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PubMed2002

Non-specific olfactory aversion induced by intrabulbar infusion of the GABA(A) receptor antagonist bicuculline in young rats.

On postnatal day 12, young rats show an aversion to an odor to which they had been exposed along with presentations of foot shock on postnatal day 11. The acquisition of this aversive learning involves and requires disinhibition of the mitral/tufted cells induced by centrifugal noradrenergic activation during somatosensory stimulation. This olfactory learning is established only for the odor to which the rat has been exposed during conditioning. Infusion of the GABA(A) receptor antagonist bicuculline at a high dose (2.0 nmol/each olfactory bulb) into the olfactory bulb in the presence of an odor is capable of developing olfactory aversive responses without somatosensory stimulation in young rats. The purpose of this study is to characterize the properties of bicuculline-induced aversive responses. In contrast to the odor specificity of aversive learning produced by odor-shock conditioning, bicuculline-induced aversive responses lack odor specificity. Namely, bicuculline infusion in the presence of a citral odor results, in a dose-dependent manner, in subsequent aversive responses to strange odors (benzaldehyde and vanillin) that have never been presented. Moreover, bicuculline infusion alone is sufficient to produce dose-dependent aversive responses to strange odors (citral, benzaldehyde and geraniol). From these results we suggest that disinhibition of mitral/tufted cells from granule cells by bicuculline infusion makes young rats aversive to strange odors non-specifically, as if the rats had learned the odor aversion as a result of odor exposure paired with foot shock. Different mechanisms of disinhibition of the mitral/tufted cells may underlie both the pharmacological manipulation and noradrenergic activation by somatosensory stimulation.

Animals↗

PubMed1984

Mutations in the dopa decarboxylase gene affect learning in Drosophila.

Fruit flies synthesize several monoamine neurotransmitters. Dopa decarboxylase (Ddc) mutations affect synthesis of two of these, dopamine and serotonin. Both transmitters are implicated in vertebrate and invertebrate learning. Therefore, we bred flies of various Ddc genotypes and tested their learning ability in positively and negatively reinforced learning tasks. Mutations in the Ddc gene diminished learning acquisition approximately in proportion to their effect on enzymatic activity. Courtship and mating sequences of the mutants appeared normal, except for one aspect of male courtship that had previously been shown to be experience dependent. In contrast, the effect on behavior patterns that do not involve learning--phototaxis, geotaxis, olfactory acuity, responsiveness to sucrose--was relatively slight under these conditions. Moderate Ddc mutations affected the acquisition of learned responses while leaving memory retention unaltered. This is in contrast to the mutations dunce , rutabaga , and amnesiac , which primarily affect short-term memory.

Animals↗

PubMed2004

Patients with schizophreniform disorder use verbal descriptions for the representation of visual categories.

BACKGROUND: Neuropsychological impairment is a common finding in schizophrenia. However, a significant proportion of patients are not impaired in conventional neuropsychological tests. In this study, we investigated whether remitted patients with schizophreniform disorder exhibited dysfunctions in specific cognitive tasks. METHOD: Twenty remitted, highly functioning patients with schizophreniform disorder and 20 control subjects participated in the study. In addition to background neuropsychological evaluation (WAIS-R IQ, Wisconsin Card Sorting Test (WCST), Trail Making B, Rey Osterrieth Complex Figure), subjects received a category learning task. The categories consisted of geometric shapes systematically changing in shape and size. Training included the sequential presentation of category members (visual learning) and verbal description of categories. RESULTS: The patients with schizophreniform disorder had normal IQ, executive functions/psychomotor speed (WCST and Trail Making B) and visual memory (Rey-Osterrieth Complex Figure). In contrast, they displayed impaired categorization performances after visual learning. The performance of the patients improved markedly after verbal description of categories. Verbal knowledge about categories positively correlated with categorization performance in the patients, but not in the controls. CONCLUSIONS: Category learning functions, which include decision-making under uncertainty and feature integration, are impaired in patients with schizophreniform disorder who display normal executive functions and visual memory. These patients may use verbal knowledge as a compensatory strategy in visual tasks.

Adult↗

PubMed1989

The neuropsychology of de novo patients with idiopathic Parkinson's disease: the effects of age of onset.

