The OI
Imager 3001 image data acquisition and analysis system
carries out optical imaging based on both intrinsic optical signal
and voltage sensitive dye (VSD) signals-as well as on signals from
calcium dyes and other extrinsic optical probes. The Imager 3001 can
monitor blood volume and flow changes, as well as arterial pulsation
and the respiratory motion of cortex. Explorations of cortical microcirculation
with the Imager 3001
may also help improve the spatial resolution and interpretation of
functional MRI and PET imaging on human subjects, or even lead to
MRI imaging based on activity-dependent changes in new physiological
parameters.
The Imager 3001 is not
a bare-bone camera-and-frame grabber combination, leaving the user
to figure out the means of adapting it to experimental use. Rather,
OI offers and supports
it as an integrated solution specifically designed for intrinsic optical
signal, VSD, and other types of neuronal optical imaging. OI
also offers many imaging accessories for use with the Imager
3001, and an on-site installation program to help
you get your imaging experiments up and running.
Not only do the imaging functions of the Imager
3001 complement each other, they can also complement
non-imaging techniques that may already be used in your lab. Imaged
maps provide information about functional context that can be used
to guide site selection for electrode recordings (intracellular or
extracellular), or to target micro-stimulation, tracer injections,
or other experimental manipulations. Designed from the experience
of working scientists, the Imager 3001's
laboratory interface can communicate with much of the standard equipment
found in neurophysiology and biophysics laboratories.
Imager 3001 Uses and Technical Overview
Intrinsic Optical
Signals
As an intrinsic signal imager, the Imager
3001 system detects tiny intrinsic changes in the
optical properties of electrically and/or metabolically active brain
tissue (signals as small as 1 part in 10,000 are detectable with
signal averaging). The pioneering work of Hill, Keynes, Chance,
Jobsis and their colleagues first demonstrated the existence of
these intrinsic signals nearly fifty years ago. However, since these
signals are very small, their use for imaging of the functional
architecture of cortex began only in 1986, as technology and techniques
were improved. One source for the activity-dependent optical signal
is a small change in the color of the tissue produced by changes
in oxygen delivery from oxy-hemoglobin within the capillaries in
response to metabolic demand. Other intrinsic signals originate
from activity-dependent light scattering changes, and changes in
the oxidation states of intrinsic chromophores such as cytochromes.
Intrinsic imaging has facilitated high-resolution imaging of the
adult functional architecture of the cerebral cortex in the living
brain of mice, rats, guinea pigs, gerbils, ferrets, cats, monkeys
and humans. In some animals, activity maps have also been obtained
through intact dura and thinned bone, which allows visualization
of the development of the functional architecture of the cortex
over long periods of time. Success has also been achieved with chronic
recording paradigms in larger and adult mammals. Activity-dependent
intrinsic signals have also facilitated in-vitro studies in brain
slices, and in the isolated but intact mammalian brain.
Voltage Sensitive Dye
The term "voltage sensitive dye" (VSD) is used for compounds
that act as optical transducers of membrane potential changes. These
probes are used to stain a living preparation. Applied to the brain,
they bind to the external surface of the membranes of living cells
without interrupting their normal function. Once introduced into
a preparation, VSDs rapidly (within a microsecond) alter the intensity
and/or wavelengths of fluorescent light they emit as a function
of changes in neuronal membrane potential.
Recent improvements in the VSD probes available for in vivo VSD
imaging (see the Voltage Sensitive Dyes
product sheet for more information) have dramatically increased
the signal-to noise-level obtainable-by as much as 10-30 times over
previous probes. Combined with the Imager
3001, in vivo or in vitro, voltage sensitive dyes
can now provide both fast time resolution and the spatial resolution
required to visualize rapid, complex spatio-temporal patterns of
neuronal activity.
Calcium Dyes and
Other Optical Probes
Calcium signals are usually more than an order of magnitude larger
than the VSD signal. Due to this fact, the Imager
3001/M New back thinned 100% fill factor high-resolution
camera performs well in detecting small calcium signals, although
it is optimized for high light level applications. See OI's technical white papers for more
information on all these imaging techniques
Imager 3001: A Multi-Purpose Approach
The Imager 3001's multi-purpose design is a powerful approach to
optical imaging. The intrinsic optical signal and VSD imaging techniques
each excel at revealing different information about the brain's
functional architecture. Intrinsic optical signal imaging is particularly
suited to revealing high-resolution spatial features of the brain's
functional architecture. VSD imaging excels at revealing the temporal
structure of neuronal responses across regions of exposed brain.
And calcium imaging extends the power of the system further. Irrespective
of the signal used to extract physiological information, the Imager
3001 is well suited to study nearly all the preparations used in
brain research explorations.
Common Features of All Models
All Imager 3001 models include the following:
VDAQ 2.4
The latest version of our time-tested data acquisition system
running under Windows XP?. It allows for a wide variety of experimental
paradigms, live image display for focusing, live display of enhanced
differential images, feedback during experiments with flexible
on-line analysis displays, and an exceptionally intuitive user
interface.
