Generalization of secondary reinforcement in discrimination learning.
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Discrimination Learning↗
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Configural associations in discrimination learning.
In 4 experiments, Sprague-Dawley rats and homing pigeons received training with an A+ AB0 BC+ discrimination, in which food (+) accompanied trials with A and BC. Food was not presented (0) on trials with the compound AB. Subsequent test trials revealed that responding during C by itself, or the compound ABC, was slower than during either A or BC. Responding during the ABC compound was also found to be slower after training with the A+ AB0 BC+ than an A0 AB+ BC+ discrimination. We argue that these findings demonstrate the importance of configural associations in discrimination learning. Two accounts for the way in which these associations exert their influence are considered.
Animals↗
Conditional discrimination learning and negative patterning in rats with neonatal hippocampal lesion induced by ionizing radiation.
This study was undertaken to investigate the associative process underlying serial feature positive conditional discrimination learning (X-->A+/A-) and the role of the hippocampus in the solution of tasks demanding a configural association strategy such as the negative patterning discrimination (XA-/X+/A+). It has been suggested that the hippocampus is essential for the learning of complex tasks, so, it is expected that hippocampal lesions would prove equally detrimental to performance in both tasks, but would not interfere with simple discrimination learning. Hippocampal lesions were made with X-radiation exposure to neonate rats after completion of a parametric study 'J. Neurosci. Methods 75 (1997) 41' that established the best radiation parameters to selectively lesion the hippocampal dentate gyrus. When adults, rats were submitted to a serial feature positive conditional discrimination task with the trials 'House light/Tone: water (H-->T+)', 'Tone: no water (T-)', and two simple discrimination with the trials 'Clicker: water (C+)' and 'Noise: no water (N-)' in Experiment I. In Experiment II, adult rats, irradiated and control, were submitted to the negative patterning task with the trials 'House light/Tone: no water (HT-)', 'House light: water (H+)', 'Tone: water (T+)', and to the non-conditional discrimination with the trial Noise: no water (N-)'. In contrast to the expectation of impaired performance in these tasks by lesioned rats, animals with damage to the hippocampal dentate gyrus learned the complex and the simple tasks as well as control subjects. These results suggest that the dentate gyrus does not participate directly in the modulation of acquisition of tasks demanding a complex strategy of occasion setting in procedures of serial conditional discrimination or a configural strategy, important for the negative patterning discrimination solution.
Age Factors↗
WAVELENGTH GENERALIZATION AFTER DISCRIMINATION LEARNING WITH AND WITHOUT ERRORS.
Pigeons were trained to discriminate between 580 mk (S+) and 540 mmicro (S-) by procedures which resulted in either a large amount of responding to S-or in little or no responding to S-. A shift in the peak of a postdiscrimination generalization gradient, away from S-, was obtained only if the discrimination was learned with a large amount of responding to S-.
Animals↗
Visual discrimination learning in dwarf goats and associated changes in heart rate and heart rate variability.
We studied visual discrimination learning in a group of Nigerian dwarf goats using a computer-based learning device which was integrated in the animals' home pen. We conducted three consecutive learning tasks (T1, T2 and T3), each of which lasted for 13 days. In each task, a different set of four visual stimuli was presented on a computer screen in a four-choice design. Predefined sequences of stimulus combinations were presented in a pseudorandom order. Animals were rewarded with drinking water when they chose the positive stimulus by pressing a button next to it. Noninvasive measurements of goats' heartbeat intervals were carried out on the first and the last 2 days of each learning task. We analysed heart rate (HR) and heart rate variability (HRV) of resting animals to study sustained physiological effects related to general learning challenge rather than acute excitement during an actual learning session. The number of trials to reach the learning criterion was 1000 in T1, when visual stimuli were presented to the goats for the first time, but decreased to 210 in T2 and 240 in T3, respectively. A stable plateau of correct choices between 70% and 80% was reached on Day 10 in T1, on Day 8 in T2 and on Day 6 in T3. We found a significant influence of the task and of the interaction between task and day on learning success. Whereas HR increased throughout T1, this relationship was inverted in T2 and T3, indicating different effects on the HR depending on how familiar goats were with the learning task. We found a significant influence of the task and the interaction between task and time within the task on HRV parameters, indicating changes of vagal activity at the heart. The results suggest that changes in HR related to learning were predominantly caused by a withdrawal of vagal activity at the heart. With regard to nonlinear processes in heartbeat regulation, increased deterministic shares of HRV indicated that the animals did not really relax until the end of T3. Comparing changes of HR and HRV in T3 and in a subsequent postexperiment (PE), we assume a positive effect of such cognitive challenges once the task had been learned by the animals.
