Research

Understanding the structure and function of the neural mechanisms that underlie visual perception and decision-making in primates. My research aims to elucidate and control the dynamic patterns of neural activity that give rise to perceptual decisions and experience. Major goals are to understand how artificial neuronal signals, reward and social learning influence neuronal signals and circuits. My research tools include in vivo electrophysiology, micro-stimulation, imaging techniques, psychophysics and histology.

Drift diffusion modelling: Probing without peeking?

Many of the central questions of human systems neuroscience boil down to ‘which brain regions do what’ and ‘how do they do it’...

Probing and intervening in perceptual decision circuits

Higher cognitive functions depend on the interaction of several brain regions...

Coding perceptual decisions: emergent signaling properties in cortical circuits

Spiking activity in single neurons of the primate visual cortex has been tightly linked to perceptual decisions. Any mechanism that reads out these perceptual signals to support behavior must respect the underlying neuroanatomy that shapes the functional properties of sensory...

MRS of visual cortex

Probing the neural and metabolic drivers of changes in brain chemistry with visual stimulation.

How accurately can we capture brain connections with MRI?

We are using Diffusion Tensor Imaging (DTI) and probabilistic tractography to predict the trajectory of visual brain pathways in primates. We compare these results to the actual neuronal connections in the same brain - revealed with small injections of tracers. Combining post mortem histology with non-invasive imaging methods, this research quantifies the extent to which MRI plus tractography can reveal real connectivity between specific brain areas.

Neurocomputational similarities and differences in perceptual decision-making of non-human primates and humans

Development of social influence in children with autism

The opinions of others have a profound influence on human decision-making. Graduate student Imogen Large tested 125 neurotypical and 30 autistic children between 6 and 14 years on a visual stereo-motion task under social influence. In neurotypical children...

Expected reward changes visual processing

Effective perceptual decisions rely upon combining sensory information with knowledge of the rewards available for different choices. Postdoctoral researcher Nela Cicmil combined electrical microstimulation of functionally specific groups of neurons in visual area V5/MT...

Micro-pool of decision neurons may include less than perfect responses

Human brain signals in real time

Postdoc Nela Cicmil recorded MEG brain responses when human subjects made a decision about the appearance of a rotating cylinder.

Comparing structural MRI and histology in individual brain

Characterizing neuronal circuits in V5/MT for perceptual decisions about 3D and visual motion

Neurons in extrastriate visual area V5/MT are tuned to conjunctions of binocular 3D depth and direction of motion.

Identifying cortical areas with myelin in vivo

A map of cortical myelin (blue-red scale) for a macaque monkey obtained in vivo. Areas with strong myelin signal (red) are for example V1, V5/MT, MST and M1.

MRI image of a Manganese injection in V5/MT (1h)

Visual motion and depth discrimination are pertinent models to study the brain signals for perception and decision-making.