Identification of the hippocampal input to medial prefrontal cortex in vitro

Cereb Cortex. 2010 Feb;20(2):393-403. doi: 10.1093/cercor/bhp108. Epub 2009 Jun 10.

Abstract

To delineate the cellular mechanisms underlying the function of medial prefrontal cortex (mPFC) networks, it is critical to understand how synaptic inputs from various afferents are integrated and drive neuronal activity in this region. Using a newly developed slice preparation, we were able to identify a bundle of axons that contain extraneocortical fibers projecting to neurons in the prelimbic cortex. The anatomical origin and functional connectivity of the identified fiber bundle were probed by in vivo track tracing in combination with optic and whole-cell recordings of neurons in layers 2/3 and 5/6. We demonstrate that the identified bundle contains afferent fibers primarily from the ventral hippocampus but does not include contributions from the mediodorsal nucleus of the thalamus, amygdala, or lateral hypothalamus/medial forebrain bundle. Further, we provide evidence that activation of this fiber bundle results in patterned activity of neurons in the mPFC, which is distinct from that of laminar stimulation of either the deep layers 5/6 or the superficial layer 1. Evoked excitatory postsynaptic potentials are monosynaptic and glutamatergic and exhibit bidirectional changes in synaptic efficacy in response to physiologically relevant induction protocols. These data provide the necessary groundwork for the characterization of the hippocampal pathway projecting to the mPFC.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Axons / physiology
  • Axons / ultrastructure
  • Brain Mapping
  • Calcium Signaling
  • Electrophysiology
  • Excitatory Postsynaptic Potentials / physiology
  • Fluorescent Dyes
  • Glutamic Acid / metabolism
  • Hippocampus / cytology*
  • Hippocampus / physiology
  • Indicators and Reagents
  • Interneurons / cytology
  • Interneurons / physiology
  • Mice
  • Neural Pathways / cytology*
  • Neural Pathways / physiology
  • Neuronal Tract-Tracers
  • Organ Culture Techniques
  • Patch-Clamp Techniques
  • Prefrontal Cortex / cytology*
  • Prefrontal Cortex / physiology
  • Pyramidal Cells / cytology
  • Pyramidal Cells / physiology
  • Synaptic Transmission / physiology
  • Voltage-Sensitive Dye Imaging

Substances

  • Fluorescent Dyes
  • Indicators and Reagents
  • Neuronal Tract-Tracers
  • Glutamic Acid