One hundred de novo patients with Parkinson's disease (PD) were classified into two groups according to age of onset of symptoms. Seventy two patients were under 70 years and 28 were 70 years and over. All patients were given neurological and neuropsychological assessments, and the severity of the signs was rated on a modified Columbia scale. The neuropsychological assessment was also administered to 50 age-and-education-matched controls. The neuropsychological test battery included tests of verbal learning, visual memory, verbal fluency, visuospatial skill, simple and choice reaction time, language and maze learning. The late-onset patients had significant impairment in nonverbal reasoning, auditory verbal learning, visual memory and choice reaction time in contrast to early-onset patients and controls. A relationship was found between bradykinesia and widespread cognitive impairment. Severity of tremor was found to be significantly correlated with impairment in auditory verbal learning, visual memory and increased choice reaction time, while rigidity was found to be associated with cognitive impairment in verbal fluency and visuospatial skill. Using DSM II criteria, 39% of the late-onset and 8% of the early-onset group were classified as demented. Dementia was more common in patients with bilateral symmetrical disease and in those patients with marked tremor and bradykinesia. The pattern of cognitive impairment in PD was consistent with that associated with a subcortical dementia. This study confirms that the expression of PD is markedly influenced by the age of onset.

Age Factors↗

PubMed2001

The declarative/procedural model of lexicon and grammar.

Our use of language depends upon two capacities: a mental lexicon of memorized words and a mental grammar of rules that underlie the sequential and hierarchical composition of lexical forms into predictably structured larger words, phrases, and sentences. The declarative/procedural model posits that the lexicon/grammar distinction in language is tied to the distinction between two well-studied brain memory systems. On this view, the memorization and use of at least simple words (those with noncompositional, that is, arbitrary form-meaning pairings) depends upon an associative memory of distributed representations that is subserved by temporal-lobe circuits previously implicated in the learning and use of fact and event knowledge. This "declarative memory" system appears to be specialized for learning arbitrarily related information (i.e., for associative binding). In contrast, the acquisition and use of grammatical rules that underlie symbol manipulation is subserved by frontal/basal-ganglia circuits previously implicated in the implicit (nonconscious) learning and expression of motor and cognitive "skills" and "habits" (e.g., from simple motor acts to skilled game playing). This "procedural" system may be specialized for computing sequences. This novel view of lexicon and grammar offers an alternative to the two main competing theoretical frameworks. It shares the perspective of traditional dual-mechanism theories in positing that the mental lexicon and a symbol-manipulating mental grammar are subserved by distinct computational components that may be linked to distinct brain structures. However, it diverges from these theories where they assume components dedicated to each of the two language capacities (that is, domain-specific) and in their common assumption that lexical memory is a rote list of items. Conversely, while it shares with single-mechanism theories the perspective that the two capacities are subserved by domain-independent computational mechanisms, it diverges from them where they link both capacities to a single associative memory system with broad anatomic distribution. The declarative/procedural model, but neither traditional dual- nor single-mechanism models, predicts double dissociations between lexicon and grammar, with associations among associative memory properties, memorized words and facts, and temporal-lobe structures, and among symbol-manipulation properties, grammatical rule products, motor skills, and frontal/basal-ganglia structures. In order to contrast lexicon and grammar while holding other factors constant, we have focused our investigations of the declarative/procedural model on morphologically complex word forms. Morphological transformations that are (largely) unproductive (e.g., in go-went, solemn-solemnity) are hypothesized to depend upon declarative memory. These have been contrasted with morphological transformations that are fully productive (e.g., in walk-walked, happy-happiness), whose computation is posited to be solely dependent upon grammatical rules subserved by the procedural system. Here evidence is presented from studies that use a range of psycholinguistic and neurolinguistic approaches with children and adults. It is argued that converging evidence from these studies supports the declarative/procedural model of lexicon and grammar.

Aphasia↗

PubMed1983

Differential effects of selective dopamine, norepinephrine or catecholamine depletion on activity and learning in the developing rat.

The present experiment investigated the behavioral changes which occurred following neonatal depletion of central catecholamine systems in the rat. The behavioral effects which resulted from selective dopamine (DA) depletion were compared with those resulting from selective norepinephrine (NE) depletion as well as depletion of both catecholamines (CA). Neonatal 6-hydroxydopamine (6-OHDA) was administered intracisternally at 5 days of age following pretreatment with desmethylimipramine in order to selectively deplete DA. NE levels were reduced by intraperitoneal injections of 6-OHDA at 1 and 2 days of age. Depletion of both catecholamines was effected by combining the procedures used for selective depletion of both DA and NE. Activity was time sampled during an hour at 3 preweanling ages. Avoidance and escape learning were measured in a T maze when pups were 20 days of age and in a Shuttlebox apparatus on day 28. Results revealed that DA and CA depleted animals were hyperactive in comparison to controls and displayed severe learning impairments in both T maze and Shuttlebox performance. In contrast, NE depleted animals showed activity levels which were similar to controls but were significantly impaired on both learning paradigms. These results suggest that selective lesions of DA and NE in infancy lead to a constellation of behaviors which are distinctly unique. The implications of these findings is discussed in terms of clinical research into the Attentional Deficit Disorder of childhood.

