Thalamocortical connection

Ray, J. P. and Price, J. L. (1992). The organization of the thalamocortical connections of the mediodorsal thalamic nucleus in the rat, related to the ventral forebrain-prefrontal cortex topography. J. Comp. Neurol. 323, 167-197. 

Cusick CG, Steindler DA, Kaas JH. 1985. Corticocortical and collateral thalamocortical connections of postcentral somatosensory cortical areas in squirrel monkeys A doublelabeling study with radiolabeled wheatgerm agglutinin and wheatgerm agglutinin conjugated to horseradish peroxidase. Somatosens Res 3 1-31. 

Possible evidence for a persistent fetal circuit is provided by the abnormal presence of an increased number of neurons in cerebrocortical layer I and in the subcortical white matter that has been noted in several autistic brains. These neurons have been shown to normally play an essential, transient role in the development of definitive cerebral cortical circuits, particularly in relationship to thalamocortical connections (Shatz et al., 1998 Super et al., 1998 Okhotin and Kalinichenko, 2003). In this regard, it is of interest to note that Kleinhans et al. (2008), in an fMRI functional study of face recognition, noted in ASD a failure of the significant activation of the thalamus that was noted in the controls. 

Kievet J, Kuypers HGJM (1977) Organization of the thalamocortical connections to the frontal lobe in the rhesus monkey. Exp. Brain Res., 29, 229-322. 

The development of serotonergic innervation to the cerebral cortex has been characterized in neonatal rats by immunohistochemical techniques and autoradiographic imaging. These experiments demonstrate early serotonergic innervation that could be involved in a transient physiological role in sensory areas of the cortex or exert a trophic influence on the development of cortical circuitry and thalamocortical connections [76]. 

In hypokinetic disorders, the discharge of efferent striatal neurons is diminished in the direct and increased in the indirect way, so that an inhibition of thalamocortical connections originates from a... 

These features are compatible with a role in the feedforward integration of eye movement commands (and perhaps other brain stem motor outputs such as gait) but also in the feedback control of thalamocortical sector activation. No such function has previously been suggested, but the intimate connection of eye movement variability, volitional change (frontal eye field), and sensorimotor facilitation and blocking warrants serious consideration of this hypothesis. 

Fig. 7. Schematic drawing of a transverse section through the forebrain depicting pathways likely to use glutamate as a neurotransmitter. I = principal subcortical afferents to the thalamus from. somatosensory relay nuclei and the spinal cord (a), cerebellar nuclei (h). and retina (c) 2 = intrinsic neurons and retinal inputs to the hypothalamus 3 = thalamocortical inputs 4 = corticothalamic inputs 5 = cortical inputs to the basal ganglia and other areas in the brainstem and spinal cord 6 = associational and commi.ssural connections in the cerebral cortex. For further details, see Sections 3.5-3.9.

Human hearing arises from airborne waves alternating 50 to 20,000 times a second about the mean atmospheric pressure. These pressure variations induce vibrations of the tympanic membrane, movement of the middle-ear ossicles connected to it, and subsequent displacements of the fluids and tissues of the cochlea in the inner ear. Biomechanical processes in the cochlea analyze sounds to frequency-mapped vibrations along the basilar membrane, and approximately 3,500 inner hair cells modulate transmitter release and spike generation in 30,000 spiral ganghon cells whose proximal processes make up the auditory nerve. This neural activity enters the central auditory system and reflects sound patterns as temporal and spatial spike patterns. The nerve branches and synapses extensively in the cochlear nuclei, the first of the central auditory nuclei. Subsequent brainstem nuclei pass auditory information to the medial geniculate and auditory cortex (AC) of the thalamocortical system. 

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