Unconditioned response

Fig. 29.2 A. Proportion of pups responding by searching movements to neutral odorant E and F, 24h after being exposed to the MP-odorant E mixture (MP-E) or to odorant E alone (E). B. Proportion of pups displaying searching to an odorant MP-leamed (dotted bar) as compared to the MP (black bar). C. Schematic of the reinforcing function of MP (US, CS and UR unconditioned stimulus, conditioned stimulus and unconditioned response, respectively) (adapted from Coureaud et al. 2006c)...

The conditioned response elicited by a CS+ might be similar to the unconditioned response to the UCS. However, it seems to be more appropriate to assume that the conditioned response is elicited by the anticipation of the UCS rather than necessarily consisting of any component of the unconditioned response (Fanselow 1994 Gray and McNaughton 2000). The nature of the conditioned response depends on the UCS and the behavioural repertoire of a distinct species and cannot be controlled by the experimenter. 

The categories of methods used in behavioral toxicology fall into two principal classes, stimulus-oriented behavior, and internally generated behavior. The former includes two types of conditioned behavior operant conditioning, in which animals are trained to perform a task in order to obtain a reward or to avoid a punishment, and classical conditioning, in which an animal learns to associate a conditioning stimulus with a reflex action. Stimulus-oriented behavior also involves unconditioned responses in which the animal s response to a particular stimulus is recorded. 

Classical or Pavlovian conditioning was first demonstrated by Ivan Pavlov in 1927. When food was presented to a hungry dog, it salivated. The food in this case was called the unconditioned stimulus, and salivating was the unconditioned response. Salivation is a natural, automatic response to the sight and smell of food, a reaction to make the chewing and digestion of the food easier. 

The conditioned association between the formerly neutral conditioned stimulus and the conditioned response is formed by the deliberate pairing of the conditioned stimulus and the unconditioned response. Suppose we now break up that pairing, continuing to present the conditioned stimulus, but no longer following it with the unconditioned stimulus. ... 

The top half of Figure 7.4 depicts the sequence of stimulus-response events occurring in classical conditioning. Actually, before learning occurs, the sequence includes only three events—conditioned stimulus (CS), unconditioned stimulus (UCS), and unconditioned response (UCR). The UCS elicits a UCR automatically, as in an autonomic reflex. That is, the food (UCS) elicited a salivation reflex (UCR) in Pavlov s dogs. In the same way, the smell of popcorn (UCS) might make your mouth water (UCR), a puff of air to your eye... 

Right on, the food which previously followed the sound of the electric can opener is the UCS, which elicits the UCR (unconditioned response) of salivating without any learning experience. This UCS-UCR reflex is natural or "wired in" the organism. 

DOU 09] Doucet S., Soussignan R., Sagot P. et al, The secretion of areolar (Montgomery s) glands from lactating women elicits selective, unconditional responses in neonates , PLoS ONE, vol. 4, p. e7579, 2009. 

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