Increased intrinsic excitability and decreased synaptic inhibition in aged somatosensory cortex pyramidal neurons.

Neurobiol Aging

Department of Pharmacology, Tulane University School of Medicine, New Orleans, LA, USA; Tulane Brain Institute, Tulane University, New Orleans, LA, USA.

Published: February 2021

AI Article Synopsis

  • Sensorimotor performance declines with age, partly due to reduced somatosensory acuity and changes in excitability and inhibition of neurons in the primary somatosensory cortex (S1).
  • Researchers examined vibrissal S1 neurons in young and aged mice, focusing on adapting and non-adapting pyramidal neurons in layer 5 (L5).
  • They found that aging increased intrinsic excitability and decreased inhibition in both neuron types, with distinct effects: adapting neurons had a lower action potential threshold, while non-adapting neurons exhibited increased excitability due to higher input resistance and decreased synaptic inhibition.

Article Abstract

Sensorimotor performance declines during advanced age, partially due to deficits in somatosensory acuity. Cortical receptive field expansion contributes to somatosensory deficits, suggesting increased excitability or decreased inhibition in primary somatosensory cortex (S1) pyramidal neurons. To ascertain changes in excitability and inhibition, we measured both properties in neurons from vibrissal S1 in brain slices from young and aged mice. Because adapting and non-adapting neurons-the principal pyramidal types in layer 5 (L5)-differ in intrinsic properties and inhibitory inputs, we determined age-dependent changes according to neuron type. We found an age-dependent increase in intrinsic excitability in adapting neurons, caused by a decrease in action potential threshold. Surprisingly, in non-adapting neurons we found both an increase in excitability caused by increased input resistance, and a decrease in synaptic inhibition. Spike frequency adaptation, already small in non-adapting neurons, was further reduced by aging, whereas sag, a manifestation of I, was increased. Therefore, aging caused both decreased inhibition and increased intrinsic excitability, but these effects were specific to pyramidal neuron type.

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Source
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8436770PMC
http://dx.doi.org/10.1016/j.neurobiolaging.2020.10.007DOI Listing

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