Friday, April 8, 2011
Parts is parts...
We have covered many functions of the thalamus in the prior sections. Rather than repeat the descriptions, this blog will instead simply provide a diagram and list of components (and functions) of the thalamus:
* anterior nuclear group - responsible for sexual dimorphism (the differences between male and female
o anteroventral nucleus
o anterodorsal nucleus
o anteromedial nucleus
o superficial ("lateral dorsal")
* medial nuclear group (or dorsomedial nucleus) - connects the prefrontal cortex and limbic system - responsible for attention, planning, organization abstract thinking, multitasking and memory
o parvocellular part
o magnocellular part
* midline nuclear group or paramedian - part of the septal system which imposes control of information under varioous states of attention. Also involved in rewarding and reinforcing behaviors.
o parvocellular part
o paratenial nucleus
o parventricular nucleus
o reuniens nucleus - particularly associated with attentional control of sensory input
o rhomboidal nucleus * Intralaminar nuclear group (Intralaminar nuclei) - associated with motor "gating" and *intent* - i.e. control of motor movements toward a target - damage to this area is associated with palsy, tremor and Parkinson's disease.
o paracentral nucleus
o central lateral nucleus
o central medial nucleus * centre median parafascicular group - connects to the "Basal Ganglia" the "unconscious" part of the forebrain, which regulates involuntary movement, unconscious movement (such as postural changes), and inhibition of movement.
Consists of the:
o centromedian nucleus
o parafascicular nucleus * lateral nuclear group
o posterior region
+ pulvinar - associated primarily with visual association areas and visual attention
+ lateral posterior nucleus belongs to pulvinar
+ (lateral dorsal nucleus) belongs to anterior group - linked to emotional association with visual scenes and objects.
o ventral nuclear group
+ ventral anterior nucleus
+ ventral lateral nucleus - these two link the cerebellum, basal ganglia and premotor cortex for planning of motor movements
+ ventral posterior nucleus - part of the ascending motor feedback system, linking spinal cord to the premotor (planning) areas.
# ventral posterolateral
# ventral posteromedial
* metathalamus (no longer used - currently called the geniculate group)
o medial geniculate body - auditory preprocessing
o lateral geniculate body - visual preprocessing
* thalamic reticular nucleus (part of the ventral thalamus, forming a capsule around the lateral thalamus) - the only part of the thalamus not to project to cerebral cortex, it regulates the flow of information between areas of thalamus.
... and that's just a *brief* survey. The thalamus is an amazing gatekeeper for the brain, virtually every connection between brain and body passes through or is regulated by the thalamus.
Just wait 'til we do the same with *hypothalamus* (which does a similar job, but via chemical control of the other systems).