Olfactory language and semantic processing in anosmia: a neuropsychological case control study

ABSTRACT

A longstanding debate within philosophy and neuroscience involves the extent to which sensory information is a necessary condition for conceptual knowledge. Much of our understanding of this relationship has been informed by examining the impact of congenital blindness and deafness on language and cognitive development. Relatively little is known about the “lesser” senses of smell and taste. Here we report a neuropsychological case-control study contrasting a young adult male (P01) diagnosed with anosmia (i.e. no olfaction) during early childhood relative to an age- and sex-matched control group. A structural MRI of P01’s brain revealed profoundly atrophic/aplastic olfactory bulbs, and standardized smell testing confirmed his prior pediatric diagnosis of anosmia. Participants completed three language experiments examining comprehension, production, and subjective experiential ratings of odor salient words (e.g. sewer) and scenarios (e.g. fish market). P01’s ratings of odor salience of single words were lower than all control participants, whereas his ratings on five other perceptual and affective dimensions were similar to controls. P01 produced unusual associations when cued to generate words that smelled similar to odor-neutral target words (e.g. ink → plant). In narrative picture description for odor salient scenes (e.g. bakery), P01 was indistinguishable from controls. These results suggest that odor deprivation does not overtly impair functional language use. However, subtle lexical-semantic effects of anosmia may be revealed using sensitive linguistic measures.

KEYWORDS:

• Olfaction
• language
• anosmia
• semantic Memory
• smell

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1. P01’s report of reactivity to noxious chemicals is consistent with at least partially preserved trigeminal chemoreception via cranial nerve V (CN V). Whereas the first cranial nerve (CN I) provides direct olfactory input to neural sensory regions, CN V responds to painful or irritating compounds by inducing changes to intranasal tissue, secretions, and respiratory patterns (see Doty et al., 1978 for details on trigeminal chemoreception in people with anosmia).

2. The supplemental data include an additional scatterplot reflecting a more granular depiction of olfactory ratings as a function of the olfactory salience (low/high) of the stimulus words. Visit https://osf.io/ujwkm/.

Additional information

Funding

This work was funded by US Public Health Service [Grant R01 DC013063].