Transcranial Direct Current Stimulation of the Temporal Cortex in Survivors of Childhood Acute Lymphoblastic Leukemia (ALL)

The Anodal intervention excites neuronal activity. For condition one, the anode will be attached to the left frontal region (Fp1) and the cathode will be attached to the right neck. The intervention involves a direct current of 1 mA applied for 20 minutes.

The Cathodal intervention inhibits or reduces neuronal activity. We propose that the use of the cathodal tDCS to the superior temporal gyrus in survivors of childhood ALL may facilitate the inhibition of over connected motor-sensory and auditory neural networks. For condition two, the cathode will be attached to the left temporal region (T3) and the anode will be attached to the right neck. The intervention involves a direct current of 1 mA applied for 20 minutes.

The sham procedure provides the same small current during ramp up to imitate the intervention, but the current is discontinued after ramping up and no intervention is provided. Sham will be applied for 20 minutes. Stimulation will start 5 minutes before testing and continue throughout completing the NIH Toolbox Cognitive Battery at each trial.

List Sorting is using information processing and storage. Performance tends to peak in early adulthood and then decline across the life span. This task assesses working memory and requires the participant to sequence different visually- and orally-presented stimuli. The list scoring task takes approximately 7 minutes to administer. List Sorting is scored by summing the total number of items correctly recalled and sequenced on Lists-1 and -2, which can range from 0-26.

The Flanker tests inhibitory control and attention and the capacity for new learning and information processing novel situations. This performance also reaches a peak in early adulthood and tends to decline across the life span. A total of 40 trials require 4 minutes. Scoring is based on both accuracy and reaction time, which will we evaluate individually as well as in combination. The raw scores are converted to a scale score with a mean of 100 and SD of 15. Higher scores indicate higher executive function.

The Grooved Peg Board test measures visual-motor coordination and motor speed. Additionally, it is cognitively challenging and has been associated with attention, perceptual speed and non-verbal reasoning. Performance is better in the dominant/preferred hand and tends to improve in childhood and decline with advancing age. The test consists of placing metal pegs with ridges along onside in matching slots as quickly as possible. The score is the time in seconds required to compete the array with each hand. Longer times reflect worse performance. Times are compared to normative data that is organized by ethnicity, age, gender and education. The test takes approximately 5 minutes to complete.

This selective reminding task purports to distinguish verbal memory into short-term and long-term components. Scores are organized by short- and long-term storage and retrieval with normative scores organized by age and gender. The task requires participants to remember a list of orally-presented words and recall them with selective reminders of the words that they didn't recall. The test will last 5-10 minutes and is available in four different versions, thus reducing rehearsal effects.