Neurobiology of Aging 32 (2011) 1896–1905 Impairment of experience-dependent cortical plasticity in aged mice Monika Liguz-Lecznar a,∗ , Ewa Siucinska a , Renata Zakrzewska a , Malgorzata Kossut a,b a Dept. of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland b Warsaw School of Social Sciences and Humanities, Chodakowska Street 19/31, 03-815 Warsaw, Poland Received 16 July 2009; received in revised form 10 November 2009; accepted 13 November 2009 Available online 14 December 2009 Abstract This study addresses the relationship between aging and experience-dependent plasticity in the mouse somatosensory cortex. Plasticity in the cortical representation of vibrissae (whiskers) was investigated in young (3 months), mature (14 months) and old (2 years) mice using [14C]2-deoxyglucose (2-DG) autoradiography. Plastic changes were evoked using two experimental paradigms. The deprivation-based protocol included unilateral deprivation of all but one row of whiskers for a week. In the conditioning protocol the animals were subjected to classical conditioning, where tactile stimulation of one row of whiskers was paired with an aversive stimulus. Both procedures evoked functional plasticity in the young group, expressed as a widening of the functional cortical representation of the spared or conditioned row. Aging had a differential effect on these two forms of plasticity. Conditioning-related plasticity was more vulnerable to aging: the plastic change was not detectable in mature animals, even though they acquired the behavioral response. Deprivation-induced plasticity also declined with age, but some effects were persistent in the oldest animals. © 2009 Elsevier Inc. All rights reserved. Keywords: Aging; Functional plasticity; 2-DG; Deprivation; Classical conditioning; Somatosensory cortex 1. Introduction Virtually all biological functions lose efficiency during aging. The aging process in the brain involves a number of physiological modifications and is associated with metabolic, structural and functional changes. Age-related decline in cog- nitive function may be associated with deficits in attention or information processing efficiency, but also with changes in neuronal plasticity or cellular alterations that affect plastic- ity. They include alterations in the biophysical properties of neurons (Ca 2+ conductance, amplitude of the after hyper- polarizing potential-AHP, input resistance, action potential amplitude, frequency of post-synaptic potentials); the effi- ciency of cell–cell interaction (number of synaptic contacts, synaptic plasticity); the function of neurotransmitter systems (glutamatergic, GABAergic, cholinergic, dopaminergic) and the pattern of gene expression (for review see Burke and Barnes, 2006). ∗ Corresponding author. Tel.: +48 22 589 22 48; fax: +48 22 822 53 42. E-mail address: m.liguz@nencki.gov.pl (M. Liguz-Lecznar). Many of the age-related changes that have been reported occur in the neocortex and hippocampus, suggesting that these structures, which are involved in associative condition- ing and memory, are particularly sensitive or vulnerable to the aging process. The decrease in synaptic plasticity in these structures may be a crucial factor in deficits in the perfor- mance of learning and memory tasks observed in old animals. Aged rats show a decline in the ability to learn and remember detailed spatial relationships (Winocur et al., 2010), and they also exhibit impaired water maze learning (Hansalik et al., 2006). Non-spatial behavior is also affected by age: the abil- ity to form flavor-reward associations was found to decrease with age, resulting in impaired conditioned flavor preference (Renteria et al., 2008). A number of studies have shown age- related changes in fear conditioning to context (Moyer and Brown, 2006). Aging can also affect plasticity of cortical representational maps, which, in young and adult animals can be modified by sensory experience and learning (see review by Buonomano and Merzenich, 1998). Although it is known that cortical rep- resentations show age-related changes (Godde et al., 2002), very few studies have investigated experience-dependent 0197-4580/$ – see front matter © 2009 Elsevier Inc. All rights reserved. doi:10.1016/j.neurobiolaging.2009.11.009