Tali Fisher

Publications (2)3.12 Total impact

• Article: Dis-regulation of response inhibition in adult Attention Deficit Hyperactivity Disorder (ADHD): an ERP study.

  Tali Fisher, Judith Aharon-Peretz, Hillel Pratt
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  ABSTRACT: To define the brain activity involved in impaired response inhibition of Attention Deficit Hyperactivity Disorder (ADHD) in adults. Performance measures and brain activity of 14 adult ADHD subjects and 14 controls, matched for age, gender, and overall intelligence were compared in an auditory Go-NoGo paradigm to tones. The task required a button press (Go) to 80% and inhibition of response (NoGo) to 20% of the tones, according to the tone's pitch. In NoGo trials ADHD subjects made significantly more commission errors compared to controls. ERPs of ADHD subjects showed smaller amplitudes of P3 (but not N2), and longer latencies of both N2 and P3. Source current density estimation revealed reduced activity in the right frontal dorsolateral cortex and in the posterior cingulate of the ADHD group. In addition, ADHD subjects showed an unexpected significantly enhanced response inhibition in Go trials, with excessive omission errors associated with significantly larger N2 amplitudes. In ADHD the neural networks sub-serving response inhibition are impaired. ADHD is a general dis-regulation of behavioral inhibition, not limited to response inhibition.
  Clinical neurophysiology: official journal of the International Federation of Clinical Neurophysiology 06/2011; 122(12):2390-9. · 3.12 Impact Factor
• Article: Dissociation between spontaneous and reactive flexibility in early Parkinson's disease.

  Rachel Tomer, Tali Fisher, Nir Giladi, Judith Aharon-Peretz
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  ABSTRACT: This study was designed to examine the relations between the severity of motor symptoms and impaired cognitive flexibility in Parkinson's disease. Studies that examine cognitive flexibility in Parkinson's disease report conflicting results. We hypothesized that such inconsistency may reflect a differential pattern of impairment on tasks that measure spontaneous versus reactive flexibility. The performance of tasks requiring either spontaneous (Alternate Uses) or reactive (Wisconsin Card Sorting Test) cognitive flexibility was examined in newly diagnosed unmedicated patients with idiopathic Parkinson's disease, as compared with age- and education-matched controls. The correlation between the degree of deficit and severity of motor symptoms was also examined. Patients were significantly worse than controls in performing both types of tasks. The patients' performance on tasks of spontaneous reactivity was not correlated with the presence or severity of the motor signs and symptoms. However, only patients showing signs of bradykinesia were impaired on a measure of reactive cognitive flexibility and the degree of impairment was significantly correlated with the severity of bradykinesia. These findings suggest that the dissociation between the two types of cognitive flexibility may reflect the differential involvement of the mesocortical and striatonigral dopaminergic circuits in the mediation of these tasks.
  Neuropsychiatry, neuropsychology, and behavioral neurology 07/2002; 15(2):106-12.