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PubMed1986

Learning sets, discrimination reversal, and hippocampal function.

Impairments of discrimination reversal are commonly found following lesions of the hippocampal system. In a recent experiment, however, acquisition of a reversed discrimination was actually facilitated, rather than impaired, by partial lesions of the fimbria-fornix (FFX), an extrinsic fiber connection to the hippocampus. That experiment differed from most previous reversal experiments in that the discriminative stimuli were olfactory rather than spatial or visual, and 3 discriminations were given prior to the reversal of the third discrimination, rather than a single discrimination. The present experiment was designed to determine the generality of the results obtained in the olfactory experiment. Rats with partial lesions of the FFX and operated controls were tested on a series of 3 Go, No-go spatial discriminations, a reversal of the third discrimination, and 4 subsequent discriminations, in that order. Control rats acquired a learning set in the first 3 discriminations, reaching criterion on the third discrimination in fewer trials than they took on the first discrimination. Their choice accuracy was not significantly affected by the reversal and discrimination performance reached an asymptotic level after the reversal. Rats with FFX lesions also acquired a learning set in the first 3 discriminations, but they consistently took longer than control rats to learn each of the 7 discriminations. These rats were especially impaired on the reversal. These results contrast markedly with those obtained when a similar procedure was used with olfactory discriminations. Identification of the variables responsible for these differences should help distinguish those behaviors that require hippocampal function from those that do not.

Acetylcholinesterase↗

PubMed1989

Synaptic plasticity and learning. II: Do different kinds of plasticity underlie different kinds of learning?

This paper discusses certain issues connected with the question of whether synaptic plasticity is involved in information storage by the brain. We begin by contrasting two well documented types of synaptic plasticity--activity-dependent modulation of presynaptic facilitation ("Kandel synapses") and NMDA receptor triggered alterations in excitatory amino acid transmission ("Hebb synapses"). We then propose that, embedded-into appropriate circuitry, these different forms of plasticity might underlie different kinds of learning. In partial support of this idea, we show that, in freely moving rats, intrahippocampal microinfusion of the NMDA-receptor antagonist D,L-AP5 causes a dose-dependent impairment of a type of spatial learning known to be sensitive to disruption by hippocampal lesions (water-maze place-navigation). In a second experiment, the same drug infusion protocol is shown to cause a blockade of hippocampal long-term potentiation in vivo across a comparable dose range. Finally, third, autoradiographic experiments indicate that diffusion of the drug was largely restricted to the hippocampus. Together, these results (1) suggest that blockade of hippocampal NMDA receptors, under conditions which leave baseline synaptic transmission relatively unaffected, blocks a type of learning with which the vertebrate hippocampus has been implicated on the basis of neuropsychological work; and (2) supports Abrams and Kandel's Trends Neurosci. 11 (1988) recent proposal that there may be several logically distinct forms of synaptic plasticity.

Animals↗

PubMed1992

What undergraduate physical education majors learn during a field experience.

Early field experiences and student teaching have a significant impact on the development of prospective teachers' perceptions of teaching and themselves as teachers (Dodds, 1989). The purpose of this study was to describe what happened to physical education majors during a secondary physical education methodology course that included two field experiences in which the undergraduates taught at least one lesson a day. The four research questions that guided the study were (a) What issues did the majors attend to as significant incidents from their teaching, and did these issues change during their field experiences? (b) What were the characteristics of field experience lessons they perceived as successful? (c) What were the characteristics of field experience lessons they perceived as unsuccessful? and (d) What were the physical education majors' conceptions of teaching? Participants in the study were 39 junior-year physical education teacher education majors. Data were collected using the critical incident technique (Flanagan, 1954) and an open-ended, written questionnaire that was designed to encourage the majors to reflect on various aspects of their teaching experience. The questionnaire and critical incidents were analyzed using an inductive analytical procedure and a series of categories developed from several readings of students' writings. The teacher preparation program affected how these trainees defined and evaluated their teaching experiences. In contrast to some of the earlier work in physical education, the results indicated pupil learning, quality lesson planning to ensure pupil learning, and efficient lesson management were major characteristics of successful lessons for these trainees. The trainees presented "theories of knowledge" that emphasized technical concepts of teaching with little attention to the social or ethical dimensions of their work or the content knowledge of their field. Additional research is needed to examine appropriate programmatic efforts to help preservice teachers reflect not only on teaching, learning, and schooling as a technical enterprise but also as a moral and ethical enterprise.

