Introduction

Brain Vision Analyzer (BVA) is software used for pre-processing and analysing EEG and other physiological data. 

Availability, support and advice

BVA can be requested for a work computer via the Helpdesk Portal. BVA is installed on the computers in the Researchdata Analysis room. 

BVA from home

• SURKO: BVA can be used remotely for a fixed period on a Windows server with higher processing capacity. Remote server access must be requested via the Helpdesk (search on ‘SURKO’). Access is granted for 4 or 8 weeks and must be approved by the faculty key user. There may be costs associated with the use of the SURKO service. For questions related to SURKO, contact the ISSC. 
• RDP: If you have windows RDP access to you machine at the FSW (i.e. not the Citrix remote environment), you can have BVA installed on that machine and access is through RDP.
• EduVPN: BVA can be accessed through EduVPN (only on Leiden Univ managed laptops, not personal devices).

SOLO provides only very limited basic support for BVA.

BVA Response Events

By default, BVA detects markers (Stimulus-type events) by looking for changes in the decimal value generated from the first 8-bits of the status channel. This produces expected results. However, BVA also detects button presses (Response-type events) using this method, which may lead to unexpected and erroneous events.

BVA interprets the middle 8-bits of the status channel as a single decimal value representing responses, and generates a response event every time that decimal value changes to a non-zero value. When a single button is pressed, its corresponding bit determines the decimal value, which is then logged as a response event. When the button is subsequently released, no event is added since the new value is zero.

The issue occurs when multiple buttons are pressed at the same time. Say button 4 (decimal value 8) is pressed and held down: BVA will register an 8-bit response value of 8 (logged as “R  8”). Then, button 5 (decimal value 16) is pressed, the response value changes, and BVA registers a response of 24 (8 + 16). This is not correct, since only button 5 was toggled at that moment, not both buttons as the value 24 might suggest. Subsequently, when button 5 is released, the response value again changes and BVA registers a response of value 8. Even though no new buttons were pressed, BVA registers the change in value caused by the release of button 5 as a response with value 8 because at that moment, button 4 is still being held down. This means that an erroneous response coming from button 4 is registered by BVA.