Brain Regions association with working memory

The working memory, as seen in Baddeley's model, is divided into several components. Each is associated with a different region of the brain.

Phonological Loop

• The phonological store is located in the parietal lobe
• The Articulatory rehearsal component is in both the frontal lobe and the cerebellum
• The speech production area associated with articulatory rehearsal is also known as Broca's area

Visuospatial Sketchpad

• This involves the dorsal and ventral streams
• The visual cache - storage takes place in the occipital and visual cortex
• The inner scribe - spatial rehearsal takes place in the inferior parietal lobe.

Central Executive

• The prefrontal cortex is associated with this component.
• This is the brain region that deals with higher level cognitive tasks.
• Evidence has found activation particularly in the dorsolateral region of the prefrontal cortex.

Episodic buffer

• There is little information available about the anatomical location of the episodic buffer.
• Similarly to the other three components, it is likely to be associated with multiple locations

Evaluation of the original working memory model

There are some advantages to the original model, and some evidence to support it. Dual task studies for example support the idea of having two specialised subcomponents. There is also neuropsychological and neuroimaging evidence that different brain regions are associated with the phonological loop and the visuospatial sketchpad and its subcomponents. Finally, there is strong evidence for an executive control system.

There are some difficulties with the original three component model however. Problems arise from the poor specification of interaction with the long term memory. There is evidence that the central executive is more than simply an attentional system, as an amenesiac patient with impaired long term memory was still found to have immediate memory for passages of prose that extend beyond the capacity of the PL and VSS. Another problem is that there is no system that allows for 'chunking'. Chunking allows for the information in the longterm memory to supplement immediate recall. If stimuli is a meaningful sentence then the memory span is increased. The model does not account for this however .

A further criticism of the original model is that there is no mechanism proposed for the interaction between the phonological loop and the visuospatial sketchpad, as well as no mechanism for the role of working memory in conscious awareness . The central executive was originally proposed to assist in binding this but how could it do this without a multimodal short term store to integrate the information.

Because of these criticisms and flaws with the model, Baddeley, in 2000, added in a 4th component to the model to account for the problems.

• Episodic Buffer: This hold on to and integrates diverse information
• It has limited capacity to temporarily store information
• it has a binding role and acts as a common multidimensional code.
• It has a temporary interface with the slave systems (VSS and PL)
• it is accessible to conscious awareness
• It links the working memory with the longterm memory more explicitly
• The information held in this buffer interacts with the visual semantics and language components and gets converted to the long term memory