Thalamic attention circuitry normal and psychotic.
Cortex is not preprogrammed to recognise transthalamic sensory patterns or to prioritize them for motor reaction. Network subsets for these abilities are taught into neocortex in early life from the hippocampi where species-significant pattern-recognition and reaction-prioritizing ARE genetically preprogrammed. Thereafter whenever an indoctrinated subset of cortex is activated via thalamic sensory relay nuclei it axonally activates a specific subset of neurons within the thalamic pulvinar. Pulvinar analogically integrates this with concurrent specific inputs from the thalamic dorsomedial nucleus which itself is integrating inputs from the prefrontal cortex (goals) and the amygdaloid nuclei (moods). The pulvinar's specific integral is then axonally projected back to cortex UNDER NON-SPECIFIC BOOST from the thalamic centromedian nucleus. This ensures unitary attention focussing influenced by acquired priorities. Given that neocortex is genetically organized as a classifying mechanism, it also permits virtually limitless part-novel learning and best-match reality-testing of percepts (and concepts in humans). In schizophrenia the non-specific booster system is bilaterally blocked at the centromedian nucleus. In mania the non-specific thalamic system is shunted, at midbrain, into the non-specific direct cortical system. In melancholia both of these brainstem systems are subnormal in non-specific output. Figure 1 schematizes the main axonal circuitry. Analogical integration occurs within predominantly dendro-dendritic networks.
D001288:Attention / Q000502:physiology*; D006801:Humans; D009434:Neural Pathways / Q000502:physiology; D011618:Psychotic Disorders / Q000503:physiopathology*; D013788:Thalamus / Q000502:physiology* / Q000503:physiopathology