Esteban Fridman

Publications of Esteban Fridman

• Kinematic improvement following Botulinum Toxin-A injection in upper limb spasticity due to stroke.

  Authors: Esteban Fridman, Marcos Crespo, Santiago Gomez Argüello, Lorena Degue, Mirta Villarreal, Stephan Bohlhalter, Lewis Wheaton, Mark Hallett

  Journal of neurology, neurosurgery, and psychiatry. 12/2009;

  Background and purpose: Focal spasticity is a significant motor disorder following stroke. Botulinum Toxin Type-A (BoNT-A) is a useful treatment for it. We evaluated kinematic modifications inducedBackground and purpose: Focal spasticity is a significant motor disorder following stroke. Botulinum Toxin Type-A (BoNT-A) is a useful treatment for it. We evaluated kinematic modifications induced by spasticity, and whether or not there is an improvement following injection of BoNT-A. METHODS: Eight stroke patients with upper limb spasticity, showing a flexor pattern, were evaluated using kinematics before and after focal treatment with BoNT-A. A group of sex and age-matched normal volunteers acted as a control group. RESULTS: Repeated-measure ANOVA showed that stroke patients performed slower in comparison to the control group. Following treatment with BoNT-A there was a significant improvement in kinematics in stroke patients while in the control group performance remained unchanged. CONCLUSIONS: Focal treatment of spasticity with Botulinum Toxin Type-A leads to an adaptive change in the upper limb of spastic stroke patients.

• Left parietal activation related to planning, executing and suppressing praxis hand movements.

  Authors: Lewis Wheaton, Esteban Fridman, Stephan Bohlhalter, Sherry Vorbach, Mark Hallett

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 05/2009;

  OBJECTIVE: We sought to investigate the activity of bilateral parietal and premotor areas during a Go/No Go paradigm involving praxis movements of the dominant hand. METHODS: A sentence was presentedOBJECTIVE: We sought to investigate the activity of bilateral parietal and premotor areas during a Go/No Go paradigm involving praxis movements of the dominant hand. METHODS: A sentence was presented which instructed subjects on what movement to make (S1; for example, "Show me how to use a hammer."). After an 8-s delay, "Go" or "No Go" (S2) was presented. If Go, they were instructed to make the movement described in the S1 instruction sentence as quickly as possible, and continuously until the "Rest" cue was presented 3s later. If No Go, subjects were to simply relax until the next instruction sentence. Event-related potentials (ERP) and event-related desynchronization (ERD) in the beta band (18-22Hz) were evaluated for three time bins: after S1, after S2, and from -2.5 to -1.5s before the S2 period. RESULTS: Bilateral premotor ERP was greater than bilateral parietal ERP after the S2 Go compared with the No Go. Additionally, left premotor ERP was greater than that from the right premotor area. There was predominant left parietal ERD immediately after S1 for both Go and No Go, which was sustained for the duration of the interval between S1 and S2. For both S2 stimuli, predominant left parietal ERD was again seen when compared to that from the left premotor or right parietal area. However, the left parietal ERD was greater for Go than No Go. CONCLUSION: The results suggest a dominant role in the left parietal cortex for planning, executing, and suppressing praxis movements. The ERP and ERD show different patterns of activation and may reflect distinct neural movement-related activities. SIGNIFICANCE: The data can guide further studies to determine the neurophysiological changes occurring in apraxia patients and help explain the unique error profiles seen in patients with left parietal damage.

• Cortico-cortical networks in patients with ideomotor apraxia as revealed by EEG coherence analysis.

  Authors: Lewis A Wheaton, Stephan Bohlhalter, Guido Nolte, Hiroshi Shibasaki, Noriaki Hattori, Esteban Fridman, Sherry Vorbach, Jordan Grafman, Mark Hallett

  Neuroscience letters. 04/2008; 433(2):87-92.

  We sought to determine whether coherent networks which circumvent lesioned cortex are seen in patients with ideomotor apraxia (IMA) while performing tool-use pantomimes. Five normal subjects and fiveWe sought to determine whether coherent networks which circumvent lesioned cortex are seen in patients with ideomotor apraxia (IMA) while performing tool-use pantomimes. Five normal subjects and five patients with IMA (three patients with corticobasal degeneration and two with left hemisphere stroke) underwent 64-channel EEG recording while performing three tool-use pantomimes with their left hand in a self-paced manner. Beta band (20-22 Hz) coherence indicates that normal subjects have a dominant left hemisphere network responsible for praxis preparation, which was absent in patients. Corticobasal degeneration patients showed significant coherence increase between left parietal-right premotor areas. Left hemisphere stroke patients showed significant coherence increases in a right parietofrontal network. The right hemisphere appears to store useable praxis representations in IMA patients with left hemisphere damage.

