial nerve nuclei
What is the output of layer VI. Plexiform layer?
Cortico-thalamic projections
1 layer that is the main afferent projection of the cortex
IV. Inner granule cell layer
What is the input of layer IV. Inner granunle cell layer?
Specific thalamo-cortical inputs
(innervate L5 pyramidal cells, directly or indirectly)
What is the organization and connections of cortical modules?
- Vertical and columnar orgnization
- Internal connections
- Columnar communication (further integration)
Width and thickness of cortical modules?
- Width: 200 - 300 µm
- Thick as the cortex
Number of neurons per column
5000 neurons/column
What does the axis of cortical modules contain?
Cortico-cortical afferentes
What are the roles of inhibitory interneurons to the cortical modules?
They seal the column to prevent lateral spreading activity
What are the afferent pathways of cortical modules?
Other modules OR specific afferents from organs of special senses
What are the efferent pathways of cortical modules
Motor pathways OR towards other modules
What is barrel cortex?
Glutamatergic spiny stellate and star pyramidal cells (yellow) of layer 4 aggregate along the walls of a barrel in the cortex
What are the 3 places that you can find cortical connections?
- Association fibers-within hemispheres
- Commissural fibers-between hemispheres
- Projections pathways-connections with non cortical structures
2 cortical connections that you can find in association fibers-within hemispheres
- short and long arucuate fibers: connect nearby structures
- Cingulum: connects different lobes
What are the cortical connections that you can find in commissural fibers-between hemispheres
- Corpus callosum
- Commissura anterior, posterior and fornicis
What are the 6 main projection pathways-connections with non-cortical structures?
- In and output pathways
- Reciprocal connections with thalamus
- Reciprocal connections with the basal ganglia
- Pyramidal tracts
- Corticoponine tracts
- Fornix (hippocampus-hypothalamus)
What are the 3 places that you can find cortical connections?
- Association fibers-within hemispheres
- Commissural fibers-between hemispheres
- Projections pathways-connections with non cortical structures
What is the general pathway of ascending tracts - somatosensory system?
Receptor
-> 1st neuron
-> 2nd neuron
-> 3rd neuron
-> cerebral cortex
What does the receptor of ascending tracts - somatosensory system include?
- Exteroceptor (pain, temperature, touch)
- Proprioceptor (muscles, joints)
What is the 1st neuron of ascending tracts - somatosensory system include?
DRG
What is the 2nd neuron of ascending tracts - somatosensory system include?
Posterior horn
What is the 3rd neuron of ascending tracts - somatosensory system include?
Subcortical centres
Where can you find ascending tracts - somatosensory system on the brain?
- Spinobulbar tr
- Ant. Spinothalamic tr
- Lat. Spinothalamic tr
- Ant. spinocerebellar tr
- Post. Spinocerebellar tr
- Spinotectal tr
- Spinoolivary tr
- Spinoreticular tr
What are the 3 roles of descending tracts - somatomotor system?
- Voluntary and involuntary movements
- Muscle tone
- Reflexes
What is the general pathway of descending tracts - somatomotor system?
1st neuron - cortex, brainstem
-> 2nd neuron - interneurons in anterior horn
-> 3rd neuron - motorneurons in anterior horn
-> Skeletal muscles, myotomes
What is the 1st neuron of descending tracts - somamotor system?
Cortex, brainstem
What is the 2nd neuron of descending tracts - somamotor system?
Interneurons in the anterior horn of spinal cord
What is the 3rd neuron of descending tracts - somamotor system?
Motorneurons of the anterior horn of spinal cord
What are the descending tracts of somamotor system on the brain? (9)
- Ant & Lat corticospinal tr
- Rubrospinal tr
- Tectospinal tr
- Med & Lat vestibulospinal tr
- Reticulospinal tr
- Olivospinal tr
- Medial longitudinal fascicle
2 places that you can find intracerebral tracts
- Limbic system
- Basal ganglia
What are the 2 divisions of limbic system?
