Protection from neuronal damage evoked by a motivational excitation is a driving force of intentional actions.

Motivation may be understood as an organism's subjective attitude to its current physiological state, which somehow modulates generation of actions until the organism attains an optimal state. How does this subjective attitude arise and how does it modulate generation of actions? Diverse lines of evidence suggest that elemental motivational states (hunger, thirst, fear, drug-dependence, etc.) arise as the result of metabolic disturbances and are related to transient injury, while rewards (food, water, avoidance, drugs, etc.

A comparison of neuronal reactions during classical and instrumental conditioning under similar conditions.

During the elaboration of an instrumental reflex, it is not obligatory to use a conditioned stimulus, which signals the necessity to generate an instrumental reaction in order to receive reinforcement. However, the presence of a conditioned stimulus simplifies analysis of instrumental reaction, which in this case is the response to the conditioned stimulus. On the other hand, it is necessary to distinguish between instrumental and classical conditioning, since in both cases the response to a conditioned stimulus increases.

Neurons evaluate both the amplitude and the meaning of signals.

The neuronal threshold, which can be determined by the level of depolarization immediately prior to spike generation, is different for responses to conditioned and discriminated stimuli after conditioning. However, it is impossible to determine excitability within a response to stimuli that failed to generate a spike. In the present study we examined the role of the AP threshold of two related Helix defensive neurons in the initiation of an AP during elaboration of the neuronal analog of a classical conditional reflex.

Collaboration of trained and foreign neurons during formations of a local instrumental reflex.

At present it is not clear how instrumental actions arise. In our experiments the mollusk Helix received an aversive stimulus when one of its neurons did not generate an action potential in response to a conditioned stimulus. The appearance of an aversive stimulus did not depend on the generation or failure of a spike in the control neuron.

Instrumental conditioning of the activity of putative command neurons in the mollusk Helix.

Gaining insight into the mechanism of generation of goal-directed actions is understanding neural function. In this study we examined the role of the action potential (AP) in a single molluscan neuron (responsible for a defensive response) in an instrumental behavior. The intracellular electrical activity of two neurons was recorded simultaneously.