Olfactory learning is associated with increased spine density along apical dendrites of pyramidal neurons in the rat piriform cortex

  1. Shira Knafo1,
  2. Yoram Grossman2,
  3. Edi Barkai1,
  4. Gadi Benshalom1

Article first published online: 20 DEC 2001

DOI: 10.1046/j.1460-9568.2001.01422.x

Issue

European Journal of Neuroscience

European Journal of Neuroscience

Volume 13, Issue 3, pages 633–638, February 2001

Additional Information

How to Cite

Knafo, S., Grossman, Y., Barkai, E. and Benshalom, G. (2001), Olfactory learning is associated with increased spine density along apical dendrites of pyramidal neurons in the rat piriform cortex. European Journal of Neuroscience, 13: 633–638. doi: 10.1046/j.1460-9568.2001.01422.x

Author Information

  1. 1

    Department of Morphology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

  2. 2

    Department of Physiology, Faculty of Health Sciences and Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel

* : Dr Edi Barkai, as above. E-mail: edi@bgumail.bgu.ac.il

Publication History

  1. Issue published online: 20 DEC 2001
  2. Article first published online: 20 DEC 2001
  3. Received 31 August 2000, revised 27 November 2000, accepted 28 November 2000

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Keywords:

  • dendritic spines;
  • Golgi method;
  • learning;
  • olfactory cortex;
  • synapses

Abstract

We studied the effect of olfactory learning on the dendritic spine density of pyramidal neurons in the rat piriform (olfactory) cortex. Rats were trained to distinguish between two pairs of odours in an olfactory discrimination task. Three days after training completion, rats were killed and layer II pyramidal neurons identified by Golgi impregnation were examined with a light microscope. Counts of visible spines were performed along the secondary and tertiary branches of both the apical dendrites and the basal dendrites, which are the sites of intracortical synaptic inputs. An estimate of the true spine density was obtained using Feldman and Peters' method (1979, The Journal of Comparative Neurology, 188, 527–542). The estimated true spine density along apical dendrites was higher in neurons from trained rats than those in pseudotrained and naive rats by 15%. As length of spiny dendrites did not change significantly after learning, the learning-related increase in spine density in neurons from trained rats may indicate on an increased number of excitatory synapses interconnecting pyramidal neurons in the piriform cortex, following olfactory learning.

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