[week 1: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday] [weeks 2-3: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday]

Methylphenidate serves as an acute stimulant challenge. [week 1: no Methylphenidate or Methylphenidate placebo] [week 2: 0mg Methylphenidate (placebo for Methylphenidate) on Monday at 10am; Methylphenidate once a day (10am) on Wednesday and Friday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)] [week 3: Methylphenidate once a day (10am) on Monday and Wednesday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)]

[week 1: no Methylphenidate or Methylphenidate placebo] [week 2: 0mg Methylphenidate (placebo for Methylphenidate) on Monday at 10am; Methylphenidate once a day (10am) on Wednesday and Friday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)] [week 3: Methylphenidate once a day (10am) on Monday and Wednesday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)]

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

The POMS is a self-rating measure of current mood, consisting of six subscales demonstrated to be sensitive to a range of acute drug effects, including amphetamine, cocaine, and caffeine. The six subscales are: depression, vigor, confusion, tension, anxiety, and fatigue. A 37-item short form of the POMS was used, which correlates highly with the full scale. The vigor subscale is reported, and the vigor subscale score ranges from 0 to 28, with 28 representing the highest score for that mood state. The higher the value, the worse the outcome.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

The DEQ is a visual analog scale questionnaire that assesses the extent to which subjects experience four subjective states: "Feel Drug," "Feel High," "Like Drug," and "Want More." The "Feel High" subscale is reported, and this subscale is scored on a visual analogue scale (scroll bar on computer screen) ranging from 0-100. 100 represents the highest score for that subjective state, and the higher the score, the worse the outcome.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

The VAS presents 100-mm horizontal lines labeled with an adjective: "stimulated," "high," "anxious," "elated," "hungry," and "nauseated." The "elated" subscale is reported, and this sub scale is anchored by "not at all" (0) on the left and "extremely" (100) on the right, with a score range of 0-100. The higher the score, the worse the outcome.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

Heart rate is the measure of heart beats per minute.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

Systolic blood pressure is the amount of pressure in the arteries during contraction of the heart muscle.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

Diastolic blood pressure is the blood pressure when the heart muscle is between beats.

Subjects are required to respond selectively to a series of stimuli (e.g., numbers) presented briefly for 500 ms with a 500 ms intertrial interval (ITI). Increases in false alarm rates are interpreted as failures in response inhibition. Five digit numbers are presented on a computer screen every 500 ms sec. Subjects are instructed to respond when the first number of a set was repeated. A "hit" response is scored when a subject correctly responds. Distracters consist of five-digit numbers that are completely different from the first, and numbers in which four of the five digits match the original, with the non-matching number occurring randomly across the five digit places. A response to the number with 4 of 5 digits correct is scored as a "false alarm." The a-prime value reflects the ability of the participant to discriminate between signal (Go stimulus) and noise (No-Go stimulus) and ranges from 0.5 (chance level) to 1 (perfect discrimination).

Subjects are required to respond selectively to a series of stimuli (e.g., numbers) presented briefly for 500 ms with a 500 ms intertrial interval (ITI). Increases in false alarm rates are interpreted as failures in response inhibition. Five digit numbers are presented on a computer screen every 500 ms sec. Subjects are instructed to respond when the first number of a set was repeated. A "hit" response is scored when a subject correctly responds. Distracters consist of five-digit numbers that are completely different from the first, and numbers in which four of the five digits match the original, with the non-matching number occurring randomly across the five digit places. A response to the number with 4 of 5 digits correct is scored as a "false alarm." The a-prime value reflects the ability of the participant to discriminate between signal (Go stimulus) and noise (No-Go stimulus) and ranges from 0.5 (chance level) to 1 (perfect discrimination).

Subjects are required to respond selectively to a series of stimuli (e.g., numbers) presented briefly for 500 ms with a 500 ms intertrial interval (ITI). Increases in false alarm rates are interpreted as failures in response inhibition. Five digit numbers are presented on a computer screen every 500 ms sec. Subjects are instructed to respond when the first number of a set was repeated. A "hit" response is scored when a subject correctly responds. Distracters consist of five-digit numbers that are completely different from the first, and numbers in which four of the five digits match the original, with the non-matching number occurring randomly across the five digit places. A response to the number with 4 of 5 digits correct is scored as a "false alarm." The a-prime value reflects the ability of the participant to discriminate between signal (Go stimulus) and noise (No-Go stimulus) and ranges from 0.5 (chance level) to 1 (perfect discrimination).

