RESUMEN
The characteristics of learning processes and long-term memory (LTM) were studied in rhesus macaques discriminating visual stimuli (geometrical figures of different shapes, sizes, and orientations, and with different spatial relationships between image components). Trained monkeys were tested for the ability to perform invariant recognition after stimulus transformation, i.e., changes in size, shape, number of objects, and spatial relationships. Analysis of behavioral characteristics (correct solutions, refusals to decide, motor response times) revealed differences associated with the type of visual information. When monkeys discriminated between black and white geometrical figures of different shapes and orientations, as well as black-and-white figures with different shapes or orientations, the learning time was short and transformation of the stimuli had no effect on correct solutions: there was complete transfer of learning. When monkeys discriminated figures of different sizes or complex images with different spatial relationships, the learning time was significantly greater. Changes in the size and shape of figures led to significant reductions in correct solutions and significant increases in refusals to solve the task and in motor reaction times. Invariance of discrimination in this case appeared after additional training. The results obtained here showed that in conditioned reflex learning, the sensory processing of stimuli has the result that discriminatory features are formed in LTM, i.e., cognitive structures (functional neurophysiological mechanisms), these supporting the classification of visual images. The temporal conditioned link of the executive reaction is established with these. Their formation is determined by the type of sensory information and the existence in LTM of separate subsystems for spatial and non-spatial information.
Asunto(s)
Cognición/fisiología , Imagen Eidética/fisiología , Reconocimiento en Psicología/fisiología , Animales , Femenino , Macaca mulatta , MasculinoRESUMEN
Two lines of rats, selected according to the excitability of nervous system to the action of an electric current, served as the model objects to study the changes of heterochromatin characteristics in neurons of hippocampus (area CA3) 24 hours, 2 weeks, 2 and 6 months after exposure to prolonged emotional painful stress. It was shown that exposure to stress caused changes in the area, occupied by heterochromatin, only in rats with low-excitability: it was decreased 24 hours, 2 weeks and 2 months following the stress, while it was increased after 6 months as compared to control values. Thus, it was demonstrated for the first time that long-term modifications of heterochromatin structural characteristics of neurons in hippocampus (area CA3) could depend on genetically determined functional state of the nervous system.
Asunto(s)
Heterocromatina/ultraestructura , Hipocampo/ultraestructura , Neuronas/ultraestructura , Trastornos por Estrés Postraumático/patología , Estrés Psicológico/patología , Animales , Modelos Animales de Enfermedad , Estimulación Eléctrica , Masculino , Fenómenos Fisiológicos del Sistema Nervioso , Ratas , Ratas Endogámicas , Estrés Psicológico/genéticaRESUMEN
The processes of learning and storage of the results of learning were studied in a model of Alzheimer's disease in two groups of rhesus macaques (three individuals in each group). Studies were performed after injection of neurotoxins (group I) and physiological saline (group II, controls). Two months after injections (stage C1), learning parameters were studied in monkeys of both groups using a new stimulus discrimination test (filled geometrical figures versus outline figures). There were significant differences between the animals of the two groups. Learning was hindered in monkeys of group I, with significant increases in the learning time (the time to achieve a stable probability of correct responding of 0.85) and in the probability of refusals. Monkeys of group II showed no learning impairment. Animals were trained to discriminate new stimuli (images of two monkeys) six months after injections (stage C3). Learning was impaired in animals of group I, such that learning measures had the same levels as previously; monkeys of group II showed no learning impairment. Analysis of the characteristics of working memory, which is involved in storing the results of new learning, was performed at stage C1; monkeys of group I showed significant degradation of these measures, with a significant decrease in the probability of correct solutions at stage C1 (to a level of 0.5), with some increase at stages C2 (at four months) and C3, along with a significant increase in the probability of refusals, values being similar at all time points. For monkeys of group II, these characteristics showed no degradation. Motor response times at stages C1, C2, and C3 were not different for the two groups of monkeys. The structural-functional organization of interactions between sensory and cognitive processes during learning and the storage of information in working memory are discussed, as is the role of the associative areas of the cortex in these interactions.
