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Hudetz AG. Microstimulation reveals anesthetic state-dependent effective connectivity of neurons in cerebral cortex. Front Neurosci 2024; 18:1387098. [PMID: 39035779 PMCID: PMC11258030 DOI: 10.3389/fnins.2024.1387098] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2024] [Accepted: 06/07/2024] [Indexed: 07/23/2024] Open
Abstract
Introduction Complex neuronal interactions underlie cortical information processing that can be compromised in altered states of consciousness. Here intracortical microstimulation was applied to investigate anesthetic state-dependent effective connectivity of neurons in rat visual cortex in vivo. Methods Extracellular activity was recorded at 32 sites in layers 5/6 while stimulating with charge-balanced discrete pulses at each electrode in random order. The same stimulation pattern was applied at three levels of anesthesia with desflurane and in wakefulness. Spikes were sorted and classified by their waveform features as putative excitatory and inhibitory neurons. Network motifs were identified in graphs of effective connectivity constructed from monosynaptic cross-correlograms. Results Microstimulation caused early (<10 ms) increase followed by prolonged (11-100 ms) decrease in spiking of all neurons throughout the electrode array. The early response of excitatory but not inhibitory neurons decayed rapidly with distance from the stimulation site over 1 mm. Effective connectivity of neurons with significant stimulus response was dense in wakefulness and sparse under anesthesia. The number of network motifs, especially those of higher order, increased rapidly as the anesthesia was withdrawn indicating a substantial increase in network connectivity as the animals woke up. Conclusion The results illuminate the impact of anesthesia on functional integrity of local cortical circuits affecting the state of consciousness.
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Affiliation(s)
- Anthony G Hudetz
- Department of Anesthesiology, Center for Consciousness Science, University of Michigan, Ann Arbor, MI, United States
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Hajnal B, Szabó JP, Tóth E, Keller CJ, Wittner L, Mehta AD, Erőss L, Ulbert I, Fabó D, Entz L. Intracortical mechanisms of single pulse electrical stimulation (SPES) evoked excitations and inhibitions in humans. Sci Rep 2024; 14:13784. [PMID: 38877093 PMCID: PMC11178858 DOI: 10.1038/s41598-024-62433-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 05/16/2024] [Indexed: 06/16/2024] Open
Abstract
Cortico-cortical evoked potentials (CCEPs) elicited by single-pulse electric stimulation (SPES) are widely used to assess effective connectivity between cortical areas and are also implemented in the presurgical evaluation of epileptic patients. Nevertheless, the cortical generators underlying the various components of CCEPs in humans have not yet been elucidated. Our aim was to describe the laminar pattern arising under SPES evoked CCEP components (P1, N1, P2, N2, P3) and to evaluate the similarities between N2 and the downstate of sleep slow waves. We used intra-cortical laminar microelectrodes (LMEs) to record CCEPs evoked by 10 mA bipolar 0.5 Hz electric pulses in seven patients with medically intractable epilepsy implanted with subdural grids. Based on the laminar profile of CCEPs, the latency of components is not layer-dependent, however their rate of appearance varies across cortical depth and stimulation distance, while the seizure onset zone does not seem to affect the emergence of components. Early neural excitation primarily engages middle and deep layers, propagating to the superficial layers, followed by mainly superficial inhibition, concluding in a sleep slow wave-like inhibition and excitation sequence.
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Affiliation(s)
- Boglárka Hajnal
- Epilepsy Center, Clinic for Neurosurgery and Neurointervention, Semmelweis University, Budapest, 1145, Hungary
- János Szentágothai Neurosciences Program, Semmelweis University School of PhD Studies, Budapest, 1083, Hungary
| | - Johanna Petra Szabó
- Epilepsy Center, Clinic for Neurosurgery and Neurointervention, Semmelweis University, Budapest, 1145, Hungary
- János Szentágothai Neurosciences Program, Semmelweis University School of PhD Studies, Budapest, 1083, Hungary
- Lendület Laboratory of Systems Neuroscience, HUN-REN Institute of Experimental Medicine, Budapest, 1083, Hungary
| | - Emília Tóth
- Epilepsy and Cognitive Neurophysiology Laboratory, University of Alabama at Birmingham, Birmingham, AL, 35294, USA
| | - Corey J Keller
- Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY, 10461, USA
- Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine and Feinstein Institute of Medical Research, 300 Community Drive, Manhasset, NY, 11030, USA
- Department of Neuroscience, Psychiatry and Behavioral Sciences, Stanford University, Palo Alto, CA, 94304, USA
| | - Lucia Wittner
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, HUN-REN, Budapest, 1117, Hungary
- Department of Information Technology and Bionics, Péter Pázmány Catholic University, Budapest, 1083, Hungary
| | - Ashesh D Mehta
- Department of Neurosurgery, Hofstra North Shore LIJ School of Medicine and Feinstein Institute of Medical Research, 300 Community Drive, Manhasset, NY, 11030, USA
| | - Loránd Erőss
- Department of Functional Neurosurgery, Clinic for Neurosurgery and Neurointervention, Semmelweis University, Budapest, 1145, Hungary
| | - István Ulbert
- Epilepsy Center, Clinic for Neurosurgery and Neurointervention, Semmelweis University, Budapest, 1145, Hungary
- Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, HUN-REN, Budapest, 1117, Hungary
- Department of Information Technology and Bionics, Péter Pázmány Catholic University, Budapest, 1083, Hungary
| | - Dániel Fabó
- Epilepsy Center, Clinic for Neurosurgery and Neurointervention, Semmelweis University, Budapest, 1145, Hungary.