The task is a rapid-presentation, probablistic gain/loss design. Reversal learning is assessed by means of a simple computerized card game. The paradigm utilizes a visual discrimination task where subjects have to learn to respond to outcome contingencies between two stimuli (high probability gain/low probability loss vs. low probability gain/high probability loss). At an unsignaled time point halfway into testing, the contingencies are reversed; the losing card becomes the winning card and the winning card becomes the losing one. Visual feedback regarding win or loss ($0.20) is provided after each trial and the cumulative total gained/lost is also shown. Using trial-and-error feedback, subjects have to discover which of the two patterns is correct and are instructed to win as much money as possible. The duration of the task is approximately 10 minutes, consisting of 80 trials.

The task is a rapid-presentation, probablistic gain/loss design. Reversal learning is assessed by means of a simple computerized card game. The paradigm utilizes a visual discrimination task where subjects have to learn to respond to outcome contingencies between two stimuli (high probability gain/low probability loss vs. low probability gain/high probability loss). At an unsignaled time point halfway into testing, the contingencies are reversed; the losing card becomes the winning card and the winning card becomes the losing one. Visual feedback regarding win or loss ($0.20) is provided after each trial and the cumulative total gained/lost is also shown. Using trial-and-error feedback, subjects have to discover which of the two patterns is correct and are instructed to win as much money as possible. The duration of the task is approximately 10 minutes, consisting of 80 trials.

The task is a rapid-presentation, probablistic gain/loss design. Reversal learning is assessed by means of a simple computerized card game. The paradigm utilizes a visual discrimination task where subjects have to learn to respond to outcome contingencies between two stimuli (high probability gain/low probability loss vs. low probability gain/high probability loss). At an unsignaled time point halfway into testing, the contingencies are reversed; the losing card becomes the winning card and the winning card becomes the losing one. Visual feedback regarding win or loss ($0.20) is provided after each trial and the cumulative total gained/lost is also shown. Using trial-and-error feedback, subjects have to discover which of the two patterns is correct and are instructed to win as much money as possible. The duration of the task is approximately 10 minutes, consisting of 80 trials.

[week 1: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday; no Methylphenidate or Methylphenidate placebo] [week 2: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday; 0mg Methylphenidate (placebo for Methylphenidate) on Monday at 10am; Methylphenidate once a day (10am) on Wednesday and Friday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)] [week 3: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday; Methylphenidate once a day (10am) on Monday and Wednesday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)]

Total of all reporting groups

The baseline reading was assessed on Monday of week 2. Participants are instructed to respond to words shown in different colors on the screen by pressing as quickly and accurately as possible on one of three colored buttons. Attentional bias is measured as the difference in reaction times on cocaine vs. neutral words. The reported score is a difference score in milliseconds (cocaine minus neutral), in which positive means slower to respond to cocaine and thus greater attentional bias, and negative means no attentional bias to cocaine words.

The baseline reading was assessed on Monday of week 2. The risky decision making task provides subjects with three choice options on each of 100 repeated trials. Options are low, moderate, and high risk, based on variance and probability in gain/loss amounts. The low risk option is more adaptive over many trials. The outcome measure is a risk index (ranging from 0.33 to 100) that factors in tolerance for variability and amount of gains and losses across the three options. 100 is highest risk. 0.33 is lowest risk.

The baseline reading was assessed on Monday of week 2. The POMS is a self-rating measure of current mood, consisting of six subscales demonstrated to be sensitive to a range of acute drug effects, including amphetamine, cocaine, and caffeine. A 37-item short form of the POMS was used, which correlates highly with the full scale. The vigor subscale is reported, and the vigor subscale score ranges from 0 to 28, with 28 representing the highest score for that mood state. The higher the value, the worse the outcome.

The baseline reading was assessed on Monday of week 2. The DEQ is a visual analog scale questionnaire that assesses the extent to which subjects experience four subjective states: "Feel Drug", "Feel High", "Like Drug", and "Want More". The "Feel High" subscale is reported, and this subscale is scored on a visual analogue scale (scroll bar on computer screen) ranging from 0-100. 100 represents the highest score for that subjective state, and the higher the score, the worse the outcome.

