Thalamic reticular neuron

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Fig. 1: Picture shows a biocytin stained thalamic reticular cell. The cell comes from the reticular sector of rat ventrobasal nucleus.

Thalamic reticular neurons are neurons found in all vertebrates.

NS neuron

Fig. 2: The thalamic receive excitatory synapses on relay cells from the primary afferent. The relay cell synapses to the thalamic nucleus (TRN) and TRN project axon to layer 4 of the cortex. Layer 6 in the cortical area then send the information back to the thalamus bypassing the TRN.

The thalamic reticular nucleus is a thin layer of GABA nerve cell that surrounds the thalamus. The external medullary lamina acts as the separator between the thalamus and the thalamic reticular nucleus. The GABA nerve cell receives its information from the external layer of the thalamus and cortex. It now acts as a inhibitory center and send the information back to the thalamus.

Neuronal Type: Interneuron

Anatomy

In thalamic reticular nucleus, both its dendrite and cell body of are arranged at the right angle of the traversing fibre bundles and parallel to its surface. The axons are widely distributed and it seems to have a connection with the dorsal lateral geniculate nucleus and with the ventrobasal nucleus. The axon organizations of Thalamic Reticular Nucleus show a more rostral and dorsal parts from the TRN projects to rostral and dorsal parts of dorsal lateral geniculate and ventrobasal nuclei.

Molecular profile

• Neurotransmitter: Gamma-aminobutyric acid cause an inhibitory response in the brain synapses by binding to its specific receptors on the plasma membrane of both pre and postsynaptic processes in neuron.

Physiology

Synaptic Connections

Synaptic Inputs and Outputs

The Thalamic Reticular Nucleus inputs are excitatory; however, its output is inhibitory. This different in input and output make it perfect for the organization of modulating visual action during the early processing.

Spiking properties

There are two phases in this response: lead and lag phases. The response of latency of the lead phase is between 10 and 100msec and the total response duration is between 50 and 250 msec. On the other hand, the minimum latency of the lag phase is 100 to 300 msec.

Behavior

There are inhibitory signal acts on the dorsal thalamus from the thalamic reticular nucleus. The thalamic reticular nucleus fire tonically when we are awake or arouse. However, they fire rhythmic high frequency bursts, when we are sleeping. The thalamic reticular nucleus effect on the dorsal thalamic neurons activity will depend on TRN firing mode.

References

1. McAlonan K., Cavanaugh J., and Robert H. Wurtz. (2006) Attentional Modulation of Thalamic Reticular Neurons. The Journal of Neuroscience. 26(16):4444-4450; doi:10.1523/JNEUROSCI.5602-05.2006

2. Moldavan, M. G. (1991) Neuronal spike response produced in the feline thalamic reticular nucleus by instrumental conditioned reflex. Neurophysiology. Vol. 23, Number 1. 6-14

3. Ohara P.T., Lieberman A.R. (1985) The thalamic reticular nucleus of the adult rat: experimental anatomical studies. Journal of Neurocytology. 14(3):365-411.

4. Warren R.A., and E. G. Jones. (1994) Glutamate activation of cat thalamic reticular nucleus: effects on response properties of ventroposterior neurons. Experimental Brain Research. Vol. 100, Number 2. 215-226

Additional information

1. | The Reticular Nucleus and Meditation
2. | Thalamic reticular nucleus