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• Both muscular and cutaneous somatosensory input arrives at the cuneate nucleus. • Muscle somatosensory input dose not evoke any low-frequency response from the cuneate nucleus. • Subcortical high-frequency oscillations include both presynaptic and postsynaptic components. To investigate the subcortical somatosensory evoked potentials (SEPs) to electrical stimulation of either muscle or cutaneous afferents. SEPs were recorded in 6 patients suffering from Parkinson's disease (PD) who underwent electrode implantation in the pedunculopontine (PPTg) nucleus area. We compared SEPs recorded from the scalp and from the intracranial electrode contacts to electrical stimuli applied to: 1) median nerve at the wrist, 2) abductor pollicis brevis motor point, and 3) distal phalanx of the thumb. Also the high-frequency oscillations (HFOs) were analysed. After median nerve and pure cutaneous (distant phalanx of the thumb) stimulation, a P1-N1 complex was recorded by the intracranial lead, while the scalp electrodes recorded the short-latency far-field responses (P14 and N18). On the contrary, motor point stimulation did not evoke any low-frequency component in the PPTg traces, nor the N18 potential on the scalp. HFOs were recorded to stimulation of all modalities by the PPTg electrode contacts. Stimulus processing within the cuneate nucleus depends on modality, since only the cutaneous input activates the complex intranuclear network possibly generating the scalp N18 potential. Our results shed light on the subcortical processing of the somatosensory input of different modalities. [ABSTRACT FROM AUTHOR]

• Single stimuli applied to the pedunculopontine tegmental nucleus (PPTg) modulate the blink reflex (BR) in Parkinson's disease. • The action of the PPTg on the BR differs from the action exerted by other basal ganglia nuclei. • The PPTg has a critical role in the pathway mediating the prepulse inhibition of the BR. To investigate the effects on the blink reflex (BR) of single stimuli applied to the pedunculopontine tegmental nucleus (PPTg). The BR was evoked by stimulating the supraorbital nerve (SON) in fifteen patients suffering from idiopathic Parkinson's disease (PD) who had electrodes monolaterally or bilaterally implanted in the PPTg for deep brain stimulation (DBS). Single stimuli were delivered to the PPTg through externalized electrode connection wires 3–4 days following PPTg implantation. PPTg stimuli increased the latency and reduced duration, amplitude and area of the R2 component of the BR in comparison to the response recorded in the absence of PPTg stimulation. These effects were independent of the side of SON stimulation and were stable for interstimulus interval (ISI) between PPTg prepulse and SON stimulus from 0 to 110 ms. The PPTg-induced prepulse inhibition of the BR was bilaterally present in the brainstem. The R1 component was unaffected. The prepulse inhibition of the R2 component may be modulated by the PPTg. These findings suggest that abnormalities of BR occurring in PD may be ascribed to a reduction of basal ganglia-mediated inhibition of brainstem excitability. [ABSTRACT FROM AUTHOR]

Purpose: To describe and compare vision screening programmes and identify variance in number and type of tests used, timing of screening, personnel involved, monitoring and funding to be used as data for optimising, disinvesting or implementing future screening programmes., Methods: A questionnaire consisting of nine domains: demography & epidemiology, administration & general background, existing screening, coverage & attendance, tests, follow-up & diagnosis, treatment, cost & benefit and adverse effects was completed by Country Representatives (CRs) recruited from 47 countries., Results: The questionnaire was sufficiently completed for 46 Countries: 42 European countries, China, India, Malawi and Rwanda. Variation of provision was found in; age of screening (0-17 years), tests included (23), types of visual acuity (VA) test used (35 different optotypes), personnel (13), number of screens per child (median 5, range 1-32), and times VA tested (median 3, range 1-30). Infant screening is offered in all countries, whereas childhood vision screening is offered at least once in all countries, but not all regions of each country. All 46 countries provide vision screening between the ages of 3-7 years. Data on screening outcomes for quality assurance was not available from most countries; complete evaluation data was available in 2% of countries, partial data from 43%., Conclusion: Vision screening is highly variable. Some form of VA testing is being undertaken during childhood. Data collection and sharing should be improved to facilitate comparison and to be able to optimise vision screening programmes between regions and countries., Competing Interests: At the time of submission, Dr Carlton was the Editor of British and Irish Orthoptic Journal. She had no role in the peer-review process of this article., (Copyright: © 2022 The Author(s).)