Aberrant oscillatory dynamics during somatosensory processing in HIV-infected adults

• Published in: NeuroImage clinical Vol. 20; pp. 85 - 91
• Main Authors: Spooner, Rachel K., Wiesman, Alex I., Mills, Mackenzie S., O'Neill, Jennifer, Robertson, Kevin R., Fox, Howard S., Swindells, Susan, Wilson, Tony W.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 01.01.2018; Elsevier
• Subjects: Adult; Evoked Potentials, Somatosensory - physiology; Female; HIV Infections - diagnostic imaging; HIV Infections - physiopathology; Humans; Magnetic Resonance Imaging - methods; Magnetoencephalography; Magnetoencephalography - methods; Male; Middle Aged; Oscillatory power; Peak gamma frequency; Regular; Sensory gating; Somatosensory Cortex - diagnostic imaging; Somatosensory Cortex - physiopathology; Sensory gating; Magnetoencephalography; Oscillatory power; Peak gamma frequency
• ISSN: 2213-1582; 2213-1582
• DOI: 10.1016/j.nicl.2018.07.009

While the arrival of combination antiretroviral therapy significantly decreased the prevalence of HIV-associated dementia, between 35 and 70% of all infected adults continue to develop some form of cognitive impairment. These deficits appears to affect multiple neural subsystems, but the mechanisms and extent of damage are not fully understood. In the current study, we utilized magnetoencephalography (MEG), advanced oscillatory analysis methods, and a paired-pulse somatosensory stimulation paradigm to interrogate pre-attentive inhibitory processing in 43 HIV-infected adults and 28 demographically-matched uninfected controls. MEG responses were imaged using a beamformer, and time series data were extracted from the peak voxel in grand-averaged functional brain images to quantify the dynamics of sensory gating, oscillatory power, spontaneous power, and other neural indices. We found a significantly weakened response to the second stimulation compared to the first across groups, indicating significant sensory gating irrespective of HIV-infection. Interestingly, HIV-infected participants exhibited reduced neural responses in the 20–75 Hz gamma range to each somatosensory stimulation compared to uninfected controls, and exhibited significant alterations in peak gamma frequency in response to the second stimulation. Finally, HIV-infected participants also had significantly stronger spontaneous activity in the gamma range (i.e., 20–75 Hz) during the baseline period before stimulation onset. In conclusion, while HIV-infected participants had the capacity to efficiently gate somatosensory input, their overall oscillatory responses were weaker, spontaneous baseline activity was stronger, and their response to the second stimulation had an altered peak gamma frequency. We propose that this pattern of deficits suggests dysfunction in the somatosensory cortices, which is potentially secondary to accelerated aging. •Around half of all HIV-infected patients will develop cognitive impairments during their life.•The underlying mechanisms are unknown, but inhibitory deficits are thought to be critical.•We examined oscillatory activity using MEG in 71 HIV-infected and uninfected adults.•Gamma oscillatory dynamics were significantly disturbed in HIV-infected adults.