Songbirds can learn flexible contextual control over syllable sequencing

The interplay between inhibition and excitation can regulate behavioral expression and control, including the expression of communicative behaviors like birdsong. Computational models postulate varying degrees to which inhibition within vocal motor circuitry influences birdsong, but few studies have tested these models by manipulating inhibition. Here we enhanced and attenuated inhibition in the cortical nucleus HVC (used as proper name) of Bengalese finches (Lonchura striata var. domestica). Enhancement of inhibition (with muscimol) in HVC dose-dependently reduced the amount of song produced. Infusions of higher concentrations of muscimol caused some birds to produce spectrally degraded songs, whereas infusions of lower doses of muscimol led to the production of relatively normal (nondegraded) songs. However, the spectral and temporal structures of these nondegraded songs were significantly different from songs produced under control conditions. In particular, muscimol infusions decreased the frequency and amplitude of syllables, increased various measures of acoustic entropy, and increased the variability of syllable structure. Muscimol also increased sequence durations and the variability of syllable timing and syllable sequencing. Attenuation of inhibition (with bicuculline) in HVC led to changes to song distinct from and often opposite to enhancing inhibition. For example, in contrast to muscimol, bicuculline infusions increased syllable amplitude, frequency, and duration and decreased the variability of acoustic features. However, like muscimol, bicuculline increased the variability of syllable sequencing. These data highlight the importance of inhibition to the production of stereotyped vocalizations and demonstrate that changes to neural dynamics within cortical circuitry can differentially affect spectral and temporal features of song.NEW & NOTEWORTHY We reveal that manipulations of inhibition in the cortical nucleus HVC affect the structure, timing, and sequencing of syllables in Bengalese finch song. Enhancing and blocking inhibition led to opposite changes to the acoustic structure and timing of vocalizations, but both caused similar changes to vocal sequencing. These data provide support for computational models of song control but also motivate refinement of existing models to account for differential effects on syllable structure, timing, and sequencing.

The songs of Bengalese finches (Lonchura striata var. domestica) have complex syntax and provide an opportunity to investigate how complex sequential behaviour emerges via the evolutionary process. In this study, we suggest that a simple mechanism, i.e. many-to-one mapping from internal states onto syllables, may underlie the emergence of apparent complex syllable sequences that have higher order history dependencies. We analysed the songs of Bengalese finches and of their wild ancestor, the white-rumped munia (L. striata), whose songs are more stereotypical and simpler compared with those of Bengalese finches. The many-to-one mapping mechanism sufficiently accounted for the differences in the complexity of song syllable sequences of these two strains.

The Bengalese finch produces a set of ordered sequences of syllables. After deafening this song syntax is disrupted, i.e. within days the sequence become randomized and unstable [1]. Interestingly, the normal song syntax is recovered when hearing is restored [2]. Studies have shown that the vocal motor control system of the Bengalese finch rely on real time auditory feedback [3] and that activity in the high vocal center (HVC) is affected by feedback perturbations [4]. This suggests a reafferent model [3] of song syntax generation in which the perception of the bird's own song (BOS) cues the motor system. Here, we present a functional network model of the song syntax generation based on realistic spiking neurons. Neurons are connected in feed-forward structures (synfire chains, SFCs) that can reproduce the neural activity observed in the HVC of the songbird [5]. Individual syllables are represented by the activity propagation throughout distinct SFCs. The auditory perception of the syllables is modeled by activity changes in an auditory network which in turn primes specific subsets of the HVC neurons to obtain the desired song syntax. If the auditory feedback is suppressed random syllable sequences are generated due to the 'winner takes all' competition of individual syllables [6].

The current study aimed to develop a behavior-analytic model of analogical reasoning. In Experiments 1 and 2 subjects (adults and children) were trained and tested for the formation of four, three-member equivalence relations using a delayed matching-to-sample procedure. All subjects (Experiments 1 and 2) were exposed to tests that examined relations between equivalence and non-equivalence relations. For example, on an equivalence-equivalence relation test, the complex sample B1/C1 and the two complex comparisons B3/C3 and B3/C4 were used, and on a nonequivalence-nonequivalence relation test the complex sample B1/C2 was presented with the same two comparisons. All subjects consistently related equivalence relations to equivalence relations and nonequivalence relations to nonequivalence relations (e.g., picked B3/C3 in the presence of B1/C1 and picked B3/C4 in the presence of B1/C2). In Experiment 3, the equivalence responding, the equivalence-equivalence responding, and the nonequivalence-nonequivalence responding was successfully brought under contextual control. Finally, it was shown that the contextual cues could function successfully as comparisons, and the complex samples and comparisons could function successfully as contextual cues and samples, respectively. These data extend the equivalence paradigm and contribute to a behaviour-analytic interpretation of analogical reasoning and complex human functioning, in general.

