UUMSI provides five basic stimulation systems:

• Auditory
• Visual
• Somatosensory
• Tactile
• Olfactory

LowFi Auditory Stimulator
The auditory stimulation system available is a 2 channel "lowFi" system. It can be used to deliver tones, words or music directly to the subjects ears via ear tubal inserts/plugs.

Advantages:

• comfortable to use

• limited frequency bandwidth
• magnetic artifacts at high intensity levels
• magnetic artifacts at low frequencies

The visual stimulation available uses an LCD projector (SHARP XG-E1200U) outside the MSR "beaming" visual information on a screen inside the MSR in front of the subject

Advantages:

• comfortable to use
• affordable

Limitations:

• projector is already old
• output is typically limited in resolution and refreshment rate (leads to distortions due to rescaling and inaccurate timing due to reduced refreshment rate)
• lightbulb looses luminance (increased latencies!)

The two available systems (Grass S88) deliver 4 independent electrical stimuli channels.

Advantages:

• constant current
• various possibilities

Limitations:

• difficult to operate
• artifacts with EEG

Available setup uses 2 independent channels (could be extended to more). The tactile stimulation uses compressed gas to move a small plastic membrane attached to fingers or elsewhere. Noise could produce auditory artifact!

Advantages:

• strong natural stimulus
• strong SI response
• fMRI compatible

Limitaions:

• low frequency (aproxx. 0.5 Hz)
• stimulus duration and pressure
• adjustment

This system was developed by research group at the Department of Physiology at the University of Utah. It can be used to deliver via air stream olfactory stimulants or -if appropriately calibrated -pheromones.

Advantages:

• simple design
• fMRI compatible

Limitations:

• low frequency (aproxx. 0.5 Hz)
• stimulus duration and pressure
• some effort for calibration

Our Stimulation Software

Stimulation Software

UUMSI uses eeVoke. It is a MS-Windows based stimulation package that can present stimuli with any kind of complexity in ERP experiments. Stimulus presentations can be visual, auditory or a combination of these. eeVoke can be interfaced with external devices such as electrical or pain stimulation.

Using the eeVoke package stimulations are controlled through a scenario. Scenarios contain information regarding timing, response pads, event codes, and multimedia files. This way, both presentation and corresponding controlling information are running in parallel, yielding a highly flexible and adaptable environment for stimulation.

Scenarios are stored in a database table and can easily be edited by MS-Office applications such as Excel or Access. Excel sheets are available for designing experiments and generating scenarios. Each scenario contains event codes to define all the necessary parameters. eeVoke works with just sixteen different codes, by means of which virtually any kind of experiment can be designed. This way, working with eeVoke becomes as easy as editing an Excel sheet!

UUMSI provides PIs with the eeVoke installation CD so they can create their scenarios on their own PC's (Excel is required to be installed already).

Stimulus responses can be made via game pads or other external devices. Responses are registered with a very high accuracy. Experiments in eeVoke can be synchronized based upon pulses generated externally, e.g. by MEG or fMRI.

Features

• Windows-based stimulation software
• Scenarios are stored in database format
• Microsoft Excel templates to esign and make scenario files
• 16 codes to define complete stimulation scenario
• Accepts TTL from external devices like fMRI scanner
• Trigger output through parallel and serial ports
• Support for dual display (stimulation and control at separate monitors)
• Superb morphing effects for visual stimulation
• Support for MIDI, WAV sounds
• Graphics support for BMP, JPG, GIF, PNG
• Movie support for AVI, MPG

EEVOKE manual