Locating Brain Areas that Activates during Tool Use.
--A brief proposal for further research--
The ability to use wide range of tools effectively distinguish humans from animals, and brain injuries (especially left hemisphere damage as stated by Donkervoort, Dekker, van den Ende, Stehmann-Saris, & Deelman, 2000) have found to disrupt the ability to use tools and/or to effectively follow verbal commands to use a tool (Goldenberg & Hagmann, 1998; Johnson & Grafton, 2003). This condition is widely seen in Ideomotor Apraxic (IA) patients (Gross & Grossman, 2008), which is a sub-classification of the neurological disorder, ‘Apraxia’.
As seen in the video below, these IA patients are capable of accurately grasping and identifying tools based on the perceptual properties, yet they typically demonstrate the inability to correctly use tools when verbally instructed (Cubelli, Marchetti, Boscolo, & Della Sala, 2000; Gross & Grossman, 2008). Studies have also found that such patients are unable to imitate gestures (Goldenberg, 2003; Makuuchi, Kaminaga, & Sugishita, 2005). However, the ability to perform the task spontaneously remains intact (Wheaton & Hallett, 2007).
https://dtube.video/#!/v/hpwa/sxnxnc00
This represents functionally separate systems in the brain (Geschwind, 1965), i.e. semantic information processing, and sensory-motor transformation for movement execution. To identify the brain areas involved in the apraxic condition, previous studies have used clinical evaluation methods such as gesture imitations (Halsband et al., 2001; Makuuchi et al., 2005), or pantomime of tool use (Goldenberg & Hagmann, 1998), and studies were also performed using images (3D or 2D) with imagined, or pantomime actions.
For instance, by using image guided stimuli, imaging studies (PET) in healthy subjects have found activations in the left ventral premotor cortex and posterior left MTG for semantic tasks, and activations in the left posterior parietal cortex for action retrieval (Kellenbach et al., 2003).
fMRI studies have found activation in the left intraparietal sulcus and bilateral precunei for gesture imitation and verbal commands (De Renzi, Faglioni, & sorgato, 1982; Makuuchi et al., 2005). Lesion studies have found damage to the left parietal area, which was prominent in IA condition (Ghika, Ghika-Schmid, & Bogousslasvky, 1998; Halsband et al., 2001) by using gesture imitation and pantomime tasks.
Apart from these methods, identifying the cortical areas involved in using real tools when verbal commands are given remains under explored and requires further evaluations.
This is a part of a research proposal that I submitted for fMRI research to identify brain areas during tool use. I hope you enjoyed reading it.