Table 1.

Summary of behavioral and neural findings examining (a) neural mechanisms of change and (b) predictors of treatment response following pivotal response treatment

Study	Participant demographics	Treatment	Behavioral outcomes	Brain-related functional outcomes
(a) Identifying neural mechanisms of change
Voos et al44	N=2 Child 1: age =5.08 years, GCA* =117 Child 2: age =5.42 years, GCA* =132	8–10 hours PRT in clinic and home setting/week; total 16 weeks	Child 1: Increased instances of initiating requests and questions, making on-topic appropriate comments Child 2: Increased narrative skills and on-topic comments	BIO versus SCR: Child l: ↑ left FG; ↑ left dlPFC Child 2: ↑ right pSTS; ↑ left vlPFC; ↑ right FG; ↑ left FG
Ventola et al38	N=15 (ASD: n=10; TD: n=5) Hyperactive ASD group (n=5): Average age =5.7 years Average GCA* =113.6 Hypoactive ASD group (n=5): Average age =5.3 years Average GCA* =116 TD group (n=5): Average age =6.2 years Average GCA* (n=4) =112	Each child with ASD received a total of 7 hours PRT/week (5 hours of direct intervention; 2 hours of parent training); total 16 weeks TD group included for comparing fMRI responses	At baseline: Hyperactive versus hypoactive symptoms of anxiety and attention deficits (CBCL, CS1-4) Posttreatment: Hyperactive versus hypoactive attention deficits and separation anxiety (CBCL, CSI-4)	BIO versus SCR: Hyperactive: → ↓ to BIO: right pSTS; right AMG; bilateral thalamus; bilateral hippocampus → ↑ to SCR: right pSTS; right AMG; bilateral thalamus; right hippocampus Hypoactive: → ↑ to BIO: right pSTS; right ventral striatum → ↓ to SCR: bilateral ventral striatum
Venkataraman et al39	N=19 Average age =5.87 years Average GCA* =104.53	Each child received a total of 7 hours PRT/week (5 hours of direct intervention; 2 hours of parent training); total 16 weeks	N/A	BIO versus SCR: Changes localized to PCC: ↑ functional connectivity between PCC and regions of the ventral occipital-temporal extrastriate cortex; ↓ functional connectivity between PCC and OFC
(b) Identifying predictors of treatment response
Sherer and Schreibman66	N=6 Responder group (n=3): Average age =3.25 years Nonresponder group (n=3): Average age =4.17 years	Each child received 90 minutes one-on-one PRT 4–5 times/week. Each 90-minute session was broken into three 30-minute intervals, alternating between two playrooms	Responders: → Language: Increase in engagement of appropriate conversation, generalizable to novel settings → Play: All showed highly baseline functional play, no significant overall change over treatment. Increases in symbolic and varied play → Social behaviors: Increased maintenance and initiation of social interactions Nonresponders: → Language: No change in communication skills → Play: Low functional play, symbolic, and varied play at baseline. No changes observed → Social behaviors: No gains in maintenance or imitation of social interactions	N/A
Schreibman et al67	N=6 High-toy-contact group (n=3): Average age =2.2 years Low-social-avoidance group (n=3): Average age =2.89 years	Each child received 18 hours of PRT, followed by DTT. Two subjects received 18 hours of DTT, 4 subjects received 36 hours of DTT Both PRT and DTT were delivered for 3 days/week for 2 hours/day	Toy contact group: → PRT: Gains in both spontaneous and cued vocalizations → DTT: No gains/slight decrease in vocalizations compared to post PRT Social avoidance group: → PRT: Two children showed no gains in cued/spontaneous vocalizations. One child showed gains in both spontaneous and cued vocalizations → DTT: Two children showed no gains in cued/spontaneous vocalizations; one child maintained gains in vocalizations following PRT	N/A
Yang et al40	N=20 Average age =5.9 years Average GCA* =103.45	Each child received a total of 7 hours PRT/week (5 hours of direct intervention; 2 hours of parent training); total 16 weeks	Significant reductions in core ASD symptom severity (decrease in parent-reported SRS-2 total raw score)	BIO versus SCR: Multivariate pattern analysis and cross validation using four identified clusters of interest: 1) Social perception regions: FG, IFG, middle TG, pSTS 2) Social attention network: IFG, superior parietal lobule 3) Emotion regulation/reward processing: OFC, vlPFC, AI, temporal pole 4) Social memory/motivation/reward: pallidum, AMG, hippocampus, ventral striatum

Note:

^*Measured by Differential Abilities Scale.

Abbreviations: GCA, general conceptual ability; PRT, pivotal response treatment; BIO, biological motion; SCR, scrambled motion; FG, fusiform gyrus; dlPFC, dorsolateral prefrontal cortex; pSTS, posterior superior temporal sulcus; vlPFC, ventrolateral prefrontal cortex; ASD, autism spectrum disorder; TD, typically developing; fMRI, functional magnetic resonance imaging; CBCL, Child Behavior Checklist; CSI-4, Child Symptom Inventory – Fourth Revision; AMG, amygdala; PCC, posterior cingulate cortex; OFC, orbitofrontal cortex; DTT, discrete trial training; SRS-2, Social Responsiveness Scale; IFG, inferior frontal gryus; TG, temporal gyrus; AI, anterior insula; N/A, not available.