# Role of the Primate Perirhinal Cortex in Memory and Emotional Regulation: Ontogeny and Early Insults

## TL;DR

This paper explores the role of the perirhinal cortex in memory and emotional regulation, focusing on its development and the effects of early damage.

## Contribution

The paper provides new insights into the functional maturation of the perirhinal cortex and its role in recognition memory and executive control.

## Key findings

- The perirhinal cortex supports familiarity judgments and recognition memory from early infancy.
- Neonatal dysfunction in the perirhinal cortex leads to compensation in memory but affects higher-order cognitive processes.
- The perirhinal cortex's role is linked to clinical markers in neurodevelopmental disorders like Alzheimer’s and schizophrenia.

## Abstract

The perirhinal cortex, a small strip of the anterior medial temporal
cortex, first came into prominence through studies of memory. While examining
patients with damage to the medial temporal lobe as well as animals with similar
regional damage, findings showed that combined damage to the hippocampus,
amygdala, and adjacent cortical areas, including the perirhinal cortex, were
responsible for the profound memory loss observed. Later, however, the evidence
demonstrated that the accompanying damage to the underlying medial temporal
cortical areas were largely responsible for the memory deficit that had been
attributed to the combined hippocampal and amygdala lesions. The perirhinal
cortex has become appreciated as a critical structure supporting familiarity
judgement, recognition memory, flexible executive control and behavioral
regulation. The objective of this article is first to review the anatomy of the
perirhinal cortex and its interactions with other medial temporal structures as
well as the neocortex. A series of neurosurgical ablation studies in nonhuman
primates will provide evidence for its role in memory and behavioral regulation
in adulthood. The next section will highlight the functional maturation of the
perirhinal from infancy through adulthood and will show that its role in support
of recognition memory emerges in early infancy. The findings will also show that
the neonatal perirhinal dysfunction results in functional compensation of
recognition and working memory in adulthood but impacts higher-order executive
processes such as cognitive control and flexibility. Interestingly, the
discovery of the role of perirhinal cortex in familiarity judgements instead of
recollection, which is mediated by the hippocampus, is now well documented in
several clinical neurodevelopmental disorders (epilepsy, Alzheimer’s
disease, schizophrenia), providing valuable markers in the prodromal phase of
the diseases for early diagnosis and treatment.