Asunto(s)
Enfermedad de Alzheimer/patología , Enfermedad de Alzheimer/fisiopatología , Corteza Cerebral/fisiopatología , Discapacidades para el Aprendizaje/etiología , Memoria a Corto Plazo/fisiología , Enfermedad de Alzheimer/inducido químicamente , Animales , Conducta Animal , Aprendizaje Discriminativo/fisiología , Modelos Animales de Enfermedad , Macaca mulatta , Neurotoxinas , Reconocimiento Visual de Modelos/efectos de los fármacos , Reconocimiento Visual de Modelos/fisiología , Estimulación Luminosa/métodos , Probabilidad , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/fisiologíaRESUMEN
The first part of the present study used a model of Alzheimer's disease in two groups of animals (three monkeys in each), given injections of neurotoxins (monkeys of group I) and physiological saline (monkeys of group II). Before injections, all monkeys were trained to discriminate stimuli containing different types of information (spatial frequency grids and geometrical figures of different colors and with different spatial relationships between objects) and to perform spatial selection. The dynamics of impairments in the characteristics of working memory were identified using delayed differentiation tasks in monkeys of both groups before injections and every two months after injections. Quantitative measures of impairments were made using the entropy of visual recognition, which characterizes uncertainty in decision-taking. The development of Alzheimer's disease in rhesus macaques was characterized by a deficit of working memory, resulting from lesions to the two component processes of memory. Impairments of the first of these in monkeys of group I were manifest as a significant increase in entropy, which is associated with correct decision-taking. The magnitude of the increase depended on the type of visual information. Impairments of the second component were characterized by increases in entropy associated with refusals to take decisions and were independent of the delay duration and the type of visual information. Monkeys given injections of physiological saline showed no significant changes in these characteristics. The features of working memory were also studied in the second part of the investigation, using four groups of Rhesus macaques: intact, those with bilateral extirpation of the sulcus principalis or field 7 or both: degradation again identified two components. Entropy associated with this was increased significantly for most of the stimuli tested on monkeys of all extirpation groups as compared with intact animals. Significant differences were found in these characteristics for a number of stimuli, which depended on the location of the structures removed. The characteristics of impairments of the components of working memory resulting in the development of Alzheimer's disease showed that the cholinergic mechanisms responsible for sensory processing differ from those involved in decision-taking. The structural-functional organization of the interaction of sensory and cognitive processes controlled by the motivation and attention systems is discussed, as is the role of the associative areas of the cortex.
Asunto(s)
Corteza Cerebral/fisiología , Cognición/fisiología , Reconocimiento Visual de Modelos/fisiología , Conducta Espacial/fisiología , Animales , Conducta Animal , Corteza Cerebral/efectos de los fármacos , Cognición/efectos de los fármacos , Toma de Decisiones/efectos de los fármacos , Toma de Decisiones/fisiología , Aprendizaje Discriminativo/efectos de los fármacos , Aprendizaje Discriminativo/fisiología , Modelos Animales de Enfermedad , Entropía , Haplorrinos , Memoria a Corto Plazo/efectos de los fármacos , Memoria a Corto Plazo/fisiología , Modelos Cardiovasculares , Pruebas Neuropsicológicas , Neurotoxinas/farmacología , Enfermedad de Parkinson/etiología , Enfermedad de Parkinson/fisiopatología , Reconocimiento Visual de Modelos/efectos de los fármacos , Estimulación Luminosa/métodos , Tiempo de Reacción/efectos de los fármacos , Tiempo de Reacción/fisiología , Conducta Espacial/efectos de los fármacos , Factores de TiempoRESUMEN