Animals↗
Fornix damage enhances successive, but not simultaneous, object-discrimination learning in cats.
The purpose of this study was to compare the effects of fornix lesions with the deficits known to follow septum lesions in cats learning visual object discriminations. In Experiment 1 when eight cats with aspiration lesions of the fornix performed successive discrimination problems, acquisition was greatly facilitated, but first- and second-reversal scores were normal by comparison with eight normal cats and two operated corpus callosum-control cats without fornix damage. Four corpus callosum-damaged cats with secondary degeneration in the medial fornix also learned the initial problem faster than normals. In Experiment 2 in a simultaneous paradigm, eight cats with fornix lesions scored like five normal controls, although they perseverated in early stages of reversal problems. The authors hypothesize that medial fornix damage, in contrast with septum lesions, enhances both initiation and maintenance of response inhibition.
Afferent Pathways↗
The contribution of within-session averaging of drug- and vehicle-appropriate responding to the graded dose-response function in drug discrimination learning.
Prior work within the taste aversion baseline of drug discrimination learning has demonstrated that the generalization function for individual rats is graded in nature. In such work, intermediate doses of the training drug produced intermediate levels of drug-appropriate responding. Under some conditions, such graded responding has been reported to be due to an averaging of quantal drug- and vehicle-appropriate responding at different periods within the session. The present experiment assessed the contribution of such averaging to the graded responding within the aversion design. Rats were first trained to discriminate either 1mg/kg naloxone or 10mg/kg pentobarbital from distilled water. They were then administered various doses of the training drug (or a different drug), and the within-session pattern of licking was monitored minute by minute over the 20min session. Responding within the session was primarily either drug- or vehicle-appropriate. The specific pattern of drug- or vehicle-appropriate responding was presumably dependent upon the onset and/or offset of the drug stimulus. Thus, for the aversion baseline the graded response function for individual rats appears to be a function of the within session averaging of quantal (either drug- or vehicle-appropriate) responding.
Journal Article↗
Operant discriminative learning and evidence of subtelencephalic plastic changes after long-term detelencephalation in pigeons.
We analyzed operant discrimination in detelencephalated pigeons and neuroanatomical substrates after long-term detelencephalation. In Experiment I, experimental pigeons with massive telencephalic ablation and control pigeons were conditioned to key peck for food. Successive discrimination was made under alternating red (variable-ratio reinforcement) and yellow (extinction) lights in one key of the chamber. These relations were interchanged during reversal discrimination. The sessions were run until steady-state rates were achieved. Experiment II analyzed the morphology of the nucleus rotundus and optic tectum in long-term detelencephalated and control birds, using a Klüver-Barrera staining and image analyzer system. Detelencephalated birds had more training sessions for response shaping and steady-state behavior (p < 0.001), higher red key peck rates during discrimination (p < 0.01), and reversal discrimination indexes around 0.50. Morphometric analysis revealed a decreased number of neurons and increased vascularity, associated with increases in the perimeter (p < 0.001) in the nucleus rotundus. In the optic tectum, increases in the perimeter (p < 0.05) associated with disorganization in the layers arrangement were seen. The data indicate that telencephalic systems might have an essential function in reversal operant discrimination learning. The structural characteristics of subtelencephalic systems after long-term detelencephalation evidence plastic changes that might be related to functional mechanisms of learning and neural plasticity in pigeons.
Animals↗
Temporal discrimination learning of operant feeding in goldfish (Carassius auratus).
Operant temporal discrimination learning was investigated in goldfish. In the first experiment, there was a fixed daily change in illumination. Eight subjects were trained to operate a lever that reinforced each press with food. The period during which responses were reinforced was then progressively reduced until it was 1 hr in every 24. The final 1-hr feeding schedule was maintained over 4 weeks. The feeding period commenced at the same time each day throughout. The food dispensers were then made inactive, and a period of extinction ensued for 6 days. The pattern of responding suggested that the fish were able to exhibit temporal discrimination in anticipation of feeding time. This pattern of responding persisted for a limited number of days during the extinction procedure. The second experiment produced evidence that operant temporal discrimination could develop under continuous illumination.
Journal Article↗
Visual discrimination learning in binocularly deprived cats: 20 years of studies in the Nencki Institute.