Attitude↗

PubMed2006

Differential decline in behavioral performance of Drosophila melanogaster with age.

Normal aging is typically accompanied by deficits in behavioral performance, independent of overt pathology. In contrast, some behaviors remain relatively unchanged with age, but the reason(s) they remain intact are not known. Here we compare the relative impact of age on a battery of standard behavioral tests using the model genetic organism Drosophila melanogaster. Consistent with previous reports, learning, locomotion, geotaxis and phototaxis show a dramatic and progressive decline beginning at 1-2 weeks of age. In contrast, using two independent behavioral assays, we observe little or no decline in the flies' ability to escape potentially threatening stimuli. Using the assay with the most rapid decline, geotaxis, we observe a delay in functional aging in a long-lived mutant of the Ecdysone Receptor. We discuss the use of Drosophila genetics to investigate the differential decline in behavioral capacity.

Aging↗

PubMed1982

State-dependent learning in children receiving methylphenidate.

Methylphenidate state-dependent learning was investigated using a paired-associate learning task of 16 pairs of pictures. Subjects were 15 children for whom methylphenidate was currently being prescribed. Each child was seen for two learning sessions and two testing sessions. Learning took place under placebo and under the child's regular dosage of methylphenidate. During retention testing all combinations of learning drug-state and testing drug-state were observed for each child. Data were analyzed using contrast variables which took into account the repeated-measures nature of the design. The results indicated that there was a trend in the direction of state-dependence in the whole sample. Significant symmetrical state-dependent effects were obtained in those subjects whose original learning was facilitated by methylphenidate.

Adolescent↗

PubMed1986

The pigeon's discrimination of movement patterns (Lissajous figures) and contour-dependent rotational invariance.

The ability of pigeons to discriminate complex motion patterns was investigated with the aid of moving Lissajous figures. The pigeons successfully learned to differentiate two successively presented cyclic trajectories of a single moving dot. This suggests that they can recognize a movement Gestalt when information about shape is minimal. They also quickly learned a new discrimination between moving-outline stimuli with repetitively changing contour patterns. Contrasting results were obtained when the dot or outline stimuli were axis-rotated through 90 degrees. Rotational invariance of pattern discrimination was clearly demonstrated only when moving contours were visible. Nevertheless, pigeons could discriminate the axis-orientation of a moving-dot or moving-outline pattern when trained to do so. Discrimination did not seem to depend on single parameters of motion but rather on the recognition of a temporally integrated movement Gestalt. The visual system of pigeons, as well as that of humans, may be well adapted to recognize the types of oscillatory movements that represent components of the motor behaviour shown by many living organisms.

Animals↗

PubMed1994

Reducing Knowledge of Results About Relative Versus Absolute Timing: Differential Effects on Learning.

The purpose of the present experiment was to examine further earlier suggestions that a reduced relative frequency of knowledge of results (KR) can enhance the learning of generalized motor programs (GMPs) but at the same time degrade parameter learning, compared with giving KR after every trial (Wulf & Schmidt, 1989; Wulf, Schmidt, & Deubel, 1993). In contrast to these earlier studies, here KR was given separately for relative timing and absolute timing. Subjects practiced three movement patterns that required the same relative timing but different absolute movement times. KR was provided on 100% or 50% of the practice trials for relative timing or absolute timing, respectively. In retention and transfer tests, the groups that had had 50% KR about relative timing demonstrated more effective learning of the relative-timing structure, that is, GMP learning, than the groups that had had 100% KR about relative timing. The KR frequency had no effect on parameterization during retention; yet, when transfer to a task with a novel overall duration was required, the groups given 100% KR about absolute timing were more accurate in parameterization than the groups provided with 50% KR about absolute timing. Thus, the reduced relative KR frequency enhanced GMP learning but had no beneficial effect, or even a degrading effect, on parameter learning. The differential effects of a reduced KR frequency on the learning of relative timing and absolute timing also provide additional support for the dissociation of GMP and parameterization processes.

Journal Article↗

PubMed1987

Effects of kappa agonists and dexoxadrol on the acquisition of conditional discriminations in monkeys.

