Sussex Neuroscience

Dr Natasha Sigala

NatashaBrain mechanisms of visual perception and memory

Visual perceptual learning (VPL) is a measurable, long-term improvement in performance on a visual task and is the result of experience and practice. VPL is the result of the changes in the connection weights between cortical areas involved in sensory processing and decision making.

The maturation of the functional Magnetic Resonance Imaging (fMRI) methodology over recent years offers unprecedented opportunities for the study of sensory, motor and cognitive representations in the cortex. The fMRI signal measured in a voxel represents the activity of all neurons within it and is determined by the selectivity of those neurons. Furthermore, multivariate analyses of the BOLD signal have revealed cortical representations of stimulus and task related features and computations that had so far not been detected with univariate analyses.

This PhD will focus on the brain mechanisms of perceptual learning and memory, and will look into the activity and connectivity profiles of early and higher visual areas, as well as of areas involved in decision-making, before and after training. A motivated candidate will combine the three main methodological approaches in systems neuroscience: behavioural measurements, computational modelling and measures of cortical activity (fMRI) in a highly supportive and interactive lab environment.

Selected References

(For a full list of publications and more details about the lab, visit:

Minati L, Sigala N. (2013) Effective connectivity reveals strategy differences in an expert calculator. PLoS One (in press)

Hon N, Thompson R, Sigala N, Duncan J. (2009) Evidence for long-range feedback in target detection: Detection of semantic targets modulates activity in early visual areas. Neuropsychologia, 47(7): 1721-7

Sigala, N (2004) Visual categorization and the inferior temporal cortex. Behav Brain Res. 149(1):1-7.

Sigala N, Gabbiani F, Logothetis NK. (2002) Visual categorization and object representation in monkeys and humans. J Cogn Neurosci. 14(2):187-98.

Sigala N, Logothetis NK. (2002) Visual categorization shapes feature selectivity in the primate temporal cortex. Nature. 2002 415(6869):318-20.