3.2. The Status of Participants

3.2.1. Classification of Participants
122 studies [7, 11–13, 15–17, 24, 25, 30–33, 35, 36, 39, 41–45, 50, 53–57, 63, 64, 66–70, 72–76, 78–83, 85–100, 102–104, 106, 107, 109–111, 113–130, 132, 135, 136, 140, 143, 144, 147–176] were performed on healthy subjects. 25 studies were [10, 26–29, 34, 38, 49, 51, 58–60, 62, 65, 71, 84, 101, 105, 108, 112, 134, 137, 139, 142, 145] performed on patients. 21 studies [14, 18–23, 37, 40, 46–48, 52, 61, 77, 131, 133, 138, 141, 146, 165] recruited both healthy subjects and patients. 25 kinds of diseases were involved in these studies (Table 1). 19 studies [10, 14, 18, 19, 29, 34, 35, 40, 46, 51, 52, 59, 62, 65, 77, 84, 112, 134, 146] classified the subtypes of diseases.

3.2.2. Age
100 studies [7, 10, 16–19, 23, 24, 26, 27, 30, 34, 35, 39–42, 44–48, 51–54, 57, 59, 60, 62, 63, 65, 69–74, 76, 77, 80–82, 84, 85, 87, 89, 92, 97, 98, 101–103, 105, 107–109, 112, 114, 116, 117, 120–122, 124, 125, 129, 131–135, 137, 139, 141–145, 148–153, 157, 158, 160, 162, 164, 166–168, 171–176] described the age range of participants. For the healthy subjects, the average age range was 18.3 years old, and the maximal age range was 62, while the minimal age range was 3. For the patients, the average age range was 29 years old, and the maximal age range was 57, while the minimal age range was 6. Taking studies on the stroke for instance, the maximal age range of the stroke patients was 52, while the minimal age range was 7. Furthermore, 66 studies [11, 13–15, 20–22, 25, 28, 29, 31–33, 36–38, 43, 49, 50, 55, 56, 58, 61, 64, 66–68, 75, 78, 79, 83, 86, 88, 90, 91, 93, 95, 96, 99, 100, 104, 106, 110, 111, 113, 115, 118, 119, 123, 126–128, 130, 136, 138, 140, 146, 147, 154–156, 159, 161, 163, 169, 176] described the average age of participants. Three studies [94, 163, 170] did not mention the age of participants.

3.2.3. Gender
159 studies [7, 10–26, 28–79, 81–93, 95–114, 116–123, 125–131, 133–151, 153–169, 172–176] described the gender of the participants (56.7% male and 43.3% female). Nine studies [27, 80, 94, 115, 124, 132, 152, 170, 171] did not mention the gender of the participants.

3.2.4. Race and Handedness
14 studies [66, 75, 87, 90, 99, 105, 115, 126, 135, 148, 151, 164, 167, 174] described and restricted the race of participants. 136 [10–24, 26, 28, 30–36, 39–56, 58, 59, 61–80, 83–87, 89–93, 95, 96, 98–100, 103–107, 109–111, 113–115, 117–131, 133, 135–138, 140–142, 144, 146–149, 151–157, 159, 162–164, 166, 168, 169, 171, 173–175] studies asked for the right-hand participants in inclusion criteria.

3.2.5. Emotional State
The psychological assessment on the participants was performed in 4 studies [21, 31, 46, 92, 93]. The self-rating depression scale (SDS) and the self-rating anxiety scale (SAS) were used in 2 studies [31, 46]. The Beck Depression Inventory (BDI) [92] and the State Trait Anxiety Inventory (STAI) [93] were used in 1 study, respectively. Nine studies [19–22, 24, 65, 76, 92, 146] have excluded the participants with claustrophobia.

3.2.6. Accompanying Symptoms
38 studies [11, 13, 15, 21, 31, 36, 42, 43, 46, 54, 57, 64, 65, 68, 73, 76, 78, 81, 87, 93, 100, 102, 104, 106, 110–121, 123, 128, 133, 135, 141, 148, 151, 153, 156, 158, 165, 174] excluded the participants with head trauma, and some studies [24, 46, 54, 73, 100, 121, 122] excluded the participants suffering from pain (including headache and dysmenorrhea).

3.2.7. Acupuncture Experience
81 articles [13–16, 18, 22, 24, 26, 28, 29, 31, 33–35, 37, 38, 42, 51, 54–59, 63, 64, 67, 68, 70, 71, 73, 75, 78, 83, 85–87, 89, 90, 92, 93, 95, 96, 99, 101, 103–106, 108, 111, 113–115, 117–121, 123, 127, 130, 135, 138, 140, 144, 147, 148, 151–153, 156–158, 162, 166–169, 174] described the acupuncture experience of participants. Among these articles, 73 articles [12–16, 18, 22, 28, 29, 31, 33–35, 37, 38, 42, 51, 55, 57–59, 63, 64, 67, 68, 70, 71, 73, 75, 78, 83, 85–87, 89, 90, 93, 95, 96, 99, 101, 103–106, 108, 111, 113–115, 117–121, 123, 127, 130, 135, 138, 140, 144, 147, 148, 151–153, 157, 158, 166–169] described the participants as acupuncture naive.