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Professor Malcolm Brown

Investigations into the neural bases of recognition memory

My research focuses on the neural processes that lie behind memory and learning.

I am particularly interested in the neural substrates of recognition memory. Differences in neuronal activity are detected electrophysiologically and by using immunocyotchemical markers such as Fos, a protein that is produced at higher levels in more active regions of the brain. By measuring activity differences after presenting stimuli that vary in familiarity - from a novel stimulus, which has never been previously encountered, to familiar stimuli, experienced many times before - it is possible to observe in which regions of the brain and under what circumstances the level of familiarity correlates with modulation of activity. These researches are conducted in close collaboration with Professor Zafar Bashir and Dr E Clea Warburton, and Professors John Aggleton and John Pearce in the Department of Psychology at the University of Wales, Cardiff.

We have found that the perirhinal cortex is differentially activated depending on stimulus familiarity; with repetition, a stimulus causes long-lasting depression of the neuronal responses. Computational modelling studies, performed in a collaboration with Dr Rafal Bogacz of the Department of Computer Science, have established that encoding familiarity in this manner can provide an efficient way to process and store information.

Our investigations have shown that different, distinct brain areas are involved in recognition memory, depending on the nature of the stimulus. A system centring on perirhinal cortex deals with the discrimination of individual item familiarity, whereas a system involving the hippocampus deals with assocational, spatial and recollective aspects of recognition memory. Thus, for example, viewing novel and familiar arrangements of items produces changes in the activity of the hippocampus.

To understand these processes we employ techniques from a range of neuroscientific disciplines, analysing at molecular, cellular, systems and behavioural levels. Thus we use pharmacological, molecular genetic and selective ablation techniques to test for consistencies and inconsistencies in the changes produced in behaviour, neuronal activity and cellular processes related to recognition memory.

Continued study of the system will allow us to characterise the basis of recognition more fully, enhancing our understanding of normal memory, the neural basis of education, and the deficits of memory in conditions such as Alzheimer's Disease.

Read more >

Research keywords

  • perirhinal
  • hippocampus
  • electrophysiology
  • immunocytochemistry
  • behaviour
  • computational modelling
  • recognition memory
  • synaptic plasticity
  • long-term depression
  • glutamate receptors

Diseases related to this field of research

  • Alzheimer's disease
  • memory deficit disorders

Processes and functions relevant to this work

  • Memory
  • learning
  • plasticity

Research findings

 

  • LTD underlies recognition memory Read more >
  • short- and long-term memory systems rely on different populations of receptors Read more >
  • The hippocampus is necessary for associational, spatial and recollective memory Read more >
  • The perirhinal cortex in necessary for familiarity discrimination Read more >

 

Collaborations

  • Professor Zafar Bashir
  • University of Bristol
    Dr Clea Warburton
  • University of Bristol
    Dr Rafal Bogacz
  • University of Oxford
    Professor James Uney
  • University of Bristol
    Professors John Aggleton and John Pearce
  • MRC Co-operative on Neuronal Plasticity
    at the University of Wales
  • Cardiff