recording-single-neurons-action-potentials-from-freely-moving-pigeons

Recording Single Neurons' Action Potentials from Freely Moving Pigeons Across Three Stages of Learning

While the subject of learning has attracted immense interest from both behavioral and neural scientists, only relatively few investigators have observed ...

Ruhr-University Bochum

A prerequisite for adaptive goal-directed behavior is that animals constantly evaluate action outcomes and relate them to both their antecedent behavior and to stimuli predictive of reward or non-reward. Here, we investigate whether single neurons in the avian nidopallium caudolaterale (NCL), a multimodal associative forebrain structure and a presumed analogue of mammalian prefrontal cortex, represent information useful for goal-directed behavior. We subjected pigeons to a go-nogo task, in which responding to one visual stimulus (S+) was partially reinforced, responding to another stimulus (S-) was punished, and responding to test stimuli from the same physical dimension (spatial frequency) was inconsequential. The birds responded most intensely to S+, and their response rates decreased monotonically as stimuli became progressively dissimilar to S+; thereby, response rates provided a behavioral index of reward expectancy. We found that many NCL neurons' responses were modulated in the stimulus discrimination phase, the outcome phase, or both. A substantial fraction of neurons increased firing for cues predicting non-reward or decreased firing for cues predicting reward. Interestingly, the same neurons also responded when reward was expected but not delivered, and could thus provide a negative reward prediction error or, alternatively, signal negative value. In addition, many cells showed motor-related response modulation. In summary, NCL neurons represent information about the reward value of specific stimuli, instrumental actions as well as action outcomes, and therefore provide signals useful for adaptive behavior in dynamically changing environments.

Stimulus-response-outcome coding in the pigeon nidopallium caudolaterale.

Performance on psychophysical tasks is influenced by a variety of non-sensory factors, most notably the magnitude or probability of reinforcement following correct responses. When reinforcement probability is unequal for hits and correct rejections, signal detection theory specifies an optimal decision criterion which maximizes the number of reinforcers. We subjected pigeons to a task in which six different stimuli (shades of gray) had to be assigned to one of two categories. Animals were confronted with asymmetric reinforcement schedules in which correct responses to five of the stimuli were reinforced with a probability of 0.5, while correct responses to the remaining stimulus were extinguished. The subjects' resultant choice probabilities clearly deviated from those predicted by a maximization account. More specifically, the magnitude of the choice bias increased with the distance of the to-be-extinguished stimulus to the category boundary, a pattern opposite to that posited by maximization. The present and a previous set of results in which animals performed optimally can be explained by a simple choice mechanism in which a variable decision criterion is constantly updated according to a leaky integration of incomes attained from both response options.

Article	Year
Stimulus-response-outcome coding in the pigeon nidopallium caudolaterale. PloS one\| PubMed ID: 23437383	2013
Suboptimal criterion setting in a perceptual choice task with asymmetric reinforcement. Behavioural processes\| PubMed ID: 23466903	2013

Sarah Starosta

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