Studies were performed on two groups of animals (three monkeys in each). Monkeys of group I received unilateral intracerebroventricular injections of the neurotoxin p75-saporin (the ribosomal toxin saporin bound to monoclonal antibody to the p75NTR receptor), which elicits irreversible degradation of cholinergic neurons in the basal nuclei of Meynert, along with the enzyme dopamine-beta-hydroxylase (DBH-saporin), which impairs the functioning of noradrenergic neurons in the locus ceruleus. Monkeys of group II received injections of sterile physiological saline (0.9% NaCI). Monkeys were trained to discriminate stimuli containing different types of information (spatial frequency grids, geometric figures with different colors, different spatial relationships between objects) and perform spatial selection. The characteristics of working memory were identified in delayed differentiation tasks in monkeys of both groups before and after injections. These studies provided the first evidence that the development of Alzheimer's disease in rhesus macaques is characterized by a deficiency of working memory, this being based on impairment of two components of these processes. Impairment of the first in monkeys of group I was minifest in delayed visual differentiation as a significant decrease in correct responses. The extent of decreases depended on the duration of the delay and the type of visual information. Impairment of the second component, associated with decision-taking processes, was characterized by an increase in refusals to take decisions and was independent of the duration of delays and the type of visual information. Monkeys given injections of physiological saline showed no significant differences in these characteristics. The features of impairments in these memory components resulting from the development of Alzheimer's disease demonstrate that the structural-functional organization of cholinergic and noradrenergic mechanisms responsible for sensory processing differ from those involved in decision-taking.
Asunto(s)
Enfermedad de Alzheimer/fisiopatología , Enfermedad de Alzheimer/psicología , Toma de Decisiones/fisiología , Aprendizaje Discriminativo/fisiología , Memoria , Enfermedad de Alzheimer/inducido químicamente , Animales , Fibras Colinérgicas/efectos de los fármacos , Fibras Colinérgicas/patología , Modelos Animales de Enfermedad , Modelos Lineales , Macaca mulatta , Neurotoxinas , Reconocimiento Visual de Modelos/fisiología , Solución de Problemas/fisiología , Tiempo de Reacción/fisiología , Receptor de Factor de Crecimiento Nervioso , Receptores de Factor de Crecimiento Nervioso/efectos de los fármacos , Percepción Espacial/fisiologíaRESUMEN
Behavioral studies were carried out on Rhesus macaques to investigate the relationship between the processes of learning a visual differentiation task and various properties of the stimuli, with the aim of identifying the effect on learning of a cognitive factor such as the biological significance of the visual object. Cluster analysis of a number of features of the learning process was used to distinguish visual stimuli (16 pairs) into separate compact classes of similar objects, each of which appeared to be characterized by its level of biological significance. A scheme describing the learning process, and including an assessment of the significance of sensory information, is proposed.
Asunto(s)
Condicionamiento Operante/fisiología , Aprendizaje Discriminativo/fisiología , Percepción Visual/fisiología , Animales , Análisis por Conglomerados , Macaca mulatta , Estimulación LuminosaRESUMEN
Experiments on rhesus macaques were used to study the relationship between the characteristics of delayed visual differentiation and stimulus properties in conditions of pharmacological treatment with the m-cholinoreceptor blocker amizil, with the aim of identifying how modification of cholinergic structures affects different types of information. Disturbances to short-term memory for all stimuli consisted of reductions in the duration of retention and increases in motor reaction times, but occurred at different doses of the blocker: amizil at a dose of 0.3 mg/kg significantly decreased the retention duration for information relating to spatial relationships. Delayed discrimination of shape, contrast, and size worsened after treatment with amizil at a dose of 0.45-0.50 mg/kg, while decreases in the duration of short-term storage of information relating to color started after amizil doses of 0.6-0.8 mg/kg. It is suggested that the short-term memory system includes a set of neurophysiological mechanisms in which the cholinergic structures are organized differently and whose specific properties result in differences in the characteristics of short-term storage of different types of visual information.
