Assistant Professor, Department of Psychology
Research Interests: Systems Neuroscience
Overview: Dr. Smear studies the neural mechanisms of olfactory function in mice. Mice have an excellent sense of smell – much of their genome encodes odorant receptors (over 1000 genes), and a large portion of their brain processes olfactory information. These neural features support a rich repertoire of olfactory behaviors. The Smear lab interrogates olfactory function with a battery of psychophysical tests, while manipulating and recording neuronal activity with genetics, electrophysiology, and imaging. From these studies, the lab will pursue general principles of how neural circuits generate behavior.
Sniff Invariant Odor Coding.
eNeuro. 2018 Nov-Dec;5(6):
Authors: Shusterman R, Sirotin YB, Smear MC, Ahmadian Y, Rinberg D
Sampling regulates stimulus intensity and temporal dynamics at the sense organ. Despite variations in sampling behavior, animals must make veridical perceptual judgments about external stimuli. In olfaction, odor sampling varies with respiration, which influences neural responses at the olfactory periphery. Nevertheless, rats were able to perform fine odor intensity judgments despite variations in sniff kinetics. To identify the features of neural activity supporting stable intensity perception, in awake mice we measured responses of mitral/tufted (MT) cells to different odors and concentrations across a range of sniff frequencies. Amplitude and latency of the MT cells' responses vary with sniff duration. A fluid dynamics (FD) model based on odor concentration kinetics in the intranasal cavity can account for this variability. Eliminating sniff waveform dependence of MT cell responses using the FD model allows for significantly better decoding of concentration. This suggests potential schemes for sniff waveform invariant odor concentration coding.
PMID: 30627641 [PubMed - in process]
Algorithms for Olfactory Search across Species.
J Neurosci. 2018 Oct 31;38(44):9383-9389
Authors: Baker KL, Dickinson M, Findley TM, Gire DH, Louis M, Suver MP, Verhagen JV, Nagel KI, Smear MC
Localizing the sources of stimuli is essential. Most organisms cannot eat, mate, or escape without knowing where the relevant stimuli originate. For many, if not most, animals, olfaction plays an essential role in search. While microorganismal chemotaxis is relatively well understood, in larger animals the algorithms and mechanisms of olfactory search remain mysterious. In this symposium, we will present recent advances in our understanding of olfactory search in flies and rodents. Despite their different sizes and behaviors, both species must solve similar problems, including meeting the challenges of turbulent airflow, sampling the environment to optimize olfactory information, and incorporating odor information into broader navigational systems.
PMID: 30381430 [PubMed - in process]