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Variation in the topography of the speech production cortex verified by cortical stimulation and high gamma activity.

Babajani-Feremi A, Rezaie R, Narayana S, Choudhri AF, Fulton SP, Boop FA, Wheless JW, Papanicolaou AC - Neuroreport (2014)

Bottom Line: In both, the expressive language cortex was defined as the cortical patch below the electrode(s) that when stimulated resulted in speech arrest, and during speech expression tasks generated HG activity.This patch fell within the borders of Broca's area, as defined anatomically, in the case of the patient with a lesion, but outside that area in the other, lesion-free patient.Such results highlight the necessity for presurgical language mapping in all cases of surgery involving the language-dominant hemisphere and suggest that HG activity during expressive language tasks can be informative and helpful in conjunction with cortical stimulation mapping for expressive language mapping.

View Article: PubMed Central - PubMed

Affiliation: aDepartment of Pediatrics, Division of Clinical Neurosciences Departments of bRadiology cNeurosurgery dPediatric Neurology eNeurobiology and Anatomy, University of Tennessee Health Science Center fNeuroscience Institute, Le Bonheur Children's Hospital, Memphis, Tennessee, USA.

ABSTRACT
In this study, we have addressed the question of functional brain reorganization for language in the presence and absence of anatomical lesions in two patients with epilepsy using cortical stimulation mapping and high gamma (HG) activity in subdural grid recordings. In both, the expressive language cortex was defined as the cortical patch below the electrode(s) that when stimulated resulted in speech arrest, and during speech expression tasks generated HG activity. This patch fell within the borders of Broca's area, as defined anatomically, in the case of the patient with a lesion, but outside that area in the other, lesion-free patient. Such results highlight the necessity for presurgical language mapping in all cases of surgery involving the language-dominant hemisphere and suggest that HG activity during expressive language tasks can be informative and helpful in conjunction with cortical stimulation mapping for expressive language mapping.

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Time–frequency (TF) analysis of the recordings during three tasks from two subdural electrodes in the two patients (see Fig. 1 for locations of the two electrodes). Power in every time–frequency bin was compared with the mean power at baseline (i.e. −0.5 to −0.1 s) to calculate a t-value across all trials. Left column: TF analysis of the overt object naming task. Middle column: TF analysis of the repeating simple syllables (/ba/pa) task. Right column: TF analysis of the auditory continuous recognition memory (CRM) task. The time course of one trial (epoch) of each task is shown at the bottom of this figure. Electrodes 32 in patient 1 and 15 in patient 2 show significant enhancement of high gamma (HG) activity (50–150 Hz) in the object naming and syllable tasks, respectively. Note that the CRM task, which is a receptive language task, does not show HG enhancement in any electrode. Electrodes 40 in patient 2 and IF4 in patient 1, as control electrodes, did not show HG activity in any task. Freq., frequency; IF4, inferior frontal strip 4.
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Figure 3: Time–frequency (TF) analysis of the recordings during three tasks from two subdural electrodes in the two patients (see Fig. 1 for locations of the two electrodes). Power in every time–frequency bin was compared with the mean power at baseline (i.e. −0.5 to −0.1 s) to calculate a t-value across all trials. Left column: TF analysis of the overt object naming task. Middle column: TF analysis of the repeating simple syllables (/ba/pa) task. Right column: TF analysis of the auditory continuous recognition memory (CRM) task. The time course of one trial (epoch) of each task is shown at the bottom of this figure. Electrodes 32 in patient 1 and 15 in patient 2 show significant enhancement of high gamma (HG) activity (50–150 Hz) in the object naming and syllable tasks, respectively. Note that the CRM task, which is a receptive language task, does not show HG enhancement in any electrode. Electrodes 40 in patient 2 and IF4 in patient 1, as control electrodes, did not show HG activity in any task. Freq., frequency; IF4, inferior frontal strip 4.

Mentions: Time–frequency analyses of the recordings during the three tasks for the two patients are presented in Fig. 3. The activities of two representative electrodes are shown (one within and one outside the speech production area). As shown in Fig. 3, HG activity during the syllable task yielded similar results as that during the object naming task in identifying the speech production areas in the two patients. Electrode 32 in patient 1 and electrode 15 in patient 2 showed significant HG activity during both the syllable and the object naming tasks. The results of the syllable production task support the notion that the areas identified as speech-specific in both the syllable and the object naming tasks are in fact specific to the preparation and production of speech and not to any other function, such as semantic retrieval that object naming might entail. In contrast, the control CRM task did not result in significant HG activity in any of the electrodes overlying the speech production area in either patient 1 or patient 2, as expected. Moreover, electrodes 40 in patient 2 and IF4 in patient 1, as control electrodes, did not show HG activity during any task.


