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Lumina Response Pads
Lumina LP-400 Controller

Cedrus Lumina Response Pads for fMRI

The Lumina LP-400 is a reliable patient response system designed specifically for use in an fMRI. Lumina was developed to satisfy the requirements of both the clinical and research fields.

Cedrus Lumina Response Pads for fMRI

The Lumina LP-400 is a reliable patient response system designed specifically for use in an fMRI. Lumina was developed to satisfy the requirements of both the clinical and research fields. The system consists of the following main components:

  • A controller (shown abovet) provides TTL and serial port output that is compatible with E-Prime, Presentation, SuperLab, Cambridge Research Systems, and other packages. The controller provides a scanner trigger input as well.
  • One of the response pads, or button response unit (BRU) pictured below. All models are built from 100% fiber optics and plastic, and come with 16 feet of fiber optic cables.
  • Two 65 foot shielded cables
  • Despite using fiber optics, the keys in a Lumina response pad are very solid and can take a lot of abuse. They are even water resistant.


Quality Construction:

From the Swiss-made shielded connectors to the lowliest electronic part, the Lumina system spells quality through and through. No expense was spared during the three year development period to make these pads the best that's out there.

Lumina comes with a 1 year "bumper to bumper" warranty which covers all parts and labour. An optional Premium Warranty is available that includes immediate replacement and 3 years extended coverage.

See the How It Works section below for information on how the Lumina system is typically installed and used.

How It Works

The most frequently asked question is how a Lumina system is installed. The following diagram gives an overview:

Lumina System Installation:


 A   Response Pads: These are built of 100% plastic and fiber optics. They are totally inert and safe.

 B   OTEC Unit: Converts electricity to light and is connected to the pads via protected fiber optic cables.

 C   Shielded Cable: Connects the OTEC unit to the penetration panel. Uses wires and connectors of the highest quality.

 D   RF Filter: Optionally installed if the penetration panel does not have a built-in filter.

 E   Shielded Cable: Connects the penetration panel to the controller.

 F   Controller: Detects key presses, times them, performs TTL I/O, and connects to the host computer. See Controller Features for all the features built into this versatile device.

 G   Serial Cable: Connects the controller to the host computer.

There are two other optional connections not shown on the diagram:

    Scanner Trigger Input: The Lumina controller can detect the scanner triggers and pass them through to the serial port.

    Accessory Connector: Provides a highly configurable TTL input/output link.

Lumina Controller Features

Under the hood, the Lumina controller packs a lot of power, much more than is apparent at first glance. All the features described below can be set once using the XID Control Panel program and then stored in non-volatile memory inside the controller.


Lumina provides the following timing capabilities. All timers have a one (1) millisecond resolution.
 Feature  What It Does
 Reaction Time Timer  Measures the patient's reaction time. The timer is triggered by the computer.
 Experiment Timer  An experiment-wide timer is provided. The computer can reset this timer and inquire at any moment about how much time has elapsed.
 Trial Alarm Some experiments require that a trial begins at fixed, precise intervals. Lumina provides a trial triggering capability. The computer sets the period, e.g. 700 milliseconds, and then simply waits for the trigger to arrive from Lumina.
Of course, a trial can also be triggered by Lumina's fMRI scanner input.
 Port Test Timer  Intended to measure any transmission delays that may be introduced by the operating system or USB-to-serial port converters.
Accessory Connector

Lumina sports an Accessory Connector that can be configured in many ways and entirely via software. It can function in one of two modes: Reflective or General Purpose.

