The RAIC and the VTA


Below are figures that illustrate some of the anatomical studies we have been conducting on the connections between the RAIC and the ventral tegmental area (VTA), the source of dopaminergic innervation of the RAIC that modulates the excitability of cortical neurons.


To examine the projection from the VTA to the RAIC we have injected the fluorescent dye Rhodamine into RAIC and immunostained the VTA with tyrosine hydroxylase as a marker for dopaminergic neurons. This figure illustrates double labeled cells (yellow) neurons in the VTA, i.e. TH containing neurons that project to the RAIC.
It is known that the VTA also projects to the prefrontal cortex (PFC). We wish to know if the same dopaminergic cells in the VTA project to both the RAIC and PFC. This figure illustrates the double labeled cells (green with blue nucleus) in the VTA following an injection of Fast Blue into the PFC and immunohistochemical staining of the VTA with tyrosine hydroxylase (FITC-green).
To fully understand the role of projections from the VTA to the RAIC it is necessary to examine some of the intrinsic connection of the VTA itself. An important modulator of VTA function is the inhibitory neurotransmitter GABA. Here the VTA is immunolabeled for tyrosine hydroxylase (green) and GAD (red) the synthetic enzyme for GABA.
Missed! In order to see which neurons in the RAIC project to the VTA we inject the VTA with Rhodaine then examine the RAIC for retrogradely labeled neurons. Here is an example of how close, yet how far, one can be with stereotaxically guided injections. The Rhodamine injection (red) is a about 100µm above the intended target in the VTA VTA visualized with immunofluorescence staining for tyrosine hydroxylase (green).


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