In each of two components of a multiple schedule, patas monkeys were required to respond on a right or left lever depending upon the stimulus combination (a color and a geometric form) presented. Reinforcement of a response in the presence of one stimulus (the form) was conditional upon the other stimulus (the color). The completion of a two-member chain of discriminations produced a food pellet. Errors produced a brief timeout. One component of the multiple schedule was a repeated-acquisition task in which the discriminative stimuli for left- and right-lever responses changed each session (learning). In the other component, the discriminative stimuli were the same each session (performance). Dose-effect curves were determined for the kappa agonists bremazocine, tifluadom, ethylketocyclazocine and U50488H. Each drug produced dose-related decreases in overall response rate but had little or no effect on accuracy in either learning or performance. The rate-decreasing effects of ethylketocyclazocine and tifluadom were due to a dose-related pause at the start of the session, whereas those of bremazocine and U50488 were due largely to sporadic pausing throughout the session. Naltrexone blocked the effects of each drug whereas quaternary naltrexone had no effect. In contrast to the kappa agonists, dexoxadrol produced a dose-related disruption in accuracy of responding in learning. Dexoxadrol also decreased response rate in both acquisition and performance in a dose-related manner. Naltrexone attenuated the effects of low doses of dexoxadrol on accuracy, but failed to block the disruptive effects of higher doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Analgesics↗

PubMed2000

Early sensory and hormonal experience modulate age-related changes in NR2B mRNA within a forebrain region controlling avian vocal learning.

Male zebra finches are most apt to mimic songs heard between posthatch days (PHD) 35 and 65, and this vocal learning depends, in part, on the activation of N-methyl-D-aspartate receptors (NMDAR) within a discrete forebrain circuit that includes the lateral magnocellular nucleus of the anterior neostriatum (lMAN) and area X. Using in situ hybridization, we show that transcripts for both the constitutive NMDAR subunit NR1 and the modulatory subunit NR2B decrease abruptly in the lMAN between PHD20 and 40. This downregulation corresponds to the onset of song learning and a transition from slow to faster NMDAR currents in lMAN neurons. In area X, NR1 mRNA increases as NR2B mRNA decreases during song development. To understand how these changes in NMDAR mRNA might regulate song learning, we next investigated how manipulations that influence song development affect NMDAR mRNA expression. Early isolation from conspecific song (which delays closure of the sensitive period for song learning) selectively increases NR2B, but not NR1 mRNA, within lMAN at PHD60. In contrast, exposure to testosterone beginning at PHD20 (which impairs song development and hastens the developmental transition to faster NMDAR current kinetics within lMAN) accelerates the decline in NR2B mRNA in lMAN, again without affecting NR1 transcript levels. Neither manipulation significantly effects NR1 or NR2B mRNA levels in area X. Our data suggest that developmental changes in the expression of specific NMDAR subunits may regulate periods of neural and behavioral plasticity and that flexibility in the timing of these sensitive periods may be achieved through experience and/or hormone-dependent modulation of NMDAR gene expression.

Animals↗

PubMed2001

Resistance of immature hippocampus to morphologic and physiologic alterations following status epilepticus or kindling.

Seizures in adult rats result in long-term deficits in learning and memory, as well as an enhanced susceptibility to further seizures. In contrast, fewer lasting changes have been found following seizures in rats younger than 20 days old. This age-dependency could be due to differing amounts of hippocampal neuronal damage produced by seizures at different ages. To determine if there is an early developmental resistance to seizure-induced hippocampal damage, we compared the effects of kainic acid (KA)-induced status epilepticus and amygdala kindling on hippocampal dentate gyrus anatomy and electrophysiology, in immature (16 day old) and adult rats. In adult rats, KA status epilepticus resulted in numerous silver-stained degenerating dentate hilar neurons, pyramidal cells in fields CA1 and CA3, and marked numerical reductions in CA3c pyramidal neuron counts (-57%) in separate rats. Two weeks following the last kindled seizure, some, but significantly less, CA3c pyramidal cell loss was observed (-26%). Both KA status epilepticus and kindling in duced mossy-fiber sprouting, as evidenced by ectopic Timm staining in supragranular layers of the dentate gyrus. In hippocampal slices from adult rats, paired-pulse stimulation of perforant path axons revealed a persistent enhancement of dentate granule-cell inhibition following KA status epilepticus or kindling. While seizures induced by KA or kindling in 16-day-old rats were typically more severe than in adults, the immature hippocampus exhibited markedly less KA-induced cell loss (-22%), no kindling-induced loss, no detectable synaptic rearrangement, and no change in dentate inhibition. These results demonstrate that, in immature rats, neither severe KA-induced seizures nor repeated kindled seizures produce the kind of hippocampal damage and changes associated with even less severe seizures in adults. The lesser magnitude of seizure-induced hippocampal alterations in immature rats may explain their greater resistance to long-term effects of seizures on neuronal function, as well as future seizure susceptibility. Conversely, hippocampal neuron loss and altered synaptic physiology in adults may contribute to increased sensitivity to epileptogenic stimuli, spontaneous seizures, and behavioral deficits.

