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PubMed2006

Neural correlates of response reversal: considering acquisition.

Previous work on response reversal has typically used a single pair of stimuli that serially reverse. This conflation of acquisition and reversal processes has prevented an examination of the functional role of neural systems implicated in response reversal during acquisition despite the relevance of such data in evaluating accounts of response reversal. In the current study, participants encountered 16 independent reversing stimulus pairs in the context of a probabilistic response reversal paradigm. Functional regions of interest identified as involved in response reversal through a contrast used in the previous literature (punished errors made in the reversal phase versus rewarded correct responses), were interrogated across conditions. Consistent with suggestions that middle frontal cortex codes reward, this region showed significantly greater responses to rewarded rather than punished trials irrespective of accuracy or learning phase (acquisition or reversal). Consistent with the suggestion that this coding of the expectation of reinforcement is acquired via input from the amygdala, we observed significant positive connectivity between activity within the amygdala and a region of rostral anterior cingulate cortex highly proximal to this region of middle frontal/mesial prefrontal cortex. In contrast, inferior frontal cortex, anterior cingulate cortex and caudate showed greater responses to punished errors than to the rewarded correct responses. These three regions also showed significant activation to rewarded errors during acquisition, in contrast to positions suggesting that inferior frontal cortex represents punishment or suppresses previously rewarded responses. Moreover, a connectivity analysis with an anterior cingulate cortex seed revealed highly significant positive connectivity among them. The implications of these data for recent accounts of response reversal and of response reversal impairments in specific neuropsychiatric populations are discussed.

Adult↗
PubMed1989

The effects of scopolamine and clonidine upon the performance and learning of a motor skill.

Twenty-eight subjects practised a task involving procedural knowledge in which a moving target has to be followed for two 3-min sessions. They were then randomly allocated to receive an IV injection of 0.4 mg scopolamine, 0.15 mg clonidine or saline. General impairment due to both active treatments was seen 20 min later in significantly decreased tracking performance. Subjects then had to learn a mirror-reversed version of the tracking task. This involved acquiring novel procedural knowledge. Subjects who had either saline or clonidine treatment showed rapid temporary improvements and also considerable permanent learning. Subjects treated with scopolamine, however, showed only slow temporary improvement and little permanent improvement in their performance at this task. This result suggests that a normally functioning cholinergic system is necessary not only for an efficient working memory but also for the long term acquisition of some kinds of procedural knowledge.

Adolescent↗
PubMed2003

Temporal discrimination in a long operant chamber.

Pigeons were placed in a long chamber equipped with one key and feeder at each end side and one key and houselight at the middle. To obtain food the birds had to choose one side key after a short signal and the other side key after a long signal. The signals consisted of the illumination of the center key and the houselight and were initiated by a peck at the center key. The chamber had sensitive floor panels that enabled us to measure the location of the bird during the signals. In Experiment 1, after the birds learned the discrimination we reversed the assignment of keys to signals. In Experiment 2, we examined performance on two pairs of discriminations holding the same ratio. In Experiment 3, after the pigeons learned to discriminate two signals, we changed the duration of the long signal. The results showed that (a) the birds' motion during the signal was highly stereotypical, i.e. the birds moved to the short side, waited a few seconds, and then departed to, and stayed on the long side; (b) this motion pattern predicted the results of generalization tests with novel durations; (c) the mean of the times of departure from the short side approached its steady state values quicker than the standard deviation and consequently superposition of behavioral measures became stronger with training; (d) only the duration of the short signal influenced significantly the moment the birds departed from the short side; finally (e) the times of arrival at and departure from the short side were positively correlated, but the times of arrival and residence at the short side were negatively correlated.

Journal Article↗
PubMed2004

EEG correlates of coordinate processing during intermanual transfer.