WinMix 2.0
The latest version of our flexible data analysis software, and
easy enough to use that it can provide critical information while
the experiment is still in progress. WinMix includes utilities
to convert or view VDAQ data files or movies, a scripting component,
easy-to-use interactive image processing tools, and various export
capabilities that let you transport your data or images to 3rd
party software.
Imaging
Camera
Camera type varies by model, details are provided in our product
sheets.
Laboratory
Interface Unit
All Imager 3001 systems include a laboratory interface panel that
allows you to connect the imager to standard experimental apparatuses
such as stimulators, shutters, respirators, etc. All systems also
include an "artificial cortex" target for calibration
and testing. The BNC Panel allows you to connect your data acquisition
system to standard laboratory equipment.
An optional Analysis Workstation computer,
so that you can perform fast WinMix data analysis while continuing
to collect data.
All systems are delivered in rugged rack-mount
chassis with heavy-duty power supplies and late model motherboards,
generous amounts of RAM and disk space, high-speed CPUs, and roomy
RAID0 disk arrays for fast data access.
All models are turn-key systems. They arrive
with all the necessary cables and software, with all software
installed and tested. Installation of the cables is shown in an
illustrated Cable Installation Guide, so you can be up and running
in a very short time.
Systems containing both an Acquisition Workstation
and an Analysis Workstation include a network hub to interconnect
the two computers.
ADAQ Option ADAQ, an integrated
Analog Data
AcQuisition
facility for VDAQ,
lets you make electrical recordings that are co-triggered with
your image recording. You can collect up to 16 channels of electrical
activity (or 8 differential channels) at speeds of up to 500,000
samples/second, with 12-bit resolution. ADAQ
data files are similar in format to existing VDAQ
block data files, and we will offer enhanced versions of our analysis
tools that can work with analog waveform data.
See our Accessories product sheets for imaging
items sold separately.
Monitors included by special order only.
To learn more
about current Imager 3001 models, see our product sheets in PDF formats:
VDAQ 2.4 (Video
Data AcQuisition)
is the next-generation data acquisition component of the Imager
3001, running under Windows XP?. VDAQ
runs intrinsic and voltage sensitive dye imaging experiments as well
as calcium dye and other extrinsic probe experiments. It controls
image acquisition, as well as external devices such as a stimulator,
respirator, and illumination shutter. All experimental parameters
can be saved to disk, to allow easily restoring experimental settings
from session to session.
Other external hardware devices can also be controlled and monitored
as required according to the experiment. Alternatively, VDAQ can itself
be controlled through a serial port connection for awake behaving
monkey experiments. VDAQ also has functions for performing the setup
tasks that are performed at the beginning of an experimental imaging
session. It provides on-line image analysis functions that are critical
to monitoring and evaluating the progress and quality of experiments
as they unfold. Finally, VDAQ contains the functions used to calibrate
and test the video, optical, and image processing components of the
instrument.
LongDaq software for continuous imaging
LongDaq collects brain imaging data continuously, limited only by the speed and free space
of the available storage. It's available as either an add-on to a Vdaq system, or as a system in its own right.
LongDaq, Optical Imaging's cost-effective continuous imaging software, now supports a stim-map
feature that provides fine-grained control of stimulus output bits during a continuous imaging session. This provides useful synchronization
information and lets LongDaq trigger stimulators and other devices during acquisition.
LongDaq's useful Quality Assurance data is now saved automatically each time data is collected.
Both Vdaq and LongDaq now allow for stimulus
input information to be provided via UDP network packets. Previously, such information could only be provided using TTL level inputs.
Data Analysis Software
WinMix WinMix is a data analysis
suite specifically designed to handle data from optical imaging experiments,
including those generated using VDAQ.
It consists of the new Block Mix
scripted data analysis program, plus a combination of powerful interactive
tools including Block View
and Block Convert. The
powerful Block Mix script
tool includes display capabilities during analysis, logging of statistics
of output images, and syntax highlighting in the edit window.
WinMix's interactive
tools include:
Viewers for image and data files.
An image-processing component for filtering,
image histograms, line profiles, image arithmetic
A polar analysis module for producing polar
plots from groups of image files
A MovieLoop facility for comparing pairs of
images, or working with movies of data
Image conversion to a variety of popular
image formats, including BMP, TIF, and JPEG
Block View Block View is an interactive
program for viewing the data files produced during an imaging experiment.
Its various display options and simple processing options let you
use it for preliminary data analysis. Block
View also lets you display a movie of specified frames,
and it can compute superpixel graphs showing the average value of
a region over the course of many frames.
Block Convert Block Convert is a powerful
data conversion and compression program. Block
Convert performs spatial and temporal binning, to
improve the efficiency of subsequent analysis operations. Other conversions
include accumulation of block files, selection of specific conditions,
and cropping the data to a smaller region of interest. The output
format can be either an OI
block file (which can be viewed with Block
View, or further processed with WinMix),
a series of floating point image frames stored in a standard, compressed
ZIP archive, or a MatLab? format data file.