Animals↗

PubMedDate not supplied

Enhanced DRL and impaired forced-choice alternation performance following hippocampal lesions in the pigeon.

In four experiments, pigeons with bilateral lesions of the hippocampus were compared to unoperated control birds and operated control subjects that received bilateral lesions of the neostriatum on tasks sensitive to hippocampal damage in mammals. Consistent with the mammalian literature, hippocampal birds were impaired on forced-choice alternation in the T-maze, although they were unimpaired on spatial alternation and reversal learning in an operant chamber. Furthermore, in contrast to hippocampal mammals, hippocampal pigeons showed enhanced performance on a differential reinforcement of low-rates of responding schedule of reinforcement. The results are discussed with respect to a behavioural homology between the avian and mammalian hippocampal formations.

Animals↗

PubMed1992

Implicit learning in psychotic patients.

Implicit verbal learning of psychotic patients (n = 59) and non-psychotic control patients (n = 20) was studied using stem completion and association tasks in lexical and semantic priming paradigms. Performance on these tasks was contrasted with explicit memory on Rey's verbal learning test. Furthermore, correlations of these aspects of memory with positive and negative symptoms of psychosis were examined. Symptom ratings were based on an interview by a psychiatrist using the CPRS and SANS. As expected, the lexical and semantic priming effects in both patient groups were not significantly different, whereas the psychotic patients compared to the controls were impaired in explicit learning. None of the memory variables was significantly correlated with negative or positive symptoms. These findings are explained by the fact that priming effects, as opposed to explicit learning, depend on automatic memory processes, which do not require conscious effort. Moreover, the findings suggest the intactness of posterior cortical functions in psychotic patients.

Adult↗

PubMed2003

Attentive tracking of objects versus substances.

Recent research in vision science, infant cognition, and word learning suggests a special role for the processing of discrete objects. But what counts as an object? Answers to this question often depend on contrasting object-based processing with the processing of spatial areas or unbound visual features. In infant cognition and word learning, though, another salient contrast has been between rigid cohesive objects and nonsolid substances. Whereas objects may move from one location to another, a nonsolid substance must pour from one location to another. In the study reported here, we explored whether attentive tracking processes are sensitive to dynamic information of this type. Using a multiple-object tracking task, we found that subjects could easily track four items in a display of eight identical unpredictably moving entities that moved as discrete objects from one location to another, but could not track similar entities that noncohesively "poured" from one location to another-even when the items in both conditions followed the same trajectories at the same speeds. Other conditions revealed that this inability to track multiple "substances" stemmed not from violations of rigidity or cohesiveness per se, because subjects were able to track multiple noncohesive collections and multiple nonrigid deforming objects. Rather, the impairment was due to the dynamic extension and contraction during the substancelike motion, which rendered the location of the entity ambiguous. These results demonstrate a convergence between processes of midlevel adult vision and infant cognition, and in general help to clarify what can count as a persisting dynamic object of attention.

Adult↗

PubMed2006

Interactions between encoding and retrieval in the domain of sequence-learning.

In this article, the authors propose to characterize sequence learning in terms of automatic versus non-automatic processing and to apply this contrast independently to knowledge acquisition and retrieval. In several experiments of sequence learning, automaticity of both the acquisition and retrieval of the acquired knowledge was independently assessed. It was found that the sequence learning order can be demonstrated under all combinations of knowledge acquisition and retrieval. In particular, at least in the simple sequences the authors used, this applies in cases in which both the acquisition and the retrieval of knowledge are strictly automatic--that is, when neither is required for the task nor beneficial to deliberate behavior. The proposed framework has implications for the notion of sequence learning and the investigation of learning in general.

Association Learning↗

PubMed2004

[Comparing students in inclusive education to those in special schools: the view of parents of children with learning disabilities].

The paper presents the results of a survey of 755 parents of learning disabled children with certified special needs who either attended classes within regular education or special schools. All parents were involved in the decision on the school placement of their children. The experiences of 547 parents of learning disabled students in inclusive classes were contrasted with those of 207 parents of children in special schools. Besides a rather high satisfaction with previous school experiences of their children a number of differences between the two groups of parents could be observed. Parents of students in special schools viewed their children as rather little challenged by their educational requirements whereas those in inclusive education found their children to be overtaxed. The social development of the students in inclusive education was judged as more positive and, generally, a higher rate of parents of learning disabled students in inclusive classes were satisfied with their choice of the educational setting. Although the requirements for parental support concerning studying were higher in inclusive classes this cannot solely explain the differences of experiences with school. In a second step, satisfied parents were compared to dissatisfied parents. It could be found that the group of dissatisfied parents had to make their choice on the educational setting of their children under less favourable conditions and many could not accept that their child had been classified as having special needs. This applied to parents of students in inclusive education as well as to parents of children in special schools. Additionally, parents of students with German as a second language reported to be discontented more frequently. No significant discrepancies could be found between different grades or federal states with different quotas of inclusive education.

