Functional neuroanatomy of different olfactory judgments

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Humans frequently make judgments about olfactory stimuli, yet the underlying functional neuroanatomy is not well understood.
• Previous research has limited exploration into the specific brain regions involved in diverse olfactory cognitive operations.

Purpose of the Study:

• To delineate the functional neuroanatomy of cognitive operations involved in olfactory judgments.
• To investigate how different types of odor-related judgments activate specific brain regions.

Main Methods:

• Employed Positron Emission Tomography (PET) to measure regional cerebral blood flow (rCBF) in 12 healthy subjects.
• Subjects performed five distinct olfactory judgment tasks: odor detection, intensity, hedonicity, familiarity, and edibility, alongside an auditory control task.

Main Results:

• All olfactory tasks showed increased rCBF in the right orbitofrontal cortex (OFC), with peak activity during familiarity judgments.
• Left OFC activation was specific to hedonic and familiarity judgments, exceeding activation in other tasks.
• Primary visual areas were engaged during hedonic and edibility judgments, but not during detection, intensity, or familiarity tasks.

Conclusions:

• Olfactory processing in the OFC is lateralized based on the specific judgment task, supporting a parallel processing model.
• Activation patterns suggest distinct roles for the left and right OFC in odor recognition versus emotional processing.
• Judgments of hedonicity and edibility uniquely recruit visual processing circuits, unlike other olfactory tasks.