Data obtained by the author and his colleagues on various forms of visual discrimination learning in cats binocularly deprived of pattern vision with cloth masks (BD cats) are reviewed. In these studies two comparison groups were used: controls reared also in the laboratory but with open eyes (C cats) and cats reared in normal environment outside the laboratory (N cats). Data from other laboratories on lid-sutured and dark-reared BD cats are also shortly reviewed. The BD cats showed several clear-cut deficits. Those in pattern discrimination and in fine contrast discrimination were presumably mainly due to impairment of the perceptual inhibitory learning, whereas those in coping with the partition in the apparatus and in successive discrimination were due to impairment of associative inhibitory learning. The deficits in object discrimination and in interocular transfer were apparently due to a reduced number of binocular neurons in the deprived visual cortex and superior colliculi. Dramatic deficit in relearning after ablation of the superior colliculi-pretectum complex shows a reduced utilization of the abnormal cortex in discrimination learning. The C cats shared fully with BD cats a dramatic impairment in the visually delayed response. This short-term memory deficit was presumably due to a limited practice in visual learning in cage-reared cats. The C cats showed also some impairment in coping with the partition and in relearning after the colliculus-pretectum ablation. The BD cats were not impaired in pattern vs. no-pattern discrimination and in grating discrimination. Thus, visual deprivation does not impair the formation of excitatory and simple inhibitory connections required in crude discrimination. Moreover, presumably due to their less distractibility by external stimuli, the BD cats could be even superior to N and C cats in very crude discrimination tasks.
Animals↗
Inhibitory stimulus control following errorless discrimination learning.
Three generalization procedures were used to investigate inhibitory stimulus control following discrimination learning with few errors. Three groups of pigeons acquired a discrimination between a green stimulus (the positive stimulus) and a vertical or horizontal line (the negative stimulus) through differential autoshaping followed by multiple schedule presentation of the two stimuli with gradually increasing stimulus durations. Genereralization testing was along a line-tilt continuum. For one group, the test involved a resistance-to-reinforcement procedure in which responses to all line tilts were reinforced on a variable-interval schedule. For a second group, also tested with the resistance-to-reinforcement procedure, the lines were superimposed on the green field that formerly served as the positive stimulus. A third group was tested in extinction with the combined stimuli. Control groups had no discrimination training but responding to green was nondifferentially reinforced. The control subjects responded more to all line tilts during testing than did the comparable experimental subjects, indicating that the negative stimulus had become an inhibitory stimulus. Both resistance-to-reinforcement groups revealed inhibitory gradients around the negative stimulus, but the gradient for the extinction group was relatively flat. These data are consistent with others that modify Terrace's early conclusion concerning the failure of inhibition to develop during errorless training.
Journal Article↗
Extinction and renewal of Pavlovian modulation in human sequential Feature Positive discrimination learning.
Using a conditioned suppression task, we investigated extinction and renewal of Pavlovian modulation in human sequential Feature Positive (FP) discrimination learning. In Experiment 1, in context a participants were first trained on two FP discriminations, X-->A+/A- and Y-->B+/B-. Extinction treatment was administered in the acquisition context a (aaa group) or in a new context b (aba group), and comprised X-->A- extinction and Y- control trials. Discriminative X-->A/A responding was lost in both groups when tested in the extinction context, but partially recovered in the aba and not in the aaa group when tested in the acquisition context, suggesting extinction and renewal of extinguished modulation. The same was observed for the Y-->B/B control pair, however, questioning whether the loss of discriminative X-->A/A responding represented genuine extinction of modulation. In Experiment 2, including only aba groups, participants were trained in context a on two FP discriminations, X-->A+/A- and Y-->B+/B-, after which the group "Extinction" was exposed to X-->A- extinction trials in context b, whereas the group "Control" was exposed to X- control trials; concurrently, both groups received further Y-->B+/B- training. In the group Control, differential Y-->B/B and X-->A/A responding were acquired and maintained throughout the experiment. In the group Extinction, while Y-->B/B responding was also maintained throughout, differential X-->A/A responding disappeared because of X-->A- extinction treatment when tested in the extinction context b, but partially reappeared when tested in the acquisition context a. This evidences aba-renewal of extinguished modulation.
Adolescent↗
Acetylcholine in the hippocampus during the discrimination learning performance in a rat model of chronic cerebral ischaemia.
Acetylcholine (ACh) release in the hippocampus of Wistar strain rats with permanent bilateral occlusion of the common carotid arteries was examined during a discrimination learning task using a microdialysis method. Such occlusion resulted in obvious impairment of the discrimination performance. The state, the basal value and released patterns, of ACh in the hippocampus differed in the sham-operated control and the experimental group, while ACh release was elevated during the dialysis experiment in both groups. These findings suggested that the bilateral occlusion produced persistent learning deficits from an early stage after the operation and that the impaired discrimination learning performance might be related to the diffusion of ACh in the hippocampus.
Acetylcholine↗
Delta opioid discrimination learning in the rat: assessment with the selective delta agonist SNC80.
