Lateral olfactory stria

The lateral olfactory stria is the largest and most prominent bundle of secondary olfactory fibres leaving the olfactory tract at the olfactory trigone. It passes posterolaterally across the basal surface of the forebrain, along the lateral aspect of the anterior perforated substance, carrying most of the output from the olfactory bulb toward the primary olfactory regions.

Its fibres project mainly to the piriform cortex, with additional projections to other olfactory-related regions, including parts of the amygdaloid/periamygdaloid region and entorhinal cortex. These areas process information about the identity and significance of odours and provide connections between smell and emotional, behavioural, and memory-related responses.

A particularly important feature of this pathway is that olfactory information can reach the primary olfactory cortex directly, without first passing through an obligatory thalamic relay.

• Simple pathway: Olfactory bulb → olfactory tract → lateral olfactory stria → primary olfactory cortex (especially piriform cortex)

In contrast to the lateral olfactory stria, the medial olfactory stria is much smaller and more variable.