Electrophysiological characterization of different types of neurons recorded in vivo in the motor cortex of the cat. II. Membrane parameters, action potentials, current-induced voltage responses and electrotonic structures

“…extracellular recording studies in vivo also emphasized the presence of burst firing in a subset of cortical neurons (e.g., Bair et al. 1994; Baranyi et al. 1993a; Calvin and Sypert 1976; Cattaneo et al. 1981; Dégenètais et al. 2002; Istvan and Zarzecki 1994; Nuñez et al. 1993; Pockberger…”

“Long-duration intracellular recordings in awake, headfixed animals have been obtained previously (Yokota et al., 1970; Baranyi et al., 1993a, 1993b; Covey et al., 1996; Swadlow et al., 1998; Fee, 2000; Aksay et al., 2001; Steriade et al., 2001; Margrie et al., 2002; Chen and Fetz, 2005).”

“…by 3 to 5 times compared to quiescent states, in both anesthetized animals (Contreras et al., 1996; Borg-Graham et al., 1998; Pare et al., 1998; Destexhe and Pare, 1999) and awake animals (Baranyi et al., 1993a, 1993b; Steriade et al., 2001; reviewed in Destexhe et al., 2003; Destexhe, 2007).”

“Similarly, fast PTNs recorded intracellularly in motor cortex of awake cats had brief spikes (mean 0.41 ms, range 0.30 – 0.80 ms, measured at half amplitude) (Baranyi et al., 1993).”

“We then examined the spike wave-forms under these two conditions and showed that they were indistingeneous (Baranyi et al. 1993; Kawaguchi 1993), motorneurons have widely varying soma sizes and resultant input guishable.”

“In agreement with previous in vivo (Nuñez et al., 1993; Baranyi et al., 1993a) and in vitro (Connors and Gutnick, 1990) recordings performed in several cortical areas, the present data indicate that RS cells constitute the main electrophysiological class of pyramidal neurons in the rat PFC.”

“In several neuronal cell types, the fAHP component probably arises due to the activation of voltage-dependent K channels (Storm, 1987; Baranyi et al., 1993; Zhang and McBain, 1995; Bevan and Wilson, 1999), whilst the mAHP component is mediated by Ca2 -activated K channels (Storm, 1989; Williamson…”

“…outside the cell had features with different shapes and with amplitudes an order of magnitude smaller than STAs of IC potentials, and (2) polarizing currents affected the IC STA features in ways expected from changes in driving force (Eccles, 1964; Thomson et al., 1988; Baranyi et al., 1993a,b).”

“…Connors 1989, 1992; Connors et al. 1982, 1988; Kasper et al. 1994a; McCormick et al. 1985) and in vivo in somatosensory (Li and Waters 1996), motor (Baranyi et al. 1993; Pockberger 1991), visual (Holt et al. 1996), and association (Nunez et al. 1993) cortices, and existing terminology has been…”

“Recordings during EEG-activated states in other preparations also reported similar depolarized states and low input resistance (Baranyi et al. 1993; Borg-Graham et al. 1998; Matsumara et al. 1988; Steriade 2001).”

“RS adapting neurons correspond very well to the RS neurons described in the somatosensory cortex of rats [tex of c8] and guinea pigs [30], in the visual cortex of guinea pigs [36] and in the motor corats [6] and rats [43].”

“The change in subthreshold membrane potential V for each neuron is as follows dV dt gNaL V ENa gKL V EK Isyn Iint / m gspike V EK / spike where m is the membrane time constant (Table 2) as derived from experimental data for excitatory and inhibitory cells (Baranyi et al. 1993b).”

“Qualitatively similar findings have been reported in the cat for neurons in motor cortex (Calvin and Sypert, 1976; Baranyi et al., 1993) and association cortical areas 5 and 7 (Nunez et al., 1993).”

“100 Hz for several hundreds of milliseconds in vivo in response to extracellular synaptic stimulations [43,69].”

“The action potential repolarization of the modeled FS-cell is fast as reported by several investigators (McCormick et al. 1985; Connors and Gutnick 1990; Baranyi et al. 1993; Foehring et al. 1991) and the half amplitude width is 0.3ms (McCormick et al. 1985; Baranyi et al. 1993).”

“These passive membrane time constants were consistent with empirical data (Connors et al., 1982; Bloomfield et al., 1987; Baranyi et al., 1993).”

“Consistent with this, the ratio of RS waveforms to FS waveforms found here is similar to the excitatory to inhibitory cell ratio identified from intracellular cortical studies (cats: Baranyi et al. 1993;monkeys: Lund et al. 1979).”

“Across cells, the mean value of θ was 0.20 ± 0.04 nA (n = 38) in accordance with that previously calculated from the same cortical region (Baranyi et al. 1993; Paz et al. 2005).”

“This function is actually a better model of the neuronal current–frequency transfer characteristics than the classic sigmoid (Baranyi et al., 1993; Schwindt et al., 1997).”

“Background synaptic conductance enables gammafrequency oscillations It has been observed in in-vivo electrophysiological recordings that neurons in the neocortex receive a constant bombardment of incoherent synaptic activity in the intact brain [64–68].”

