Biology subjects

Espinoza, A. I.

Publications and source records attributed to Espinoza, A. I..

3 recordsLinked to original sources

bioRxiv2020

Timing variability and midfrontal ~4 Hz rhythms correlate with cognition in Parkinson's disease

Patients with Parkinsons disease (PD) can have significant cognitive dysfunction; however, the mechanisms for these cognitive symptoms are unknown. Here, we used scalp electroencephalography (EEG) to investigate the cortical basis for PD-related cognitive impairments during interval timing, which requires participants to estimate temporal intervals of several seconds. Time estimation is an ideal task demand for investigating cognition in PD because it is simple, requires medial frontal cortical areas, and recruits basic executive processes such as working memory and attention. However, interval timing has never been systematically studied in PD patients with cognitive impairments. We report three main findings. First, 71 PD patients had increased temporal variability compared to 37 demographically-matched controls, and this variability correlated with cognitive dysfunction as measured by the Montreal Cognitive Assessment (MOCA). Second, PD patients had attenuated ~4 Hz EEG oscillatory activity at midfrontal electrodes in response to the interval-onset cue, which was also predictive of MOCA. Finally, trial-by-trial linear mixed-effects modeling demonstrated that cue-triggered ~4 Hz power predicted subsequent temporal estimates as a function of PD and MOCA. Our data suggest that impaired cue-evoked midfrontal ~4 Hz activity predicts increased timing variability that is indicative of cognitive dysfunction in PD. These findings link PD-related cognitive dysfunction with cortical mechanisms of cognitive control, which could advance novel biomarkers and neuromodulation for PD.

neuroscience↗

bioRxiv2020

TMS bursts can modulate local and networks oscillations during lower-limb movement in elderly subjects

IntroductionLower-limb motor functions involve processing information via both motor and cognitive control networks. Measuring oscillations is a key element in communication within and between cortical networks during high order motor functions. Increased midfrontal theta oscillations are related to improved lower-limb motor performances in patients with movement disorders. Non-invasive neuromodulation approaches have not been explored extensively to understand the oscillatory mechanism of lower-limb motor functions. This study aims to examine the effects of repetitive transcranial magnetic stimulation (rTMS) on local and network EEG oscillations in healthy elderly subjects. MethodsEleven healthy elder subjects (67-73 years) were recruited via advertisements, and underwent both active and sham stimulation procedures in a random, counterbalanced design. TMS bursts ({theta}-TMS; 4 pulses/sec) were applied over the midfrontal lead (vertex) before a GO-Cue pedaling task, and signals were analyzed using time-frequency methods. ResultsTMS bursts increase the theta activity in the local (p=0.02), as well as the associated network during the lower-limb pedaling task (p = 0.02). Furthermore, after task-related TMS burst sessions, increased resting-state alpha activity was observed in the midfrontal region (p= 0.01). ConclusionOur study suggests the ability of midfrontal TMS bursts to directly modulate local and network oscillations in a frequency manner during lower-limb motor task. TMS burst-induced modulation may provide insights into the functional roles of oscillatory activity during lower-limb movement in normal and disease conditions.

neuroscience↗

bioRxiv2019

Frontal theta and beta oscillations during lower-limb movement in Parkinson’s disease

BackgroundMotor and cognitive dysfunction has been linked in patients with Parkinsons disease (PD). EEG theta and beta rhythms are reliably associated with cognitive and motor functions, respectively. We tested the hypothesis that PD patients with lower-limb abnormalities would exhibit abnormal beta and theta rhythms in the mid-frontal region during action initiation.\n\nMethodsWe recruited thirty-nine subjects, including PD patients with FOG (PDFOG+; n=13) and without FOG (PDFOG-; n=13), and demographically-matched healthy subjects (n=13). Scalp electroencephalogram (EEG) signals were collected during a lower-limb pedaling motor task, which required intentional initiation and stopping of a motor movement.\n\nResultsFOG scores were correlated with disease severity and cognition. PDFOG+ patients pedaled with reduced speed and decreased acceleration compared to PDFOG- patients and to controls. PDFOG+ patients exhibited attenuated theta-band (4-8 Hz) power and increased beta-band (13-30 Hz) power at mid-frontal electrode Cz during pedaling. Frontal theta- and beta-band oscillations also correlated with lower-limb movement in PD patients.\n\nConclusionsFrontal theta and beta oscillations are predictors of lower-limb motor symptoms in PD. These data provide insight into the mechanism of lower-limb dysfunction in PD, and could be used to design neuromodulation for PD-related lower-limb abnormalities.

neuroscience↗