Aging Alters Olfactory Bulb Network Oscillations and Connectivity: Relevance for Aging-Related Neurodegeneration...

Area of Science:

• Neuroscience
• Aging Research
• Synaptic Plasticity

Background:

• Aging leads to synaptic plasticity and connectivity breakdown, affecting memory.
• The olfactory bulb (OB) and hippocampus are crucial for odor and spatial memory, and are impacted by aging.

Purpose of the Study:

• To investigate the effects of aging on hippocampal plasticity and cortical circuit integrity in C57B/6 mice.
• To define age-related changes in neural network oscillations and connectivity.

Main Methods:

• Measured high-frequency stimulation long-term potentiation (HFS-LTP) at CA1 pyramidal synapses.
• Assessed local field potential (LFP) spectra, theta-gamma phase-amplitude coupling (PAC), and coherence in olfactory bulb, cortex, CA1, and amygdala.
• Quantified histone H2AX-positive neurons in the OB as a marker of DNA damage.

Main Results:

• Aged mice showed increased DNA damage (histone H2AX) in the OB.
• While basal synaptic activity was unchanged, hippocampal synaptic transmission declined in response to HFS in aged mice.
• Aging induced spontaneous network alterations in the OB, including deficits in gamma oscillations, reduced coherence, and theta-gamma PAC.

Conclusions:

• Hippocampal synaptic transmission impairment in aging occurs primarily under high-frequency stimulation.
• Age-dependent neural network alterations in the OB circuit occur spontaneously, suggesting a neurophysiological basis for olfactory processing deficits.
• OB LFP network oscillations and connectivity serve as sensitive electrophysiological markers for aging-related neurodegeneration studies.