Prelimbic cortex

The ultrastructural observations of Sesack et al. (1998) indicated that considerable extracellular diffusion of DA in the prelimbic prefrontal cortex may result, at least in part, from a paucity of DAT content in dopaminergic mesocortical axons, as well as from a distribution of DAT protein at a distance from synaptic release sites. In this study, DAT-immunoreactive profiles in the striatum and in the cingulate cortex included both varicose and intervaricose segments of axons, but intervaricose axon segments predominated in the prelimbic cortex. 

The determination of the compartmental target of neurons in different sublaminae of the prelimbic cortex was based on a large number of cases of injections of PHA-L... 

Sesack, S. R.,Hawrylak, V. A., Matus, C., Guido, M. A and Levey, A. I. Dopamine axon varicosities in the prelimbic division of the rat prefrontal cortex exhibit sparse immuno-reactivity for the dopamine transporter. /. Neurosci. 18 2697-2708,1998. 

Miner LA, Backstrom JR, Sanders-Bush E, Sesack SR. Ultrastructural localization of serotonin(2 A) receptors in the middle layers of the rat prelimbic prefrontal cortex. Neuroscience 2003 116 107-117. 

In the rat, the limbic or ventral striatum, which includes the ventral striatum proper and the ventromedial portion of the CPu, receives extensive input from limbic structures, such as the hippocampus and amygdala, as well as prefrontal cortical areas subserving limbic and autonomic functions (orbital, infralimbic, prelimbic and agranular insular fields) (see Section 7.2). In primates, the limbic striatum comprises the NAc and the most ventral parts of the caudate and the putamen and, as in the rat, receives input from the hippocampus and amygdala its cortical input is further defined by projections deriving from the orbitofrontal cortex and the anterior cingulate area. 

The NAc core and the shell show differences in their input-output organization. For example, although hippocampal projections reach both the core and the shell, the ventral subiculum projects to the shell, whereas the dorsal subiculum projects to the core. Different regions of the prefrontal cortex also target differentially the shell and core the prelimbic area projects to the core, whereas the infralimbic and piriform cortices project to the shell (Berendse et al., 1992). Amygdaloid fiber subsets are also differentially distributed to the two main NAc territories. 

Strong parvalbumin immunoreactivity is present in layer 4 of the primary somatosensory cortex. SMl-32 immunoreactivity formed distinctive patches in layer 4 of the barrel field and forelimb and hindlimb regions. The primary auditory area was identified on the basis of reduced calbindin immunoreactivity in the deep layers. All the auditory areas were marked by the presence of SMl-32 positive cells in the superficial layers. AChE marked the location of the prelimbic and agranular insular cortices. NADPH-diaphorase assisted in defining the agranular insular, perirhinal, and retrosplenial granular cortices. Additionally, NADPH-diaphorase immunoreactivity indicated the ventral part of the medial entorhinal cortex. Calretinin immunoreactivity assisted in delineation of the lateral entorhinal cortex where the outer part of layer one is densely stained. 

Fig. 26. The relationship between the laminar organization of the cortex and the striatal patch-matrix compartments is diagrammed showing inputs from the prelimbic (A) and cingulate (D) cortices to the striatum. Corticostriatal neurons located in the deeper part of layer 5 (black cells in A and B) in each cortical area provide inputs directed to the patch compartment (black stippling in B,C, E and F), whereas corticostriatal neurons located in the superficial part of layer 5 (white cells in A and D) provide inputs directed to the matrix compartment (white stippling in B,C, E and F). Inputs from these cortical areas are somewhat greater to the patch compartment as compared to their inputs to the matrix compartment. The prelimbic and cingulate cortical areas provide inputs to a topographically related region in the striatum which overlaps to some extent for these two corticostriatal projections.

---