radiocarbon dating and the prehistoric archaeology of china - Right hemisphere brain damage impairs strategy updating

With regard to direct biological mechanisms underlying plasticity in language networks, relatively few specific hypotheses have been put forth.While some investigators, including ourselves, have previously described different patterns of reorganization (e.g., compensatory “takeover” by a new area), these descriptions do not generally hypothesize a specific biological basis for these changes. The study of language network plasticity following left hemisphere stroke is foundational to the understanding of aphasia recovery and neural plasticity in general.

right hemisphere brain damage impairs strategy updating-2

Additionally, right hemisphere recruitment identified in neuroimaging studies may not be a consequence of plasticity at all.

In neurologically healthy control subjects, right hemisphere activation has been shown to increase as a function of task difficulty [22, 23].

However, transcranial magnetic stimulation (TMS) studies show that inhibiting the right IFG pars triangularis (PTr) improves fluency, naming, and other language measures in people with left hemisphere stroke [10–15].

This suggests that the right IFG, specifically right PTr, may be limiting recovery in people with left hemisphere lesions.

In the context of a picture naming f MRI task, we tested whether lesion size and location relate to activity in surviving left hemisphere language nodes, as well as homotopic activity in the right hemisphere during covert name retrieval and overt name production.

We found that lesion size was positively associated with greater right hemisphere activity during both phases of naming, a pattern that has frequently been suggested but has not previously been clearly demonstrated.

Recovery rates vary greatly, for reasons that are poorly understood [3].

The relationships between lesion site, activity pattern changes, and recovered language functions remain unclear.

For example, particularly severe participants may have larger lesions or lesions in highly critical areas.

If this is the case, then the relationship between left hemisphere activity and language performance may be indirect, in that both are actually dependent on the severity and size of the stroke itself, as well as the availability of left hemisphere tissue adjacent to the critical areas.

Within the right hemisphere, the relationship between plasticity and language performance is even less clear.

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