We proposed a new scheme on automatic annotation and analysis for songs of Bengalese finches, that have variability in terms of syllable sequencing. The scheme annotates songs by using the beta process hidden Markov model, a Bayesian non-parametrics method. The annotation was confirmed to agree to the results by the manual annotation by an expert almost perfectly (0.81–1.00) for songs by three out of four Bengalese finches. Our scheme also analyzed the syntactic rules of the birdsongs and found that the difference of the variations in sequencing of four different birds was accounted for by the difference of tutors, giving a new insight to development of syntax.

Sleep deprivation consistently decreases vigilant attention, which can lead to difficulty in performing a variety of cognitive tasks. However, sleep-deprived individuals may be able to compensate for degraded vigilant attention by means of top-down attentional control. We employed a novel task to measure the degree to which individuals overcome impairments in vigilant attention by using top-down attentional control, the Flexible Attentional Control Task (FACT). The FACT is a two-choice task that has trials with valid, invalid, and neutral cues, along with an unexpected switch in the probability of cue validity about halfway in the task. The task provides indices that isolate performance components reflecting vigilant attention and top-down attentional control. Twelve healthy young adults completed an in-laboratory study. After a baseline day, the subjects underwent 39 hours of total sleep deprivation (TSD), followed by a recovery day. The FACT was administered at 03:00, 11:00, and 19:00 during sleep deprivation (TSD condition) and at 11:00 and 19:00 after baseline sleep and at 11:00 after recovery sleep (rested condition). When rested, the subjects demonstrated both facilitation and interference effects on cued trials. While sleep deprived, the subjects showed vigilant attention deficits on neutral cue trials, and an impaired ability to reduce these deficits by using predictive contextual cues. Our results indicate that the FACT can dissociate vigilant attention from top-down attentional control. Furthermore, they show that during sleep deprivation, contextual cues help individuals to compensate partially for impairments in vigilant attention, but the effectiveness of top-down attentional control is diminished.

Acetylcholine is an important modulator of striatal activity, and it is vital to controlling striatal-dependent behaviors, including motor and cognitive functions. Despite this significance, the mechanisms determining how acetylcholine impacts striatal signaling are still not fully understood. In particular, little is known about the role of nAChRs expressed by striatal interneurons. In the present study, we used FISH to determine which neuronal types express the most prevalent beta2 nicotinic subunit in the mouse striatum. Our data support a common view that nAChR expression is mostly restricted to striatal interneurons. Surprisingly though, cholinergic interneurons were identified as a population with the highest expression of beta2 nicotinic subunit. To investigate the functional significance of beta2-containing nAChRs in striatal interneurons, we deleted them by injecting the AAV-Cre vector into the striatum of beta2-flox/flox male mice. The deletion led to alterations in several behavioral domains, namely, to an increased anxiety-like behavior, decrease in sociability ratio, deficit in discrimination learning, and increased amphetamine-induced hyperlocomotion and c-Fos expression in mice with beta2 deletion. Further colocalization analysis showed that the increased c-Fos expression was present in both medium spiny neurons and presumed striatal interneurons. The present study concludes that, despite being relatively rare, beta2-containing nAChRs are primarily expressed in striatal neurons by cholinergic interneurons and play a significant role in behavior.SIGNIFICANCE STATEMENT A large variety of nAChRs are expressed in the striatum, a brain region that is crucial in the control of behavior. The complexity of receptors with different functions is hindering our understanding of mechanisms through which striatal acetylcholine modulates behavior. We focused on the role of a small population of beta2-containing nAChRs. We identified neuronal types expressing these receptors and determined their impact in the control of explorative behavior, anxiety-like behavior, learning, and sensitivity to stimulants. Additional experiments showed that these alterations were associated with an overall increased activity of striatal neurons. Thus, the small population of nicotinic receptors represents an interesting target for a modulation of response to stimulant drugs and other striatal-based behavior.

While learning frameworks, such as iterative learning control (ILC), offer excellent performance improvements for systems that execute a task repetitively; algorithm constraints have often limited the effectiveness of this approach for applications with non-repetitive system dynamics or trajectories. Systems with slowly varying parameters often behave like time-invariant systems for long periods. However, at a certain point, the drift state will shift enough to impact system performance and render the learned control input invalid. For these systems, the learning process must be reinitiated, leading to production losses in terms of time, money, and part fidelity while the learning controller reoptimizes the input signal. This paper presents a novel learning control strategy that utilizes an interpolated input signal derived from a library of converged signals to reinitiate the learning process for new drift states. In this manner, the controller uses training from a few critical states to inform the optimized initial inputs that span the space of the drift state. The proposed ILC framework is presented here, along with simulation results that illustrate savings in the convergence rate without a loss of performance.