Goal-directed movements require mapping of target information to patterns of muscular activation. While visually acquired information about targets is initially encoded in extrinsic, object-centered coordinates, muscular activation patterns are encoded in intrinsic, body-related coordinates. Intermanual transfer of movements previously learned with one hand is accomplished by the recall of unmodified extrinsic coordinates if the task is performed in original orientation. Intrinsic coordinates are retrieved in case of mirror-reversed orientation. In contrast, learned extrinsic coordinates are modified during the mirror movement and intrinsic coordinates during the originally oriented task. To investigate the neural processes of recall and modification, electroencephalogram (EEG) recording was employed during the performance of a figure drawing task previously trained with the right hand in humans. The figure was reproduced with the right hand (Learned-task) and with the left hand in original (Normal-task) and mirror orientations (Mirror-task). Prior to movement onset, beta-power and alpha- and beta-coherence decreased during the Normal-task as compared with the Learned-task. Negative amplitudes over fronto-central sites during the Normal-task exceeded amplitudes manifested during the Learned-task. In comparison to the Learned-task, coherences between fronto-parietal sites increased during the Mirror-task. Results indicate that intrinsic coordinates are processed during the pre-movement period. During the Normal-task, modification of intrinsic coordinates was revealed by cerebral activation. Decreased coherences appeared to reflect suppressed inter-regional information flow associated with utilization of intrinsic coordinates. During the Mirror-task, modification of extrinsic coordinates induced activation of cortical networks.

Adult↗
PubMed2004

Effect of aging on stimulus-reward association learning.

The flexible learning of stimulus-reward associations when required by situational context is essential for everyday behavior. Older adults experience a progressive decline in several cognitive functions and show deficiencies in neuropsychological tasks requiring flexible adaptation to external feedback, which could be related to impairments in reward association learning. To study the effect of aging on stimulus-reward association learning 20 young and 20 older adults performed a probabilistic object reversal task (pORT) along with a battery of tests assessing executive functions and general intellectual abilities. The pORT requires learning and reversing associations between actions and their outcomes. Older participants collected fewer points, needed more trials to reach the learning criterion, and completed less blocks successfully compared to young adults. This difference remained statistically significant after correcting for the age effect of other tests assessing executive functions. This suggests that there is an age-related difference in reward association learning as measured using the pORT, which is not closely related to other executive functions with respect to the age effect. In human aging, structural alterations of reward detecting structures and functional changes of the dopaminergic as well as the serotonergic system might contribute to the deficit in reward association learning observed in this study.

Adult↗
PubMed1981

Frontal EEG coherence, H-reflex recovery, concept learning, and the TM-Sidhi program.

This study investigated the relationship between frontal bilateral EEG coherence, H-reflex recovery (an index of CNS flexibility), and solution of a concept learning problem on which the correct concept is reversed during the task. It also assessed the longitudinal effect of the TM-Sidhi program on concept learning among the same sample of college students. Frontal EEG coherence and H-reflex recovery were significantly correlated with flexible performance on the concept learning task following the reversal. Instruction in the TM-Sidhi program significantly improved efficiency of concept-learning performance before the concept was reversed, although not afterward.

Computers↗
PubMed2003

A heparin derived oligosaccharide normalizes the fear response of old Brown Norway rats.

Old animals exhibit impaired spatial learning and an exaggerated response to stress. It was predicted that the heparin derived oligosaccharide (HDO), C3, would reverse these age-related deficits. Young (4-5 months) and old (19-20 months) Brown Norway male rats ingested C3 (25 mg/kg per day, p.o.) or vehicle (drinking water) daily for 42-44 days. Two weeks after the initiation of drug treatment, the rats were examined using a series of behavioral tests. The old control rats evidenced: (1) increased neophobia and reduced exploratory behavior in a novel open field (OF); and (2) exaggerated freezing during the acquisition and retention of a conditioned response (CR) to a Pavlovian light-shock pairing ("foreground" conditioning). C3 treatment attenuated or reversed this age-related impairment of emotional behavior. Analysis of spatial learning using the Morris water maze (MWM), and of CR formation to the place in which the foreground conditioning was conducted ("background" conditioning) during context dependent fear conditioning (CDFC) did not reveal major age or drug effects on memory processes. It is hypothesized that C3 repairs damage to the extracellular matrix (ECM) that occurs during the aging process and thereby normalizes age-related exacerbated fear behaviors without affecting mnestic processes.

