The Experts below are selected from a list of 48006 Experts worldwide ranked by ideXlab platform
Elisabeth A Murray - One of the best experts on this subject based on the ideXlab platform.
-
rhinal cortex lesions produce mild deficits in visual Discrimination Learning for an auditory secondary reinforcer in rhesus monkeys
Behavioral Neuroscience, 1999Co-Authors: Mark G Baxter, Wendy S Hadfield, Elisabeth A MurrayAbstract:Aspiration, but not neurotoxic, lesions of the amygdala impair performance on a visual Discrimination Learning task in which an auditory secondary reinforcer signals which of 2 stimuli will be reinforced with food. Because aspiration lesions of the amygdala interrupt projections of the rhinal cortex traveling close to the amygdala, it was hypothesized that damage to the rhinal cortex would severely impair Learning in this task. Rhesus monkeys (Macaca mulatta) were trained to solve visual Discrimination problems based on an auditory secondary reinforcer, were given lesions of the rhinal cortex or the perirhinal cortex alone, and were then retested. The monkeys displayed a reliable, albeit mild, deficit in postoperative performance. It is concluded that the aspiration lesions of the amygdala that,produced a severe impairment did so because they interrupted connections of temporal cortical fields beyond the rhinal cortex that are also involved in Learning in this task.
-
monkeys macaca fascicularis with rhinal cortex ablations succeed in object Discrimination Learning despite 24 hr intertrial intervals and fail at matching to sample despite double sample presentations
Behavioral Neuroscience, 1992Co-Authors: David Gaffan, Elisabeth A MurrayAbstract:: Six cynomolgus monkeys (Macaca fascicularis) learned preoperatively a set of 10 concurrent object Discriminations with 24-hr intertrial intervals. Three then had the rhinal cortex removed bilaterally, whereas the other 3 remained as unoperated controls. The animals with ablations were impaired in reacquiring the preoperatively acquired set but subsequently learned without any impairment a new set of 10 Discriminations that was presented in the same way. The monkeys with rhinal cortex ablations then failed to learn delayed matching to sample, with double sample presentations, in 510 trials, whereas the control animals learned this task in 270 trials on average. The results add to existing evidence that rhinal cortex ablation produces a severe impairment in visual short-term recognition memory and show for the first time that this impairment is accompanied by normal long-term Discrimination Learning ability.
David Gaffan - One of the best experts on this subject based on the ideXlab platform.
-
visual agnosia and kluver bucy syndrome in marmosets callithrix jacchus following ablation of inferotemporal cortex with additional mnemonic effects of immunotoxic lesions of cholinergic projections to medial temporal areas
Brain Research, 2001Co-Authors: R M Ridley, David Gaffan, Kerry A Warner, C J Maclean, H F BakerAbstract:Inferotemporal ablations in the New World monkey, the common marmoset (Callithrix jacchus), produced a persistent impairment on visual Discrimination Learning and a florid, but transient, Kluver-Bucy syndrome. Monkeys with these ablations were impaired on acquisition of object Discriminations to a high criterion and on concurrent Discrimination Learning, to a single high criterion across all trials. Neither the control monkeys nor the monkeys with inferotemporal ablations found acquisition more difficult when the component Discriminations of a set were presented concurrently compared to consecutively, although the monkeys with inferotemporal ablations found acquisition under both these conditions somewhat more difficult than did control monkeys. This suggests that the severe impairment caused by inferotemporal ablations on concurrent Learning measured across all trials is due to the need for sustained performance across a concurrent set rather than to the extra mnemonic demands of concurrent presentation. When immunotoxic lesions of the cholinergic projection to the hippocampal formation were added to the inferotemporal ablations, a further impairment on retention, and a differential impairment on concurrent, compared to consecutive, Learning was observed. Previous studies have shown that lesions of the cholinergic projection to the hippocampus alone, or excitotoxic hippocampal lesions, do not affect simple visual Discrimination Learning. It is suggested that large inferotemporal ablations in monkeys produce a visual agnosia which causes severe 'psychic blindness' in the first instance, and a persistent impairment on visual Discrimination Learning. The hippocampus makes a contribution, which may be mnemonic, to Discrimination performance after inferotemporal ablations.
-
impairment of visual object Discrimination Learning after perirhinal cortex ablation
Behavioral Neuroscience, 1997Co-Authors: Mark J. Buckley, David GaffanAbstract:Eight cynomolgus monkeys learned preoperatively 20 concurrent visual Discriminations between pairs of colored shapes presented on a touch screen with 24-hr intertrial intervals. Three then received bilateral perirhinal cortex ablation, and 5 remained controls. The ablated monkeys were severely impaired in reacquiring the preoperatively acquired set, whereas postoperative Learning of 20 new Discriminations was not significantly affected. The task was then made more difficult. First, the number of foils from which the stimulus had to be selected was increased to 2, 4, 7, and then 14. Second, larger sets of 40, 80, and 160 problems were presented. Both manipulations revealed some significant but relatively mild impairments in the monkeys with ablations. It is suggested that perirhinal cortex ablation impairs the monkey's capacity to identify individual objects, which leads to deficits in both visual-object recognition memory and Discrimination Learning.