Asunto(s)
Benactizina/farmacología , Memoria a Corto Plazo/fisiología , Antagonistas Muscarínicos/farmacología , Sistema Nervioso Parasimpático/fisiología , Percepción Visual/fisiología , Animales , Percepción de Color/efectos de los fármacos , Femenino , Percepción de Forma/efectos de los fármacos , Macaca mulatta , Masculino , Memoria a Corto Plazo/efectos de los fármacos , Sistema Nervioso Parasimpático/efectos de los fármacos , Estimulación Luminosa , Receptores Muscarínicos/efectos de los fármacos , Percepción del Tamaño/fisiología , Percepción Espacial/fisiología , Percepción Visual/efectos de los fármacosRESUMEN
The effects of modification of NMDA-ergic structures by microdialysis perfusion in the prefrontal cortex (field 8) with NMDA glutamate (2 mM) on visual recognition and short-term memory (STM) were studied in rhesus macaques, using methods based on the deferred differentiation of stimuli of different colors. Impulse activity of neurons in the prefrontal and visual cortex was measured during these experiments, both before and after administration of NMDA. NMDA increased (2-fold) the duration of short-term retention of information and significantly reduced the latent period of the motor response at all delay periods, and also produced significant changes in neuron activity in the prefrontal cortex: depending on the stage of behavior, activity decreased in 60-75% of neurons and increased in 8-26%. NMDA produced significant increases in the cross-correlation coefficients between the responses of neurons in the visual and prefrontal cortex. The results showed that glutaminergic structures in the prefrontal cortex are involved in processes of visual recognition and STM in monkeys. The effect of NMDA, which synchronized cortical neuronal processes, improved the short-term understanding of visual information.
Asunto(s)
Cognición/fisiología , Agonistas de Aminoácidos Excitadores/farmacología , N-Metilaspartato/fisiología , Corteza Prefrontal/fisiología , Animales , Cognición/efectos de los fármacos , Electrofisiología , Macaca mulatta , Memoria a Corto Plazo/efectos de los fármacos , Microdiálisis , N-Metilaspartato/farmacología , Corteza Prefrontal/efectos de los fármacos , Corteza Visual/efectos de los fármacos , Corteza Visual/fisiologíaRESUMEN
The activity of individual neurons of the visual cortex was recorded simultaneously in behavioral experiments on monkeys before and after the systemic administration of a blocker of M-cholinoreceptors, amizil (0.8-1.0 mg/kg). The animals were trained to delayed visual differentiation of stimuli of various colors. After the administration of amizil, the characteristics of recognition deteriorated substantially: the duration of the storage of information in short-term memory sharply declined, while the time of the motoric reaction increased. The deterioration of these characteristics was accompanied by inhibition of the activity of the neurons of the visual cortex, inhibition which depended on the stage of recognition, and which intensified when there was an increase in the delay interval. The results obtained suggest that cholinergic mechanisms of the visual cortex are included in visual recognition, and apparently play various functional roles at various stages of behavior.
Asunto(s)
Cognición/fisiología , Antagonistas Muscarínicos , Neuronas/fisiología , Corteza Visual/fisiología , Percepción Visual/fisiología , Animales , Benactizina/farmacología , Cognición/efectos de los fármacos , Discriminación en Psicología/efectos de los fármacos , Lincomicina/farmacología , Macaca mulatta , Memoria a Corto Plazo/efectos de los fármacos , Neuronas/efectos de los fármacos , Corteza Visual/citología , Corteza Visual/efectos de los fármacos , Percepción Visual/efectos de los fármacosRESUMEN
Behavioral experiments were carried out in which monkeys had to solve a task involving delayed visual discrimination, and activity was simultaneously recorded from several neurons of the visual, prefrontal, and lower temporal regions of the cortex before and after modification of cholinergic (by systemic infusion of the M-cholinoceptor blocker amizil) and glutaminergic (by intracortical perfusion with glutaminergic agonists and antagonists, i.e., NMDA, aminophosphonovalerianic acid (APV) and aminophosphonobutyric acid (APB)) systems. Amizil and APV reduced the duration of short-term information retention and increased the delay before the motor response was made. Worsening of these parameters was accompanied by a significant level of desynchronization of activity in the groups of neurons studied. NMDA and APB improved short-term memory and increased neuron synchronization. The role of synchronization of information processes in the mechanisms of short-term memory and the involvement of the cholinergic and glutaminergic systems are discussed.
