Santiago Jaramillo

Assistant Professor, Department of Biology
Member, ION

215 LISB


Research Interests: Neuronal circuits that mediate behavioral flexibility and attention; auditory coding; neural computation

Overview: We study the neural circuits that mediate auditory cognition. Our goal is to understand how we assign meaning to sounds, how we attend to sounds or ignore them, how we remember them, and how disorders of the brain can affect these processes.
Of particular interest is how our responses to sounds can change depending on context, a phenomenon called behavioral flexibility. Behaving appropriately after changes in context requires that organisms rapidly modify their expectations, associations between cues and rewards, or attentional state. Our lab investigates these cognitive processes by addressing three questions:

  • What happens to the speed and accuracy of behavioral responses after a change in context?
  • Where in the brain is information selected and re-routed to allow for different interpretations of the same stimulus?
  • How do neural circuits implement this flexibility?

In our experiments, we use tools for monitoring and manipulating neuronal activity of specific cell types in behaving rodents, together with theoretical and computational approaches, to uncover the mechanisms that underlie flexible behaviors.


Related Articles

Somatostatin-Expressing Interneurons in the Auditory Cortex Mediate Sustained Suppression by Spectral Surround.

J Neurosci. 2020 04 29;40(18):3564-3575

Authors: Lakunina AA, Nardoci MB, Ahmadian Y, Jaramillo S

Sensory systems integrate multiple stimulus features to generate coherent percepts. Spectral surround suppression, the phenomenon by which sound-evoked responses of auditory neurons are suppressed by stimuli outside their receptive field, is an example of this integration taking place in the auditory system. While this form of global integration is commonly observed in auditory cortical neurons, and potentially used by the nervous system to separate signals from noise, the mechanisms that underlie this suppression of activity are not well understood. We evaluated the contributions to spectral surround suppression of the two most common inhibitory cell types in the cortex, parvalbumin-expressing (PV+) and somatostatin-expressing (SOM+) interneurons, in mice of both sexes. We found that inactivating SOM+ cells, but not PV+ cells, significantly reduces sustained spectral surround suppression in excitatory cells, indicating a dominant causal role for SOM+ cells in the integration of information across multiple frequencies. The similarity of these results to those from other sensory cortices provides evidence of common mechanisms across the cerebral cortex for generating global percepts from separate features.SIGNIFICANCE STATEMENT To generate coherent percepts, sensory systems integrate simultaneously occurring features of a stimulus, yet the mechanisms by which this integration occurs are not fully understood. Our results show that neurochemically distinct neuronal subtypes in the primary auditory cortex have different contributions to the integration of different frequency components of an acoustic stimulus. Together with findings from other sensory cortices, our results provide evidence of a common mechanism for cortical computations used for global integration of stimulus features.

PMID: 32220950 [PubMed - indexed for MEDLINE]

Related Articles

Author Correction: Response outcomes gate the impact of expectations on perceptual decisions.

Nat Commun. 2020 Jul 07;11(1):3470

Authors: Hermoso-Mendizabal A, Hyafil A, Rueda-Orozco PE, Jaramillo S, Robbe D, de la Rocha J

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

PMID: 32636370 [PubMed - in process]