- Effects of neurofeedback therapy in healthy young subjects. [Journal Article]
- CIClin Invest Med 2016 Dec 01; 39(6):27496
- CONCLUSIONS: These results suggest that neurofeedback can be used to restore sympathovagal imbalances. Also, it may be accepted as a preventive therapy for psychological and neurological problems.
- Discrimination of frequency modulated sweeps by mice. [Journal Article]
- JAJ Acoust Soc Am 2016; 140(3):1481
- Mice often produce ultrasonic vocalizations (USVs) that sweep upwards in frequency from around 60 to around 80 kHz and downwards in frequency from 80 to 60 kHz. Whether or not these USVs are used for...
Mice often produce ultrasonic vocalizations (USVs) that sweep upwards in frequency from around 60 to around 80 kHz and downwards in frequency from 80 to 60 kHz. Whether or not these USVs are used for communication purposes is still unknown. Here, mice were trained and tested using operant conditioning procedures and positive reinforcement to discriminate between synthetic upsweeps and downsweeps. The stimuli varied in bandwidth, duration, and direction of sweep. The mice performed significantly worse when discriminating between background and test stimuli when the stimuli all occupied the same bandwidths. Further, the mice's discrimination performance became much worse for stimuli that had durations similar to those natural vocalizations of the mice. Sweeps composed of different frequency ranges and longer durations had improved discrimination. These results collected using artificial stimuli created to mimic natural USVs indicate that the bandwidth of the vocalizations may be much more important for communication than the frequency contours of the vocalizations.
- Human instrumental performance in ratio and interval contingencies: a challenge for associative theory. [Journal Article]
- QJQ J Exp Psychol (Hove) 2016 Nov 29; :1-33
- Associative learning theories regard the probability of reinforcement as the critical factor determining responding. However, the role of this factor in instrumental conditioning is not completely cl...
Associative learning theories regard the probability of reinforcement as the critical factor determining responding. However, the role of this factor in instrumental conditioning is not completely clear. In fact, a wealth of evidence from instrumental free-operant experiments has shown that participants respond at a higher rate on variable ratio than on variable interval schedules even though the reinforcement probability on the interval schedule is the same as or greater than that on the ratio schedule. This difference has been attributed to the differential reinforcement of long inter-response times (IRT) by interval schedules, which acts to slow responding. In the present study, we used a novel experimental design to investigate human responding under random ratio (RR) and regulated probability interval (RPI) schedules, a type of interval schedule that sets a reinforcement probability independently of the IRT duration. We trained participants separately on each type of schedule before a final choice test in which they distributed responding between two schedules similar to those experienced during training. Although response rates on the various schedules did not differ reliably during training, the participants responded at a lower rate on the RPI schedule than on the matched RR schedule during the choice test. This preference cannot be attributed to a higher probability of reinforcement for long IRTs and questions the idea that similar associative processes underlie instrumental and classical conditioning.
- Reducing spontaneous recovery and reinstatement of operant performance through extinction-cues. [Journal Article]
- BPBehav Processes 2016 Nov 23; 135:1-7
- It has been argued that the response recovery effects share a common mechanism. A possible way to test it is evaluating whether the techniques that impaired renewal would impair the other recovery ef...
It has been argued that the response recovery effects share a common mechanism. A possible way to test it is evaluating whether the techniques that impaired renewal would impair the other recovery effects as well. Two experiments with rats used a free operant procedure to explore whether an extinction-cue could prevent the spontaneous recovery and reinstatement of an extinguished lever-pressing. Both experiments consisted of four phases: Acquisition, Extinction and Test 1 and Test 2. First, all rats were trained to perform one instrumental response (R1) for food in context A, and a different instrumental response (R2) for food in context B. Then, responses were extinguished within the same context: R1 in context A and R2 in context B. Throughout this phase all rats received brief presentations of a tone (extinction-cue). In both experiments animals were tested twice. The first test was conducted immediately after the last extinction session. In this test, rats received the extinction-cue for both responses. During the second test, rats experienced the tone only for R1. In Experiment 1 rats were tested after 5days, while for Experiment 2 test 2 took place after a single session of re-exposure to the food. Both experiments showed a recovery effect (spontaneous recovery in Experiment 1 and reinstatement in Experiment 2) for both responses. However, a cue featured in extinction attenuated recovery of R1 in both experiments when presented on the test. The findings suggest that spontaneous recovery, reinstatement and renewal might share a common mechanism. In addition, the present data shows that using an extinction-cue could help to reduces relapsing of voluntary behaviors.