Asunto(s)
Corteza Cerebral/fisiología , Ácido Glutámico/fisiología , Memoria a Corto Plazo/fisiología , Sistema Nervioso Parasimpático/fisiología , Aminobutiratos/administración & dosificación , Aminobutiratos/farmacología , Animales , Antagonistas Colinérgicos/administración & dosificación , Antagonistas Colinérgicos/farmacología , Discriminación en Psicología/fisiología , Agonistas de Aminoácidos Excitadores/administración & dosificación , Agonistas de Aminoácidos Excitadores/farmacología , Inyecciones , Macaca mulatta , Neuronas/fisiología , Corteza Prefrontal/citología , Corteza Prefrontal/fisiología , Lóbulo Temporal/citología , Lóbulo Temporal/fisiología , Corteza Visual/citología , Corteza Visual/fisiologíaRESUMEN
The effect of intracortical perfusion with the glutamate agonist NMDA on visual recognition and short-term memory, as well as an on the responses of visual cortex neurons, were studied in rhesus macaques. A microdialysis technique was used in combination with multichannel microelectrode recording of single cortical cells in the immediate vicinity of the dialysis tube in a behavioral experiment in which the monkey had to solve a task involving delayed visual differentiation of stimuli of different colors. NMDA altered the characteristics of recognition in monkeys. The duration of information storage in short-term memory was increased significantly (2-4-fold), and there was a significant reduction in the motor response time for all delay periods. These changes were accompanied by a significant rearrangement of neuron activity in the visual cortex at all stages of the behavioral task. At different stages of the task, 70-85% of the neurons showed 2-5-fold increases in activity, while 6-20% showed reductions in activity. These results demonstrate an involvement of visual cortex glutaminergic structures in the process of visual recognition and short-term memory, as well as a nootropic effect obtained by intracortical administration of NMDA.
Asunto(s)
Agonistas de Aminoácidos Excitadores/farmacología , Ácido Glutámico/fisiología , N-Metilaspartato/farmacología , Reconocimiento Visual de Modelos/efectos de los fármacos , Corteza Visual/efectos de los fármacos , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Animales , Cognición/fisiología , Electrodos Implantados , Electrofisiología , Agonistas de Aminoácidos Excitadores/administración & dosificación , Macaca mulatta , Memoria a Corto Plazo/efectos de los fármacos , Microdiálisis , N-Metilaspartato/administración & dosificación , Neuronas/efectos de los fármacos , Neuronas/fisiología , Tiempo de Reacción/fisiología , Corteza Visual/citologíaRESUMEN
Experiments were performed on Rhesus macaques to study the relationship between delayed visual differentiation processes and stimulus properties. These investigations showed that the processes of short-term storage of visual information in monkeys has significant features associated with differences in stimulus properties. These consisted of different durations of storage and motor response times. Because of these differences, stimuli (15 pairs) could be grouped into compact clusters on the bases of similarity between their delayed differentiation characteristics. These experiments characterized the processes of short-term information storage during the differentiation of stimuli differing in terms of spatial relationships between elements, as compared with stimuli differing in terms of other attributes (shape, color, etc.); spatial information was stored for shorter periods of time and motor response times were longer. It is suggested that visual short-term memory involves a set of mechanisms operating on attributes of different types and which, along with signs and working programs associated with the visual system, stores spatial discriminatory signs, in which the major role is played by visual-vestibular interactions.