Attitude↗

PubMed2000

Profiles of cognitive dysfunction in chronic amphetamine and heroin abusers.

Groups of subjects whose primary drug of abuse was amphetamine or heroin were compared, together with age- and IQ-matched control subjects. The study consisted of a neuropsychological test battery which included both conventional tests and also computerised tests of recognition memory, spatial working memory, planning, sequence generation, visual discrimination learning, and attentional set-shifting. Many of these tests have previously been shown to be sensitive to cortical damage (including selective lesions of the temporal or frontal lobes) and to cognitive deficits in dementia, basal ganglia disease, and neuropsychiatric disorder. Qualitative differences, as well as some commonalities, were found in the profile of cognitive impairment between the two groups. The chronic amphetamine abusers were significantly impaired in performance on the extra-dimensional shift task (a core component of the Wisconsin Card Sort Test) whereas in contrast, the heroin abusers were impaired in learning the normally easier intra-dimensional shift component. Both groups were impaired in some of tests of spatial working memory. However, the amphetamine group, unlike the heroin group, were not deficient in an index of strategic performance on this test. The heroin group failed to show significant improvement between two blocks of a sequence generation task after training and additionally exhibited more perseverative behavior on this task. The two groups were profoundly, but equivalently impaired on a test of pattern recognition memory sensitive to temporal lobe dysfunction. These results indicate that chronic drug use may lead to distinct patterns of cognitive impairment that may be associated with dysfunction of different components of cortico-striatal circuitry.

Adolescent↗

PubMed1995

The differences in learning abilities between spontaneously hypertensive (SHR) and Wistar normotensive rats are cue dependent.

We examined the performance of spontaneously hypertensive (SHR) and Wistar normotensive (NT) rats in acquisition, retention after a 2-month interval, and reversal learning in two tasks: simultaneous brightness discrimination (Experiment I) and conditional discrimination of directional locomotor responses (Experiment II). In both tasks food reinforcement was used. In Experiment I both SHR and NT groups comprised younger (3-month-old) and older (10-month-old) rats. In each experimental stage SHRs of both age groups mastered the task earlier and made fewer errors than the respective NT groups. Reversal learning took longer than acquisition of discrimination in both age groups of NT rats. Conversely, reversal learning was an easier task for SHR. In Experiment II only younger rats were used. The forced turn at the start in the modified T-maze was utilized as the cue to guide performance at the choice point of the maze. In acquisition and retention, rats were trained to select at the choice point the arm in the same direction as in the forced turn; in the reversal, opposite contingencies were applied. At all stages the choice accuracy of SHR was the same as that in NT rats. The contrasting findings of Experiment I and Experiment II indicate that SHR learned better than NT when exteroceptive visual stimuli were used, but performed at the same level as NT rats in the task where interoceptive kinesthetic cues were relevant. We suggest that SHR pay more attention to visual stimuli than NT rats.

Age Factors↗

PubMed1996

Expression of the transcription factor Zif268 in the temporal cortex of monkeys during visual paired associate learning.

In humans and monkeys, memory consists of various components which were initially revealed through neuropsychological studies of amnesic patients. One memory component, the long-term memory about facts and events (declarative memory), has been shown to require the integrity of the medial temporal lobe and the neocortex. To investigate a map of gene expression during declarative memory formation in the primate, we monitored expression of immediate early genes in the temporal lobe of macaque monkeys. We trained the monkeys to learn visual associative memory tasks, and immunohistochemically analysed the expression of protein products of immediate early genes. We found that Zif268, a transcription factor regulated by neuronal activity, accumulated in patches in the anterior temporal lobe during visual stimulus-stimulus association learning, whereas other transcription factors, c-Fos and JunD, were not. By contrast, the patchy expression of Zif268 was not observed during another type of learning, visual discrimination learning. These results suggest that Zif268 activates a gene cascade related to the formation of long-term memory in the primate.

Animals↗

PubMed2006

Inactivation of cerebellar output axons impairs acquisition of conditioned eyeblinks.