• Synchronization of parietal and premotor areas during preparation and execution of praxis hand movements.

  Authors: Lewis A Wheaton, Guido Nolte, Stephan Bohlhalter, Esteban Fridman, Mark Hallett

  Clinical neurophysiology : official journal of the International Federation of Clinical Neurophysiology. 07/2005; 116(6):1382-90.

  OBJECTIVE: We sought to determine temporal patterns of functional connectivity between the parietal, premotor, and motor cortices during preparation and execution of praxis hand movements. METHODS:OBJECTIVE: We sought to determine temporal patterns of functional connectivity between the parietal, premotor, and motor cortices during preparation and execution of praxis hand movements. METHODS: Normal subjects were instructed to perform six transitive (tool use) and intransitive (communicative gesture) self-paced pantomimes with the right hand while recording 64-channel electroencephalography (EEG) and electromyography (EMG) from right thumb and forearm flexors. Focusing on corticocortical coherence, we explored the time-course of synchronously active parietal and premotor circuits involved in these motor tasks. Trials were marked for EMG onset and averaged across subjects to determine changes in coherence relative to baseline between parietal, premotor, and motor areas. RESULTS: Coherence of homologous electrode pairs was similar when comparing transitive and intransitive movements. During preparation, beta band (18-22 Hz) coherence was maximal between electrodes over the left parietal lobe and left premotor electrodes. Additionally during preparation, the premotor area showed high coherence to the motor hand area and the parietal cortex. Electrodes over the supplementary motor area also showed coherence to the motor and parietal, but not the premotor area. Before and during execution, a second peak of high coherence increase was present in each area that demonstrated coherence increases during preparation. There was no coherence increase between parietal and motor areas. Coherence rapidly diminished 1.5-2.0 s after movement onset. CONCLUSIONS: Patterns of increased corticocortical coupling within a parietal, premotor, and motor network are present during preparation and execution of praxis movements. SIGNIFICANCE: This study adds to evidence that parietofrontal networks may be critical for integrating preparatory and motor-related activity for praxis movements.

• Synchronization of parietal and premotor areas during preparation and execution of praxis hand movements

  Authors: Lewis A. Wheaton, Guido Nolte, Stephan Bohlhalter, Esteban Fridman, Mark Hallett

  Clinical Neurophysiology.

  ObjectiveWe sought to determine temporal patterns of functional connectivity between the parietal, premotor, and motor cortices during preparation and execution of praxis hand movements.MethodsNormalObjectiveWe sought to determine temporal patterns of functional connectivity between the parietal, premotor, and motor cortices during preparation and execution of praxis hand movements.MethodsNormal subjects were instructed to perform six transitive (tool use) and intransitive (communicative gesture) self-paced pantomimes with the right hand while recording 64-channel electroencephalography (EEG) and electromyography (EMG) from right thumb and forearm flexors. Focusing on corticocortical coherence, we explored the time-course of synchronously active parietal and premotor circuits involved in these motor tasks. Trials were marked for EMG onset and averaged across subjects to determine changes in coherence relative to baseline between parietal, premotor, and motor areas.ResultsCoherence of homologous electrode pairs was similar when comparing transitive and intransitive movements. During preparation, beta band (18–22 Hz) coherence was maximal between electrodes over the left parietal lobe and left premotor electrodes. Additionally during preparation, the premotor area showed high coherence to the motor hand area and the parietal cortex. Electrodes over the supplementary motor area also showed coherence to the motor and parietal, but not the premotor area. Before and during execution, a second peak of high coherence increase was present in each area that demonstrated coherence increases during preparation. There was no coherence increase between parietal and motor areas. Coherence rapidly diminished 1.5–2.0 s after movement onset.ConclusionsPatterns of increased corticocortical coupling within a parietal, premotor, and motor network are present during preparation and execution of praxis movements.SignificanceThis study adds to evidence that parietofrontal networks may be critical for integrating preparatory and motor-related activity for praxis movements.