Somatosensory Temporal Discrimination Threshold in Patients with Cognitive Disorders

D'Antonio, Fabrizia; Bartolo, Maria Ilenia De; Ferrazzano, Gina; Trebbastoni, Alessandro; Amicarelli, Sara; Campanelli, Alessandra; Lena, Carlo de; Berardelli, Alfredo; Conte, Antonella

doi:10.3233/jad-190385

Cited by 9 publications

(4 citation statements)

References 58 publications

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“…Before closing, it is important to acknowledge several possible limitations of the study. First, neural processing of somatosensory input like that used in our study includes relays in the thalamus and primary somatosensory cortex, as well as the potential involvement of the basal ganglia through cortical-basal ganglia-cortical loops ( McCormick and Bal, 1994 ; Seki and Fetz, 2012 ; Colder, 2015 ; Lei et al , 2018 ; Conte et al , 2020 ; D’Antonio et al , 2019 ). Given this, we cannot rule out that gating like that observed in the primary somatosensory and DLPFC of this study also occurs in subcortical regions such as the basal ganglia.…”

Section: Discussionmentioning

confidence: 99%

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Prefrontal gating of sensory input differentiates cognitively impaired and unimpaired aging adults with HIV

Spooner

Wiesman

O’Neill³

et al. 2020

Brain Communications

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Despite effective therapies that have extended the life expectancy of persons living with HIV, 35-70% of these adults still develop some form of cognitive impairment, and with a growing population of aging adults with HIV, the prevalence of these cognitive deficits is likely to increase. The mechanisms underlying these HIV-associated neurocognitive disorders remain poorly understood but are often accelerated by the aging process and accompanied by disturbances in sensory processing, which may contribute to the observed cognitive decline. The goal of the current study was to identify the impact of aging on HIV-related alterations in inhibitory processing and determine whether such alterations are related to cognitive impairment in neuroHIV. We used magnetoencephalographic imaging, advanced time series analysis methods, and a paired-pulse stimulation paradigm to interrogate inhibitory processing in 87 HIV-infected aging adults and 92 demographically-matched uninfected controls (22-72 years-old). Whole-brain maps linking age and neural indices were computed for each group and compared via Fisher’s Z transformations. Peak voxel time series data were also extracted from the resulting images to quantify the dynamics of spontaneous neural activity preceding stimulation onset in each group. Whole-brain analyses using the somatosensory gating index, a metric of inhibitory processing, and age distinguished impaired adults with HIV from unimpaired HIV-infected adults and controls. Briefly, younger cognitively impaired adults with HIV strongly utilized the prefrontal cortices to gate somatosensory input and the role of this region in gating was uniquely and significantly modulated by aging only in impaired adults with HIV. Spontaneous neural activity preceding stimulus onset was also significantly elevated in the prefrontal cortices of those with HIV-associated neurocognitive disorder, and this elevation was significantly related to the CD4 nadir across both HIV-infected groups. This is the first study to examine the impact of aging on inhibitory processing in HIV-infected adults with and without cognitive impairment. Our findings suggest that young adults with HIV-associated neurocognitive disorder utilize the prefrontal cortices to gate (i.e., suppress) redundant somatosensory input, and that this capacity uniquely diminishes with advancing age in impaired adults with HIV.

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Section: Discussionmentioning

confidence: 99%

“…In addition, there is evidence of altered temporal discrimination abilities in some neurological conditions (e.g. D’Antonio et al , 2019 ), and such altered processing could contribute to gating and similar aberrations in these populations. Future studies should focus on teasing apart these inter-related constructs.…”

Section: Discussionmentioning

confidence: 99%

Prefrontal gating of sensory input differentiates cognitively impaired and unimpaired aging adults with HIV

Spooner

Wiesman

O’Neill³

et al. 2020

Brain Communications

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“…Resting state EEG showed reduced parieto-occipital alpha activity and increased delta/theta activity in occipital, parietal, and temporal areas in patients with amnesic mild cognitive impairment [33]. Measures of the temporal processing of somatosensory information evaluated by testing the discrimination threshold are abnormal both in patients with mild cognitive impairment and in patients with mild-to-moderate AD [34]. Cortical inhibition tested by short latency afferent inhibition, a technique that explores the inhibition exerted by sensory stimuli on motor areas, is found reduced both in patients with AD [35] and in patients with amnestic mild cognitive impairment [36], thus suggesting that this abnormality begins early in the history of the disease.…”