Acquisition of classically conditioned eyeblink responses (CRs) in the rabbit critically depends on intermediate cerebellum-related neural circuits. A highly efficient method for determining possible sites of plasticity within eyeblink circuits is the reversible inactivation of circuit components during learning. Inactivation of either the HVI region of the cerebellar cortex or the cerebellar interposed nuclei (IN) during learning is known to prevent CR acquisition. In contrast, inactivating cerebellar efferent axons in the brachium conjunctivum (BC) with small injections of tetrodotoxin (TTX) has been reported to have no effect on CR acquisition. This suggested that the intermediate cerebellum is essential for learning CRs and that activity mediated by the BC is not required for this process. Since we previously found that BC inactivation blocks CR extinction we re-examined its role in CR acquisition. To ensure complete and long-lasting inactivation of the BC, we injected before each training session doses of TTX that were larger than those in the previous acquisition study. Contrary to the previous negative findings, we found that this temporary block of axons in the brachium conjunctivum prevented normal acquisition of CRs. Injecting TTX directly in the adjacent lateral lemniscus, which could possibly influence CR acquisition, had no effect on learning. In addition, a functional test of TTX diffusion around the BC indicated that the inactivation did not affect other known parts of eyeblink circuits, such as the cerebellar interposed nuclei, the middle cerebellar peduncle or the contralateral red nucleus. We conclude that this form of associative learning in the rabbit eyeblink system requires extra-cerebellar learning and/or cerebellar learning that depends on the operation of cerebellar feedback loops.

Anesthetics, Local↗

PubMed1996

Analysis of cognitive and psychological deficits in systemic lupus erythematosus patients without overt central nervous system disease.

OBJECTIVE: To examine cognitive and psychological functioning in relation to antiribosomal P protein autoantibodies in patients with systemic lupus erythematosus (SLE) who had no previous history of central nervous system disease (non-CNS SLE). METHODS: Comprehensive neuropsychological and psychological tests were administered to 51 non-CNS SLE patients, 29 rheumatoid arthritis (RA) patients, and 27 healthy controls. RESULTS: Twenty-nine percent of the non-CNS SLE patients, 31% of the RA patients, and 11% of the control subjects were classified as cognitively impaired. Similar reductions in intelligence, attention, and fluency were detected in the non-CNS SLE and RA patients compared with controls. The non-CNS SLE patients showed a distinct deficit in learning compared with the RA and control groups. Forty-two percent of the non-CNS SLE patients demonstrated psychological distress, compared with 7% of the RA patients and 6% of the controls. In the patient groups, neither cognitive dysfunction nor psychological distress was associated with disease activity or prednisone dosage. Elevated serum levels of autoantibodies to ribosomal P protein were not associated with either psychological or cognitive abnormalities. CONCLUSION: These results suggest that certain cognitive deficits in non-CNS SLE patients may not be specific to the immunopathology of SLE. In contrast, it is possible that deficits in learning, as well as psychological distress without major psychiatric pathology, may be subtle manifestations of CNS lupus.

Adult↗

PubMed1997

The role of the hypothalamic-pituitary-adrenocortical axis in memory-related effects of anxiolytics.

Two major classes of antianxiety drugs, benzodiazepines and partial agonists of 5-HT1A receptors, have dissimilar effects on learning. Benzodiazepines induce amnesic effects in humans and animals. In contrast, partial agonists of 5-HT1A receptors do not suppress memory in humans and have variable effects in animal learning models. The two groups of drugs shift activity of the hypothalamic-pituitary-adrenocortical (HPA) axis in opposite ways. Benzodiazepines, given at antianxiety doses, suppress HPA axis excitability. Partial agonists of 5-HT1A receptors facilitate HPA excitability and, at higher doses, directly stimulate ACTH secretion. Assuming that certain components of the HPA axis are involved in memory acquisition, it is hypothesized that antianxiety drugs may affect learning through the regulation of HPA axis excitability.

Adrenocorticotropic Hormone↗

PubMed1998

Learning difficulties of diabetic patients: a survey of educators.

This study was designed to shed light on the learning difficulties of diabetic patients. An open-ended questionnaire was sent to 85 health care professionals working in the field of diabetes and nutrition who had been trained in patient education techniques. They were asked to describe the skills that were the easiest to teach patients and those that patients mastered the best, as well as the skills they found hardest to teach patients, those that patients mastered the least and those that gave rise to errors persisting after the patients education was completed. On the whole, the results showed that the educators found it easy to teach techniques: patients mastered procedures well and made few mistakes. In contrast, diabetic patients seem to have problems learning skills, such as insulin dose adjustment, that require complex problem-solving (involving multiple variables). Based on these findings, the authors discuss the notions of learning complexity and the time needed for successful patient education.

Attitude of Health Personnel↗