Thalamus-Cortex Flashcards
Thalamic Non-specific nuclei
Mainly the intralaminar nuclei that send non-specific projections to cerebral cortex after inputs from basal ganglia.
What kind of potential is produced by low threshold calcium current
all or non triangular shaped potential wiht a low threshold called low threshold spike
What are the two functions of thalamus
What is basic concept of sensory and motor information flow in cortex
A is old model, B is modern model
Location of nucleus reticulares on coronal cut
General Design of Thalamocoritcal circuits
What kind of neuron constitutes 80% of all nuclei
Glutamatergic excitatory projections make up 80%
Also GABAnergic of nucleus reticularis surrounding the thalamus providing inhibitory
Thalamic relay limbic nuclei
maiary obdies - anterior nucleus - cingulate gyrus
Organization of cortex - neurons from layers 1,3,5,6 go out to what areas respectively
1 - Other cortical ares
3 - Other cortical areas, opposite hemisphere
5 - Subcortical structures
6 - Thalamus
Giant pyramidal cells are called
Betz cells
What are the two fundamental properties of bursting
all-or-none and refractory period.
Onset of sleep defined by?
Diminshed amplitude of alpha waves in occipital EEG channel and change in firing pattern
Wake to sleep 2 main changes in TC cells
Tonic to bursting, rhythmicity
How do Thalamic cells respond differently to sensory signals in Wake and Sleep
Unreliable bursts. Opposite of fixed reliable single spike in wake
Agranular cortex more likely to be found?
Granular cortex more likely to be found in what region?
What ist he dramatic change in thalamus firing pattern from wake to sleep
High frequency low amplitude single spikes to burst firing mode
EEG - General measure of neural activity
Spike wave pattern
What layers are traveresed in vertical flow of information of cortex
Granular (4) - Super Granular (2/3) - infragranular (5/6) - Out of cortex
Wake to Sleep 3 main changes in EEG
amplitude, frequency, synchronization
What is basis of cytoarchitecture and how many layers are there in neocortex
Basis is layers from differences in cell packing density, presence of fiber bundles.
6 Layers in neocortex but only Layer 4 aka granular layer used
How does a thalamic cell in burst mode respond to repeated stimulus
Thalamus 3 Sensory Relay nuclei
Auditory - Medial geniculate
Visual - Lateral geniculate
Somastosensory - Ventrobasal
Thalamus Motor Relay nuclei
Ventral anterior and ventral lateral
Changes in EP produced by disease usually lead to what EEG finding
Delayed response in evoked potentials
Thalamus limited laterally and internally by
Sleep EEG characterized by
Low activity, high amplitude
What channels are active when you hyperpolarize TC cells
Calcium channels
3 States of the T-channel and how they contribute to the rhythmic burst firing mode in TC cells
How are evoked potentials measured
Smaller but usally determiend by averaging techniques of othe recordings
Anatomic Divisions of the Thalamus (5)
Internal medullary divides the Medial and Lateral Nuclei
Also the Anterior group of nuclei
Intralaminar nuclei
reticular nucleus
Thalamic 2 association nuclei
Pulvinar - serves parietal-occipital-temporal assocation cortex
mediodorsal - serves prefrontal cortex
What are the two types of excitatory cells that use Glutamate neurotransmitter
Granular cells aka spiny stellate in layer 4
Pyramidal cels that are 80% of cortical cells
Columnar organization shows
Visual cells respond to same stimulus in one vertical field. Shows massive parallel processing device
Areas of cortex receiving relay vs association nuclei
What nuclei does not have any projections outside of the thalamus
reticular nucleus
General pattern of oscillatory mode that is due to similarites with heart calcium channels
A rise in (Ih) current -> Low threshold calcium (It) opens depolarizes Activating sodium/potassium. Depolarization inactivates (Ih) - repolarization then hyperpolarization bc Ih was incativated. Hyperpolarization de-inactivates It and activates Ih reaching level for low threshold calcium to fire again
Functional consequence of rhythic bursting in thalamus and cortex
Global synchrony in thalamacortical networks
What maintains the thalamic membrane potential during wake and is less active in sleep
brainstem and basal forebrain neuromodulatory systems releasing acetylcholine and noradreniline.
Less activation allows K current to dominate and lead to hyperpolarization.
What are the 2 main types of thalamic cells?
Thalamocortical projections - excitatory and projecting to cortex
Reticular thalamic neurons - inhibitory projecting reciprocally to thalamic nuclei