- A Cognitive Model Based on Neuromodulated Plasticity. [Journal Article]
- CIComput Intell Neurosci 2016; 2016:4296356
- Associative learning, including classical conditioning and operant conditioning, is regarded as the most fundamental type of learning for animals and human beings. Many models have been proposed surr...
Associative learning, including classical conditioning and operant conditioning, is regarded as the most fundamental type of learning for animals and human beings. Many models have been proposed surrounding classical conditioning or operant conditioning. However, a unified and integrated model to explain the two types of conditioning is much less studied. Here, a model based on neuromodulated synaptic plasticity is presented. The model is bioinspired including multistored memory module and simulated VTA dopaminergic neurons to produce reward signal. The synaptic weights are modified according to the reward signal, which simulates the change of associative strengths in associative learning. The experiment results in real robots prove the suitability and validity of the proposed model.
- Functional states of rat cortical circuits during the unpredictable availability of a reward-related cue. [Journal Article]
- SRSci Rep 2016 Nov 21; 6:37650
- Proper performance of acquired abilities can be disturbed by the unexpected occurrence of external changes. Rats trained with an operant conditioning task (to press a lever in order to obtain a food ...
Proper performance of acquired abilities can be disturbed by the unexpected occurrence of external changes. Rats trained with an operant conditioning task (to press a lever in order to obtain a food pellet) using a fixed-ratio (1:1) schedule were subsequently placed in a Skinner box in which the lever could be removed randomly. Field postsynaptic potentials (fPSPs) were chronically evoked in perforant pathway-hippocampal CA1 (PP-CA1), CA1-subiculum (CA1-SUB), CA1-medial prefrontal cortex (CA1-mPFC), mPFC-nucleus accumbens (mPFC-NAc), and mPFC-basolateral amygdala (mPFC-BLA) synapses during lever IN and lever OUT situations. While lever presses were accompanied by a significant increase in fPSP slopes at the five synapses, the unpredictable absence of the lever were accompanied by decreased fPSP slopes in all, except PP-CA1 synapses. Spectral analysis of local field potentials (LFPs) recorded when the animal approached the corresponding area in the lever OUT situation presented lower spectral powers than during lever IN occasions for all recording sites, apart from CA1. Thus, the unpredictable availability of a reward-related cue modified the activity of cortical and subcortical areas related with the acquisition of operant learning tasks, suggesting an immediate functional reorganization of these neural circuits to address the changed situation and to modify ongoing behaviors accordingly.
- Dopamine D2L Receptor Is Required for Visual Discrimination and Reversal Learning. [Journal Article]
- MNMol Neuropsychiatry 2016; 2(3):124-132
- The corticostriatothalamic circuit regulates learning behaviors via dopamine neurotransmission. D2 long (D2L) receptors are an isoform of dopamine D2 receptors (D2Rs) and may act mainly at postsynapt...
The corticostriatothalamic circuit regulates learning behaviors via dopamine neurotransmission. D2 long (D2L) receptors are an isoform of dopamine D2 receptors (D2Rs) and may act mainly at postsynaptic sites. It is well known that D2Rs influence high brain functions, but the roles of individual D2R isoforms are still unclear. To assess the influence of D2L receptors in visual discrimination learning, we performed visual discrimination and reversal tasks with D2L knockout mice using a touchscreen operant system. There were no significant differences in an operant conditioning task between genotypes. However, D2L knockout mice were impaired in both visual discrimination and reversal learning tasks. D2L knockout mice were also significantly slower than wild-type mice in collecting the reward in the visual discrimination task. These results indicate that D2L receptors play an important role in visual discrimination and reversal learning.
- Kissing bugs can generalize and discriminate between different bitter compounds. [Journal Article]
- JPJ Physiol Paris 2016 Nov 16
- Animals make use of contact chemoreception structures to examine the quality of potential food sources. During this evaluation they can detect nutritious compounds that promote feeding and recognize ...
