Above hypothalamus is golf-ball-sized ellipsoidal region {thalamus}|.
functions
Thalamus is for attention, respiration, short-term memory, and long-term memory. It can detect sensations, temperature, pain, and moderate skin stimulation. It identifies objects and initiates avoidance behavior. In mammals and humans, it directs attention to language. It affects autonomic system.
Thalamus has feeding center that controls eating behavior. It has satiety center that has glucose receptors.
anatomy
Ventral reticular nucleus is thin shell that surrounds walnut-sized dorsal thalamus. Thalamus has few intrinsic neurons.
anatomy: nuclei
Thalamic nuclei include anterior, centromedian, dorsolateral, dorsomedial, intralaminar, lateral geniculate for vision, medial geniculate for audition, multimodal, pulvinar, reticular, ventral anterior, ventral lateral, ventral posterior, and ventrobasal complex for somatosensation [Jones and Peters, 1986] [Jones, 1985] [Sherman and Guillery, 2001].
input
Main inputs to cortex first pass through two dozen thalamus regions. Glomeruli and glia surround incoming sense-nerve axons. Thalamus has projection areas for skin regions, with subareas for touch, pressure, muscle, and joint movement. Thalamus has input neurons for taste and for taste and touch.
Number of cortical fibers projecting back to thalamic nuclei is much larger than number of fibers from senses to thalamus.
output
All nuclei have matrix cells with diffuse projections. Thalamus has as many outputs as inputs but has no axon collaterals.
Thalamus inhibits optic tectum in lower vertebrates.
Core relay neurons send to cortex layer 4. Matrix neurons send to cortex layers 1, 2, and 3. Clustered neurons {core neuron}, such as magnocellular and parvocellular neurons, excite layer 4 in small cortex regions. Other neurons, such as koniocellular neurons, send to layers 2 and 3 in larger cortical regions {matrix neuron} [Jones, 2002].
damage
Non-specific thalamus damage causes consciousness loss. Thalamic damage can cause sense or motor loss.
processing
Input causes one spike and then 100 milliseconds of inhibition. Thalamic neurons can replicate sense input or can burst in 30-Hz to 40-Hz pattern unrelated to input. Thalamus reticular nucleus can switch lateral geniculate nucleus into burst mode.
Biological Sciences>Zoology>Organ>Nerve>Brain>Cerebrum>Diencephalon>Thalamus
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Date Modified: 2022.0224