Previous research has suggested that changing the context after instrumental (operant) conditioning can weaken the strength of the operant response. That result contrasts with the results of studies of Pavlovian conditioning, in which a context switch often does not affect the response elicited by a conditioned stimulus. To begin to make the methods more similar, Experiments 1-3 tested the effects of a context switch in rats on a discriminated operant response (R; lever pressing or chain pulling) that had been reinforced only in the presence of a 30-s discriminative stimulus (S; tone or light). As in Pavlovian conditioning, responses and reinforcers became confined to presentations of the S during training. However, in Experiment 1, after training in Context A, a switch to Context B caused a decrement in responding during S. In Experiment 2, a switch to Context B likewise decreased responding in S when Context B was equally familiar, equally associated with reinforcement, or equally associated with the training of a discriminated operant (a different R reinforced in a different S). However, there was no decrement if Context B had been associated with the same response that was trained in Context A (Experiments 2 and 3). The effectiveness of S transferred across contexts, whereas the strength of the response did not. Experiment 4 found that a continuously reinforced response was also disrupted by context change when the same response manipulandum was used in both training and testing. Overall, the results suggest that the context can have a robust general role in the control of operant behavior. Mechanisms of contextual control are discussed.

Contextual control is a key component of behavioral accounts of complex human behavior. Relational contextual cues afford such contextual control, and are routinely established and employed in experimental analyses of relational responding (i.e., responding to one stimulus based on its relationship with another stimulus). Surprisingly, the functional properties of relational contextual cues have not yet been subjected to systematic experimental analysis. Across several pairs of experiments, we investigated these properties, and in each case compared them to the properties of discriminative stimuli because comparisons with a more well studied stimulus property would be informative. Experiment 1 assessed the sensitivity to counterconditioning and reductions in the contingency between cue occurrence and response opportunity. Experiment 2 assessed the impact of three fixed ratio schedules on the acquisition of the function of relational contextual cue. Experiment 3 investigated the impact of higher-order contextual control. Results indicated that relational contextual cues and discriminative stimuli are equally sensitive to counterconditioning, the reinforcement contingency strength, and higher-order contextual control. These results shed new light on the functional properties of relational contextual cues, which has implications for researchers and practitioners designing protocols to establish patterns of relational responding.

<div class="abstract_container"> <strong>Abstract:</strong> The World Wide Web has become a widely available platform for learning with hypermedia. However, WWW hypermedia is often limited in both guidance and navigation support. To improve hypermedia in these aspects, we propose a spatial hypermedia browser for educational purposes. A prototype browser, named HyperMap, has been designed to integrate guided explorative browsing with external control over a learnerís navigation. The flexible control by authors over navigation allows the integration of traditional courseware elements into hypermedia. We explain how the direct manipulation authoring environment in HyperMap simplifies the construction of a curriculum in spatial hypermedia. Object libraries and scripting of adaptive hypermedia objects help a HyperMap author to be productive. We include recent follow-up field-tests at NTU that confirmed the effectiveness of learning with HyperMap spatial hypermedia. The theoretical prospects of further integration of hypermedia with rules for intelligent tutoring are outlined as well.</P> </div> <p class="editors_container"> <strong>Editors:</strong> Gerry Stahl (U. Colorado). <p class="reviewers_container"> <strong>Reviewers:</strong> Chaomei Chen (Brunel U.), Jim Hewitt (OISE, U. Toronto), Timothy Koschmann (Southern Illinois U.), Rogerio dePaula (U. Colorado), Lydia Plowman (Scottish Council for Research in Education), Frank Shipman (Texas A&M U.) <p class="demo_container"> <strong>Interactive elements:</strong> <em>The HyperMap system described in this article is provided as a Java applet</em>. <div class="demo_container d2"> <strong>Interactive demonstrations:</strong> A Java applet of the HyperMap system is embedded in this article (<A HREF="verhoeven-99-1-19.html">Appendix</A>) for which you will need a Java-aware web browser compatible with Sun's JDK 1.1.4 or higher (Internet Explorer 4.0 and Netscape Navigator 4.5 work without difficulty). If you have these, you can try the demo now (<A href="applet/netscape.html" target="hmap-netscape-demo">Netscape 4.5+</A> | <A href="applet/iexplorer.html" target="hmap-explorer-demo">Explorer 4.0+</A>). A local copy of the system can be downloaded for offline execution from the <A HREF="http://members.xoom.com/tverhoeven/">HyperMap site</A>, or from JIME (Mac: <A HREF="JIME-HyperMap-applet.sea">JIME-HyperMap-applet.sea</A> | PC/Unix: <A HREF="JIME-HyperMap-applet.zip">JIME-HyperMap-applet.zip</A>). </div>

