Desarrollo de diferentes marcos de referencia espacial para la orientación en entornos a pequeña escala / Development of different spatial frames of reference for orientation in small-scale environments

Background: Previous studies show that there is a developmental transition in the frames of reference children use to orientate from a body-centered to an allocentric strategy. However, there is no agreement concerning the age at which they begin to integrate and flexibly use both strategies in small scale environments. Method: 6-10-year-old children and adults were trained to locate a hidden object in an arm-maze placed within a small-scale model, which maintained stable relationships with the frames of reference provided by the experimental room and by the subject (Experiment 1), and in a situation of inconsistency between the frame provided by the small scale model and the other two (Experiment 2). Results: When the frames of reference provided by the room and by the subject conflict with that of the manipulative space, the performance deteriorates compared to the situation when multiple frames of reference can be used cooperatively to locate the goal. The flexible use of the information provided by the model (i.e., the cues surrounding the maze and the geometrical features) emerged at 10 years. Conclusions: Through development, children acquire new spatial abilities and increasing flexibility in the conjoint use of egocentric and allocentric frames of reference in small-scale environments (AU)

Antecedentes: estudios previos muestran una transición durante el desarrollo en las estrategias que los niños utilizan para orientarse, aunque no hay consenso en la edad de inicio para emplear conjuntamente estrategias alocéntricas y egocéntricas en entornos a pequeña escala. Método: niños de 6-10 años y adultos fueron entrenados para encontrar un objeto escondido en un laberinto radial ubicado en una maqueta que mantiene una relación constante con los marcos de referencia proporcionados por la habitación experimental y por el participante (experimento 1), y en una situación de inconsistencia entre el marco de referencia del entorno a pequeña escala y los de la habitación y el sujeto (experimento 2). Resultados: cuando los marcos de referencia de la habitación y el sujeto entran en conflicto con el del espacio manipulativo, la ejecución empeora respecto a una situación en que múltiples marcos de referencia cooperan para localizar la meta. Desde los 10 años los niños usan la información del espacio manipulativo, tanto las claves que rodean al laberinto como la geometría de dicho entorno. Conclusiones: durante el desarrollo los niños adquieren nuevas habilidades espaciales y mayor flexibilidad en el uso conjunto de marcos de referencia egocéntricos y alocéntricos en entornos a pequeña escala(AU)

Development of different spatial frames of reference for orientation in small-scale environments.

BACKGROUND: Previous studies show that there is a developmental transition in the frames of reference children use to orientate from a body-centered to an allocentric strategy. However, there is no agreement concerning the age at which they begin to integrate and flexibly use both strategies in small-scale environments. METHOD: 6-10-year-old children and adults were trained to locate a hidden object in an arm-maze placed within a small-scale model, which maintained stable relationships with the frames of reference provided by the experimental room and by the subject (Experiment 1), and in a situation of inconsistency between the frame provided by the small-scale model and the other two (Experiment 2). RESULTS: When the frames of reference provided by the room and by the subject conflict with that of the manipulative space, the performance deteriorates compared to the situation when multiple frames of reference can be used cooperatively to locate the goal. The flexible use of the information provided by the model (i.e., the cues surrounding the maze and the geometrical features) emerged at 10 years. CONCLUSIONS: Through development, children acquire new spatial abilities and increasing flexibility in the conjoint use of egocentric and allocentric frames of reference in small-scale environments.

Lateral but not medial telencephalic pallium ablation impairs the use of goldfish spatial allocentric strategies in a "hole-board" task.

Strong evidence suggests that the ventral region of the lateral telencephalic pallium of teleost fish, a structure involved in allocentric spatial cognition, is homologous to the hippocampus of tetrapods. This homology was first proposed on basis of anatomical data, and subsequently confirmed by developmental, functional and behavioural studies. Nonetheless, Saito and Watanabe [30,32] claim that not the lateral but, rather, the medial pallium participates in goldfish spatial navigation and should be considered the homologue of the hippocampus. Here, we further investigate the effects of selective pallial lesions on the spatial cognition abilities of goldfish, trained in a "hole-board" analogue task, to find the baited feeder within a 5 x 5 feeder matrix surrounded by visual cues. The task in the present experiment is similar to that used by Saito and Watanabe, but including thorough probe tests that enabled to define clearly the spatial strategies employed by the animals, and, therefore, the spatial deficits caused by the pallial lesions. The results showed that the lateral, but not the medial pallium lesions, produced a dramatic impairment in the implementation of allocentric spatial strategies. Thus, only lateral pallium lesioned goldfish, like hippocampus lesioned tetrapods, failed to reach the goal when the cues in its proximity were excluded, indicating that they used a guidance strategy. These results do not replicate Saito and Watanabe's, but are consistent to previous data indicating a close functional similarity between the lateral pallium of teleost fish and the hippocampus of amniotes.