Variation in the topography of the speech production cortex verified by cortical stimulation and high gamma activity.

Babajani-Feremi A, Rezaie R, Narayana S, Choudhri AF, Fulton SP, Boop FA, Wheless JW, Papanicolaou AC - Neuroreport (2014)

Time–frequency (TF) analysis of the recordings during three tasks from two subdural electrodes in the two patients (see Fig. 1 for locations of the two electrodes). Power in every time–frequency bin was compared with the mean power at baseline (i.e. −0.5 to −0.1 s) to calculate a t-value across all trials. Left column: TF analysis of the overt object naming task. Middle column: TF analysis of the repeating simple syllables (/ba/pa) task. Right column: TF analysis of the auditory continuous recognition memory (CRM) task. The time course of one trial (epoch) of each task is shown at the bottom of this figure. Electrodes 32 in patient 1 and 15 in patient 2 show significant enhancement of high gamma (HG) activity (50–150 Hz) in the object naming and syllable tasks, respectively. Note that the CRM task, which is a receptive language task, does not show HG enhancement in any electrode. Electrodes 40 in patient 2 and IF4 in patient 1, as control electrodes, did not show HG activity in any task. Freq., frequency; IF4, inferior frontal strip 4.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4232293&req=5

Figure 3: Time–frequency (TF) analysis of the recordings during three tasks from two subdural electrodes in the two patients (see Fig. 1 for locations of the two electrodes). Power in every time–frequency bin was compared with the mean power at baseline (i.e. −0.5 to −0.1 s) to calculate a t-value across all trials. Left column: TF analysis of the overt object naming task. Middle column: TF analysis of the repeating simple syllables (/ba/pa) task. Right column: TF analysis of the auditory continuous recognition memory (CRM) task. The time course of one trial (epoch) of each task is shown at the bottom of this figure. Electrodes 32 in patient 1 and 15 in patient 2 show significant enhancement of high gamma (HG) activity (50–150 Hz) in the object naming and syllable tasks, respectively. Note that the CRM task, which is a receptive language task, does not show HG enhancement in any electrode. Electrodes 40 in patient 2 and IF4 in patient 1, as control electrodes, did not show HG activity in any task. Freq., frequency; IF4, inferior frontal strip 4.
Mentions: Time–frequency analyses of the recordings during the three tasks for the two patients are presented in Fig. 3. The activities of two representative electrodes are shown (one within and one outside the speech production area). As shown in Fig. 3, HG activity during the syllable task yielded similar results as that during the object naming task in identifying the speech production areas in the two patients. Electrode 32 in patient 1 and electrode 15 in patient 2 showed significant HG activity during both the syllable and the object naming tasks. The results of the syllable production task support the notion that the areas identified as speech-specific in both the syllable and the object naming tasks are in fact specific to the preparation and production of speech and not to any other function, such as semantic retrieval that object naming might entail. In contrast, the control CRM task did not result in significant HG activity in any of the electrodes overlying the speech production area in either patient 1 or patient 2, as expected. Moreover, electrodes 40 in patient 2 and IF4 in patient 1, as control electrodes, did not show HG activity during any task.

Bottom Line: In both, the expressive language cortex was defined as the cortical patch below the electrode(s) that when stimulated resulted in speech arrest, and during speech expression tasks generated HG activity.This patch fell within the borders of Broca's area, as defined anatomically, in the case of the patient with a lesion, but outside that area in the other, lesion-free patient.Such results highlight the necessity for presurgical language mapping in all cases of surgery involving the language-dominant hemisphere and suggest that HG activity during expressive language tasks can be informative and helpful in conjunction with cortical stimulation mapping for expressive language mapping.

View Article: PubMed Central - PubMed

Affiliation: aDepartment of Pediatrics, Division of Clinical Neurosciences Departments of bRadiology cNeurosurgery dPediatric Neurology eNeurobiology and Anatomy, University of Tennessee Health Science Center fNeuroscience Institute, Le Bonheur Children's Hospital, Memphis, Tennessee, USA.

ABSTRACT
In this study, we have addressed the question of functional brain reorganization for language in the presence and absence of anatomical lesions in two patients with epilepsy using cortical stimulation mapping and high gamma (HG) activity in subdural grid recordings. In both, the expressive language cortex was defined as the cortical patch below the electrode(s) that when stimulated resulted in speech arrest, and during speech expression tasks generated HG activity. This patch fell within the borders of Broca's area, as defined anatomically, in the case of the patient with a lesion, but outside that area in the other, lesion-free patient. Such results highlight the necessity for presurgical language mapping in all cases of surgery involving the language-dominant hemisphere and suggest that HG activity during expressive language tasks can be informative and helpful in conjunction with cortical stimulation mapping for expressive language mapping.

Show MeSH
Related in: MedlinePlus