Fig. 1. Median split by performance on the Percent Correct Target Trials (PCTT) Go/No-go task measure. The seven good young performers all had perfect performance and the four good elder performers all had performance at 99% or better.

Fig. 2. Depicted is putamen/globus pallidus (PGp) and caudate (C) activation by both age group and performance group, separately by hemisphere (A = left; B = right). Older participants had greater activation for PGp, while younger participants had greater C activation. In addition, poor performers had generally greater activation than good performers, although this was significant for both regions only in the left hemisphere. In the right hemisphere, only young poor performers had significantly greater C activation.

Fig. 3. Z-transformed activation in to the left putamen/globus pallidus (PGp) correlated with Percent Correct Target Trials (PCTT) performance, denoted by age group (▲ for elders, ▼ for young adults) and performance group (good in pale gray, poor in dark gray). Increased activation with poorer performance is evident irrespective of age group.

Fig. 4. Depiction of the Go/No-go task.

Fig. 5. Regions of Interest (ROI) for the fMRI and vMRI analyses including the caudate (1), putamen/globus pallidus (2), and brain volume in the horizontal AC–PC plane (3).

Correlations between Go/No-go performance, age, and functional and volumetric MRI measurements for all participants

Lt. = Left, Rt. = Right. PGp = Putamen and Globus Pallidus. C = Caudate. BV = brain volume in the axial plane through the anterior commissure–posterior commissure and perpendicular to the longitudinal fissure. *p = 0.05, **p = 0.01, N = 22 for all correlations.

Correlations between neuropsychological test measures, Go/No-go performance, and vMRI and fMRI measurements for elder participants

GNG = Go/No-go; PCTT = percent correct target trials; PCIT = percent correct inhibition trials; RTT = reaction time to targets; WCST = Wisconsin Card Sorting Test; COWA = Controlled Oral Word Association test; Persev. = perseverative responses; Cat. = categories; Digit Sym Raw = Digit Symbol Raw Score; N = 11 for all correlations except WCST categories (N = 10) and WCST perseverative responses (N = 9); *p = 0.05 (r > 0.595); **p = 0.01.

Demographic and neuropsychological data for older adults (N = 11) and young adults (N = 11)

MMSE = Mini Mental State Exam; GDS = Geriatric Depression Scale; *from the Wechsler Adult Intelligence Scale-III; SS = Scaled Score (M = 10, S.D. = 3); LMI = Logical Memory I (Wechsler Memory Scale-III; VRI = Visual Reproduction I; WCST = Wisconsin Card Sorting Test (N = 9 valid scores); COWA = Controlled Oral Word Association Test.