# Experiments | Locations

Locations, or coordinates, describe a specific point in the three-dimensional space of a spatially normalized brain. These coordinates are the locations of **structural** atrophy or **functional** activation found in this experiment's SPI.

## Individual subject?

Indicates if the coordinates are from the data of an individual subject, as opposed to a group mean.

## Hemisphere

The hemisphere (left or right) of a coordinate is often reported even though that information is already described by the X value of the coordinate. This additional information is also recorded here as a verification of the coordinates.

Adhere to the standard that left means a negative value for X. Inspect your table carefully to be sure that all coordinates listed from the left hemisphere have X values that are negative and those from the right hemisphere are positive. If not, switch the signs of your X values before entering them into the table.

## X, Y, Z

Enter the values for X, Y, and Z for each coordinate as printed in the table (with the exception noted in the Hemisphere section).

## Statistical Parametric Image (SPI)

SPI are three-dimensional maps of statistical values created as a part of the analysis. These results of these statistical images are described as a set of locations.

The type of analysis can change by using a different statistical test, such as Z scores, t-statistics or r values. Do not use voxel-wise P values; if only P values are reported then do not enter SPI units and values.

**SPI Value**: the statistical value reported in the paper for this location in the SPI. The Z-score or t-statistic can be either the maximum or the mean value for the cluster.

**SPI Unit**: the statistical test or variable used to create the SPI

## Extent

The extent is the volume or size of a region. Record the extent of the results in cubic millimeters (mm³). This number usually ranges from the low hundreds to the low thousands of mm³.

Be sure to convert the extent to mm³ if necessary. Do not record the number of voxels, which relies on the volume of the voxels and varies across studies.

• 1 ml (milliliter) = 1 cc (cubic centimeter) = 1 cm³ = 1000 mm³

• 1 μl (microliter) = 1 ml / 1000 = 1 mm³