Amygdala Input to Medial Prefrontal Cortex (mPFC) in the Rat: A Light and Electron Microscope Study

Brain Res. 1996 May 13;720(1-2):211-9. doi: 10.1016/0006-8993(96)00155-2.


This paper describes the termination pattern and synaptic connectivity of the pathway from the basolateral nucleus of the amygdala (BLA) to the medial prefrontal cortex (mPFC; areas 25, 32, and 24b) of the rat. Discrete injections of the anterograde tracer Phaseolus vulgaris-leucoagglutinin (PHA-L) were made in the BLA and detailed light microscopical observations made of the distribution of PHA-L labelled fibres and boutons in the mPFC. Labelled fibres were distributed in two tiers: predominantly within deep layer 1/layer 2 and also in layers 5/6. Fibre plexi in layers 2 and 5 were highly varicose. Electron microscopical examination of 120 labelled boutons in area 32 (60 in layer 2 and 60 in layer 5) indicated that 116 (97%) established asymmetrical synaptic contacts with dendritic spines and 4 (3%) were in synaptic contact with small dendritic shafts. No significant differences in target structures were found between layers 2 and 5. The results indicate that BLA input to mPFC in the rat predominantly innervates spine bearing dendrites in layers 2 and 5. This suggests that the neuronal operations of these processes are influenced by direct feedforward excitation from the BLA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Afferent Pathways / physiology
  • Afferent Pathways / ultrastructure
  • Amygdala / physiology*
  • Amygdala / ultrastructure
  • Animals
  • Axons / physiology
  • Axons / ultrastructure
  • Dendrites / physiology
  • Dendrites / ultrastructure
  • Male
  • Microscopy, Electron
  • Phytohemagglutinins
  • Prefrontal Cortex / physiology*
  • Prefrontal Cortex / ultrastructure
  • Rats
  • Rats, Sprague-Dawley
  • Synapses / physiology
  • Synapses / ultrastructure


  • Phytohemagglutinins
  • leukoagglutinins, plants