Assistant Professor, Department of Biology
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.
Stable representation of sounds in the posterior striatum during flexible auditory decisions.
Nat Commun. 2018 04 18;9(1):1534
Authors: Guo L, Walker WI, Ponvert ND, Penix PL, Jaramillo S
The neuronal pathways that link sounds to rewarded actions remain elusive. For instance, it is unclear whether neurons in the posterior tail of the dorsal striatum (which receive direct input from the auditory system) mediate action selection, as other striatal circuits do. Here, we examine the role of posterior striatal neurons in auditory decisions in mice. We find that, in contrast to the anterior dorsal striatum, activation of the posterior striatum does not elicit systematic movement. However, activation of posterior striatal neurons during sound presentation in an auditory discrimination task biases the animals' choices, and transient inactivation of these neurons largely impairs sound discrimination. Moreover, the activity of these neurons during sound presentation reliably encodes stimulus features, but is only minimally influenced by the animals' choices. Our results suggest that posterior striatal neurons play an essential role in auditory decisions, and provides a stable representation of sounds during auditory tasks.
PMID: 29670112 [PubMed - indexed for MEDLINE]
Auditory thalamostriatal and corticostriatal pathways convey complementary information about sound features.
J Neurosci. 2018 Nov 20;:
Authors: Ponvert ND, Jaramillo S
Multiple parallel neural pathways link sound-related signals to behavioral responses. For instance, the striatum, a brain structure involved in action selection and reward-related learning, receives neuronal projections from both the auditory thalamus and auditory cortex. It is not clear whether sound information that reaches the striatum through these two pathways is redundant or complementary. We used an optogenetic approach in awake mice of both sexes to identify thalamostriatal and corticostriatal neurons during extracellular recordings, and characterized neural responses evoked by sounds of different frequencies and amplitude modulation rates. We found that neurons in both pathways encode sound frequency with similar fidelity, but display different coding strategies for amplitude modulated noise. While corticostriatal neurons provide a more accurate representation of amplitude modulation rate in their overall firing rate, thalamostriatal neurons convey information about the precise timing of acoustic events. These results demonstrate that auditory thalamus and auditory cortex neurons provide complementary information to the striatum, and suggest that these pathways could be differentially recruited depending on the requirements of a sound-driven behavior.SIGNIFICANCE STATEMENTSensory signals from the cerebral cortex and the thalamus converge onto the striatum, a nucleus implicated in reward-related learning. It is not clear whether these two sensory inputs convey redundant or complementary information. By characterizing the sound-evoked responses of thalamostriatal and corticostriatal neurons, our work demonstrates that these neural pathways convey complementary information about the temporal features of sounds. This work opens new avenues for investigating how these pathways could be selectively recruited depending on task demands, and provides a framework for studying convergence of cortical and thalamic information onto the striatum in other sensory systems.
PMID: 30459227 [PubMed - as supplied by publisher]