Asunto(s)
Memoria a Corto Plazo/fisiología , Percepción Espacial/fisiología , Animales , Análisis por Conglomerados , Percepción de Color/fisiología , Condicionamiento Operante/fisiología , Percepción de Forma/fisiología , Macaca mulatta , Percepción del Tamaño/fisiologíaRESUMEN
A delayed visual differentiation task using stimuli of different colors was used in rhesus macaques to study the characteristics of visual recognition, short-term memory, and the responses of neurons recorded simultaneously in the visual and prefrontal areas of the cortex, along with their relationships with the site of intracortical (fields 17 or 46) perfusion of the glutamate receptor antagonist 2-amino-5-phosphonovaleric acid (APV). The behavioral characteristics and spike activity of individual cells in cortical fields 17 and 46 were recorded before and after perfusion with APV and after washing away of traces of APV. Multifactor dispersion analysis showed that the effect of APV in monkeys consisted of decreases in the probability of correct responses, leading to a decrease (two-fold) in the duration of short-term storage of information and a significant increase in the motor reaction time. The probability of correct solutions depended on the site of APV perfusion in the cortex, while the motor response time was independent of the perfusion site. Perfusion of field 46 with APV, unlike perfusion of field 17, altered the spike activity only of neurons in the prefrontal cortex, while no significant changes were seen in the neuron activity of the visual cortex. The actions of APV were accompanied by significant desynchronization of neuron activity in these two areas as compared with the level of synchronization in normal conditions; after traces of APV were washed away, the extent of desynchronization decreased. The neurophysiological correlates of cognitive dysfunctions associated with degradation of visual recognition and short-term memory due to modification of glutamatergic structures by blockade of NMDA receptors are discussed.
Asunto(s)
Discriminación en Psicología/efectos de los fármacos , Discriminación en Psicología/fisiología , Antagonistas de Aminoácidos Excitadores/farmacología , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores , Corteza Visual/efectos de los fármacos , Corteza Visual/fisiología , Percepción Visual/efectos de los fármacos , Percepción Visual/fisiología , 2-Amino-5-fosfonovalerato/farmacología , Animales , Macaca mulatta , Microdiálisis , Tiempo de Reacción/fisiologíaRESUMEN
The effects of perfusion of field 17 with the glutamate receptor antagonist 2-amino-5-phosphonovaleric acid (APV) on the characteristics of visual recognition and short-term memory were studied, along with the effects of APV on the responses of neurons in the visual and prefrontal areas of the cortex in rhesus macaques. In the test for delayed visual differentiation of stimuli of different colors, behavioral data were recorded simultaneously with multichannel recordings of the spike activity of single cells in cortical field 17 (directly within the microdialysis zone) and field 8. Multifactor dispersion analysis (ANOVA) showed that APV significantly worsened the behavioral characteristics in monkeys, with significant reductions in the duration of short-term storage of information (by factors of 2-4) and significant increases in the motor response times. These changes in cognitive characteristics induced by APV were accompanied by changes in the spike activity of neurons in the visual and prefrontal areas of the cortex during the sensory analysis and delay stages; changes in spike activity consisted of significant desynchronization. These results show that cognitive dysfunctions consisting of worsening of short-term remembering of information and increases in the duration of motor responses during exposure to APV may be caused by desynchronization of neuron activity in various areas of the cortex, these being involved in neuron ensembles responsible for the mechanisms of short-term memory, in which glutamatergic structures play an important role.
