A thesis submitted in partial fulfilment of - Queen Margaret University

ehabilitation, function can be limited (Pulvermüller et al. 2001) (suggesting that
perhaps maladaptive neuronal connections are created). However it does not
address the process of rehabilitation and why some people with aphasia who
receive therapeutic intervention recover more language functioning than others.
It is important therefore to investigate the limitations on the rehabilitation of
language (which requires accurate neuronal connections), as it would be
envisaged that these limitations would have similar impact upon the learning of
new vocabulary (which also requires accurate neuronal connections).
2.6 FACTORS INFLUENCING LANGUAGE RECOVERY
As previously discussed (see section 2.4.1), while aphasia therapy is considered
efficacious, the extent to which language recovers is variable within the aphasic
population. The evidence presented indicates that recovery of language function
involves the reorganisation of neuronal connections. It can therefore be
speculated that any factors limiting the recovery of language function could
directly affect the potential for cortical plasticity, which in turn may affect the
ability of the individual to make new neuronal connections in the form of new
vocabulary learning. The literature provides evidence identifying limitations such
as pre-morbid factors, biological limitations and severity of loss of functions
following stroke. These issues will now be discussed below.
2.6.1 Pre-morbid factors
2.6.1.1 Age at onset
Buell and Coleman (1981) state that human ageing brings with it many clinical
signs indicating that the brain is subject to age-associated degenerative
processes. Jacobs and Scheibel (1993) found that brains (post-mortem) under
aged 50 years had significantly greater total dendritic length values in the left
hemisphere than older brains. However this was not the case for all brains as
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