The majority of reports assessing opioid drug discrimination learning (DDL) have concentrated on characterizing the stimulus properties of compounds selective for mu and kappa opioid receptors. Assessments of delta opioid DDL have been limited and, to date, these assessments have been restricted to the monkey and pigeon. No assessment of delta stimulus control has been examined in rodents. To that end, the present experiment examined discriminative control by the selective delta agonist SNC80 in rats and its generalization to and antagonism by compounds relatively selective to the delta and mu receptor subtypes using the conditioned taste aversion baseline of DDL. Animals injected with 5.6 mg/kg of SNC80 prior to a saccharin-LiCl pairing and with the SNC80 vehicle prior to saccharin alone acquired the discrimination within seven conditioning cycles. The discriminative effects of SNC80 were maximal at 20 min, partial at 120 min, and lost at 240 min. The discrimination was dose dependent in that as the dose of SNC80 increased, the amount of saccharin consumed decreased. In subsequent generalization tests, the delta agonist SNC162 produced SNC80-appropriate responding at a dose of 18 mg/kg. Conversely, the mu agonist morphine produced vehicle-appropriate responding at all doses tested. These selective generalization patterns with SNC162 and morphine suggest that the discriminative effects of SNC80 are mediated at the delta, but not the mu, receptor, a conclusion supported by the fact that SNC80's discriminative control was completely blocked by the delta-selective antagonist NTI, but not by the mu-selective antagonist naltrexone. The present findings indicate that not only do rats readily discriminate both mu- and kappa-selective agonists from their respective vehicles, but they also discriminate compounds that are selective for the delta receptor subtype, thus extending the class of compounds that can serve such discriminative functions for the rat.
Animals↗
Septo-hippocampal cholinergic system under the discrimination learning task in the rat: a microdialysis study with the dual-probe approach.
To investigate regulation of the septo-hippocampal cholinergic system by dopaminergic inputs to the septum in rats which performed a discrimination learning task, an in vivo microdialysis method with the dual-probe approach was used. Rats were trained to discriminate between lamp-on and -off states under an operant-type learning procedure. After stable discriminative behavior was established, dialysis probes were implanted into the hippocampus and the lateral septum area of each rat. The concentration of dopamine (DA) in the septum rapidly increased within 20 min after the beginning of a learning session. However, another group of rats trained on a similar but non-discriminative task showed no such increase. The concentration of acetylcholine (ACh) in the hippocampus was significantly enhanced during the learning session and rapidly returned to the basal value after the session, but showed a delayed and diminished increase in the non-discrimination group. These results suggest that DAergic inputs to the septum may be involved in control of the septo-hippocampal cholinergic system which is of importance for discrimination learning behavior.
3,4-Dihydroxyphenylacetic Acid↗
Learning discrimination trajectories in EEG sensor space: application to inferring task difficulty.
We describe a spatio-temporal linear discriminator for single-trial classification of multi-channel electroencephalography (EEG). No prior information about the characteristics of the neural activity is required, i.e., the algorithm requires no knowledge about the timing and spatial distribution of the evoked responses. The algorithm finds a temporal delay/window onset time for each EEG channel and then spatially integrates the channels for each channel-specific onset time. The algorithm can be seen as learning discrimination trajectories defined within the space of EEG channels. We demonstrate the method for detecting auditory-evoked neural activity and discrimination of task difficulty in a complex visual-auditory environment.
Adult↗
Effect of "irrelevant" maze arm angle on brightness discrimination learning and reversal.
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Arm↗
The role of homecage environmental stimuli in the facilitation of shock-motivated spatial discrimination learning in rat pups.
In three experiments we examined the role of homecage environmental stimuli on learning an aversively motivated spatial discrimination task in 11-day-old rats. Varying the presence and absence of nest shavings in the correct and incorrect arms of a T-maze in Experiment 1 revealed that nest shavings had both nondirective facilitation and approach-eliciting properties. Training the 11-day-old rats in the presence or absence of shavings over three daily sessions and comparing their performance on the third day of training with that of a maturation control in Experiment 2 indicated that there is a residual training effect of the approach-eliciting property of nest shavings on shock-escape behavior. In Experiment 3, using nest shavings either as an irrelevant stimulus or as a redundant relevant cue in an aversively motivated T-maze reversal task suggested that 11-day-old rats acquire the discrimination task using non-nest spatial or directional cues as well as those provided by nest shavings. Overall, these results suggest that nest shavings introduced into aversively motivated tasks create a learning environment comparable to that of appetitively motivated instrumental tasks utilizing suckling from an anesthetized dam as a reinforcer.
Animals↗