Asunto(s)
Discriminación en Psicología/efectos de los fármacos , Neuronas/fisiología , Corteza Prefrontal/fisiología , Receptores de N-Metil-D-Aspartato/antagonistas & inhibidores , Corteza Visual/fisiología , Percepción Visual/efectos de los fármacos , 2-Amino-5-fosfonovalerato/farmacología , Animales , Potenciales Evocados/efectos de los fármacos , Potenciales Evocados/fisiología , Antagonistas de Aminoácidos Excitadores/farmacología , Macaca mulatta , Actividad Motora/efectos de los fármacos , Actividad Motora/fisiología , Corteza Prefrontal/citología , Corteza Visual/citologíaRESUMEN
The impulse activity of individual neurons of the prefrontal and inferotemporal cortex was recorded during the performance of a task of delayed visual differentiation of stimuli of various colors in monkeys before and after the systemic administration of the antioxidant, oxymethacil (4-5 mg/kg). The improvement in cognitive characteristics induced by oxymethacil was accompanied by changes in the activity of neurons of the prefrontal cortex in which activation dependant upon the stage of recognition and intensifying during an increase in the duration of the delay predominated. Inhibition of activity predominated during recognition without delay in these neurons; by contrast, activation predominated in neurons of the inferotemporal cortex under these conditions. During delayed differentiation, the activity of these neurons under the influence of oxymethacil changed principally in the same way as in neurons of the prefrontal cortex: activation predominated in the majority of the stages of recognition. Oxymethacil induced a substantial increase in the coefficients of cross correlation between simultaneous respondent reactions of groups of neurons in these different areas of the cortex. The results obtained attest to the contribution of neuronal structures of the prefrontal and inferotemporal cortex to the improvement of cognitive characteristics of monkeys in the presence of the effect of oxymethacil, and to the increase in synchronization of informational processes in these regions of the cortex.
Asunto(s)
Antioxidantes/farmacología , Cognición/efectos de los fármacos , Neuronas/efectos de los fármacos , Corteza Prefrontal/citología , Lóbulo Temporal/citología , Uracilo/análogos & derivados , Animales , Antioxidantes/administración & dosificación , Color , Inyecciones Intramusculares , Macaca mulatta , Microelectrodos , Corteza Prefrontal/efectos de los fármacos , Lóbulo Temporal/efectos de los fármacos , Uracilo/administración & dosificación , Uracilo/farmacologíaRESUMEN
Monkeys performed a task of delayed visual differentiation of differently colored stimuli in behavioral experiments. The impulse activity of individual neurons of the prefrontal and inferotemporal cortex before and after the systemic administration of a blocker of M-cholinoreceptors, amyzil (0.8-1.0 mg/kg), was recorded simultaneously. Deterioration of the characteristics of recognition induced by amyzil was accompanied mainly by a significant increase in the activity of neurons of the prefrontal cortex which was dependant on the stage of recognition, and intensified with an increase in the delay interval. The impulse activity of the neurons of the inferotemporal cortex varied in the process without a regular pattern: at some stages of recognition it increased, at others it was inhibited. Amyzil induced a substantial decrease in the coefficients of cross correlation between the simultaneous respondent reactions of groups of neurons of the prefrontal and inferotemporal cortex. The results obtained point to the fact that the cholinergic structures of the inferotemporal and prefrontal cortex participate, at various stages of visual recognition in monkeys, in the formation of the dynamic functional systems which make their specific contribution to informational processes.
Asunto(s)
Cognición/fisiología , Sistema Nervioso Parasimpático/fisiología , Corteza Prefrontal/fisiología , Lóbulo Temporal/fisiología , Animales , Benactizina/farmacología , Macaca mulatta , Antagonistas Muscarínicos/farmacología , Neuronas/fisiología , Sistema Nervioso Parasimpático/citología , Corteza Prefrontal/anatomía & histología , Corteza Prefrontal/citología , Lóbulo Temporal/anatomía & histología , Lóbulo Temporal/citologíaRESUMEN
After the injection of the antioxidant, oxymethacil (4-5 micrograms/kg), in an investigation in monkeys of the processes of delayed visual recognition, their cognitive characteristics were significantly improved.: the duration of the short-term storage of information increased (by a factor of 2-3) and the time of the motor reaction decreased. The improvement of the cognitive characteristics was accompanied by changes in the neuronal activity in the visual cortex at all stages of recognition. The activity of the majority of the neurons increased in the case of discrimination without delay, it decreased significantly in the case of delayed discrimination. The administration of oxymethacil induced an increase in the auto- and cross-correlation coefficients in the respondent reactions of the recorded groups of neurons. The results obtained suggest that oxymethacil possesses nootropic properties, and the participation of the visual cortex of monkeys in the realization of these properties for the improvement of cognitive characteristics.
