Significance of the deep layers of entorhinal cortex for transfer of both perirhinal and amygdala inputs to the hippocampus

The rat perirhinal cortex: A review of anatomy, physiology, plasticity, and function

“…Based on this evidence, Kajiwara et al (2003) posit that the perirhinal cortex acts as an association area for emotional and sensory information before these types of information enter the hippocampus. This hypothesis is supported by electrophysiological evidence in vitro which shows that the perirhinal cortex does act as a gateway between the amygdala and the hippocampal-parahippocampal network (Koganezawa et al, 2008). Koganezawa et al (2008) also show using slices cut along a different axis to Kajiwara et al (2003) that stimulation of the lateral nucleus or of area 35 alone is enough to propagate information to the entorhinal cortex and dentate gyrus but that simultaneous stimulation of the lateral nucleus and area 36 was needed to elicit a response in the entorhinal cortex or the dentate gyrus.…”

“…This hypothesis is supported by electrophysiological evidence in vitro which shows that the perirhinal cortex does act as a gateway between the amygdala and the hippocampal-parahippocampal network (Koganezawa et al, 2008). Koganezawa et al (2008) also show using slices cut along a different axis to Kajiwara et al (2003) that stimulation of the lateral nucleus or of area 35 alone is enough to propagate information to the entorhinal cortex and dentate gyrus but that simultaneous stimulation of the lateral nucleus and area 36 was needed to elicit a response in the entorhinal cortex or the dentate gyrus. Further electrophysiological analysis of these projections is required to fully flesh out the hypothesis of the perirhinal cortex as an associative area for sensory and emotional information although we review the functional evidence for this hypothesis in Section 4.4.…”

“…For example, a number of subcortical afferents to the perirhinal cortex terminate in superficial layers but the return projections from the perirhinal cortex tend to originate in deep layers. Equally, sensory and amygdalar input to the perirhinal cortex terminate in superficial layers but the associational properties of the perirhinal cortex appear to require deep layer neurons Koganezawa et al, 2008). As described in Sections 2.2 and 2.3, there are different distributions of neuron types in the various layers of the perirhinal cortex and where the various projections to and from the perirhinal cortex begin or terminate may be dependent on what cell types (and therefore what layers) are involved.…”

Hippocampal Formation

“…The projection terminates preferentially in the superficial EC layers (Naber et al, 1997;Burwell and Amaral, 1998b), targeting both principal neurons as well as parvalbumin-positive interneurons in the dorsolateral portions of the EC (Wouterlood et al, 1998). Interestingly, the information transfer from PER to the EC exhibits a strong inhibition in vivo and in vitro (Kajiwara et al, 2003;de Curtis and Paré, 2004;Paz et al, 2006;Pinto et al, 2006;Koganezawa et al, 2008). Neurons in layers II, III and V of POR project to layers I and III of EC (Burwell andAmaral, 1998a, 1998b;Furtak et al, 2007b;Kerr et al, 2007).…”

Memory effects on scale-free dynamics in foraging Drosophila

“…The internal states are assumed to be characterized in terms of the number of activated 'units', such as neurons or neural networks. The area or volume of the assembly of activated units is measured by a time-varying quantity N(t) called an activity level, increasing up to a maximum value of N c (Iijima et al, 1996;Koganezawa et al, 2008). During the time evolution of N(t) the animal follows a particular persistent behavior.…”