Michael J. Gutnick

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Neurons of the neocortex differ dramatically in the patterns of action potentials they generate in response to current steps. Regular-spiking cells adapt strongly during maintained stimuli, whereas fast-spiking cells can sustain very high firing frequencies with little or no adaptation. Intrinsically bursting cells generate clusters of spikes (bursts),(More)
1. Intracellular recordings were obtained from neurons of the guinea pig sensorimotor cortical slice maintained in vitro. Under control recording conditions input resistances, time constants, and spiking characteristics of slice neurons were well within the ranges reported by other investigators for neocortical neurons in situ. However, resting potentials(More)
1. Spike adaptation of neocortical pyramidal neurones was studied with sharp electrode recordings in slices of guinea-pig parietal cortex and whole-cell patch recordings of mouse somatosensory cortex. Repetitive intracellular stimulation with 1 s depolarizing pulses delivered at intervals of < 5 s caused slow, cumulative adaptation of spike firing, which(More)
Extracellular calcium and potassium activities (aCa and aK) as well as neuronal activity were simultaneously recorded with ion-sensitive electrodes in the somatosensory cortex of cats. Baseline aCa was 1.2–1.5 mM/1, baseline a k 2.7–3.2 mM/1. Transient decreases in aCa and simultaneous increases in aK were evoked by repetitive stimulation of the(More)
In intracellular recordings from three neocortical pyramidal cells in vitro, intracellular dye injection identified the impalement site as the primary trunk of the apical dendrite. Dendritic recordings displayed two types of regenerative events: relatively fast, low-threshold spikes with amplitudes of 12-69 mV, and slower, higher-threshold spikes up to 80(More)
Although cortical dendrites have classically been thought of as passive structures, recent evidence suggests that active conductances, including Ca2+ conductance, are also present in the dendritic membrane. To investigate this, we have recorded intracellularly in slices of rat neocortex bathed in 24 mM tetraethylammonium chloride and 1 microM TTX. Under(More)
The presence of developmental cortical malformations has been associated with the occurrence of epilepsy, and correlative anatomic-clinical electrophysiological studies suggest that microdysgenic lesions may actually initiate epileptiform activity. We have investigated the electrophysiological properties of an animal model of polymicrogyria created by(More)
In cortical pyramidal neurons, the axon initial segment (AIS) is pivotal in synaptic integration. It has been asserted that this is because there is a high density of Na(+) channels in the AIS. However, we found that action potential-associated Na(+) flux, as measured by high-speed fluorescence Na(+) imaging, was about threefold larger in the rat AIS than(More)
Apical dendrites constitute a prominent feature of the microcircuitry in the neocortex, yet their function is poorly understood. Using fura-2 imaging of layer 5 pyramidal neurons from slices of rat somatosensory cortex, we have investigated the Ca2+ influx into dendrites under intracellular, antidromic, synaptic, and receptor-agonist stimulation. We find(More)
1. In whole cell recordings from layer V neurons in slices of mouse somatosensory neocortex, tetrodotoxin (TTX)-sensitive persistent Na+ current (INaP) was studied by blocking K+ currents with intracellular Cs+ and Ca2+ currents with extracellular Cd2+. During slow voltage ramps, INaP began to activate at around -60 mV, and attained a peak at around -25 mV.(More)