Animals make use of contact chemoreception structures to examine the quality of potential food sources. During this evaluation they can detect nutritious compounds that promote feeding and recognize toxins that trigger evasive behaviors. Although animals can easily distinguish between stimuli of different gustatory qualities (bitter, salty, sweet, etc.), their ability to discriminate between compounds of the same quality may be limited. Numerous plants produce alkaloids, compounds that elicit aversive behaviors in phytophagous insects and almost uniformly evoke a bitter taste for man. In hematophagous insects, however, the effect of feeding deterrent molecules has been barely studied. Recent studies showed that feeding in Rhodnius prolixus can be negatively modulated by the presence of alkaloids such as quinine (QUI) and caffeine (CAF), compounds that elicit similar aversive responses. Here, we applied associative and non-associative learning paradigms to examine under two behavioral contexts the ability of R. prolixus to distinguish, discriminate and/or generalize between these two bitter compounds, QUI and CAF. Our results show that bugs innately repelled by bitter compounds can change their behavior from avoidance to indifference or even to preference according to their previous experiences. After an aversive operant conditioning with QUI or CAF, R. prolixus modified its behavior in a direct but also in a cross-compound manner, suggesting the occurrence of a generalization process between these two alkaloids. Conversely, after a long pre-exposure to each alkaloid, bugs decreased their avoidance to the compound used during pre-exposure but still expressed an avoidance of the novel compound, proving that QUI and CAF are detected separately. Our results suggest that R. prolixus is able to discriminate between QUI and CAF, although after an associative conditioning they express a symmetrical cross-generalization. This kind of studies adds insight into the gustatory sense of a blood-sucking model but also into the learning abilities of hematophagous insects.
- Dietary 2'-Fucosyllactose Enhances Operant Conditioning and Long-Term Potentiation via Gut-Brain Communication through the Vagus Nerve in Rodents. [Journal Article]
- PlosPLoS One 2016; 11(11):e0166070
- 2´-fucosyllactose (2´-FL) is an abundant human milk oligosaccharide (HMO) in human milk with diverse biological effects. We recently reported ingested 2´-FL stimulates central nervous system (CNS) fu...
2´-fucosyllactose (2´-FL) is an abundant human milk oligosaccharide (HMO) in human milk with diverse biological effects. We recently reported ingested 2´-FL stimulates central nervous system (CNS) function, such as hippocampal long term potentiation (LTP) and learning and memory in rats. Conceivably the effect of 2´-FL on CNS function may be via the gut-brain axis (GBA), specifically the vagus nerve, and L-fucose (Fuc) may play a role. This study had two aims: (1) determine if the effect of ingested 2´-FL on the modulation of CNS function is dependent on the integrity of the molecule; and (2) confirm if oral 2´-FL modified hippocampal LTP and associative learning related skills in rats submitted to bilateral subdiaphragmatic vagotomy. Results showed that 2´-FL but not Fuc enhanced LTP, and vagotomy inhibited the effects of oral 2´-FL on LTP and associative learning related paradigms. Taken together, the data show that dietary 2´-FL but not its Fuc moiety affects cognitive domains and improves learning and memory in rats. This effect is dependent on vagus nerve integrity, suggesting GBA plays a role in 2´-FL-mediated cognitive benefits.
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- Augmentation of Heroin Seeking Following Chronic Food Restriction in the Rat: Differential Role for Dopamine Transmission in the Nucleus Accumbens Shell and Core. [Journal Article]
- NNeuropsychopharmacology 2016 Nov 08
- Caloric restriction during drug abstinence increases the risk for relapse in addicts. In rats, chronic food restriction during a period of withdrawal following heroin self-administration augments her...
Caloric restriction during drug abstinence increases the risk for relapse in addicts. In rats, chronic food restriction during a period of withdrawal following heroin self-administration augments heroin seeking. The mechanisms underlying this effect are largely unknown. Here, we investigated the role of nucleus accumbens (NAc) shell and core dopamine (DA) in food restriction-induced augmentation of heroin seeking. Rats were trained to self-administer heroin (0.1 mg/kg/infusion) for 10 days. Next, rats were moved to the animal colony for a withdrawal period, during which rats were food restricted to 90% of their original body weight (FDR group) or given unrestricted access to food (sated group). On day 14 of food restriction, rats were returned to the operant conditioning chambers for a heroin-seeking test under extinction conditions. Extracellular DA levels were assessed using in vivo microdialysis. In separate experiments, the DA D1-like receptor antagonist SCH39166 (12.5, 25.0, or 50.0 ng/side) was administered into the NAc prior to the heroin-seeking test. In the NAc shell, pre-test exposure to the heroin-associated context increased DA only in FDR rats; but in the NAc core, DA increased regardless of feeding condition. Food restriction significantly augmented heroin seeking and increased DA in the NAc shell and core during the test. Intra-NAc shell administration of SCH39166 decreased heroin seeking in all rats. In contrast, in the NAc core, SCH39166 selectively decreased the augmentation of heroin seeking induced by chronic food restriction. Taken together, these results suggest that activation of the DA D1-like receptor in the NAc core is important for food restriction-induced augmentation of heroin seeking.Neuropsychopharmacology accepted article preview online, 08 November 2016. doi:10.1038/npp.2016.250.