Perforant path

Bliss, TVP and Loma, T (1973) Long-lasting potentiation of synaptic transmission in the dentate area of the anaesthetised rabbit following stimulation of the perforant path. J. Physiol. 232 331-356. 

Buxbaum, J. D., Thinakaran, G.,Koliatsos,V. etal. Alzheimer amyloid protein precursor in the rat hippocampus transport and processing through the perforant path. /. Neurosci. 18 9629-9637,1998. 

Figure 1. A. SimpMed diagram of the rodent hippocampal formation illustrating the major glutamatergic circuitry. The principal neuronal helds granule cells (GC) of the dentate gyrus and pyramidal cells of CAl and CA3 in Ammon s horn are shown. The main excitatory connections are also indicated the perforant path from entorhinal cortex to the granule cells, from there the mossy hbre (mf) axonal projections to CA3 and then the Schaffer collaterals (Sch) from CA3 to ipsilateral CAl and commissural (Comm) to contralateral CAl cells. Evoked responses in (B) were obtained by stimulating the afferent pathway from entorhinal cortex, the medial perforant path (Med), and recording the granule cell (GC) response in the hilus of the dentate gyrus.

Several other behavioral abnormalities have also been described in 5-HT2C-R KOs. These mice display several types of repetitive behavior that have been likened to compulsions (110). 5-HT2C-R KO mice also display altered stress responses (111), a deficit in maternal behavior (Storm, unpublished data), decreased spatial memory performance in the Morris water maze, and decreased long-term potentiation (LTP) in medial perforant path-dentate gyrus synapses (112). 

Arrigoni E, Greene RW. 2004. Schaffer collateral and perforant path inputs activate subtypes of NMDA receptors on the same CA1 pyramidal cell. J Pharmacol 142 317-322. 

Myhrer, T. (1988). The role of medial and lateral hippocampal perforant path lesions and object distinctiveness in rats reaction to novelty. Physiol. Behav. 42 371-7. 

One striking feature of hippocampal circuitry is the pattern of afferent termination. Major hippocampal afferents originating from entorhinal cortex and ipsilateral and contralateral hippocampal subfields synapse on the dendrites of the principal cells in a laminated pattern. For instance, hippocampal commissural and associafional fibers synapse within the proximal one-third of the granule cell dendritic field, which is close to the cell body layer. The massive perforant path fibers terminate topographically in the outer two-thirds of the dendritic field. Afferents also have a laminar organization in the hippocampal proper. 

Affa ents to the Dentate Gyrus—The Perforant Path... 

As emphasized by Cajal (1911) and later corroborated by Lor-ente de No (1934), the main input to the dentate gyrus is from the entorhinal cortex (but also perirhinal cortex, among others) by way of a fiber system called the perforant path. It is the major input to the hippocampus. The axons of the perforant path arise principally in layers II and III of the entorhinal cortex, with minor contributions from the deeper layers IV and V. Axons... 

Although LTP was first demonstrated at the perforant path synapses on the granule cells in the dentate gyrus (Bliss and Gardner-Medwin, 1973), the majority of experiments on understanding the mechanisms of LTP have been performed on the Schaffer collateral/commrssural synapses on the CAl pyramidal cells in the hippocampus. 

Tlie medial and lateral perforant paths project to wliich part of the dendrite tuft of the granule cells ... 

Figure 6.1. Schematic drawing by Ramon y Cajal (1911) of the main cells, connections and flow of impulse traffic in the hippocampus. Alv alvus, CA Cornu Ammonis, DG dentate gyrus, EC entorhinal cortex, MF mossy fibers, PP perforant path, Sch C ffer collaterals. Sub subiculum...

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