Insect pest management is dynamic. Tactics used to manage insect pests may change depending upon the pest species, commodity, season, region, field, or the philosophy of the grower or pest control advisor. Control methods commonly lose effectiveness for one reason or another and new ones are constantly being introduced into agricultural systems. There are various reasons for introducing new methods for controlling pests, to name a few: (1) desire to reduce reliance on insecticides, (2) loss of effective controls (e.g., chemical, biological, cultural) due to selection, (3) desire to minimize hazards to crops, human health, and the environment, and (4) need to maintain flexible and effective control programs that do not rely upon a single management tactic (Johnson 2004). Single tactic (e.g., chemical, biological, cultural, behavioral) control programs always run the risk of eventual failure because of the high potential that insects possess to evolve mechanisms to overcome our control efforts (Johnson 2004) or our inability to predict outcomes in all real life situations. Examples of chemical control failures are quite common (Croft 1990), but failures also occur with other management tactics. The loss of effective biological control due to the application of broad spectrum chemicals is quite common (Johnson and Tabashnik 1999). Less common is the loss of a cultural control, but it does happen as illustrated by the evolution of the corn root-worm, Diabrotica barberi Smith and Lawrence, to overcome annual corn/soybean rotations (Levine and Oloumi-Sadeghi 1991; Levine et al. 1992). Another example is the adaptation of the Hessian fly, Mayetiola destructor (Say), to infest resistant wheat varieties (Kogan 1975). Even behavioral controls may fail given the right circumstances. Attempts to control infestations of peach twig borer, Anarsia lineatella Zeller, on cling peaches when using pheromone mating-disruption techniques may be ineffective if peach orchards are adjacent to large, untreated acreages of infested almonds (Pickel et al. 2002).

A discrete-time formulation of Cartesian-based iterative learning control with input preshaping method is developed in which partial knowledge of the flexible robot kinematic model is utilized. An advantage of this control method in real implementation is that it does not require the derivative of the end-effector's position, i.e. the velocity of the end-effector. From the characteristics and implementation points of view, it appears to be more attractive than existing control schemes. The convergence analysis is particularly addressed.

The mechanisms underlying the transition from acute to chronic pain are unclear but may involve the persistence or strengthening of pain memories acquired in part through associative learning. Contextual cues, which comprise the environment in which events occur, were recently described as a critical regulator of pain memory; both male rodents and humans exhibit increased pain sensitivity in environments recently associated with a single painful experience. It is unknown, however, how repeated exposure to an acute painful unconditioned stimulus in a distinct context modifies pain sensitivity or the expectation of pain in that environment. To answer this question, we conditioned mice to associate distinct contexts with either repeated administration of a mild visceral pain stimulus (intraperitoneal injection of acetic acid) or vehicle injection over the course of 3 days. On the final day of experiments, animals received either an acid injection or vehicle injection prior to being placed into both contexts. In this way, contextual control of pain sensitivity and pain expectation could be tested respectively. When re-exposed to the noxious stimulus in a familiar environment, both male and female mice exhibited context-dependent conditioned analgesia, a phenomenon mediated by endogenous opioid signaling. However, when expecting the presentation of a painful stimulus in a given context, males exhibited conditioned hypersensitivity whereas females exhibited endogenous opioid-mediated conditioned analgesia. These results are evidence that pain perception and engagement of endogenous opioid systems can be modified through their psychological association with environmental cues. Successful determination of the brain circuits involved in this sexually dimorphic anticipatory response may allow for the manipulation of pain memories, which may contribute to the development of chronic pain states.

The control exerted by contextual cues over classically conditioned responding was assessed for rats with electrolytic lesions of the dorsal hippocampus and sham-operated controls. In 3 experiments the rats received initial training with 2 reinforced cues, each presented in its own distinctive context, followed by a nonreinforced test in which the cues were presented in the other context. Both control and operated subjects showed context specificity, as evidenced by less vigorous responding to these cues than to cues presented on test in their original contexts. The groups did not differ in their ability to learn an explicit discrimination in which a given cue was reinforced in one context and nonreinforced in a different context (although the groups did differ on a simple autoshaping task). It is concluded that a special role for the hippocampus in the contextual control of conditioned responding still remains to be demonstrated.