When in Reflective Mode, the pins on the Accessory Connector reflect the status of the response pads' push buttons. The following options are offered:

 Reflective Mode  When a Push Button is Pressed...
 Continuous  ...the corresponding pin on the Accessory Connector goes high and stays high until the push button is released.
 Single Pulse Mode  ...a single pulse is sent on the corresponding pin. The pulse's duration can be adjusted. This mode works well with products from Neuroscan and Brain Products GmbH.
 Double Pulse Mode  ...a pulse is sent on the corresponding pin; when the push button is released, a second pulse is sent.
Two additional features are available when in Reflective Mode:

  • A pin on the Accessory Connector provides an "OR" output. It goes high when any push button is pressed. This feature helps make Lumina compatible with systems from Cambridge Research Systems.
  • The logic of the output pins can be set to active high or active low.

When in General Purpose Mode, the Accessory Connector can be used for general purpose input/output (I/O) operations.

  • Any I/O lines can be used for either input or output.
  • Lines selected for input can be pulled high or pulled low.

Serial Port

Lumina's serial port operates at 9600, 19200, 38K, 56K, or 110K baud. Four different data communication protocols are currently supported:
  • Lumina / XID. This mode supports all the timing features described above.
  • Cedrus RB Series mode. This mode emulates the popular Cedrus RB Series response pads.
  • E-Prime / MEL mode.
  • ASCII / MEDx mode.


An additional feature allows the user to lock the Mode and Switch push buttons on the back of the Lumina controller to prevent an accidental change.


Lumina LP-400 Specifications

The Lumina LP-400 system has several components. Here is a list of all the components that come with the system along with detailed information about the individual components.

Lumina Response Pads  

The Lumina LP-400 system includes two fiber optic response pads, each with two colored push buttons. They are:

  • Built of 100% plastic and fiber optic parts
  • Magnetically and RF inert
  • Water resistant
  • Delivered with right hand and left hand versions
  • Safe -- no laser lights are used

The pads come permanently connected to a unit called the OTEC (see below) via a 5 m (15 ft.) fiber optic cable. This cable is protected by a sturdy crush resistant cover. The dimensions of the pads are as follows:

 Side A:  7 cm (2.75)
Side B:  2.4 cm (0.94")
Side C:  12.55 cm (4.94")


The OTEC is the unit that converts the electrical signals to light. It is housed in an aluminum enclosure and is typically installed under the magnet.


The picture above on the left shows the OTEC unit connected to the two response pads via the protected fiber optic cable. The picture on the right shows more details of the OTEC unit.


The controller is where everything connects.

The controller:

  • Powers the OTEC unit and detects input from the response pads
  • Times the reaction time of the patient and provides other timing functions
  • Accepts triggers from the MRI scanner via an optically isolated input (see below).
  • Has lights with colors that match the push buttons to show when the patient has pressed a button
  • Interacts with the host computer via the serial port
  • Provides TTL input and output via the Accessory Connector.

Controller's Trigger Input

The controller features a scanner trigger input. Physically, this is a BNC connector (75 ohm). The minimum width of a trigger pulse is 300 microseconds and there must be at least 25 milliseconds between pulses when in XID mode at 9600 baud. This can be 12 milliseconds for all other modes and baud rates.

In optical isolation mode, the trigger is guaranteed to be 'OFF' when the voltage is 1.1V or less, and 'ON' when the voltage is 1.5V or higher with an input current of 2mA.  The input must be positive with respect to the enclosure's ground.

When not using the optical isolation, the trigger is guaranteed to be 'OFF' when the voltage is below 1.0V, and 'ON' when the voltage is 1.5V or higher with an input current of 2mA.


Two shielded cables are included, each about 21 m (65 ft.) long.

The first cable is installed inside the magnet room. It has a circular connector that plugs into the OTEC unit on one end, and a DB9 male connector that plugs into a DB9 cutout on the MRI room's penetration panel.

The second cable has a DB9 female connector that plugs into the penetration panel from outside the magnet room, and a circular connector that plugs into the controller.

Other Components

The Lumina system comes with the following additional components:

  • A filter for the penetration panel. This item is not normally included but is provided free of charge upon request. It is needed only if your penetration panel is not filtered already.
  • A 9 volt A/C adapter
  • USB-to-serial port converter
  • A serial port cable