The baseline reading was assessed on Monday of week 2. The VAS presents 100-mm horizontal lines labeled with an adjective: "stimulated", "high", "anxious", "elated", "hungry", and "nauseated." The "elated" subscale is reported, and this sub scale is anchored by "not at all" (0) on the left and "extremely" (100) on the right, with a score range of 0-100. The higher the score, the worse the outcome.

The baseline reading was assessed on Monday of week 2. Heart rate is the measure of heart beats per minute.

The baseline reading was assessed on Monday of week 2. Systolic blood pressure is the amount of pressure in the arteries during contraction of the heart muscle.

The baseline reading was assessed on Monday of week 2. Diastolic blood pressure is the blood pressure when the heart muscle is between beats.

[week 1: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday; no Methylphenidate or Methylphenidate placebo] [week 2: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday; 0mg Methylphenidate (placebo for Methylphenidate) on Monday at 10am; Methylphenidate once a day (10am) on Wednesday and Friday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)] [week 3: Placebo for Buspirone twice a day (9am and 6pm) on Monday through Sunday; Methylphenidate once a day (10am) on Monday and Wednesday, and on each of these 2 days the Methylphenidate dose will be different (15 mg, 30mg, 60 mg, or 0mg)]

The mean score over all 4 time points is reported in this outcome measure (i.e., a summary score is reported). Each subject contributed 1 data point for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 20 data points per dose level per arm.

The risky decision making task provides subjects with three choice options on each of 100 repeated trials. Options are low, moderate, and high risk, based on variance and probability in gain/loss amounts. The low risk option is more adaptive over many trials. The outcome measure is a risk index (ranging from 0.33 to 100) that factors in tolerance for variability and amount of gains and losses across the three options. 100 is highest risk. 0.33 is lowest risk.

The ARCI short form will be used. It is a 49-item true / false questionnaire that has been empirically-derived to assess five different factors, including euphoria, sedation, and dysphoria. The PCAG scale has proven to be a sensitive measure of subjective effects in many studies administering stimulant drugs.

ARCI data were not collected.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

The POMS is a self-rating measure of current mood, consisting of six subscales demonstrated to be sensitive to a range of acute drug effects, including amphetamine, cocaine, and caffeine. The six subscales are: depression, vigor, confusion, tension, anxiety, and fatigue. A 37-item short form of the POMS was used, which correlates highly with the full scale. The vigor subscale is reported, and the vigor subscale score ranges from 0 to 28, with 28 representing the highest score for that mood state. The higher the value, the worse the outcome.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

The DEQ is a visual analog scale questionnaire that assesses the extent to which subjects experience four subjective states: "Feel Drug," "Feel High," "Like Drug," and "Want More." The "Feel High" subscale is reported, and this subscale is scored on a visual analogue scale (scroll bar on computer screen) ranging from 0-100. 100 represents the highest score for that subjective state, and the higher the score, the worse the outcome.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

The VAS presents 100-mm horizontal lines labeled with an adjective: "stimulated," "high," "anxious," "elated," "hungry," and "nauseated." The "elated" subscale is reported, and this sub scale is anchored by "not at all" (0) on the left and "extremely" (100) on the right, with a score range of 0-100. The higher the score, the worse the outcome.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

Heart rate is the measure of heart beats per minute.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

Systolic blood pressure is the amount of pressure in the arteries during contraction of the heart muscle.

The mean score over all 44 time points is reported in this outcome measure (i.e., the summary score is reported). Each subject contributed 11 data points for each dose level of Methylphenidate (15mg, 30mg, 60mg, or 0mg), resulting in a total of 220 data points per dose level per arm.

Diastolic blood pressure is the blood pressure when the heart muscle is between beats.