Aging↗
PubMed1998

Object recognition using spatiotemporal signatures.

The sequence of images generated by motion between observer and object specifies a spatiotemporal signature for that object. Evidence is presented that such spatiotemporal signatures are used in object recognition. Subjects learned novel, three-dimensional, rotating objects from image sequences in a continuous recognition task. During learning, the temporal order of images of a given object was constant. During testing, the order of images in each sequence was reversed, relative to its order during learning. This image sequence reversal produced significant reaction time increases and recognition rate decreases. Results are interpreted in terms of object-specific spatiotemporal signatures.

Form Perception↗
PubMed1970

The effects of amount of training per reversal on successive reversals of a color discrimination.

Three groups of pigeons were trained on a red-green discrimination in which the stimuli were alternately presented in a multiple schedule of reinforcement. The discrimination was reversed 24 times. Groups were given 1, 2, or 4 hr of training on each discrimination. Increasing the length of training had two principal effects on reversal performance: it increased the rate of extinction of responding to one of the stimuli and increased the rate of reacquisition of responding to the other. The latter effect involved both an increase in reacquisition of responding to a positive stimulus within reversals and an increase in recovery of responding to the previous negative stimulus between reversals. Improvements in performance of each group over the series of reversals were qualitatively similar to the two effects of length of training on each discrimination, and were analogous to effects obtained in other studies involving overtraining and successive reversals of simultaneous discriminations.

Animals↗
PubMed2000

Perception of temporal properties in self-generated songs by Bengalese finches (Lonchura striata var. domestica).

In the songbird forebrain, neuronal selectivity for temporal properties of each bird's self-generated song has been well described, but the behavioral and perceptual correlates of this selectivity are not known. By operant procedures, the authors trained Bengalese finches (Lonchura striata var. domestica) to discriminate between songs that were played normally and in reverse. Male Bengalese finches learned the discrimination quicker when their self-generated song was used as a stimulus than when a song of another conspecific bird was used. When the global note order was retained but each note was locally reversed, the song was more likely to be regarded as a forward song by the singer himself, but not by other birds. These results provide psychophysical evidence that the special processing of the self-generated song observed at the neural level might reflect an individual's perception of his self-produced song.

Analysis of Variance↗
PubMed1999

Reversal of a postnatal alcohol-induced deficit in learned persistence in the rat by d-amphetamine.

Periodic (high peak) exposure to alcohol during early infancy in the rat has been shown to disrupt the partial reinforcement extinction effect (PREE), a measure of persistence learning, when rats were tested at weaning age. The current study examined the effects of d-amphetamine (0.3 mg/kg, i.p.) on the PREE after early postnatal exposure to alcohol (4.5 mg/kg) delivered in a milk-based diet or an isocaloric control diet via oral intubation once a day on postnatal days 4 to 9. On postnatal days 20 and 21, rats were trained on either a continuously reinforced or partially reinforced schedule of food reward, followed by extinction. Rats were randomly assigned to eight conditions, depending on diet, drug, and reward schedule. The results were (1) a replication of the finding that periodic (high peak) exposure to alcohol diminishes the PREE, and (2) that amphetamine restores the PREE to normal levels in alcohol-treated animals, and may reduce the PREE in control subjects. The possible role of noradrenergic and dopaminergic systems in situations of extinction and nonreward are discussed.

Animals↗
PubMed2005

Learning performance on the discrimination-shift task in patients with cortical and subcortical lesions.

Patients with brain damage completed reversal and nonreversal shift-learning tasks and we compared their performance with that of normal adults. The overall group differences revealed that many patients could not reach the task criterion regardless of the location of damage and the shift condition of the task. When we compared patients with subcortical and cortical damage, we also found no group differences with regard to the total number of trials required to reach the learning criterion and in terms of their learning processes during shift learning. However, when we compared patients with subcortical and unilateral cortical damage, the results revealed that the learning processes of patients with subcortical damage were normal, whereas the patients with unilateral cortical damage showed lesion-specific effects on shift learning. These findings are discussed in light of previous developmental findings and the proposed role of subcortical structures in learning.

Aged↗