- Cortical divisions
- Subcortical divisions
What does cortical divisions include? (5)
- Orbitofrontal cortex
- Hippocampus
- Insula
- Cingulate gyrus
- Parahippocampal gyrus
What does the subcortical divisions include? (4)
- Amygdala
- Olfactory bulb
- Anterior thalamic nuclei
- Septal nuclei
What are the 5 intracerabral tracts that you can find in the limbic system?
- Alveus
- Fimbira
- Fornix
- Mamillothalamic tract
- Stria terminalis
What is the role of basal ganglia?
Control of voluntary and involuntary movements
What are the 4 components of basal ganglia?
striatum, globus pallidus, subthalamic nucleus, substantita nigra
What are the 3 cortical areas?
- Sensory areas
- Motor areas
- Association areas
2 characterstics of sensory areas (level, type of areas)
Primary sensory areas: 1st level areas in sensory processing
2 characterstics of motor areas (level, type of areas)
Primary motor area: final level in the hierarchy of motor execution
4 functions of association areas
- Integration
- Planning
- Decision making
- Memory storage
How many neocortical areas are there? (based on cytoarchitecture and function)
52
How many neocortical areas are there? (based on cytoarchitecture and function)
52
Name of this field and Brodmann areas
Primary somatosensory field (Brodmann (3,1,2)
Name of this field and Brodmann areas
Primary somatomotor field (Brodmann 4)
Name of this field and Brodmann areas
Praemotor field
(Brodmann 6,8)
Name of this field and Brodmann areas
Broca’s motor speech area
Brodmann 44, 45
Name of this field and Brodmann areas
Secondary + Tertiary visual fields
(Brodmann 18,19)
Name of this field and Brodmann area(s)
Primary visual field
Brodmann 17
Name of this field and Brodmann area(s)
Wernicke’s speech area
Brodmann 39, 40
Name of this field and Brodmann area(s)
Auditory cortex
Brodmann 41, 42
Parietal multimodal associations cortex
-> What does the input of anterior part include? (2)
Wernicke’s area, infratemporal assoc. cort
Parietal multimodal associations cortex
-> What does the output of anterior part include?
dorsolat. prefrontalis és premotoros kéreg
Parietal multimodal associations cortex
-> What is the 4 main roles of anterior part?
- Association of hearing, seeing and talking
- Store for signs, langauages, words
- Sensorimotor control of writing
- Formation of speech
Parietal multimodal associations cortex
-> What does the input of superior part include? (3)
vision, touch, hearing (unimodal cortices)
Parietal multimodal associations cortex
-> What does the output of superior part include? (3)
dorsolat. Prefrontal and premotor cortices
Parietal multimodal associations cortex
-> What is the role of superior part?
Control of hand movements („usage”)
Parietal multimodal associations cortex
-> What does the input of posterior part include? (2)
visual cortex, hippocampus
Parietal multimodal associations cortex
-> What does the output of posteruir part include? (2)
dors. premotor area, FEF
Parietal multimodal associations cortex
-> What are the 2 functions of posterior part?
- Spatial cognition
- Navigation abilities („GPS”)
What is the ouput of temporal multimodal associations cortex?
prefrontal cortex
What are the 3 functions of temporal multimodal associations cortex?
- Integration of visual auditory information
- Recognition of (shape of) face, hand and objects
- Memorization of people, names and faces
What is the role of dorsolateral prefrontal cortex?
- decision – working memory
- planning of execution – motor program
What is the role of ventrolateral prefrontal cortex?
- recognition - understanding (comprehension)
- Monitoring of the environment
What is the role of orbitofrontal prefrontal cortex?
- emotion, motivation
- social behavior
What are the 3 functional cortical networks?
- Resting state networkds
- Central executive networkds
- Salience network (SN)
The role of resting state networks (functional cortical networks)
Exploration, new ideas/thoughts, planning, remembering
What is the role of central executive networkds?
Motor executive systems
What is the salience network (SN)
Focus, selection, targeted activity, correction
