Ipsilesional anodal tDCS enhances the functional benefits of rehabilitation in patients after stroke.

Anodal transcranial direct current stimulation (tDCS) can boost the effects of motor training and facilitate plasticity in the healthy human brain. Motor rehabilitation depends on learning and plasticity, and motor learning can occur after stroke. We tested whether brain stimulation using anodal tDCS added to motor training could improve rehabilitation outcomes in patients after stroke.

Tool-use and the left hemisphere: what is lost in ideomotor apraxia?

Impaired tool related action in ideomotor apraxia is normally ascribed to loss of sensorimotor memories for habitual actions (engrams), but this account has not been tested against a hypothesis of a general deficit in representation of hand-object spatial relationships. Rapid reaching for familiar tools was compared with reaching for abstract objects in apraxic patients (N=9) and in a control group with right hemisphere posterior stroke. The apraxic patients alone showed an impairment in rotating the wrist to correctly grasp an inverted tool but not when inverting the hand to avoid a barrier and grasp an abstract object, and the severity of the impairment in tool reaching correlated with pantomime of tool-use.

Tool use and action planning in apraxia.

Apraxia after left inferior parietal lesions has been widely interpreted as evidence of damage or impaired access to representations of tool-use, but most research has investigated pantomime of tool actions, not handling of actual tools. An alternative account is that inferior parietal damage does not affect tool-use representations but impairs cognitive processing about postural and hand-tool spatial relationships which is necessary for planning and controlling any complex action. Four apraxic patients and 10 age-matched controls were asked to reach rapidly for tools or abstract objects of similar dimensions.