The perceptual-mnemonic/feature conjunction model of perirhinal cortex function

The perirhinal cortex was once thought to be “silent cortex”, virtually ignored by researchers interested in the neurobiology of learning and memory. Following studies of brain damage associated with cases of amnesia, perirhinal cortex is now widely regarded as part of a “medial temporal lobe (MTL) memory system”. This system is thought to be more or less functionally homogeneous, having a special role in declarative memory, and making little or no contribution to other functions such as perception. In the present article, we summarize an alternative view. First, we propose that components of the putative MTL system such as the hippocampus and perirhinal cortex have distinct and dissociable functions. Second, we provide evidence that the perirhinal cortex has a role in visual discrimination. In addition, we propose a specific role for perirhinal cortex in visual discrimination: the contribution of complex conjunctive representations to the solution of visual discrimination problems with a high degree of “feature ambiguity”. These proposals constitute a new view of perirhinal cortex function, one that does not assume strict modularity of function in the occipito-temporal visual stream, but replaces this idea with the notion of a hierarchical representational continuum.     

DIAGNOSTIC PSYCHOLOGICAL TESTING FOR READING/LEARNING DISORDERS IN PRESCHOOL CHILDREN

ABSTRACT

The assessment of preschool children who are at risk for having specific language/learning disorders when they enter school is a complex undertaking which must involve examining a wide variety of developmental processes. In addition to a thorough medical, developmental and academic history, the clinician should obtain data regarding perceptual‐motor functioning, language and cognitive development, nominal recall, cerebral dominance and directionality, sequential memory, and the integrity of basic sensory modalities. Although the diagnosis of potential learning disorders in preschool children 1s difficult because of the variability in developmental rate of young children, a systematic evaluation of the developmental functions which are classically associated with learning disabilities allows the psychologist to make a responsible and generally accurate statement of the child's current functioning and future potential