Peririnal

Peririnal refers to structures related to the perirhinal cortex, a region of the medial temporal lobe that lies along the rhinal fissure near the entorhinal cortex. The perirhinal cortex is situated on the ventral surface of the temporal lobe and forms part of the limbic system, closely adjoining the entorhinal cortex and the hippocampal formation.

Anatomy and connections: The perirhinal cortex receives substantial input from higher-order sensory and association areas, particularly from the ventral visual stream, and it sends projections to the entorhinal cortex, through which information can be relayed to the hippocampus. These connections position the perirhinal cortex as an important hub for integrating perceptual features into stable representations that contribute to memory formation.

Function: The perirhinal cortex is associated with object recognition and familiarity judgments, aiding the distinction between familiar and novel stimuli. In memory research, it is often linked to familiarity-based recognition, a process that helps identify whether an item has been seen before without requiring detailed recollection. The region also participates in associative learning and the linking of item-specific information with contextual details, though its role in complex recollection is generally considered to be supplementary to the hippocampus.

Clinical relevance: Damage or degeneration affecting the perirhinal cortex can impair recognition memory and the discrimination of complex visual objects. Atrophy in this region is observed in aging and in neurodegenerative diseases such as Alzheimer’s disease. Functional imaging studies commonly show increased perirhinal activity during recognition tasks involving previously encountered objects.

This article describes the peririnal region within the broader context of the medial temporal lobe memory system and its connections to adjacent cortices.