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1.
Exp Brain Res ; 202(3): 529-42, 2010 May.
Article in English | MEDLINE | ID: mdl-20107980

ABSTRACT

The purpose of this study was to determine if recovery of neurologically impaired hand function following isolated motor cortex injury would occur without constraint of the non-impaired limb, and without daily forced use of the impaired limb. Nine monkeys (Macaca mulatta) received neurosurgical lesions of various extents to arm representations of motor cortex in the hemisphere contralateral to the preferred hand. After the lesion, no physical constraints were placed on the ipsilesional arm/hand and motor testing was carried out weekly with a maximum of 40 attempts in two fine motor tasks that required use of the contralesional hand for successful food acquisition. These motor tests were the only "forced use" of the contralesional hand. We also tested regularly for spontaneous use of the contralesional hand in a fine motor task in which either hand could be used for successful performance. This minimal intervention was sufficient to induce recovery of the contralesional hand to such a functional level that eight of the monkeys chose to use that hand on some trials when either hand could be used. Percentage use of the contralesional hand (in the task when either hand could be used) varied considerably among monkeys and was not related to lesion volume or recovery of motor skill. These data demonstrate a remarkable capacity for recovery of spontaneous use of the impaired hand following localized frontal lobe lesions. Clinically, these observations underscore the importance of therapeutic intervention to inhibit the induction of the learned nonuse phenomenon after neurological injury.


Subject(s)
Arm/physiology , Brain Injuries/rehabilitation , Motor Cortex/physiology , Recovery of Function/physiology , Animals , Arm/innervation , Brain Injuries/physiopathology , Disease Models, Animal , Exercise Therapy/methods , Female , Functional Laterality/physiology , Macaca mulatta , Male , Motor Cortex/injuries , Paresis/etiology , Paresis/rehabilitation , Random Allocation
2.
J Comp Neurol ; 518(5): 586-621, 2010 Mar 01.
Article in English | MEDLINE | ID: mdl-20034062

ABSTRACT

Brain injury affecting the frontal motor cortex or its descending axons often causes contralateral upper extremity paresis. Although recovery is variable, the underlying mechanisms supporting favorable motor recovery remain unclear. Because the medial wall of the cerebral hemisphere is often spared following brain injury and recent functional neuroimaging studies in patients indicate a potential role for this brain region in the recovery process, we investigated the long-term effects of isolated lateral frontal motor cortical injury on the corticospinal projection (CSP) from intact, ipsilesional supplementary motor cortex (M2). After injury to the arm region of the primary motor (M1) and lateral premotor (LPMC) cortices, upper extremity recovery is accompanied by terminal axon plasticity in the contralateral CSP but not the ipsilateral CSP from M2. Furthermore, significant contralateral plasticity occurs only in lamina VII and dorsally within lamina IX. Thus, selective intraspinal sprouting transpires in regions containing interneurons, flexor-related motor neurons, and motor neurons supplying intrinsic hand muscles, which all play important roles in mediating reaching and digit movements. After recovery, subsequent injury of M2 leads to reemergence of hand motor deficits. Considering the importance of the CSP in humans and the common occurrence of lateral frontal cortex injury, these findings suggest that spared supplementary motor cortex may serve as an important therapeutic target that should be considered when designing acute and long-term postinjury patient intervention strategies aimed to enhance the motor recovery process following lateral cortical trauma.


Subject(s)
Brain Injuries/physiopathology , Frontal Lobe/physiology , Motor Cortex/physiology , Neuronal Plasticity/physiology , Pyramidal Tracts/physiology , Animals , Arm/innervation , Arm/physiopathology , Axons/physiology , Axons/ultrastructure , Brain Mapping , Dextrans , Disease Models, Animal , Female , Fluorescein , Frontal Lobe/anatomy & histology , Functional Laterality/physiology , Interneurons/cytology , Interneurons/physiology , Macaca mulatta , Male , Motor Cortex/anatomy & histology , Motor Cortex/injuries , Motor Neurons/cytology , Motor Neurons/physiology , Muscle, Skeletal/innervation , Muscle, Skeletal/physiopathology , Nerve Regeneration/physiology , Neuroanatomical Tract-Tracing Techniques , Paresis/physiopathology , Pyramidal Tracts/anatomy & histology , Recovery of Function/physiology , Spinal Cord/cytology , Spinal Cord/physiology , Time , Time Factors
3.
Anal Chem ; 80(1): 123-8, 2008 Jan 01.
Article in English | MEDLINE | ID: mdl-18031020

ABSTRACT

Microdialysis membranes (3 mm lengthx200 microm i.d.) have been used to extract volatile analytes from aqueous samples into the gas phase and interfaced with fast gas chromatography. Gas-phase extracts generated from aqueous samples reach steady-state concentrations and are transported to the detector in 5 s. The recovery of the system ranges from 1.28% for toluene to less than 0.1% for ethanol. The lowest detectable concentration without preconcentration was 5 mM for most compounds using a flame ionization detector, and as low as 0.01 mM for more volatile hydrophobic analytes. When interfaced with a fast GC system, changes in aqueous phase concentrations were monitored with a temporal resolution of 10 s.

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