organisation - the Instituto Gulbenkian de Ciência

We compared speed-accuracy trade-offs (SATs) in odour detection and categorisation
and found large differences between tasks, demonstrating that SAT is
problem-specific and suggesting that the locus of performance-limiting noise
is a critical variable (manuscript in preparation). We developed a computational
model of these tasks, which can be fit to the data, and which has allowed us to
formalise these hypotheses.
ACTION SELECTION AND ACTION TIMING IN THE PREMOTOR CORTEX
Executing the right action at the right moment is important for adaptive behaviour.
Thus, not only how we choose one action among multiple options but also
how we determine the timing of actions are fundamental questions.
Our goal is to understand what features of future actions are represented in
the neuronal firing patterns in these areas, and how the interaction between
neurons gives rise to the action selection and action timing processes.
To achieve this goal, we are using multiple single-unit recording techniques
in behaving rodents. By correlating the activity of neurons with the animal’s
behaviour, we are seeking to understand the internal representation of future
actions in the motor cortex. Furthermore, by analysing the relationships of
spiking activity amongst multiple neurons, we hope to gain insight into computations
within the microcircuits in the motor cortex. Finally, we will apply
optogenetic techniques to perturb specific circuits and observe the impact on
behaviour.
We analysed neural correlates of action timing in the premotor cortex, documenting
two classes of waiting-time predictive neurons and a dynamical systems
analysis of the ensemble activity (manuscript submitted). We also developed a
task in which we can manipulate the availability of potential action options. We
began testing optogenetic interventions in these contexts.
EVALUATING THE RELIABILITY OF KNOWLEDGE:
NEURAL MECHANISMS OF CONFIDENCE ESTIMATION
Humans and other animals must often make decisions on the basis of imperfect
evidence. What is the neural basis for such judgments? How does the brain
compute confidence estimates about predictions, memories and judgments?
Previously, we found that a population of neurons in the orbitofrontal cortex
(OFC) tracks the confidence in decision outcomes. We are seeking to extend
these observations by testing whether confidence-related neural activity in the
OFC is causally related to confidence judgments. We are also addressing how
the uncertainty about a stimulus in the course of decision-making is computed
in olfactory sensory cortex. We are currently establishing similar confidencereporting
tasks in humans and testing them in a range of behaviours. These
experiments will give us further insights into the nature of the neural processes
underlying confidence estimation.
In rats, we used chronic multi-electrode recordings to assay neural ensemble
function in the olfactory tubercule of rats performing a confidence reporting
task (study in progress). We also found that inactivation of the rat orbitofrontal
cortex impairs confidence reporting but not choice behaviour (manuscript under
review). In humans we tested confidence reporting tasks similar to those we
deployed in rats under several different psychophysical paradigms.
IGC ANNUAL REPORT ‘11
RESEARCH GROUPS
48