Subjects are required to respond selectively to a series of stimuli (e.g., numbers) presented briefly for 500 ms with a 500 ms intertrial interval (ITI). Increases in false alarm rates are interpreted as failures in response inhibition. Five digit numbers are presented on a computer screen every 500 ms sec. Subjects are instructed to respond when the first number of a set was repeated. A "hit" response is scored when a subject correctly responds. Distracters consist of five-digit numbers that are completely different from the first, and numbers in which four of the five digits match the original, with the non-matching number occurring randomly across the five digit places. A response to the number with 4 of 5 digits correct is scored as a "false alarm." The a-prime value reflects the ability of the participant to discriminate between signal (Go stimulus) and noise (No-Go stimulus) and ranges from 0.5 (chance level) to 1 (perfect discrimination).

Subjects are required to respond selectively to a series of stimuli (e.g., numbers) presented briefly for 500 ms with a 500 ms intertrial interval (ITI). Increases in false alarm rates are interpreted as failures in response inhibition. Five digit numbers are presented on a computer screen every 500 ms sec. Subjects are instructed to respond when the first number of a set was repeated. A "hit" response is scored when a subject correctly responds. Distracters consist of five-digit numbers that are completely different from the first, and numbers in which four of the five digits match the original, with the non-matching number occurring randomly across the five digit places. A response to the number with 4 of 5 digits correct is scored as a "false alarm." The a-prime value reflects the ability of the participant to discriminate between signal (Go stimulus) and noise (No-Go stimulus) and ranges from 0.5 (chance level) to 1 (perfect discrimination).

Subjects are required to respond selectively to a series of stimuli (e.g., numbers) presented briefly for 500 ms with a 500 ms intertrial interval (ITI). Increases in false alarm rates are interpreted as failures in response inhibition. Five digit numbers are presented on a computer screen every 500 ms sec. Subjects are instructed to respond when the first number of a set was repeated. A "hit" response is scored when a subject correctly responds. Distracters consist of five-digit numbers that are completely different from the first, and numbers in which four of the five digits match the original, with the non-matching number occurring randomly across the five digit places. A response to the number with 4 of 5 digits correct is scored as a "false alarm." The a-prime value reflects the ability of the participant to discriminate between signal (Go stimulus) and noise (No-Go stimulus) and ranges from 0.5 (chance level) to 1 (perfect discrimination).

The task is a rapid-presentation, probablistic gain/loss design. Reversal learning is assessed by means of a simple computerized card game. The paradigm utilizes a visual discrimination task where subjects have to learn to respond to outcome contingencies between two stimuli (high probability gain/low probability loss vs. low probability gain/high probability loss). At an unsignaled time point halfway into testing, the contingencies are reversed; the losing card becomes the winning card and the winning card becomes the losing one. Visual feedback regarding win or loss ($0.20) is provided after each trial and the cumulative total gained/lost is also shown. Using trial-and-error feedback, subjects have to discover which of the two patterns is correct and are instructed to win as much money as possible. The duration of the task is approximately 10 minutes, consisting of 80 trials.

The task is a rapid-presentation, probablistic gain/loss design. Reversal learning is assessed by means of a simple computerized card game. The paradigm utilizes a visual discrimination task where subjects have to learn to respond to outcome contingencies between two stimuli (high probability gain/low probability loss vs. low probability gain/high probability loss). At an unsignaled time point halfway into testing, the contingencies are reversed; the losing card becomes the winning card and the winning card becomes the losing one. Visual feedback regarding win or loss ($0.20) is provided after each trial and the cumulative total gained/lost is also shown. Using trial-and-error feedback, subjects have to discover which of the two patterns is correct and are instructed to win as much money as possible. The duration of the task is approximately 10 minutes, consisting of 80 trials.

The task is a rapid-presentation, probablistic gain/loss design. Reversal learning is assessed by means of a simple computerized card game. The paradigm utilizes a visual discrimination task where subjects have to learn to respond to outcome contingencies between two stimuli (high probability gain/low probability loss vs. low probability gain/high probability loss). At an unsignaled time point halfway into testing, the contingencies are reversed; the losing card becomes the winning card and the winning card becomes the losing one. Visual feedback regarding win or loss ($0.20) is provided after each trial and the cumulative total gained/lost is also shown. Using trial-and-error feedback, subjects have to discover which of the two patterns is correct and are instructed to win as much money as possible. The duration of the task is approximately 10 minutes, consisting of 80 trials.

week 1: Placebo BID weeks 2-3: Placebo BID

Placebo: week 1 = placebo BID weeks 2-3 = placebo BID