The hippocampus, conditional operations, and cognition

Abstract

This paper argues that the hippocampus is involved in mnemonic processes by virtue of being necessary to the execution of conditional operations occurring during the retrieval of acquired information from memory. A series of experiments indicating that animals suffering from hippocampal dysfunction are incapable of behaving conditionally in learning situations is described. Other effects of hippocampal dysfunction are then explained in terms of disruption of conditional retrieval processes. The paper continues by defining retrieval as the selection of one piece of information from among many possible candidates. It is argued that such a process is of little utility in basic associative theories, as associative processes result in one predominant memory for any given stimulus. Cognitive theories, in contrast, have held that many things may be known about a given stimulus and thus selection among memories is mandatory. The process of conditional retrieval is then defined as the result of interaction between a categorical operator, representing global factors, and a local operator, representing local considerations. Interaction between these two types of operators is shown to be necessary for constructing dimensional representation, including maps. To hold that the hippocampus is involved in the construction of dimensional representations in general affords an opportunity to begin relating cognitive processes to physiological knowledge and to answer some of the broad conflicts between associative and cognitive theories of learning. It is further suggested that studies of hippocampal development may shed light on cognitive development.Studies on the function of brain structures in producing behavior must be done within some sort of psychological framework; otherwise the results cannot be interpreted. The capability of the framework in interpreting the results is, in turn, an indicator of the validity of the framework. Thus, studies of the behavioral function of structures deal not only with neurological mechanisms, but also with psychological processes. Studies of the role of the hippocampus in producing behavior have something quite important to say about the nature of learning and memory and, very possibly, about cognitive development. Memory

Psychological theories of hippocampal function

“…However, when the CS and the context signaled the absence of the US and the context alone signaled its presence (Micco & Schwartz, 1971), the development of conditioned inhibition was impaired. These findings provide support for the idea that context or spatial representations are affected by the lesion, as suggested by Hirsh (1980) and O' Keefe and Nadel (1978), but not the internal inhibition mechanism itself. Moore (1979) and Solomon (1979) proposed a new attentional role for the hippocampus.…”

“…The theta frequency is proportional to the distance covered by the animal in the environment (O'Keefe & Nadel, 1978, p. 226). Hirsh (1980) supported O'Keefe and Nadel's (1978) model, suggesting that spatial maps were a particular variety of dimensional representation. According to Hirsh, the contextual retrieval model could explain any dimensional representation, including maps, as the interaction between contextual factors and stimuli.…”

Temporal determinants of occasion setting in feature-positive discriminations

“…Other stimulustype contrasts, for example, short versus long, discrete versus diffuse (e.g., Jenkins, 1985;Rescorla, 1985), or explicit versus contextual (e.g., Balaz, Capra, Hartl, & Miller, 1981;Bouton & Bolles, 1985) might similarly encourage the engaging of a more hierarchical coding of sequence information (e.g., Fountain, Henne, & Hulse, 1984). Furthermore, the contrast of place and event (e.g., Hirsh, 1980;Nadel & Willner, 1980) and the spatial discontinuities encountered as an organism ranges over a variety of food locations (e.g., Olton, Becker, & Handelmann, 1979) might especially encourage occasion setting.…”

Context representations, context functions, and the parahippocampal–hippocampal system

“…Many researchers believe that the hippocampal formation makes a critical contribution to contextual control over behavior. This idea first emerged 35 yr ago when Hirsh (1974Hirsh ( , 1980 proposed that the hippocampal formation is critical to what is referred to above as the ''disambiguation function of context.'' However, it was shortly thereafter that Nadel, Willner, and others (Nadel and Willner 1980;Nadel et al 1985; see also Nadel 2008) provided a more general view of how the brain supports context functions.…”