Aging↗

PubMed1987

Passionate love/sexual desire: can the same paradigm explain both?

Two decades ago, experimental social psychologists became interested in the emotion of passionate love, "the desire for union with another." Recently, sex researchers have begun to focus on sexual desire, "the desire for sexual union with another," or the loss thereof. In this paper we review what experimental social psychologists have learned about the nature of passionate love in the last two decades and contrast their view of passion with that of sex researchers, especially with regard to the role that anxiety plays in the intensification/diminution of passion. Finally, we suggest that researchers might probably use the same paradigm to study these heretofore separate phenomena.

Anxiety↗

PubMedDate not supplied

Nimodipine facilitates retention of the classically conditioned nictitating membrane response in aged rabbits over long retention intervals.

Aged rabbits initially underwent 18 days of acquisition of the classically conditioned nictitating membrane response (NMR) using a tone conditioned stimulus (CS) and an air puff unconditioned stimulus (UCS). They were then treated with a low or high dose of nimodipine or a vehicle for 90 days. During this time no further CS-UCS pairings were presented. They underwent testing for retention of the conditioned response (CR) at 30 and 90 days. Retention testing consisted of 20 presentations of the CS alone. Rabbits in the control condition retained 46.4% of their predrug levels of conditioned responding and rabbits receiving the low dose of nimodipine retained 37.3% of their predrug levels after 30 days. After 90 days, retention in these animals declined to 8.1% and 14.1%, respectively. In contrast, rabbits receiving the high dose of nimodipine retained 85% of their predrug learning at 30 days with little decline at 90 days (77.1%). Nonassociative factors such as sensitivity to the CS or UCS could not explain these effects.

Aging↗

PubMedDate not supplied

Effects of prenatal cocaine exposure on behavior during the early postnatal period.

Offspring of Sprague-Dawley dams injected SC with 40 mg/kg/3 cc cocaine HCl daily from gestational days 8-20, pair-fed dams injected with the vehicle alone and nontreated control dams were examined behaviorally during the early postnatal period. No significant differences were observed among the treatment conditions in maternal weight gain during pregnancy, duration of pregnancy, or number of live male and female pups/litter. Offspring body weights at birth and weaning, physical maturation and reflex development were not significantly affected by prenatal cocaine exposure. In contrast, neonates exposed prenatally to cocaine were observed to exhibit significant deficits in learning of an odor/milk association that nontreated offspring learned and retained for a 24 hr period. On postnatal day 12, cocaine offspring exhibited an increase in locomotor activity and attenuated wall climbing precipitated by footshock, in the absence of any alteration in sensitivity to footshock. Given that wall climbing has been previously shown to be strongly related to levels of catecholamine activity at this age, these data suggest the possibility that there may be some attenuation in catecholaminergic function in pups exposed gestationally to cocaine. The results of this study provide evidence that prenatal cocaine exposure may have an impact upon behavioral and cognitive function even during the early postnatal period. More work is needed to fully characterize the range of alterations observed and the neural mechanisms underlying these early exposure effects.

Animals↗

PubMed2006

Sex differences in mental rotation: top-down versus bottom-up processing.

