Table 2.
Anatomical, neuronal, synaptic, and molecular parameters in the monkey hippocampus and related cortical regions in the context of chronological and cognitive aging
| Brain area | Measure | Change with aging | Correlation with behavior | Citation |
|---|---|---|---|---|
| Hippocampus | Total volume | No change | DR acquisition, accuracy | Shamy et al. 2010 |
| Glucose metabolism | No change | DR accuracy | Eberling et al. 1997 | |
| Dopamine | No change | n/a | Goldman-Rakic and Brown 1981 | |
| Norepinephrine | No change | n/a | Goldman-Rakic and Brown 1981 | |
| Serotonin | No change | n/a | Goldman-Rakic and Brown 1981 | |
| DG | Volume | No change | n/a | Calhoun et al. 2004 |
| Neuron number | No change | n/a | West et al. 1993; Keuker et al. 2003 | |
| Cerebral blood volume | ↓ | DNMS accuracy | Small et al. 2004 | |
| Vertical dendritic extent | ↓ | Not significant (DNMS, CPI) | Luebke and Rosene 2003 | |
| Dendritic branching | ↓ distal, ↑ proximal | Not significant (DNMS, CPI) | Luebke and Rosene 2003 | |
| Input resistance | ↑ | Not significant (DNMS, CPI) | Luebke and Rosene 2003 | |
| IPSC decay time constant | ↑ | Not significant (DNMS, CPI) | Luebke and Rosene 2003 | |
| NR2B mRNA | No change (trend for ↓) | n/a | Bai et al. 2004 | |
| Cholinergic fiber length | ↓ by 27% | Not significant (DNMS) | Calhoun et al. 2004 | |
| DG OML | Axospinous synapse density | No change | Not significant (DNMS) | Hara et al. 2010 |
| Axodendritic synapse density | ↓ | n/a | Tigges et al. 1995 | |
| PSD length | No change | Not significant (DNMS) | Hara et al. 2010 | |
| Perforated synapse density | No change | DNMS accuracy | Hara et al. 2010 | |
| Axon terminal size | No change | Not significant (DNMS) | Hara et al. 2011 | |
| Nonsynaptic bouton | ↑ | DNMS acquisition, accuracy | Hara et al. 2011 | |
| Multiple-synaptic bouton | ↓ | DNMS acquisition | Hara et al. 2011 | |
| NR1 expression | ↓ by 30% | n/a | Gazzaley et al. 1996 | |
| GluR2/3, GluR5/6/7 expression | No change | n/a | Gazzaley et al. 1996 | |
| DG IML | Synapse density | No change | Not significant (DNMS) | Hara et al. 2010 |
| PSD length | No change | Not significant (DNMS) | Hara et al. 2010 | |
| Perforated synapse density | No change | Not significant (DNMS) | Hara et al. 2010 | |
| Axon terminal size | No change | n/a | Tigges et al. 1996 | |
| DG SGZ | Proliferating cells | ↓ | Visual pattern discrimination | Aizawa et al. 2009 |
| CA3 | Volume | No change | n/a | Calhoun et al. 2004 |
| Neuron number | No change | n/a | West et al. 1993; Keuker et al. 2003 | |
| NR2B mRNA | No change (trend for ↓) | n/a | Bai et al. 2004 | |
| CA2/3-hilus | Cholinergic fiber length | ↓ by 18% | Not significant (DNMS) | Calhoun et al. 2004 |
| CA1 | Volume | No change | n/a | Calhoun et al. 2004 |
| Neuron number | No change | n/a | West et al. 1993; Keuker et al. 2003 | |
| Cerebral blood volume | No change | Not significant (DNMS) | Small et al. 2004 | |
| NR2B mRNA | No change | n/a | Bai et al. 2004 | |
| Cholinergic fiber length | ↓ by 26% | Not significant (DNMS) | Calhoun et al. 2004 | |
| Subiculum | Cerebral blood volume | No change | Not significant (DNMS) | Small et al. 2004 |
| Neuron number | No change | n/a | West et al. 1993; Keuker et al. 2003 | |
| Dendritic length, branches | ↑ until middle aged, then ↓ | n/a | Uemura 1985a | |
| Synapse density | ↓ by 19% | n/a | Uemura 1985b | |
| NR2B mRNA | No change | n/a | Bai et al. 2004 | |
| EC | Neuron number | No change | n/a | Merrill et al. 2000 |
| Cerebral blood volume | No change | Not significant (DNMS) | Small et al. 2004 | |
| EC layer II | Neuron number | No change | n/a | Gazzaley et al. 1997; Merrill et al. 2000 |
| Neuronal size | No change | n/a | Gazzaley et al. 1997; Merrill et al. 2000 | |
| Parahippocampal gyrus | NR2B mRNA | No change | n/a | Bai et al. 2004 |
CPI Cognitive Performance Index, DG dentate gyrus, DNMS delayed nonmatching-to-sample, DR delayed response, EC entorhinal cortex, IML inner molecular layer, IPSC inhibitory postsynaptic current, OML outer molecular layer, PSD postsynaptic density, SGZ subgranular zone