Asunto(s)
Antioxidantes/farmacología , Cognición/efectos de los fármacos , Corteza Visual/efectos de los fármacos , Estimulación Acústica , Animales , Condicionamiento Operante/efectos de los fármacos , Macaca mulatta , Memoria a Corto Plazo/efectos de los fármacos , Neuronas/efectos de los fármacos , Nootrópicos/farmacología , Uracilo/análogos & derivados , Uracilo/farmacología , Corteza Visual/citologíaRESUMEN
The impulse activity of groups of neurons of the visual, prefrontal, and inferotemporal cortex was recorded simultaneously in behavioral experiments on monkeys solving a problem of delayed visual differentiation of variously colored stimuli. The neurophysiological correlates of the decision-making processes were studied. Erroneous motoric reactions were accompanied in all monkeys by significant reorganizations of the patterns of impulse activity of the neurons. In the case of correct solutions of the monkeys, synchronization in time and cross-correlation which was significant in magnitude between the activity of the groups of neurons were observed. Incorrect solutions were accompanied by desynchronization and by a decrease in cross-correlation between the activity of these groups of neurons. Possible decision-making mechanisms of the causes of the desynchronization of the informational processes during erroneous reactions are discussed.
Asunto(s)
Corteza Cerebral/fisiología , Cognición/fisiología , Toma de Decisiones/fisiología , Estimulación Acústica , Animales , Corteza Cerebral/citología , Macaca mulatta , Microelectrodos , Neuronas/fisiología , Estimulación Luminosa , Corteza Prefrontal/citología , Corteza Prefrontal/fisiología , Lóbulo Temporal/citología , Lóbulo Temporal/fisiología , Visión Ocular/fisiología , Corteza Visual/citología , Corteza Visual/fisiologíaRESUMEN
Experiments on three groups of rhesus macaques (intact and with bilateral removal of field 7 and the sulcus principalis) were performed to study the functional characteristics of the associative areas of the cortex while the monkeys learned visual discrimination. Significant differences in learning processes associated with removal of structures and the properties of the stimuli were seen in all animals, in the form of different types of learning curves. As compared with intact monkeys, removal of field 7 had no effect on learning processes for images with properties such as spatial frequency, color, and animal images, though there was a significant worsening in the characteristics of learning during visual discrimination of spatial relationships between objects. Learning processes became unstable, the number of peaks and troughs on learning curves increased, and as a result the training periods were significantly lengthened and 85% of the animals were unable to achieve the learning criterion. Removal of the sulcus principalis significantly worsened the characteristics of discrimination of the sizes of geometric objects, the spatial relationships between them, and stimuli of different colors. The stable reaction time and the probability of refusal in most cases also increased for monkeys of both these groups. Cluster analysis based on the quantitative characteristics of learning processes, despite individual differences between the monkeys, demonstrated a tendency for stimuli to be separated into classes corresponding to different types of information. These data show that the result of sensory processing is that several (at least three) functional visual information flows are generated and that different areas of the cortex deal with these different flows.
Asunto(s)
Aprendizaje por Asociación/fisiología , Mapeo Encefálico , Aprendizaje Discriminativo/fisiología , Lóbulo Parietal/fisiología , Corteza Prefrontal/fisiología , Percepción Visual/fisiología , Animales , Condicionamiento Operante , Macaca mulatta , Procesos Mentales/fisiología , Desempeño Psicomotor/fisiologíaRESUMEN
The influence of an effective antioxidant, oxymethacil, was studied in a model of the disruption of visual recognition induced by the antidepressant fluoracyzine. The normal discrimination of black and white visual stimuli in monkeys is restored with the systemic administration of oxymethacil in a dose of 3 mg/kg following disruption brought about by the effect of fluoracyzine. The discrimination of colored visual stimuli, as in the norm, is restored following the systemic administration of oxymethacil in a dose of 4 mg/kg. The results obtained attest to the corrective properties of oxymethacil.