“This is also consistent with in vivo measurements [85], although there is again a wide range from {84+5 mV [86] to {64+4 mV [87].”

“Intracellular recordings of cortical neurons in awake adult cats [1, 2, 3], monkey [4] or mice [5] show that the neurons are always active and rarely exhibit periods of quie scence (reviewed in [6]).”

“2 subunits in RS neurons (Baranyi et al. 1993; Cauli et al. 1997; Erisir et al. 1999; Huettner and Baughman 1988; Kawaguchi and Kubota 1998; Massengill et al. 1997; McCormick et al. 1985).”

“However, Baranyi et al. (1993a; 1993b) described a larger number of neuronal subtypes in motor cortex, with overlapping firing statistics and spike waveform shapes, and we found that 63% (185/292) of units exhibited ISIs that could not be clearly identified with any of the categories in Chen and…”

“PV basket cells are equipped with everything that is necessary to make them fast reacting, time-keeping machines, including short membrane time constants [45], ultra-fast AMPA receptor conductance [45–48], an abrupt, non-adapting high-frequency firing (that can reach up to several hundred Hz) [11 ,49–52], as well as r…”

“Cortical cells displayed a depolarized ( –65 mV) and less fluctuating Vm than during oscillatory activity and firing occurs irregularly (Baranyi et al. 1993; Steriade et al. 2001; Rudolph et al. 2007; Constantinople & Bruno, 2011).”

“J Neurophysiol • VOL 96 • AUGUST 2006 • www.jn.org between consecutive spikes using sustained current pulses (Baranyi et al. 1993; Castro et al. 2002).”

“In vivo intracellular recordings in awake and anesthetized animals have shown that neurons in the neocortex (Matsumura et al., 1988; Baranyi et al., 1993; Borg-Graham et al., 1998; Paré et al., 1998; Destexhe and Paré, 1999) and other regions of the nervous system (Jörntell and Ekerot, 2006;…”

“On average, the input resistances of neocortical fast-spiking (FS) interneurons are slightly higher than in neocortical PCs (Baranyi et al., 1993; Kawaguchi, 1993a).”

“Indeed, intracellular recordings in awake animals reveal that cortical neurons are subjected to an intense synaptic bombardment and, as a result, are depolarized and have a low input resistance (Matsumara et al., 1988; Baranyi et al., 1993; Steriade et al., 2001) compared with brain slices kept in vitro.”

“5D3), which fit the characteristics described previously for ''inactivatingbursting'' neurons (Baranyi et al. 1993; Degenetais et al. 2002).”

“In addition, this intense synaptic activity sets the cellular membrane into a high-conductance state, in which the input resistance is reduced by 3 to 5 times compared to quiescent states [2,3,8,23,67].”

“In addition to axonal conduction velocities, a number of other biophysical properties such as the duration of the spike, membrane resistance, amplitude of after-hyperpolarization, and others distinguish fastand slow-conducting PTNs (Takahashi, 1965; Baranyi et al. 1993).”

“Differences in membrane properties between functionally distinct classes of cortical neurons have been studied extensively for over a decade (Baranyi et al. 1993; Chen et al. 1996a; Cheney and Fenz 1980; McCormick et al. 1985; Nunez et al. 1993; Sutor and Hablitz 1989).”

“…basket cells in the cortex of other species are also referred to as fast-spiking basket cells, because of their short duration action potentials (AP) and high frequency firing in vivo and in vitro (McCormick et al., 1985; Baranyi et al., 1993; Kawaguchi, 1995; Erisir et al., 1999).”

“This is about 10 ms (Baranyi et al. 1993).”

“Although not examined in the BLA, studies that have examined cortex and other cortical-like structures indicate that neurons do tend to be more depolarized during wakefulness (Baranyi et al., 1993; Steriade et al., 2001; Chen and Fetz, 2005; Rudolph et al., 2007; Poulet and Petersen, 2008; Lee et al., 2009).”

“Indeed, intracellular recordings in awake animals reveal that cortical neurons are subject to an intense synaptic bombardment and, as a result, are depolarized and have a low input resistance (Matsumura et al., 1988; Baranyi et al., 1993; Paré et al., 1998; Steriade et al., 2001) compared to brain slices kept in vitro.”

“The first intracellular recordings of cortical neurons in awake animals [1–3] showed that neurons are depolarized and subject to an intense and irregular synaptic bombardment of both excitatory and inhibitory inputs.”

“8 (Table 1), while the values in awake animals were estimated from the literature to be in a range of about 1 to 12 [4, 10, 11, 15, 29, 33, 34, 41, 49].”

“From the first intracellular recordings performed in awake cats [1, 2] to more recent recording in cats [3], monkeys [4], mice [5], and even in freely behaving rats [6], it has been shown that the membrane potential displays large fluctuations and is very rarely at the resting potential.”

“Other studies using sharp electrodes in the motor cortex of adult cats have found even much higher current thresholds, ranging from 600-1800 pA, depending on recorded cell type (Woody & Black-Cleworth, 1973; Baranyi et al., 1993).”