Functional magnetic resonance imaging data of incremental increases in visuo-spatial difficulty in an adult lifespan sample

These data provide coordinates generated from a large healthy adult lifespan sample undergoing functional Magnetic Resonance Imaging (fMRI) while completing a spatial judgment task with varying levels of difficulty, as well as a control categorical condition. The data presented here include the average blood-oxygen-dependent (BOLD) response to the spatial judgment vs. the control task, as well as the BOLD response to incremental increasing difficulty; see also “Age-related Reduction of BOLD Modulation to Cognitive Difficulty Predicts Poorer Task Accuracy and Poorer Fluid Reasoning Ability” (Rieck et al., 2017) [1].

This dataset provides a sizable sample of healthy adults who performed a spatial judgment task. These data show differential BOLD responses for varying levels of visuo-spatial difficulty across the sample.
The data provide specific MNI coordinates of brain regions evoked by the task. These data are potentially useful to investigators studying differences in fMRI activation to nonverbal, spatial stimuli across the adult lifespan.

Data
While undergoing fMRI, healthy adult participants completed a blocked-design spatial judgment task with three levels of difficulty (Easy, Medium, and Hard). These data have previously been analyzed with regard to age [1]. The data shown here represent the group level analyses examining the effect of the distance judgment task (Easy, Medium, Hard vs. Control - Table 1 and Fig. 1) as well as the effect of incremental increasing difficulty (Medium vs. Easy - Table 2 and Hard vs. Medium - Table 3, both shown in Fig. 2).

Participants
Participants included 161 healthy adults, ages 20-94 (mean age¼51.93 718.9 years; 95 women; 66 men) who volunteered from the Dallas-Fort Worth area. Inclusion criteria for the study required that all participants be right-handed, fluent English speakers, and have normal or corrected-tonormal vision (at least 20/40). Participants were also screened for dementia using the Mini Mental State Examination (MMSE; [2]), with a cutoff of 26; volunteers were also required to have no history of neurological or psychiatric conditions, head trauma, drug or alcohol problems, or significant cardiovascular disease (however, n ¼32 with a self-reported diagnosis of hypertension). Participants were compensated for their time and informed consent was obtained in accordance with protocol approved by the University of Texas at Dallas and the University of Texas Southwestern Medical Center.

Experimental design
The data shared here are from a large lifespan dataset in which 161 healthy adults completed a blocked-design distance judgment task while undergoing fMRI. The spatial judgment task involved two types of judgments (modeled after [3] and [4]). The first type of judgment, which served as the control condition, required participants to make a categorical (LEFT/RIGHT) judgment. Participants saw a dot on the left or right side of a horizontal bar and had to indicate using a button press on which side of the bar the dot was present. Participants also made a coordinate (NEAR/FAR) distance judgment which had three levels of difficulty: Easy, Medium, and Hard. First, participants saw a vertical reference line, next they were shown a horizontal line with a dot either above or below the line; the judgment required participants to determine whether the dot was "nearer to" or "farther from" the horizontal bar, given the previously seen vertical line. As difficulty increased, the distance between the dot and the horizontal line became harder to determine the "nearness" or "farness" compared to the reference line. A schematic of the task can be found in Fig. 1 of Rieck and colleagues [1]. Prior to the scanning session, participants completed a practice session to ensure that the participants were comfortable with the instructions. Each participant completed three runs of the task, resulting in $15 min of scan time. The task was presented using PsychoPy v1.77.02 [5,6].

Image processing
Data from each individual were preprocessed using SPM8 (Wellcome Department of Cognitive Neurology, London, UK). Preprocessing included the following steps: slice time acquisition correction, motion correction, normalization, and smoothing (using an isotropic 8 mm 3 full-width-halfmaximum Gaussian kernel). In order to identify runs with motion outliers, ArtRepair [7] was used to determine potential outlier volumes for each participant. We examined all three runs for each participant, and runs that had more than 15% outlier volumes ( $ 30 volumes) with greater than 3% deviation from the mean in global intensity spikes or greater than 2 mm of motion displacement were flagged. Five participants had one run with more than 15% percent outlier volumes, so that run was excluded.
At the individual subject level, BOLD response to each condition (Control, Easy, Medium, Hard) was modeled in SPM as a block convolved with a canonical hemodynamic response function; six directions of motion-estimates for each volume generated from ArtRepair were also included as nuisance covariates. Several contrasts of interest were computed at the individual level for subsequent analysis at the group level: Easy þMedium þ Hard vs. Control (Table 1, Fig. 1), which represents the effect of the distance judgment task; and Medium vs. Easy (Table 2, Fig. 2), Hard vs. Medium (Table 3, Fig. 2) to examine the brain regions responsive to increment increases in difficulty for visuo-spatial judgments.

Conflict of Interest
The authors (KMK, JRR, MAB, KMR) of this manuscript (Functional magnetic resonance imaging data of incremental increases in visuo-spatial difficulty in an adult lifespan sample) have no conflicts of interest to report.