Some individuals are better at learning about rewarding situations, whereas others are inclined to avoid punishments (i.e., enhanced approach or avoidance learning, respectively). In reinforcement learning, action values are increased when outcomes are better than predicted (positive prediction errors [PEs]) and decreased for worse than predicted outcomes (negative PEs). Because actions with hi...

In the framework of dynamic neural networks, learning refers to the slow process by which a neural network modi es its own structure under the in uence of environmental pressure. Our simulations take place on large random recurrent neural networks (RRNNs). We present several results obtained with the use of a TD (temporal di erence) and STDP (Spike-Time Dependent Plasticity) rule. First, we sho...

Excessive avoidance behavior, in which an instrumental action prevents an upcoming aversive event, is a defining feature of anxiety disorders. Left unchecked, both fear and avoidance of potentially threatening stimuli may generalize to perceptually related stimuli and situations. The behavioral consequences of generalization mean that aversive learning experiences with specific threats may lead...

Morphine’s effects on learning and memory processes are well known to depend on synaptic plasticity in the hippocampus. Whereas the role of the hippocampus in morphine-induced amnesia and state-dependent learning is established, the biochemical and molecular mechanisms underlying these processes are poorly understood. The present study intended to investigate whether administration of morphine ...

Open field activity was studied in Wistar rats. Animals with low scores of ambulatory and rearing behaviours were grouped as hypoactive and those with high scores as hyperactive. Acquisition of active avoidance learning in a shuttle box was studied in the two groups. Hyperactive rats in contrast to hypoactive rats showed a better acquisition of avoidance learning. Learning was suppressed in bot...

Much of the early research in aversive learning concerned motivation and reinforcement in avoidance conditioning and related paradigms. When the field transitioned toward the focus on Pavlovian threat conditioning in isolation, this paved the way for the clear understanding of the psychological principles and neural and molecular mechanisms responsible for this type of learning and memory that ...

Psychotic fear and anxiety disturbances are seen at a relatively high frequency in patients with schizophrenia. Atypical anti-psychotics are believed to show superior efficacy in reducing these symptoms. However, clinical and preclinical evidence regarding their anxiolytic efficacy has been mixed. In this study, we evaluated the possible anxiolytic property of two atypicals clozapine and olanza...

One of the most common causes of mortality in acute kidney injury is brain dysfunction. Here we investigated the possible protective effect of erythropoietin (EPO) on cognitive impairments induced by bilateral renal ischemia (BRI). Eighty male Wistar rats were allocated into 8 groups: 1, 2) Sham+V (Vehicle), 3, 4) Sham+EPO, 5, 6) BRI+V, 7, 8) BRI+EPO. The groups followed by the reperfusion per...

The aim of this study was to compare the learning performance of Wistar rats in passive avoidance box and open field behavior. Animals were placed in the center of the open field and their behavior was manually recorded for 5 min. Two latency periods, first motion, and exit to the center, the number of inner and outer squares crossed, grooming activity, the number of rearing in the center of th...