Functional MRI during performance of a validated mental rotation task was used to assess a neurobiological basis for sex differences in visuospatial processing. Between-sex group analysis demonstrated greater activity in women than in men in dorsalmedial prefrontal and other high-order heteromodal association cortices, suggesting women performed mental rotation in an effortful, "top-down" fashion. In contrast, men activated primary sensory cortices as well as regions involved in implicit learning (basal ganglia) and mental imagery (precuneus), consistent with a more automatic, "bottom-up" strategy. Functional connectivity analysis in association with a measure of behavioral performance showed that, in men (but not women), accurate performance was associated with deactivation of parieto-insular vestibular cortex (PIVC) as part of a visual-vestibular network. Automatic evocation by men to a greater extent than women of this network during mental rotation may represent an effective, unconscious, bottom-up neural strategy which could reasonably account for men's traditional visuospatial performance advantage.

Brain↗

PubMed2002

Picture reality decision, semantic categories and gender. A new set of pictures, with norms and an experimental study.

We present a new corpus of 80 pictures of unreal objects, useful for a controlled assessment of object reality decision. The new pictures were assembled from parts of the Snodgrass and Vanderwart [J. Exp. Psychol., Hum. Learning Memory 6; 1980: 174] set and were devised for the purpose of contrasting natural categories (animals, fruits and vegetables), artefacts (tools, vehicles and furniture), body parts and musical instruments. We examined 140 normal subjects in a free-choice and a multiple-choice object decision task, assembled with 80 pictures of real objects and above 80 new pictures of unreal objects in order to obtain a difficulty index for each picture. We found that the tasks were more difficult with pictures representing natural entities than with pictures of artefacts. We found a gender by category interaction, with a female superiority with some natural categories (fruits and vegetables, but not animals), and a male advantage with artefacts. On this basis, the difficulty index we calculated for each picture is separately reported for males and females. We discuss the possible origin of the gender effect, which has been found with the same categories in other tasks and has a counterpart in the different familiarity of the stimuli for males and females. In particular, we contrast explanations based on socially determined gender differences with accounts based on evolutionary pressures. We further comment on the relationship between data from normal subjects and the domain-specific account of semantic category dissociations observed in brain-damaged patients.

Adult↗

PubMed1999

The effect of deprivation on child health in Bro Taf.

Infant mortality rate (IMR) and disability indices were compared in 16 y birth cohorts (1979-1994) inclusive) from two neighbouring but contrasting boroughs in Bro Taf. The comparison was extended to children with mild learning difficulties. Children with and without learning problems were compared for birth weight (BW). Further data on infant mortality by cause of death, BW and maternal age were analysed for 6 y within this period (all births from 1979-1984 inclusive). The more deprived area had a higher IMR and a greater number of deaths attributed to low birth weight. It had a higher rate of childhood disability which was due to a higher rate of moderate learning disabilities. There was also a higher rate of mild learning difficulty. Learning problems were associated with low birth weight. The more deprived area had a greater proportion of low birth weight and very low birth weight babies and more mothers who were in their teens and early teens.

Adolescent↗

PubMed1995

Implicit memory performance of patients with Alzheimer's disease: a brief review.

Memory can be assessed with either explicit or implicit tasks. Implicit memory tasks, in contrast with explicit tasks, do not refer to conscious recollection of a previous learning experience. Implicit memory is revealed by a change in task performance that can be attributed to previous learning. Amnesic patients perform poorly on explicit memory tasks, but exhibit normal performance on implicit tasks. Recently, researchers have studied the implicit memory performance of patients with Alzheimer's disease. This article aims to give an overview of the performance of Alzheimer patients on four tasks of implicit memory. Compared with normal elderly controls, patients with Alzheimer's disease seem to demonstrate impaired performance on conceptual, but not on perceptual, implicit memory tasks. This dissociation could yield important information about the neurologic systems subserving implicit memory processes. Some suggestions for future research into the implicit memory of Alzheimer patients are given.

Aged↗

PubMed2006

Sociocultural contexts for the early development of semiotic production.

Children constantly encounter signs during cultural practices, although many theories do not fully acknowledge sociocultural aspects of semiotic development. The author examines research on cultural practices and contexts in which children learn to produce signs involving representational drawing and pretend play. This work is contrasted with more individualistic views of semiotic development that fail to adequately address sociocultural aspects of semiotic functioning to varying degrees. The author also presents a theoretical model for understanding the structure of any sign system and for comparing semiotic systems, using examples from the drawing and pretense literatures. It is proposed that the sign-making practices in which children participate are shaped by a complex hierarchy of conventions.

Art↗