PMID- 10960057
OWN - NLM
STAT- MEDLINE
DCOM- 20000928
LR  - 20190513
IS  - 0006-8950 (Print)
IS  - 0006-8950 (Linking)
VI  - 123 ( Pt 9)
DP  - 2000 Sep
TI  - Time-dependent activation of parieto-frontal networks for directing attention to 
      tactile space. A study with paired transcranial magnetic stimulation pulses in 
      right-brain-damaged patients with extinction.
PG  - 1939-47
AB  - Tactile extinction has been interpreted as an attentional disorder, closely 
      related to hemineglect, due to hyperactivation of the unaffected hemisphere, 
      resulting in an ipsilesional attentional bias. Paired transcranial magnetic 
      stimulation (TMS) techniques, with a subthreshold conditioning stimulus (CS) 
      followed at various interstimulus intervals (ISIs) by a suprathreshold test 
      stimulus (TS), are useful for investigating intracortical inhibition and 
      facilitation in the human motor cortex. In the present work, we investigated the 
      effects of paired TMS over the posterior parietal and frontal cortex of the 
      unaffected hemisphere in a group of eight right-brain-damaged patients with 
      tactile extinction who were carrying out a bimanual tactile discrimination task. 
      The aim of the study was to verify if paired TMS could induce selective 
      inhibition or facilitation of the unaffected hemisphere depending on the ISI, 
      resulting, respectively, in an improvement and a worsening of contralesional 
      extinction. In addition, we wanted to investigate if the effects of parietal and 
      frontal TMS on contralesional extinction appeared at different intervals, 
      suggesting time-dependent activation in the cortical network for the processing 
      of tactile spatial information. Paired TMS stimuli with a CS and a TS, separated 
      by two ISIs of 1 and 10 ms, were applied over the left parietal and frontal 
      cortex after various intervals from the presentation of bimanual cutaneous 
      stimuli. Single-test parietal TMS stimuli improved the patients' performance, 
      whereas paired TMS had distinct effects depending on the ISI: at ISI = 1 ms the 
      improvement in extinction was greater than that induced by single-pulse TMS; at 
      ISI = 10 ms we observed worsening of extinction, with complete reversal of the 
      effects of single-pulse TMS. Compared with TMS delivered over the frontal cortex, 
      parietal TMS improved the extinction rate in a time window that began earlier. 
      These findings shed further light on the mechanism of tactile extinction, 
      suggesting relative hyperexcitability of the parieto-frontal network in the 
      unaffected hemisphere, which is amenable to study and modulation by paired TMS 
      pulses. In addition, the results show time-dependent processing of tactile 
      spatial information in the parietal and frontal cortices, with a bimodal 
      distribution of activity, at least in the attentional network of the unaffected 
      hemisphere.
FAU - Oliveri, M
AU  - Oliveri M
AD  - IRCCS S. Lucia, Rome, Italy. maxoliveri@tiscalinet.it
FAU - Rossini, P M
AU  - Rossini PM
FAU - Filippi, M M
AU  - Filippi MM
FAU - Traversa, R
AU  - Traversa R
FAU - Cicinelli, P
AU  - Cicinelli P
FAU - Palmieri, M G
AU  - Palmieri MG
FAU - Pasqualetti, P
AU  - Pasqualetti P
FAU - Caltagirone, C
AU  - Caltagirone C
LA  - eng
PT  - Journal Article
PL  - England
TA  - Brain
JT  - Brain : a journal of neurology
JID - 0372537
SB  - IM
MH  - Aged
MH  - Agnosia/pathology/physiopathology
MH  - Attention/*physiology
MH  - Brain Injuries/pathology/*physiopathology
MH  - Female
MH  - Frontal Lobe/pathology/*physiopathology
MH  - Functional Laterality/physiology
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Neural Inhibition/physiology
MH  - Neural Pathways/pathology/*physiopathology
MH  - Neuropsychological Tests
MH  - Parietal Lobe/pathology/*physiopathology
MH  - Psychomotor Performance/physiology
MH  - Reaction Time/physiology
MH  - Space Perception/*physiology
MH  - Time Factors
MH  - Touch/*physiology
MH  - Transcranial Magnetic Stimulation
EDAT- 2000/08/26 11:00
MHDA- 2000/09/30 11:01
CRDT- 2000/08/26 11:00
PHST- 2000/08/26 11:00 [pubmed]
PHST- 2000/09/30 11:01 [medline]
PHST- 2000/08/26 11:00 [entrez]
AID - 10.1093/brain/123.9.1939 [doi]
PST - ppublish
SO  - Brain. 2000 Sep;123 ( Pt 9):1939-47. doi: 10.1093/brain/123.9.1939.