Multimodality language mapping in patients with left-hemispheric language dominance on Wada test

Self Cite

Objective Our recent electrocorticography (ECoG) study suggested reverse speech, a widely used control task, to be a poor control for non-language-related auditory activity. We hypothesized that this may be due to retained perception as a human voice. We report a follow-up ECoG study in which we contrast forward and reverse speech with a signal-correlated noise (SCN) control task that cannot be perceived as a human voice. Methods Ten patients were presented 90 audible stimuli, including 30 each of corresponding forward speech, reverse speech, and SCN trials, during ECoG recording with evaluation of gamma activity between 50–150 Hz. Results Sites of the lateral temporal gyri activated throughout speech stimuli were generally less activated by SCN, while some temporal sites seemed to process both human and non-human sounds. Reverse speech trials were associated with activities across the temporal lobe similar to those associated with forward speech. Conclusions Findings herein externally validate functional neuroimaging studies utilizing SCN as a control for non-language-specific auditory function. Our findings are consistent with the notion that stimuli perceived as originating from a human voice are poor controls for non-language auditory function. Significance Our findings have implications in functional neuroimaging research as well as improved clinical mapping of auditory functions.

Section: Methodsmentioning

confidence: 99%

Evaluating signal-correlated noise as a control task with language-related gamma activity on electrocorticography

Brown¹,

Muzik²,

Robert³

et al. 2014

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“…Finally, sites surviving correction showing significant amplitude augmentation spanning (i) at least 20-Hz in width and (ii) at least 20-ms in duration were defined as significant gamma-augmentation elicited by a given task. We previously discussed the advantage and limitation of this analytic approach (Wu et al, 2011; Brown et al, 2012), which was, in short, validated by correlation with electrical stimulation data as well as post-surgical symptoms (Fukuda et al, 2008; Nagasawa et al, 2010a; 2010b; Kojima et al, 2012; 2013a; 2013b). …”

Section: Methodsmentioning

confidence: 99%

Gamma activity modulated by naming of ambiguous and unambiguous images: Intracranial recording

Cho-Hisamoto

Kojima

Brown

et al. 2015

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OBJECTIVE Humans sometimes need to recognize objects based on vague and ambiguous silhouettes. Recognition of such images may require an intuitive guess. We determined the spatial-temporal characteristics of intracranially-recorded gamma activity (at 50–120 Hz) augmented differentially by naming of ambiguous and unambiguous images. METHODS We studied ten patients who underwent epilepsy surgery. Ambiguous and unambiguous images were presented during extraoperative electrocorticography recording, and patients were instructed to overtly name the object as it is first perceived. RESULTS Both naming tasks were commonly associated with gamma-augmentation sequentially involving the occipital and occipital-temporal regions, bilaterally, within 200 ms after the onset of image presentation. Naming of ambiguous images elicited gamma-augmentation specifically involving portions of the inferior-frontal, orbitofrontal, and inferior-parietal regions at 400 ms and after. Unambiguous images were associated with more intense gamma-augmentation in portions of the occipital and occipital-temporal regions. CONCLUSIONS Frontal-parietal gamma-augmentation specific to ambiguous images may reflect the additional cortical processing involved in exerting intuitive guess. Occipital gamma-augmentation enhanced during naming of unambiguous images can be explained by visual processing of stimuli with richer detail. SIGNIFICANCE Our results support the theoretical model that guessing processes in visual domain occur following the accumulation of sensory evidence resulting from the bottom-up processing in the occipital-temporal visual pathways.

“…In this issue, Kojima et al (2012) take gamma-oscillations a step further to the bedside by comparing language mapping via electrical brain stimulation to mapping using event-related gamma-oscillations. Using a task in which patients were asked simple questions (e.g.…”

Section: Gamma-oscillations From Bench To Bedmentioning

confidence: 99%

Gamma-oscillations from bench to bed

Grünwald

Sarnthein²

2012

In the presurgical evaluation of patients with pharmacoresistant epilepsies, the borders between disciplines tend to oscillate. In particular, the necessity to evaluate the functional capacity of a cortical area that has been shown to be epileptogenic and is thus being considered for resection often makes it impossible not to trespass between neurophysiology and neuropsychology. In epilepsy surgery, the principle of "first, do no harm", often blurs the distinction between "bed and bench": findings from basic sciences that implicate a certain brain region in specific neurological or neuropsychological functions must be taken into account when an elective resection of a structure is considered -even if resection might relieve the patient from frequent intolerable seizures. That may seem to go without saying and, in fact, several examinations that are used routinely in modern presurgical evaluation are really shortcuts in the path from bench to bed. It may be an excuse that there are still are no generally accepted protocols for examinations such as the intracarotid amobarbital ("Wada") test or language mapping by electrostimulation, be the latter intrasurgical or by chronically implanted subdural electrodes. On the other hand, the opposite way "from bed to bench and back" has a famous history in epilepsy surgery: a new area of memory research followed Brenda Milner's analysis of the famous anterograde amnesia caused by the resection of both hippocampi in Henry Molaison (H.M.) and, eventually, this has led to important clinical applications in both neuropsychology and neurophysiology.