This article considers the role of the hippocampus in memory function. A central thesis is that work with rats, monkeys, and humans--which has sometimes seemed to proceed independently in 3 separate literatures--is now largely in agreement about the function of the hippocampus and related structures. A biological perspective is presented, which proposes multiple memory systems with different functions and distinct anatomical organizations. The hippocampus (together with anatomically related structures) is essential for a specific kind of memory, here termed declarative memory (similar terms include explicit and relational). Declarative memory is contrasted with a heterogeneous collection of nondeclarative (implicit) memory abilities that do not require the hippocampus (skills and habits, simple conditioning, and the phenomenon of priming). The hippocampus is needed temporarily to bind together distributed sites in neocortex that together represent a whole memory.

Memory and the hippocampus: A synthesis from findings with rats, monkeys, and humans.

Researchers have wondered how the brain creates emotions since the early days of psychological science. With a surge of studies in affective neuroscience in recent decades, scientists are poised to answer this question. In this target article, we present a meta-analytic summary of the neuroimaging literature on human emotion. We compare the locationist approach (i.e., the hypothesis that discrete emotion categories consistently and specifically correspond to distinct brain regions) with the psychological constructionist approach (i.e., the hypothesis that discrete emotion categories are constructed of more general brain networks not specific to those categories) to better understand the brain basis of emotion. We review both locationist and psychological constructionist hypotheses of brain-emotion correspondence and report meta-analytic findings bearing on these hypotheses. Overall, we found little evidence that discrete emotion categories can be consistently and specifically localized to distinct brain regions. Instead, we found evidence that is consistent with a psychological constructionist approach to the mind: A set of interacting brain regions commonly involved in basic psychological operations of both an emotional and non-emotional nature are active during emotion experience and perception across a range of discrete emotion categories.

/pdf/the-brain-basis-of-emotion-a-meta-analytic-review-32zzrbb78z.pdf

The brain basis of emotion: A meta-analytic review

▪ Abstract Learning the relationships between aversive events and the environmental stimuli that predict such events is essential to the survival of organisms throughout the animal kingdom. Pavlovian fear conditioning is an exemplar of this form of learning that is exhibited by both rats and humans. Recent years have seen an incredible surge in interest in the neurobiology of fear conditioning. Neural circuits underlying fear conditioning have been mapped, synaptic plasticity in these circuits has been identified, and biochemical and genetic manipulations are beginning to unravel the molecular machinery responsible for the storage of fear memories. These advances represent an important step in understanding the neural substrates of a rapidly acquired and adaptive form of associative learning and memory in mammals.

/pdf/neurobiology-of-pavlovian-fear-conditioning-3beoazhpf8.pdf

Neurobiology of Pavlovian fear conditioning.

Sah, P., E. S. L. Faber, M. Lopez de Armentia, and J. Power. The Amygdaloid Complex: Anatomy and Physiology. Physiol Rev 83: 803–834, 2003; 10.1152/physrev.00002.2003.—A converging body of literatu...

The Amygdaloid Complex: Anatomy and Physiology

Cortical pathways to the mammalian amygdala

Learned taste aversions in rats as a function of dosage, concentration, and route of administration of LiCl.

https://psycnet.apa.org/journals/com/87/4/622.pdf

Effects of basolateral amygdala lesions on neophobia, learned taste aversions, and sodium appetite in rats.

Several toxic agents were compared in order to test the effect of various types of illness in producing learned taste aversions. After a 10-min sucrose drinking trial, groups of rats were injected intraperitoneally with lithium chloride or with a strong, near lethal dose of a rodenticide. Strong sucrose aversions were acquired by groups injected with lithium chloride, copper sulfate, sodium fluoroacetate, or red squill, and very weak or no aversions were learned by groups injected with thallium, warfarin cyanide, or strychnine. The results were discussed in terms of onset of symptoms, duration of symptoms, and kinds of physiological effects necessary to produce aversions. It was concluded that the effects of different drugs may be mediated by different physiological systems learned taste aversions.

Role of illness in producing learned taste aversions in rats: a comparison of several rodenticides.

Injections of p-chlorophenylalanine or n-butyraldoxime given after rats were first given a 10-minute drinking test with saccharin or ethanol solutions produced a learned aversion to these solutions. These findings suggest that the reduced self-selection of alcohol (preference) resulting from the administration of these drugs, reported by others, is not specifically alcohol-related. The technique described offers a sensitive procedure for the assessment of unpleasant effects of drugs.

https://science.sciencemag.org/content/sci/168/3936/1244.full.pdf

Alcohol aversion in the rat: behavioral assessment of noxious drug effects.

One of the more intriguing issues in contemporary learning theory is the idea that stimuli are not equally associable. This idea, that some associations are more easily formed than others, has been formulated in various ways using such concepts as belongingness (Thorndike, 1932; Rozin and Kalat, 1971), stimulus relevance (Capretta, 1961), cue to consequence (Garcia and Koelling, 1966), and preparedness (Seligman, 1970). In food aversion learning, it is clear that animals readily learn to avoid ingesting material which was associated with sickness. (We use the words illness or sickness as arbitrary convenient terms in this chapter, realizing full well that they represent a gross oversimplification. The nature of the UCS is an important problem deserving of more consideration than can be given in this chapter.) The early field studies on bait shyness added poisons to bait and it became evident that animals learned to avoid the specific bait (Chitty, 1954). In subsequent laboratory experiments, the use of solutions permitted the control of other stimulus factors and it was possible to demonstrate that it was primarily the taste rather than any other sensory quality that was avoided (Garcia, Kimeldorf, and Koelling, 1955; Nachman, 1963).

Marvin Nachman

Papers

Learned taste aversions in rats as a function of dosage, concentration, and route of administration of LiCl.

Effects of basolateral amygdala lesions on neophobia, learned taste aversions, and sodium appetite in rats.

Role of illness in producing learned taste aversions in rats: a comparison of several rodenticides.

Alcohol aversion in the rat: behavioral assessment of noxious drug effects.

Stimulus Characteristics in Food Aversion Learning