Neuroanatomy: Thalamus
Relays sensory information from the body to the cerebral cortex
ventral posterolateral nucleus (VPL)
Relays auditory afferents from the inferior colliculus to the primary auditory cortex.
Medial Geniculate Body (MGB)
receives input from several brain areas including the solitary nucleus, substancia nigra reticulate, amygdala and ventral pallidum and projects to limbic areas of the cortex.
Mediodorsal nucleus (DM)
Reticular nucleus is a __________ nucleus.
Non-specific
Project quite broadly through the cerebral cortex, may be involved in general functions such as arousal and alertness. e.g. Reticular Nuclei
Nonspecific nuclei
Nonspecific thalamic nuclei are embedded in the:
internal medullary lamina
relays sensory information from the head and face to the inferior portion of the postcentral gyrus
ventral posteromedial nucleus (VPM)
Thalamus is part of the:
Diencephalon
Connections similar to the LD nucleus. Receives input from the hippocampus via the mammillary bodies and projects to the posterior cingulate cortex.
Anterior thalamic nuclei (ATN)
Korsakoff's syndrome can cause both ___________ memory issues.
Anterograde and retrograde.
Medial nuclei of thalamus are more associated with ____________ type of information
Association
Motor function of thalamus relays outputs from the ____________
Basal Ganglia and Cerebellum
Also known as "oscillatory mode", neurons in this state have an intrinsic rhythmicity.
Burst Mode
Located laterally and separates reticular nucleus from the rest of thalamus
External medullary lamina
The main neurotransmitter from the reticular nucleus is:
Gamma-aminobutyric acid
Gamma-aminobutyric acid (GABA) from the reticular nucleus __________ responses in the brain.
Inhibits
Separates medial, lateral and anterior nuclei
Internal medullary lamina
Reticular nucleus controls thalamic output largely through _____________
Interneuron inhibitory connections and GABA transmission.
Vegetative functions of the thalamus can be associated with disorders of consciousness and has:
Intrinsic nucleus associated with alertness and arousal.
Chronic memory disorder stemming from a severe deficiency of thiamine (VitB-1) commonly caused by alcohol misuse. Damage to mammillary bodies, mamillothalamic tract, or limbic specific nuclei of the thalamus.
Korsakoff's Syndrome
Inputs from the Retina relay through the ______ and project to the primary visual cortex.
LGN
receives projections from superior colliculus, olfactory cortex and ventral pallidum, with efferent projections to the frontal eye fields and to the anterior cingulate cortex of the frontal lobes.
Lateral Dorsal Nucleus (LD)
relays input from the optic tract to the primary visual cortex via optic radiations
Lateral Geniculate Body (LGB)
Inputs from the Cochlea relay through the ______ and project to the primary auditory cortex.
MGN
Which information does not reach the thalamus directly?
Olfactory
Emotion/Memory function of the thalamus is part of the ____________ circuit that helps control some emotional and memory information going to the __________ (cingulate Gyrus).
Papez/Limbic circuit, Limbic Cortex
Receives afferent from the superior colliculus and association cortex and projects to secondary visual areas and to association areas in the Parietotemporal region
Pulvinar (association nuclei) (Lateral posterior has similar connections)
Thalamic Reticular nucleus is an source of:
Regulatory inputs to the thalamus
Sensory function of the thalamus
Relay all sensory information to the cortex.
Lateral portion of thalamus contains many of the ___________ such as lateral and medial GN
Relay nuclei
Thalamic nuclei, which the exception of ____________, project primarily to the cerebral cortex.
Reticular thalamic nucleus
Thalamic reticular neurons may be important in _____________.
Sleep/wake cycles
Relay nuclei receive specific inputs from ________ pathways and project to a well defined functional area of the cortex.
Subcortical pathways
Receive most of their input from the cerebral cortex and project back to the cerebral cortex where they appear to regulate activity. e.g. dorsomedial nucleus
Thalamic Association Nuclei
Receive very well defined inputs and project this signal to functionally distinct areas of the cerebral cortex. e.g. Medial Geniculate
Thalamic Relay Nuclei
The output of each reticular nucleus goes to the ________ from which it receives input.
Thalamic nucleus
Sheet of neurons overlaying the thalamus that receives input from the cortex and from thalamic projection neurons.
Thalamic reticular neurons
Two types of fibers present in the thalamus:
Thalamo-cortical fibers and cortico-thalamic fibers
Primary site of relay for all of the sensory information to the cerebral cortex
Thalamus
When thalamic neurons respond similar to other neurons to depolarization and hyperpolarization.
Tonic Mode
Thalamic projection neurons can exist in one of two basic physiological states:
Tonic Mode and Burst Mode
Thalamic reticular nucleus fires _________ when we are awake or aroused. they fire ________ when we are sleeping.
Tonically, burts
Inputs from the Spinothalamic (body) Relay through the ______ and project to the ___________
VPL, Somatosensory cortex
Inputs from the Trigeminothalamic (face) relay through the _____ and project to the __________
VPM, somatosensory cortex