Formation of cognitive structures in conditioned-reflex behavior in monkeys: Relationship with type of visual information.

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.

[Forming of the visual cognitive structures in the monkey conditioned-reflex behaviour: the dependence on the sensory information].

In monkeys, changes in size and shape of figures led to a significant decrease of correct solutions in training and a considerable increase of refusals from solution of tasks as well as the time of their motor response. The invariance of differentiation in this case was achieved after additional training. The data obtained show that, based on the stimulus sensory processing in conditioned-reflex training, in the long-term memory some differentiating signs are formed: the cognitive structures (the functional neurophysiological mechanisms) maintaining the classification of visual images.

Disorders of learning and memory processes in a monkey model of Alzheimer's disease: the role of the associative area of the cerebral cortex.

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).

[Disorders in learning and memory processes in the monkey model of Alzheimer's disease: the role of the cerebral cortex associative areas].

Processes of novelty learning and keeping the results in Alzheimer's disease in two groups of rhesus-monkeys (three monkeys in each group), were studied: following neurotoxins administrati- on (I group) and saline administration (II group). In two months after the injections (the C1 stage), considerable differences between the groups were revealed in the task of differentiation among contour shapes. For the I group monkeys the learning was difficult: the correct decision making did not reach 85 %, and the probability of refusing to make a decision increased.

Interaction of sensory and cognitive processes during visual recognition: the role of the associative areas of the cerebral cortex.

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.