-
monkeys macaca fascicularis with rhinal cortex ablations succeed in object Discrimination Learning despite 24 hr intertrial intervals and fail at matching to sample despite double sample presentations
Behavioral Neuroscience, 1992Co-Authors: David Gaffan, Elisabeth A MurrayAbstract:: Six cynomolgus monkeys (Macaca fascicularis) learned preoperatively a set of 10 concurrent object Discriminations with 24-hr intertrial intervals. Three then had the rhinal cortex removed bilaterally, whereas the other 3 remained as unoperated controls. The animals with ablations were impaired in reacquiring the preoperatively acquired set but subsequently learned without any impairment a new set of 10 Discriminations that was presented in the same way. The monkeys with rhinal cortex ablations then failed to learn delayed matching to sample, with double sample presentations, in 510 trials, whereas the control animals learned this task in 270 trials on average. The results add to existing evidence that rhinal cortex ablation produces a severe impairment in visual short-term recognition memory and show for the first time that this impairment is accompanied by normal long-term Discrimination Learning ability.
Brian D Kangas - One of the best experts on this subject based on the ideXlab platform.
-
Discrimination Learning in oxycodone treated nonhuman primates
Drug and Alcohol Dependence, 2020Co-Authors: Sarah L Withey, Rachel J Doyle, Erica N Porter, Jack Bergman, Brian D KangasAbstract:Abstract Background Prescription opioid abuse continues to be a public health concern of epidemic proportions. Notwithstanding the extensive literature regarding opioid action, there has been little systematic research regarding the effects of opioid dependence and withdrawal on aspects of cognition-related behavior in laboratory animals. The present studies examined the effects of the prescription opioid oxycodone on Learning processes in nonhuman primates. Methods The ability of subjects to repeatedly learn novel touchscreen-based visual Discriminations was examined during three conditions of opioid exposure. Discrimination Learning was examined, first, during oxycodone self-administration (3-hr sessions, 0.1 mg/kg/injection) and, next, during non-contingent chronic treatment with oxycodone (10 mg/kg/day). Finally, Discrimination Learning was re-examined during antagonist-precipitated opioid withdrawal (0.001-0.1 mg/kg naltrexone) and, subsequently, following abrupt discontinuation of oxycodone treatment. Results Although motoric behavior was disrupted by oxycodone, neither the development of Discrimination Learning nor steady-state performance were impaired following oxycodone self-administration or during non-contingent chronic oxycodone treatment. However, Discrimination Learning was substantially impaired during oxycodone withdrawal, whether elicited by naltrexone or by abrupt oxycodone discontinuation. Moreover, these Learning impairments were concordant with autonomic signs of opioid withdrawal. Conclusions Taken together, the present studies indicate that impairment of Learning processes can accompany the unconditioned signs of opioid withdrawal.
-
effects of self administered methamphetamine on Discrimination Learning and reversal in nonhuman primates
Psychopharmacology, 2016Co-Authors: Brian D Kangas, Jack BergmanAbstract:Frequent exposure to methamphetamine has been reported to adversely influence cognitive behavior and, in particular, inhibitory control processes. The present studies were conducted in squirrel monkeys to assess the effects of daily intravenous methamphetamine self-administration on touch screen-based repeated acquisition and Discrimination reversal tasks thought to reflect behavioral dimensions of, respectively, Learning and response inhibition. First, stable methamphetamine-maintained behavior was established in each subject (0.35–1.6 mg/kg/session), and subsequently, a second daily session of Discrimination Learning was conducted (20 h later). Subjects first learned to discriminate between two simultaneously presented stimuli (acquisition) and, subsequently, to re-learn the Discrimination with the contingencies switched (reversal). The role of the interval between self-administration and touch screen sessions was evaluated, as well as the effects of abrupt methamphetamine discontinuation. Results indicate that daily methamphetamine self-administration markedly disrupted the development of Discrimination Learning, initially requiring nearly twice the number of trials to master Discriminations. The magnitude of adverse effects in individual subjects correlated to the level of daily methamphetamine intake. Importantly, however, behavioral disruption of Discrimination Learning was surmounted following remedial training. Once criterion levels of Discrimination performance were achieved, subsequent development of reversal performance was largely unaffected except when the interval between self-administration and touch screen session was short and, thus, likely a result of methamphetamine’s direct effects. Discontinuation of methamphetamine produced no disruption in acquisition or reversal. These results indicate that self-administered methamphetamine can markedly disrupt Learning processes and highlight key differences in its effects on different aspects of Discrimination Learning.
Edward D Levin - One of the best experts on this subject based on the ideXlab platform.