| | - László Entz
- Department of Functional Neurosurgery, Clinic for Neurosurgery and Neurointervention, Semmelweis University, Budapest, 1145, Hungary
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Dadarlat MC, Sun YJ, Stryker MP. Activity-dependent recruitment of inhibition and excitation in the awake mammalian cortex during electrical stimulation. Neuron 2024; 112:821-834.e4. [PMID: 38134920 PMCID: PMC10949925 DOI: 10.1016/j.neuron.2023.11.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Revised: 08/04/2023] [Accepted: 11/22/2023] [Indexed: 12/24/2023]
Abstract
Electrical stimulation is an effective tool for mapping and altering brain connectivity, with applications ranging from treating pharmacology-resistant neurological disorders to providing sensory feedback for neural prostheses. Paramount to the success of these applications is the ability to manipulate electrical currents to precisely control evoked neural activity patterns. However, little is known about stimulation-evoked responses in inhibitory neurons nor how stimulation-evoked activity patterns depend on ongoing neural activity. In this study, we used 2-photon imaging and cell-type specific labeling to measure single-cell responses of excitatory and inhibitory neurons to electrical stimuli in the visual cortex of awake mice. Our data revealed strong interactions between electrical stimulation and pre-stimulus activity of single neurons in awake animals and distinct recruitment and response patterns for excitatory and inhibitory neurons. This work demonstrates the importance of cell-type-specific labeling of neurons in future studies.
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Affiliation(s)
- Maria C Dadarlat
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Weldon School of Biomedical Engineering, Purdue University, West Lafayette, IN 47906, USA.
| | - Yujiao Jennifer Sun
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA; Institute of Ophthalmology, University College London, London EC1V 9EL, UK
| | - Michael P Stryker
- Department of Physiology, University of California, San Francisco, San Francisco, CA 94158, USA
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Kumaravelu K, Grill WM. Neural mechanisms of the temporal response of cortical neurons to intracortical microstimulation. Brain Stimul 2024; 17:365-381. [PMID: 38492885 PMCID: PMC11090107 DOI: 10.1016/j.brs.2024.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 02/20/2024] [Accepted: 03/12/2024] [Indexed: 03/18/2024] Open
Abstract
BACKGROUND Intracortical microstimulation (ICMS) is used to map neuronal circuitry in the brain and restore lost sensory function, including vision, hearing, and somatosensation. The temporal response of cortical neurons to single pulse ICMS is remarkably stereotyped and comprises short latency excitation followed by prolonged inhibition and, in some cases, rebound excitation. However, the neural origin of the different response components to ICMS are poorly understood, and the interactions between the three response components during trains of ICMS pulses remains unclear. OBJECTIVE We used computational modeling to determine the mechanisms contributing to the temporal response to ICMS in model cortical neurons. METHODS We implemented a biophysically based computational model of a cortical column comprising neurons with realistic morphology and synapses and quantified the temporal response of cortical neurons to different ICMS protocols. We characterized the temporal responses to single pulse ICMS across stimulation intensities and inhibitory (GABA-B/GABA-A) synaptic strengths. To probe interactions between response components, we quantified the response to paired pulse ICMS at different inter-pulse intervals and the response to short trains at different stimulation frequencies. Finally, we evaluated the performance of biomimetic ICMS trains in evoking sustained neural responses. RESULTS Single pulse ICMS evoked short latency excitation followed by a period of inhibition, but model neurons did not exhibit post-inhibitory excitation. The strength of short latency excitation increased and the duration of inhibition increased with increased stimulation amplitude. Prolonged inhibition resulted from both after-hyperpolarization currents and GABA-B synaptic transmission. During the paired pulse protocol, the strength of short latency excitation evoked by a test pulse decreased marginally compared to those evoked by a single pulse for interpulse intervals (IPI) < 100 m s. Further, the duration of inhibition evoked by the test pulse was prolonged compared to single pulse for IPIs <50 m s and was not predicted by linear superposition of individual inhibitory responses. For IPIs>50 m s, the duration of inhibition evoked by the test pulse was comparable to those evoked by a single pulse. Short ICMS trains evoked repetitive excitatory responses against a background of inhibition. However, the strength of the repetitive excitatory response declined during ICMS at higher frequencies. Further, the duration of inhibition at the cessation of ICMS at higher frequencies was prolonged compared to the duration following a single pulse. Biomimetic pulse trains evoked comparable neural response between the onset and offset phases despite the presence of stimulation induced inhibition. CONCLUSIONS The cortical column model replicated the short latency excitation and long-lasting inhibitory components of the stereotyped neural response documented in experimental studies of ICMS. Both cellular and synaptic mechanisms influenced the response components generated by ICMS. The non-linear interactions between response components resulted in dynamic ICMS-evoked neural activity and may play an important role in mediating the ICMS-induced precepts.
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Affiliation(s)
| | - Warren M Grill
- Department of Biomedical Engineering, Duke University, Durham, NC, USA; Department of Electrical and Computer Engineering, Duke University, Durham, NC, USA; Department of Neurobiology, Duke University, Durham, NC, USA; Department of Neurosurgery, Duke University, Durham, NC, USA.
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