Perforant path
Encyclopedia
In the brain, the perforant pathway provides a connectional route from the entorhinal cortex
to all fields of the hippocampal formation, including the dentate gyrus
, all CA fields (including CA1), and the subiculum.
Though it arises mainly from entorhinal layers II and III, it comprises a smaller component that originates in deep layers V and VI.
There is a major dichotomy with respect to the laminar origin and related terminal distribution: neurons in layer II (and possibly layer VI) project to the dentate gyrus
and CA3, whereas layer III (and possibly layer V) cells project to CA1 and the subiculum.
It may play a role in temporal lobe seizures.
and stellate cell
s in layer II of entorhinal cortex
project through the subiculum
of the hippocampus, giving rise to the name "perforant pathway". These glutamatergic fibers form a laminar pattern and terminate in the dentate gyrus and cornu ammonis 3 (CA3) region of the hippocampus. Fibers arising in the lateral portions of the entorhinal cortex show enkephalin
immunoreactivity, whereas medial portions appear to contain cholecystokinin
. Additionally, pyramidal cells in layer III of the entorhinal cortex send topographic projections along the perforant pathway which branch into the subiculum and CA1.
Entorhinal cortex
The entorhinal cortex is located in the medial temporal lobe and functions as a hub in a widespread network for memory and navigation. The EC is the main interface between the hippocampus and neocortex...
to all fields of the hippocampal formation, including the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...
, all CA fields (including CA1), and the subiculum.
Though it arises mainly from entorhinal layers II and III, it comprises a smaller component that originates in deep layers V and VI.
There is a major dichotomy with respect to the laminar origin and related terminal distribution: neurons in layer II (and possibly layer VI) project to the dentate gyrus
Dentate gyrus
The dentate gyrus is part of the hippocampal formation. It is thought to contribute to new memories as well as other functional roles. It is notable as being one of a select few brain structures currently known to have high rates of neurogenesis in adult rats, .The dentate gyrus cells receive...
and CA3, whereas layer III (and possibly layer V) cells project to CA1 and the subiculum.
It may play a role in temporal lobe seizures.
In rats
In rats, pyramidalPyramidal cell
Pyramidal neurons are a type of neuron found in areas of the brain including cerebral cortex, the hippocampus, and in the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract. Pyramidal neurons were first discovered and...
and stellate cell
Stellate cell
In neuroscience, stellate cells are neurons with several dendrites radiating from the cell body giving them a star shaped appearance. The three most common stellate cells are the inhibitory interneurons found within the molecular layer of the cerebellum, excitatory spiny stellate interneurons and...
s in layer II of entorhinal cortex
Entorhinal cortex
The entorhinal cortex is located in the medial temporal lobe and functions as a hub in a widespread network for memory and navigation. The EC is the main interface between the hippocampus and neocortex...
project through the subiculum
Subiculum
The subiculum is the most inferior component of the hippocampal formation. It lies between the entorhinal cortex and the CA1 subfield of the hippocampus proper.-Paths:...
of the hippocampus, giving rise to the name "perforant pathway". These glutamatergic fibers form a laminar pattern and terminate in the dentate gyrus and cornu ammonis 3 (CA3) region of the hippocampus. Fibers arising in the lateral portions of the entorhinal cortex show enkephalin
Enkephalin
An enkephalin is a pentapeptide involved in regulating nociception in the body. The enkephalins are termed endogenous ligands, or specifically endorphins, as they are internally derived and bind to the body's opioid receptors. Discovered in 1975, two forms of enkephalin were revealed, one...
immunoreactivity, whereas medial portions appear to contain cholecystokinin
Cholecystokinin
Cholecystokinin is a peptide hormone of the gastrointestinal system responsible for stimulating the digestion of fat and protein...
. Additionally, pyramidal cells in layer III of the entorhinal cortex send topographic projections along the perforant pathway which branch into the subiculum and CA1.
In mice
In mice, the projection to CA3, CA1, and the subiculum all come primarily from EC layer III.External links
- http://thebrain.mcgill.ca/flash/a/a_07/a_07_cl/a_07_cl_tra/a_07_cl_tra.html