RESUMEN
The role of the posterior parahippocampal area of the brain in spatial types of memory in conditions of one-trial visual perception of the positions of objects was studied by training eight cats to remember the spatial positions of either two different objects covering two of three feeders placed on a test tray (tests for the "object-place" association) or the positions of two of three feeders (tests for place). Each trial used new objects and new positions for the two of three feeders. After training, four cats were subjected to electrolytic lesioning of the posterior parahippocampal area, primarily the parahippocampal cortex, parasubiculum, and presubiculum; the remaining four cats underwent all the surgical procedures except electrocoagulation of nervous tissue; this was the sham-operated control group. Cats of this group showed no impairment to the performance of tests of both types, while the experimental group showed similar levels of impairment to the performance of both tests. Thus, memory for one-trial perception of "object-place" associations and, more simply, two different object places in cats were critically dependent on the posterior parahippocampal area.
Asunto(s)
Hipocampo/fisiopatología , Memoria/fisiología , Reconocimiento Visual de Modelos/fisiología , Percepción Espacial/fisiología , Animales , Mapeo Encefálico/métodos , Gatos , Femenino , Masculino , Giro Parahipocampal/fisiopatologíaRESUMEN
To determine the contribution of the posterior parahippocampal region to spatial form of one-trial memory in cats, we trained 8 cats to remember the spatial positions of either two different trial-unique objects overlying two of three feeders in a feeder test tray (object-place trials) or simply two of the three feeders (place trials). Four cats then received electrolytic lesions restricted to the posterior parahippocampal region (experimental group) including mainly parahippocampal cortex, parasubiculum and presubiculum. Four other cats comprised sham-operated control group. This group was found to be completely unaffected postoperatively in both types of trials, whereas experimental group showed impaired performance in both types of trials equally. Thus, one-trial memory for object-place association and one-trial memory for two different places in cats appear to be critically dependent on the posterior parahippocampal region.
Asunto(s)
Hipocampo/fisiopatología , Memoria/fisiología , Reconocimiento Visual de Modelos/fisiología , Percepción Espacial/fisiología , Animales , Mapeo Encefálico/métodos , Gatos , Femenino , Masculino , Giro Parahipocampal/fisiopatologíaRESUMEN
Memory for visual recognition in primates is at least partially mediated by the peripheral and entorhinal (i.e., rhinal) areas of the cerebral cortex. The roles of these structures in visual recognition in cats was studied by producing electrolytic combined lesions of the rhinal (perirhinal + entorhinal) areas in a group of cats trained in a modified Wisconsin test apparatus to delayed selection of an object on the basis of its image on presentation of a new object in every trial in the test. Control groups consisted of intact and sham-operated cats. Animals with rhinal lesions were no different from sham-operated and intact animals in the initial training to the rules for correct responding to the objects presented; they also showed no difference at the minimum delay period of 5 sec used in these experiments. However, a statistically significant difference was seen on testing with a delay of 10 sec, demonstrating impairment of intrinsic visual recognition memory.
Asunto(s)
Corteza Cerebral/fisiología , Sistema Límbico/fisiología , Reconocimiento en Psicología/fisiología , Percepción Visual/fisiología , Animales , Gatos , Condicionamiento Clásico/fisiología , Corteza Entorrinal/fisiología , Femenino , Masculino , Giro Parahipocampal/fisiología , Estimulación Luminosa , Vías Visuales/fisiologíaRESUMEN
Visual recognition memory in primates is mediated at least in part by the perirhinal and entorhinal (i.e., rhinal) cortices. To examine the role of these structures in cats' visual recognition memory, we performed combined electrolytic rhinal (perirhinal and entorhinal) lesions in a group of cats trained in visual delayed matching-to-sample with trial-unique objects in the modified Wisconsin General Testing Apparatus. Sham-operated and intact cats were used as control groups. Cats with rhinal lesions did not differ from the control sham-operated and unoperated groups in initial learning of the rules of the task; difference between experimental and control groups under conditions of minimum 5-sec delay was nonsignificant as well. However, significant difference between experimental and control groups was revealed under conditions of testing with 10-sec delay. This finding suggests a disorder in the visual recognition memory.
Asunto(s)
Corteza Entorrinal/fisiología , Reconocimiento Visual de Modelos , Percepción Visual , Animales , Mapeo Encefálico/métodos , Gatos , Femenino , Masculino , Memoria a Corto Plazo , Tiempo de ReacciónRESUMEN
In acute and chronic experiments on 35 cats an inhibitory influence was found of the caudal reticular nucleus of pons Varolii on unit activity of the sensorimotor cortex and dorsal part of the midbrain reticular formation. The influence of this structure on unit activity of the ventral part of the midbrain reticular formation was mainly of a facilitatory character. Activation of the ventral part inhibited the unit activity of the dorsal part of the same structure. Consequently, the caudal reticular nucleus of pons Varolii elicits inhibition at the level not only of the cerebral cortex but also of the midbrain reticular formation (of its dorsal part). The character of these influences coincides with that of unit activity changes of these two areas of the midbrain reticular formation during the development of the paradoxical phase of sleep. The obtained facts must underlie the stopping of convulsive activity in this phase of sleep.
Asunto(s)
Corteza Cerebral/fisiología , Mesencéfalo/fisiología , Puente/fisiología , Formación Reticular/fisiología , Animales , Mapeo Encefálico , Gatos , Potenciales Evocados , Femenino , Masculino , Corteza Motora/fisiología , Vías Nerviosas/fisiología , Fases del Sueño/fisiología , Corteza Somatosensorial/fisiologíaRESUMEN
Activation of the mesencephalic RF facilitates triggering of paroxysmal potentials and augments existing epileptic activity. Stimulation of nucleus reticularis pontis caudalis inhibits triggering of epileptic discharges. The microelectrode studies corroborated these data. The desynchronization elicited by the mesencephalic RF seems to be mostly activating, whereas desynchronization elicited by the nucleus reticularis pontis caudalis--mostly inhibitory.