A method for placing Heschl gyrus depth electrodes: Technical note
ABSTRACT A wide range of devices is used to obtain intracranial electrocorticography recordings in patients with medically refractory epilepsy, including subdural strip and grid electrodes and depth electrodes. Penetrating depth electrodes are required to access some brain regions, and 1 target site that presents a particular technical challenge is the first transverse temporal gyrus, or Heschl gyrus (HG). The HG is located within the supratemporal plane and has an oblique orientation relative to the sagittal and coronal planes. Large and small branches of the middle cerebral artery abut the pial surface of the HG and must be avoided when planning the electrode trajectory. Auditory cortex is located within the HG, and there are functional connections between this dorsal temporal lobe region and medial sites commonly implicated in the pathophysiology of temporal lobe epilepsy. At some surgical centers, depth electrodes are routinely placed within the supratemporal plane, and the HG, in patients who require intracranial electrocorticography monitoring for presumed temporal lobe epilepsy. Information from these recordings is reported to facilitate the identification of seizure patterns in patients with or without auditory auras. To date, only one implantation method has been reported to be safe and effective for placing HG electrodes in a large series of patients undergoing epilepsy surgery. This well-established approach involves inserting the electrodes from a lateral trajectory while using stereoscopic stereotactic angiography to avoid vascular injury. In this report, the authors describe an alternative method for implantation. They use frameless stereotaxy and an oblique insertion trajectory that does not require angiography and allows for the simultaneous placement of subdural grid arrays. Results in 19 patients demonstrate the safety and efficacy of the method.
- SourceAvailable from: ncbi.nlm.nih.gov[Show abstract] [Hide abstract]
ABSTRACT: Speech comprehension relies on temporal cues contained in the speech envelope, and the auditory cortex has been implicated as playing a critical role in encoding this temporal information. We investigated auditory cortical responses to speech stimuli in subjects undergoing invasive electrophysiological monitoring for pharmacologically refractory epilepsy. Recordings were made from multicontact electrodes implanted in Heschl's gyrus (HG). Speech sentences, time compressed from 0.75 to 0.20 of natural speaking rate, elicited average evoked potentials (AEPs) and increases in event-related band power (ERBP) of cortical high-frequency (70-250 Hz) activity. Cortex of posteromedial HG, the presumed core of human auditory cortex, represented the envelope of speech stimuli in the AEP and ERBP. Envelope following in ERBP, but not in AEP, was evident in both language-dominant and -nondominant hemispheres for relatively high degrees of compression where speech was not comprehensible. Compared to posteromedial HG, responses from anterolateral HG-an auditory belt field-exhibited longer latencies, lower amplitudes, and little or no time locking to the speech envelope. The ability of the core auditory cortex to follow the temporal speech envelope over a wide range of speaking rates leads us to conclude that such capacity in itself is not a limiting factor for speech comprehension.The Journal of Neuroscience : The Official Journal of the Society for Neuroscience 12/2009; 29(49):15564-74. DOI:10.1523/JNEUROSCI.3065-09.2009 · 6.75 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: In this work, we show that electrophysiological responses during pitch perception are best explained by distributed activity in a hierarchy of cortical sources and, crucially, that the effective connectivity between these sources is modulated with pitch strength. Local field potentials were recorded in two subjects from primary auditory cortex and adjacent auditory cortical areas along the axis of Heschl's gyrus (HG) while they listened to stimuli of varying pitch strength. Dynamic causal modeling was used to compare system architectures that might explain the recorded activity. The data show that representation of pitch requires an interaction between nonprimary and primary auditory cortex along HG that is consistent with the principle of predictive coding.Journal of Cognitive Neuroscience 03/2011; 23(10):3084-94. DOI:10.1162/jocn_a_00021 · 4.69 Impact Factor
Chapter: Invasive Research Methods[Show abstract] [Hide abstract]
ABSTRACT: Auditory cortex, in the classic sense of the term, is taken to be the cluster of anatomically and physiologically distinct areas of temporal neocortex that are uniquely and reciprocally connected with one another and with the medial geniculate body and related thalamic nuclear groups. In humans, as many as seven or eight anatomically distinct auditory cortical fields have been identified on the supratemporal plane and posterolateral superior temporal gyrus (STG) (see Clarke and Morosan, Chapter 2).The Human Auditory Cortex, 01/2012: pages 39-67;