Two experiments were run to demonstrate the presence of a partial reinforcement extinction effect (PREE) and a partial punishment effect (PPE) 4 weeks after training in a 1-trial/day procedure. In the PREE paradigm, two groups of animals were trained to run a straight alley for food reward; one group was rewarded on every trial (CRF), whereas the other was rewarded on only 50% of the trials (PRF). In the test phase, extinction, no reward was present on any trial. Four weeks (...) after the end of acquisition, and subsequent to 7 days of CRF retraining, PRF animals showed greater resistance to extinction than did their CRF controls. The PPE paradigm resembled the PREE paradigm in all aspects, except that mild electric foot shock, together with the food reward, was used instead of nonreward on 50% of the acquisition trials. In the test phase, all animals were shocked and given a food reward on every trial. Four weeks after the end of acquisition and retraining, the animals with previous experience of shock in acquisition showed greater resistance to punishment than did their controls. (shrink)

Macphail’s (1985) null hypothesis challenged researchers to demonstrate any differences in intelligence between vertebrate species. Rather than focus on differences, we asked whether rats would show the same unexpected, counterintuitive features of skill learning observed in humans: Factors that degrade performance during acquisition often enhance performance in a subsequent retention/autonomy phase. Providing post-trial “knowledge of results” (KR) on 30%-67% of trials instead of 100% degrades accuracy, yet increases retention in a subsequent phase without KR. We tested this feature by (...) providing three groups of rats with KR on every trial (100% KR), 67% KR, or 0% KR. We also provided operant feedback in every trial for completing the left-right lever-press skill (food for correct sequences, timeout for all others). In the autonomy phase, we assessed their ability to complete the skill independently—in the absence of differential cues and KR feedback. In agreement with human performance in the autonomy phase, 67% KR yielded higher skill accuracy than providing 100% KR. Also, providing 67% KR improved skill accuracy above that observed with operant feedback alone (0% KR). Rather than degrading performance during acquisition, the 67% KR condition yielded unexpected higher accuracy than the other conditions. Accuracy increased systematically across our extended acquisition phase, which provided each rat with over 3600 trials compared to 20-30 trials for human studies. Providing limited KR promoted skill learning in rats as it does in humans, consistent with the conjecture that both species share common learning processes. Introducing difficulties to rats during training improved their autonomy. (shrink)

Prevailing theories of the neural basis of at least a subset of individuals with autism spectrum disorder include an imbalance of excitatory and inhibitory neurotransmission. These circuitry imbalances are commonly probed in adults using auditory steady-state responses to elicit coherent electrophysiological responses from intact circuitry. Challenges to the ASSR methodology occur during development, where the optimal ASSR driving frequency may be unknown. An alternative approach is the amplitude-modulated sweep in which the amplitude of a tone is modulated as a (...) sweep from 10 to 100 Hz over the course of ∼15 s. Phase synchrony of evoked responses, measured via intra-trial coherence, is recorded as a function of frequency. We applied such AM sweep stimuli bilaterally to 40 typically developing and 80 children with ASD, aged 6–18 years. Diagnoses were confirmed by DSM-5 criteria as well as autism diagnostic observation schedule observational assessment. Stimuli were presented binaurally during MEG recording and consisted of 20 AM swept stimuli with a duration of ∼30 s each. Peak intra-trial coherence values and peak response frequencies of source modeled responses were examined. First, the phase synchrony or inter-trial coherence of the ASSR is diminished in ASD; second, hemispheric bias in the ASSR, observed in typical development, is maintained in ASD, and third, that the frequency at which the peak response is obtained varies on an individual basis, in part dependent on age, and with altered developmental trajectories in ASD vs. TD. Finally, there appears an association between auditory steady-state phase synchrony and clinical assessment of language ability/impairment. We concluded that the AM sweep stimulus provides a mechanism for probing ASSR in an unbiased fashion, during developmental maturation of peak response frequency, peak frequencies vary, in part due to developmental age, and importantly, ITC at this peak frequency is diminished in ASD, with the degree of ITC disturbance related to clinically assessed language impairment. (shrink)