research

Our aim is to understand the neuronal mechanisms underlying perception. We focus on visual motion perception, because it is relatively simple to present precisely controlled moving stimuli to a subject. We correlate the subject's perceptual reports, or the responses of single neurons in visual cortex, with the presented stimulus. This gives us insights into the neuronal mechanisms that underlie the encoding of a visual stimulus, and decoding of sensory activity to generate perception or behaviour.

Techniques

We employ a range of techniques including:

  • human psychophysics
  • animal psychophysics
  • extracellular recordings from single and multiple neurons
  • eye tracking during smooth pursuit, ocular following and saccades
  • computational modeling

Current projects

Enquiries from potential students and postdocs are always welcome. Experience in electrophysiology, psychophysics, computer programming or Matlab is desirable, but enthusiasm is more important than experience.
If you are interested in undertaking a period of research in the laboratory, please contact Nic Price.

The influence of stimulus history and task context on neuronal sensitivity and perception

Survival requires analysing a barrage of sensory stimulation from the environment. However, the brain cannot encode every event, requiring strategies for efficient processing of sensory information. By monitoring neuronal activity in animals performing behavioural tasks, we will determine how sensory encoding in the brain depends on stimulus history and task context. We hypothesize that neuronal sensitivity is matched to prevailing stimuli and to the current behavioral task, enhancing perceptual performance. This is similar to a camera adjusting its sensitivity under different lighting. The results of this work could be incorporated into adaptive environmental sensors or neuro-prosthetics.


Neuronal sensitivity and variability underlying perception and action

Perception and behaviour are often unpredictable. We do not identically perceive repeated stimuli, and even professional athletes cannot precisely replicate their actions. This has implications for survival, which demands accurate responses to a barrage of environmental stimulation. In the brain, sensory information is represented by patterns of electrical activity across populations of neurons, with unique patterns producing different conscious perceptions or actions. Intriguingly, neuronal responses to repeated stimuli are highly variable, suggesting that perceptual and behavioural variability originates in sensory cortex.

Vision is an excellent model for studying the variability in sensory processing: in behaving animals, we can compare neuronal responses to a stimulus with eye movements and perceptual judgments of the stimulus. This will give insights into how the variable activity of neuronal populations underlies perception and behaviour. Importantly, deficits in motion perception and eye movements are associated with medical conditions including schizophrenia, Parkinson’s disease and dyslexia. Thus, understanding the properties of motion-sensitive neurons and their role in oculomotor control could improve treatment of these conditions.

We will record extracellular neuronal activity in animals trained to make perceptual judgements of the speed of a moving stimulus, while they simultaneously make smooth tracking eye movements. We can compare the activity of multiple sensory neurons on each trial with the accuracy of the animal’s judgments and eye movements. This allows us to characterise how populations of sensory neurons with variable responses encode stimuli, and how this activity is decoded to generate perception and action. We will also examine how neuronal activity, motion perception and tracking eye movements are modulated by rapid, saccadic eye movements and by localised electrical microstimulation within sensory cortex.