Adaptation and Selective Information Transmission in the Cricket Auditory Neuron AN2

Sensory systems adapt their neural code to changes in the sensory environment, often on multiple time scales. Here, we report a new form of adaptation in a first-order auditory interneuron (AN2) of crickets. We characterize the response of the AN2 neuron to amplitude-modulated sound stimuli and find that adaptation shifts the stimulus–response curves toward higher stimulus intensities, with a time constant of 1.5 s for adaptation and recovery. The spike responses were thus reduced for low-intensity sounds. We then address the question whether adaptation leads to an improvement of the signal's representation and compare the experimental results with the predictions of two competing hypotheses: infomax, which predicts that information conveyed about the entire signal range should be maximized, and selective coding, which predicts that “foreground” signals should be enhanced while “background” signals should be selectively suppressed. We test how adaptation changes the input–response curve when presenting signals with two or three peaks in their amplitude distributions, for which selective coding and infomax predict conflicting changes. By means of Bayesian data analysis, we quantify the shifts of the measured response curves and also find a slight reduction of their slopes. These decreases in slopes are smaller, and the absolute response thresholds are higher than those predicted by infomax. Most remarkably, and in contrast to the infomax principle, adaptation actually reduces the amount of encoded information when considering the whole range of input signals. The response curve changes are also not consistent with the selective coding hypothesis, because the amount of information conveyed about the loudest part of the signal does not increase as predicted but remains nearly constant. Less information is transmitted about signals with lower intensity

Does General Parenting Context Modify Adolescents' Appraisals and Coping with a Situation of Parental Regulation? The Case of Autonomy-Supportive Parenting

Theory and research suggest that adolescents differ in their appraisals and coping reactions in response to parental regulation. Less is known, however, about factors that determine these differences in adolescents’ responses. In this study, we examined whether adolescents' appraisals and coping reactions depend upon parents’ situation-specific autonomy-supportive or controlling communication style (i.e., the situation) in interaction with adolescents’ past experiences with general autonomy-supportive parenting (i.e., the parenting context). Whereas in Study 1 (N = 176) adolescents’ perceived general autonomy-supportive parenting context was assessed at one point in time, in Study 2 (N = 126) it was assessed multiple times across a 6-year period, allowing for an estimation of trajectories of perceived autonomy-supportive parenting context. In each study, adolescents read a vignette-based scenario depicting a situation of maternal regulation (i.e., a request to study more), which was communicated in either an autonomy-supportive or a controlling way. Following this scenario, they reported upon their appraisals and their anticipated coping reactions. Results of each study indicated that both the autonomy-supportive (relative to the controlling) situation and the perceived autonomy-supportive parenting context generally related to more positive appraisals (i.e., more autonomy need satisfaction, less autonomy need frustration), as well as to more constructive coping responses (i.e., less oppositional defiance and submission, more negotiation and accommodation). In addition, situation × context interactions were found, whereby adolescents growing up in a more autonomy-supportive context seemed to derive greater benefits from the exposure to an autonomy-supportive situation and reacted more constructively to a controlling situation

Changes of synaptic efficacy in the medial geniculate nucleus as a result of auditory classical conditioning

In this study we examined inputs to neurons in the medial subnucleus of the medial geniculate nucleus (mMG) for changes of synaptic efficacy associated with heart-rate conditioning to an auditory conditioned stimulus (CS). Conditioning-related changes of synaptic efficacy were measured in awake animals by examining mMG single-unit responses evoked by stimulation of one of two areas that send auditory CS and nonauditory information monosynaptically to the mMG, the brachium of the inferior colliculus (BlC) and the superior colliculus (SC). Synaptic efficacy was measured before, immediately after, and 1 hr after one session of classical conditioning with a tone CS and a corneal airpuff unconditioned stimulus. To determine whether conditioning produced changes of synaptic efficacy on the auditory BlC inputs to mMG cells and not general changes of cellular excitability, analyses of synaptic efficacy were performed on the mMG units that exhibited short-latency evoked responses (< 3.5 msec) to both BlC and SC stimulation. Analyses revealed that the BlC but not the SC test stimulus-evoked unit activity from the same neurons exhibited the following changes immediately after conditioning: decreases in unit response latency, increases in unit response reliability, and increases in spike frequency. BlC-evoked unit responses after pseudoconditioning did not exhibit these changes in unit responding. These results suggest that the synapses carrying auditory CS information to mMG neurons increase in strength as the result of associative conditioning with an acoustic CS. Some of these changes of synaptic efficacy remained 1 hr after training