Impact of HIV‐infection on human somatosensory processing, spontaneous cortical activity, and cortical thickness: A multimodal neuroimaging approach

Abstract

HIV‐infection has been associated with widespread alterations in brain structure and function, although few studies have examined whether such aberrations are co‐localized and the degree to which clinical and cognitive metrics are related. We examine this question in the somatosensory system using high‐resolution structural MRI (sMRI) and magnetoencephalographic (MEG) imaging of neural oscillatory activity. Forty‐four participants with HIV (PWH) and 55 demographically‐matched uninfected controls completed a paired‐pulse somatosensory stimulation paradigm during MEG and underwent 3T sMRI. MEG data were transformed into the time‐frequency domain; significant sensor level responses were imaged using a beamformer. Virtual sensor time series were derived from the peak responses. These data were used to compute response amplitude, sensory gating metrics, and spontaneous cortical activity power. The T1‐weighted sMRI data were processed using morphological methods to derive cortical thickness values across the brain. From these, the cortical thickness of the tissue coinciding with the peak response was estimated. Our findings indicated both PWH and control exhibit somatosensory gating, and that spontaneous cortical activity was significantly stronger in PWH within the left postcentral gyrus. Interestingly, within the same tissue, PWH also had significantly reduced cortical thickness relative to controls. Follow‐up analyses indicated that the reduction in cortical thickness was significantly correlated with CD4 nadir and mediated the relationship between HIV and spontaneous cortical activity within the left postcentral gyrus. These data indicate that PWH have abnormally strong spontaneous cortical activity in the left postcentral gyrus and such elevated activity is driven by locally reduced cortical gray matter thickness.

Signatures of somatosensory cortical dysfunction in Alzheimer’s disease and HIV-associated neurocognitive disorder

“…To identify the impact of Alzheimer’s disease and HAND pathologies on somatosensory gating and be consistent with previous studies, 13 , 14 , 40 we computed the gating ratio (i.e. response to Stimulation 2 divided by the response to Stimulation 1) and ran a 3 × 1 ANOVA.…”

“… 13 , 15 , 36–39 While numerous studies have found aberrant auditory gating in Alzheimer’s disease, somatosensory gating has been examined only once in Alzheimer’s disease 40 and only a handful of times in HAND. 13–15 To the best of our knowledge, no study to date has compared somatosensory gating deficits in participants with HAND versus those with Alzheimer’s disease. Thus, whether differences in gating and somatosensory processing more broadly can distinguish those with Alzheimer’s disease and HAND remains unknown.…”

Somatosensory dysfunction is masked by variable cognitive deficits across patients on the Alzheimer's disease spectrum

“…Somatosensory function has been found to be impaired in a number of other neurological, developmental, and psychiatric disorders, including Parkinson's disease [58] , HIV-associated neurocognitive disorders [ 42 , [59] , [60] , [61] ], autism [62] , cerebral palsy [ 63 , 64 ], schizophrenia [65] , and others. Typically, such deficits are indicated by a reduced neural response to somatosensory stimuli, however, our findings indicate the inverse in AD: a hyper-sensitivity to stimulation.…”

Central Nervous System Impact of Perinatally Acquired HIV in Adolescents and Adults: an Update

“…Several recent papers have focused on structural measures such as cortical thickness, surface area, and gyrification [62, 65 •, 66] that have increasingly been used in studies of HIV among children [67], as well as adults [68][69][70][71][72], and are sensitive to developmental processes. The few studies focusing on adolescents and young adults show regionally specific decreases in cortical thickness, including temporal, orbitofrontal, and occipital lobes in combination with lower gray matter volume in subcortical structures among Spanish young adults [62], decreased cortical thickness in right temporal lobe and fusiform gyrus among Zambian adolescents with PHIV [73], and increased thickness in left occipital and right olfactory areas and decreased cortical thickness in temporal and orbitofrontal regions among Chinese youth [60].…”