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