-
spatial and non spatial visual Discrimination Learning in zebrafish danio rerio
Animal Cognition, 2001Co-Authors: David Arthur, Edward D LevinAbstract:Zebrafish (Danio rerio) provide an excellent model for assessment of molecular processes of neurodevelopment. To determine the functional importance of molecular events during neurodevelopment, we have developed methods for assessing Learning in zebrafish in a three-chambered fish tank. In the first study, simple escape response was assessed. Zebrafish tested with a moving net learned to escape to another chamber more rapidly over the six sessions of training than the fish with the still net which did not learn. Upon reversal of the contingencies, the fish switched to the inactive net rapidly learned to suppress the escape response and fish formerly in the inactive net condition learned to avoid the moving net. In the second study, spatial Discrimination Learning was assessed. Zebrafish were trained on a right-left position Discrimination to avoid the active net. Zebrafish showed significant improvement in escape responses over six sessions of training with three trials per session. In the third study, red-blue non-spatial Discrimination Learning was assessed. There was a significant improvement over the first six training sessions. With the reversal of contingencies, there was a significant decline of performance. With continued training, the fish again significantly improved avoidance. These studies found an effective motivational stimulus and procedure for studying escape behavior in zebrafish; a procedure whereby zebrafish would learn both spatial and non-spatial Discrimination. These methods are being developed to help determine the functional importance of molecular events during zebrafish neurodevelopment.
Jack Bergman - One of the best experts on this subject based on the ideXlab platform.
-
Discrimination Learning in oxycodone treated nonhuman primates
Drug and Alcohol Dependence, 2020Co-Authors: Sarah L Withey, Rachel J Doyle, Erica N Porter, Jack Bergman, Brian D KangasAbstract:Abstract Background Prescription opioid abuse continues to be a public health concern of epidemic proportions. Notwithstanding the extensive literature regarding opioid action, there has been little systematic research regarding the effects of opioid dependence and withdrawal on aspects of cognition-related behavior in laboratory animals. The present studies examined the effects of the prescription opioid oxycodone on Learning processes in nonhuman primates. Methods The ability of subjects to repeatedly learn novel touchscreen-based visual Discriminations was examined during three conditions of opioid exposure. Discrimination Learning was examined, first, during oxycodone self-administration (3-hr sessions, 0.1 mg/kg/injection) and, next, during non-contingent chronic treatment with oxycodone (10 mg/kg/day). Finally, Discrimination Learning was re-examined during antagonist-precipitated opioid withdrawal (0.001-0.1 mg/kg naltrexone) and, subsequently, following abrupt discontinuation of oxycodone treatment. Results Although motoric behavior was disrupted by oxycodone, neither the development of Discrimination Learning nor steady-state performance were impaired following oxycodone self-administration or during non-contingent chronic oxycodone treatment. However, Discrimination Learning was substantially impaired during oxycodone withdrawal, whether elicited by naltrexone or by abrupt oxycodone discontinuation. Moreover, these Learning impairments were concordant with autonomic signs of opioid withdrawal. Conclusions Taken together, the present studies indicate that impairment of Learning processes can accompany the unconditioned signs of opioid withdrawal.
-
effects of self administered methamphetamine on Discrimination Learning and reversal in nonhuman primates
Psychopharmacology, 2016Co-Authors: Brian D Kangas, Jack BergmanAbstract:Frequent exposure to methamphetamine has been reported to adversely influence cognitive behavior and, in particular, inhibitory control processes. The present studies were conducted in squirrel monkeys to assess the effects of daily intravenous methamphetamine self-administration on touch screen-based repeated acquisition and Discrimination reversal tasks thought to reflect behavioral dimensions of, respectively, Learning and response inhibition. First, stable methamphetamine-maintained behavior was established in each subject (0.35–1.6 mg/kg/session), and subsequently, a second daily session of Discrimination Learning was conducted (20 h later). Subjects first learned to discriminate between two simultaneously presented stimuli (acquisition) and, subsequently, to re-learn the Discrimination with the contingencies switched (reversal). The role of the interval between self-administration and touch screen sessions was evaluated, as well as the effects of abrupt methamphetamine discontinuation. Results indicate that daily methamphetamine self-administration markedly disrupted the development of Discrimination Learning, initially requiring nearly twice the number of trials to master Discriminations. The magnitude of adverse effects in individual subjects correlated to the level of daily methamphetamine intake. Importantly, however, behavioral disruption of Discrimination Learning was surmounted following remedial training. Once criterion levels of Discrimination performance were achieved, subsequent development of reversal performance was largely unaffected except when the interval between self-administration and touch screen session was short and, thus, likely a result of methamphetamine’s direct effects. Discontinuation of methamphetamine produced no disruption in acquisition or reversal. These results indicate that self-administered methamphetamine can markedly disrupt Learning processes and highlight key differences in its effects on different aspects of Discrimination Learning.