Telencephalon ablation impairs goldfish allocentric spatial learning in a "hole-board" task.

The present work analyzes the involvement of telencephalon of goldfish in spatial strategies, using a procedure analogue to the hole-board task. With this aim, goldfish with sham operation or telencephalon ablation were trained to find a baited feeder within a twenty-five feeder matrix, which maintained stable spatial relationships relative to five peripheral landmarks. After training, different types of probe tests were conducted. Although both groups learned the task, probe trials showed that whereas the sham animals used the whole configuration of cues to implement map-like strategies the telencephalic animals used a guidance strategy based on cues located in the vicinity of the baited feeder. These results confirm the role of teleost fish telencephalon in the use of allocentric strategies obtained with other spatial procedures, and indicate that the hole-board task described here for goldfish is a useful tool to assess the neural bases of spatial cognition in teleost fish.

Neuropsychology of learning and memory in teleost fish.

Traditionally, brain and behavior evolution was viewed as an anagenetic process that occurred in successive stages of increasing complexity and advancement. Fishes, considered the most primitive vertebrates, were supposed to have a scarcely differentiated telencephalon, and limited learning capabilities. However, recent developmental, neuroanatomical, and functional data indicate that the evolution of brain and behavior may have been more conservative than previously thought. Experimental data suggest that the properties and neural basis of learning and memory are notably similar among teleost fish and land vertebrates. For example, lesion studies show that the teleost cerebellum is essential in classical conditioning of discrete motor responses. The lateral telencephalic pallium of the teleost fish, proposed as homologous to the hippocampus, is selectively involved in spatial learning and memory, and in trace classical conditioning. In contrast, the medial pallium, considered homologous to the amygdala, is involved in emotional conditioning in teleost fish. The data reviewed here show a remarkable parallelism between mammals and teleost fish concerning the role of different brain centers in learning and memory and cognitive processes. These evidences suggest that these separate memory systems could have appeared early during the evolution of vertebrates, having been conserved through phylogenesis.

Evolution of forebrain and spatial cognition in vertebrates: conservation across diversity.

Historically the dominant trend in comparative brain and behavior research has emphasized the differences in cognition and its neural basis among species. In fact, the vertebrate forebrain shows a remarkable range of diversity and specialized adaptations. Probably the major morphological variation is that observed in the telencephalon of the actinopterygian fish, which undergoes a process of eversion during embryonic development, relative to the telencephalon of non-actinopterygians (for instance, amniotes), which develops by a process of evagination. These different developmental processes produce notable variation, mainly two solid telencephalic hemispheres separated by a unique ventricle in the actinopterygian radiation that contrasts with the hemispheres with internal ventricles in other groups. However, an increasing amount of evidence reveals that the forebrain of vertebrates, whether everted or evaginated, presents a common pattern of basic organization that supports highly conserved cognitive functions. We analyze here recent data indicating a close functional similarity between spatial cognition mechanisms in different groups of vertebrates, mammals, birds, reptiles, and teleost fish, and we show in addition that they rely on homologous neural mechanisms. Thus, recent functional and behavioral comparative evidence is added to the developmental and neuroanatomical data suggesting that the evolution of cognitive capabilities and their neural basis in vertebrates could have been more conservative than previously realized.

Conservation of spatial memory function in the pallial forebrain of reptiles and ray-finned fishes.

The hippocampus of mammals and birds is critical for spatial memory. Neuroanatomical evidence indicates that the medial cortex (MC) of reptiles and the lateral pallium (LP) of ray-finned fishes could be homologous to the hippocampus of mammals and birds. In this work, we studied the effects of lesions to the MC of turtles and to the LP of goldfish in spatial memory. Lesioned animals were trained in place, and cue maze tasks and crucial probe and transfer tests were performed. In experiment 1, MC-lesioned turtles in the place task failed to locate the goal during trials in which new start positions were used, whereas sham animals navigated directly to the goal independently of start location. In contrast, no deficit was observed in cue learning. In experiment 2, LP lesion produced a dramatic impairment in goldfish trained in the place task, whereas medial and dorsal pallium lesions did not decrease accuracy. In addition, none of these pallial lesions produced deficits in cue learning. These results indicate that lesions to the MC of turtles and to the LP of goldfish, like hippocampal lesions in mammals and birds, selectively impair map-like memory representations of the environmental space. Thus, the forebrain structures of reptiles and teleost fish neuroanatomically equivalent to the mammalian and avian hippocampus also share a central role in spatial cognition. Present results suggest that the presence of a hippocampus-dependent spatial memory system is a primitive feature of the vertebrate forebrain that has been conserved through evolution.