In this article, we introduce this special issue by establishing a conceptual foundation for the distinction between approach and avoidance motivation. We do so primarily by explicating several reasons why the approach–avoidance distinction should be viewed as fundamental and basic to the study of human behavior. In addition, we compare and contrast the “approach–avoidance” designation with other designations that have been used in the motivational literature to cover the same or similar conceptual ground. Finally, we conclude by briefly overviewing the other contributions to this special issue, specifically highlighting how they make use of the approach–avoidance distinction.

https://www.jstor.org/stable/info/23363527

Approach and avoidance motivation.

Stimulus-evoked oscillatory synchronization of neural assemblies has been described in the olfactory and visual systems of several vertebrates and invertebrates In locusts, information about odour identity is contained in the timing of action potentials in an oscillatory population response, suggesting that oscillations may reflect a common reference for messages encoded in time Although the stimulus-evoked oscillatory phenomenon is reliable, its roles in sensation, perception, memory formation and pattern recognition remain to be demonstrated--a task requiring a behavioural paradigm Using honeybees, we now demonstrate that odour encoding involves, as it does in locusts, the oscillatory synchronization of assemblies of projection neurons and that this synchronization is also selectively abolished by picrotoxin, an antagonist of the GABA(A) (gamma-aminobutyric acid) receptor By using a behavioural learning paradigm, we show that picrotoxin-induced desynchronization impairs the discrimination of molecularly similar odorants, but not that of dissimilar odorants It appears, therefore, that oscillatory synchronization of neuronal assemblies is functionally relevant, and essential for fine sensory discrimination This suggests that oscillatory synchronization and the kind of temporal encoding it affords provide an additional dimension by which the brain could segment spatially overlapping stimulus representations

Impaired Odour Discrimination on Desynchronization of Odour-Encoding Neural Assemblies

The understanding of the physiology of learning is dominated by two basically different hypotheses. The deterministic view, following Hebb’s (1949) concept of the memory engram, presupposes a memory groove which is built during memory formation by the adaptive change of a relatively small number of reacting sites or switch points. These so-called ’switchpoint theories’ or ‘place theories’ assume that memory involves a discrete set of cells reserved for the special function of information storage (Young 1964; Eccles 1964; Ungar 1970). The non-deterministic or statistical theory is based on Lashley’s (1950) findings which suggest that all, or nearly all, stored information is distributed throughout the whole association cortex rather than by distinct association paths or centres. The individual neuronal switch points may then be involved in the storage of many different memory traces (John 1967, 1972). The two views are similar in that they take the adaptivity of single synapses between neurones as the basic modifiable component of the nervous system (Eccles and McIntyre 1953; Eccles 1964; Ungar 1970; John 1972). They differ, however, in their conception of the gross structure of the memory system. The crucial problem, then, is to locate the stored information. The spatio-temporal pattern of activity during memory formation produces a localised change in the excitability of specific neurones. It should be possible to find such neurones using the same techniques as have been employed for the location of units in the sensory integration centres.

https://www.jneurosci.org/content/jneuro/15/3/1617.full.pdf

Learning and memory in the honeybee

Learning and memory in honeybees is analyzed on five levels, using a top-down approach. (a) Observatory learning is applied during navigation and dance communication. (b) Local cues at the feeding site are learned associatively. (c) Classical conditioning of the proboscis extension response to olfactory stimuli provides insight into behavioral, neural, and neuropharmacological mechanisms of associative learning. (d) At the neural level, the pathways coding the conditioned and the unconditioned stimulus are identified. The reinforcing function of the unconditioned stimulus is traced to a particular neuron. (e) At the cellular level, the cAMP pathway is found to be critically involved. Nitric oxide is an essential mediator for the transfer from short- to long-term memory.

Learning and memory in honeybees: from behavior to neural substrates.

Reward learning in honeybees initiates a sequence of events which leads to long-lasting memory passing through multiple phases of transient memories. The study of memory dynamics is performed at the behavioral (both natural foraging behavior and appetitive conditioning), neural circuit and molecular levels. The results of these combined efforts lead to a model which assumes five kinds of sequential memories, each characterized by a set of behavioral and mechanistic properties. It is argued that these properties, although reflecting general characteristics of step-wise memory formation, are adapted to the species-specific adaptations in natural behavior, here to foraging at scattered and unreliable food sources.

Memory dynamics in the honeybee

Extension of the proboscis was conditioned in restrained honeybees with odor as the conditioned stimulus (CS) and sucrose solution--delivered to the antenna (to elicit extension of the proboscis) and then to the proboscis itself--as the unconditioned stimulus (US). In a first series of experiments, acquisition was found to be very rapid, both in massed and in spaced trials; its associative basis was established by differential conditioning and by an explicitly unpaired control procedure (which produced marked resistance to acquisition in subsequent paired training); and both extinction and spontaneous recovery in massed trials were demonstrated. In a series of experiments on the nature of the US, eliminating the proboscis component was found to lower the asymptotic level of performance, whereas eliminating the antennal component was without effect; reducing the concentration of sucrose from 20% to 7% slowed acquisition but did not lower the asymptotic level of performance; and second-order conditioning was demonstrated. In a series of experiments on the role of the US, an omission contingency designed to eliminate adventitious response-reinforcer contiguity was found to have no adverse effect on acquisition. In a series of experiments designed to analyze the resistance to acquisition found after explicitly unpaired training in the first experiments, no significant effect was found of prior exposure either to the CS alone or to the US alone, although the unpaired procedure again produced substantial resistance that was shown to be due to inhibition rather than to inattention; extinction after paired training was found to be facilitated by unpaired presentations of the US. The relation between these results for honeybees and those of analogous experiments with vertebrates is considered.

M. E. Bitterman

Papers

Classical conditioning of proboscis extension in honeybees (Apis mellifera).