Section: Discussionmentioning

confidence: 98%

Habituation of Somatosensory Evoked Potentials in Patients with Alzheimer’s Disease and Those with Vascular Dementia

et al. 2021

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Background and Objectives: The most prevalent dementia are Alzheimer’s disease and vascular dementia. There is evidence that cortical synaptic function may differ in these two conditions. Habituation of cortical responses to repeated stimuli is a well-preserved phenomenon in a normal brain cortex, related to an underlying mechanism of synaptic efficacy regulation. Lack of habituation represents a marker of synaptic dysfunction. The purpose of this study was to assess the habituation of somatosensory evoked potentials (SEPs) in 29 patients affected by mild-to-moderate Alzheimer’s disease (AD-type) or vascular (VD-type) dementia. Materials and Methods: All patients underwent a clinical history interview, neuropsychological evaluation, and neuroimaging examination. SEPs were elicited by electrical stimulation of the right median nerve at the wrist. Six-hundred stimuli were delivered, and cortical responses divided in three blocks of 200. Habituation was calculated by measuring changes of N20 amplitude from block 1 to block 3. SEP variables recorded in patients were compared with those recorded in 15 age- and gender-matched healthy volunteers. Results: SEP recordings showed similar N20 amplitudes in AD-type and VD-type patients in block 1, that were higher than those recorded in controls. N20 amplitude decreased from block 1 to block 3 (habituation) in normal subjects and in VD-type patients, whereas in AD-type patients it remained unchanged (lack of habituation). Conclusions: The findings suggest that neurophysiologic mechanisms of synaptic efficacy that underneath habituation are impaired in patients with AD-type dementia but not in patients with VD-type dementia. SEPs habituation may contribute to early distinction of Alzheimer’s disease vs. vascular dementia.

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“…Neurophysiologist investigators were blinded to the clinical evaluation. The inclusion criteria were age over 18 years, clinical stability, no corticosteroid intake in the 30 days preceding the assessment, and a Mini-Mental State Examination (MMSE) score >26 for STDT testing [ 26 ]. Exclusion criteria were contraindications to TMS (i.e., history of epilepsy, pacemaker implantation, head trauma).…”

Section: Methodsmentioning

confidence: 99%

Are Neurophysiological Biomarkers Able to Discriminate Multiple Sclerosis Clinical Subtypes?

et al. 2022

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Secondary progressive multiple sclerosis (SPMS) subtype is retrospectively diagnosed, and biomarkers of the SPMS are not available. We aimed to identify possible neurophysiological markers exploring grey matter structures that could be used in clinical practice to better identify SPMS. Fifty-five people with MS and 31 healthy controls underwent a transcranial magnetic stimulation protocol to test intracortical interneuron excitability in the primary motor cortex and somatosensory temporal discrimination threshold (STDT) to test sensory function encoded in cortical and deep grey matter nuclei. A logistic regression model was used to identify a combined neurophysiological index associated with the SP subtype. We observed that short intracortical inhibition (SICI) and STDT were the only variables that differentiated the RR from the SP subtype. The logistic regression model provided a formula to compute the probability of a subject being assigned to an SP subtype based on age and combined SICI and STDT values. While only STDT correlated with disability level at baseline evaluation, both SICI and STDT were associated with disability at follow-up. SICI and STDT abnormalities reflect age-dependent grey matter neurodegenerative processes that likely play a role in SPMS pathophysiology and may represent easily accessible neurophysiological biomarkers for the SPMS subtype.

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Somatosensory Temporal Discrimination Threshold in Patients with Cognitive Disorders

Cited by 9 publications

References 58 publications

Prefrontal gating of sensory input differentiates cognitively impaired and unimpaired aging adults with HIV

Prefrontal gating of sensory input differentiates cognitively impaired and unimpaired aging adults with HIV

Habituation of Somatosensory Evoked Potentials in Patients with Alzheimer’s Disease and Those with Vascular Dementia

Are Neurophysiological Biomarkers Able to Discriminate Multiple Sclerosis Clinical Subtypes?

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