You are here

Evoked Potentials from Concurrent TMS-EEG Demonstrate Altered Visual Pathway Efficiency in Parkinson's Disease with Dementia

Evoked Potentials from Concurrent TMS-EEG Demonstrate Altered Visual Pathway Efficiency in Parkinson's Disease with Dementia

Authors: 
Nik Murphy, Alison Killen, Lynn Rochester and John-Paul Taylor
Year: 
2017
Journal: 
Conference paper: 13th International Conference on Alzheimer’s & Parkinson’s Diseases, At Vienna
Abstract: 

Aims The distribution of Lewy related pathology within the dorsal and ventral visual streams of Parkinson’s disease dementia (PDD) patients suggests that visual processing is impaired, and might contribute to the experience of visual hallucinations (VH). Here we used the evoked potential from concurrent transcranial magnetic current stimulation (TMS) and electroencephalography (EEG; TEP) as a metric of synaptic efficiency in response to occipital stimulation in patients with PDD relative to controls.

Method TEP’s were recorded from n = 17 healthy controls (75.47 years ± 5.4), and n = 21 PDD patients (73.43 years ± 5.66), using 128 channel EEG. The temporal response to stimulation was compared between groups at posterior, central, and lateral electrodes using cluster corrected mass-univariate non-parametric testing (significant at a minimum cluster size of 20ms).

Results Waveform morphology was not significantly different between groups at any of the four global field power (GFP) maxima, but demonstrated significant regional variations in amplitude-latency pairing between 66-91ms (posterior), 181-201ms (central), and 437-468ms (lateral) between the groups. VH severity was positively correlated with the increasing amplitude of GFP components three and four at lateral electrodes, but unrelated to the intermittent waveform variations.

Conclusion Perceptual disturbances in PDD might arise due to periodic lapses in neuron synchronisation within the dorsal and ventral processing networks. Further study is required to understand how top-down control interacts with the quality of bottom-up processing and visual input to generate the variety of VH experienced by patients with PDD.

Read more >>

© Copyright 1999 - 2017 ANT Neuro | www.ant-neuro.com | Terms of Use | Privacy Statement | Contact | USA Customers