Single-unit and polygraphic recordings associated with systemic or local pharmacology: A multi-purpose stereotaxic approach for the awake, anaesthetic-free, and head-restrained rat

172

137

Striatal medium-sized spiny neurons (MSNs) integrate and convey information from the cerebral cortex to the output nuclei of the basal ganglia. Intracellular recordings from anesthetized animals show that MSNs undergo spontaneous transitions between hyperpolarized and depolarized states. State transitions, regarded as necessary for eliciting action potential firing in MSNs, are thought to control basal ganglia function by shaping striatal output. Here, we use an anesthetic-free rat preparation to show that the intracellular activity of MSNs is not stereotyped and depends critically on vigilance state. During slow-wave sleep, much as during anesthesia, MSNs displayed rhythmic step-like membrane potential shifts, correlated with cortical field potentials. However, wakefulness was associated with a completely different pattern of temporally disorganized depolarizing synaptic events of variable amplitude. Transitions from slow-wave sleep to wakefulness converted striatal discharge from a cyclic brisk firing to an irregular pattern of action potentials. These findings illuminate different capabilities of information processing in basal ganglia networks, suggesting in particular that a novel style of striatal computation is associated with the waking state.

Section: Methodssupporting

confidence: 63%

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Distinct Patterns of Striatal Medium Spiny Neuron Activity during the Natural Sleep–Wake Cycle

Mahon

Vautrelle²,

Pézard³

et al. 2006

172

137

“…Constant, Quebec, Canada) were deeply anesthetized with ketamine, xylazine, and acepromazine (65:5:1 mg/kg in a mixture of 2 ml/kg initial dose and 1 ml/kg booster as needed, i.p.) for implantation of a metal U-frame to hold the head by screws to a sliding carriage adapter within the stereotaxic frame (Souliere et al, 2000) along with EEG and EMG electrodes, as described previously (Lee et al, 2004). For the EEG, small screws were threaded into the skull so that they were in contact with the dura over the anterior medial prefrontal (PF) cortex, the retrosplenial (RS) (also known as the posterior cingulate) cortex, the parietal (P) cortex, and the occipital (O) cortex of each side and over the olfactory bulb (OB) on one side.…”

Section: Methodsmentioning

confidence: 99%

Cholinergic Basal Forebrain Neurons Burst with Theta during Waking and Paradoxical Sleep

Lee¹,

Hassani²,

Alonso³

et al. 2005

401

325

It is known that acetylcholine can stimulate activation and promote plasticity in the cerebral cortex, yet it is not known how the cholinergic basal forebrain neurons, which release acetylcholine in the cortex, discharge in relation to natural cortical activity and sleep-wake states. By recording basal forebrain units in association with electroencephalographic activity across the sleep-wake cycle and labeling individual neurons with Neurobiotin for immunohistochemical identification, we show for the first time that cholinergic neurons discharge in bursts at maximal rates during active waking and paradoxical sleep, when gamma and theta electroencephalographic activity are maximal. They virtually cease firing during slow-wave sleep. Notably, their bursting discharge is synchronized with theta oscillations. Through their maximal firing and rhythmic theta discharge during active waking and paradoxical sleep, the cholinergic neurons can thus modulate the cortex to promote activation along with plasticity during these two states.

“…Four bolts in each angle of the U piece allow fixing it to a sliding carriage adapter, itself fastened to the stereotaxic apparatus. This device allows a painless restraint of the rat's head with high mechanical stability (Souliere et al, 2000). Rats were anesthetized with pentobarbital (60 mg/kg) and placed in a stereotaxic frame.…”

Section: Unanesthetized Ratsmentioning

confidence: 99%

Firing Properties of Anatomically Identified Neurons in the Medial Septum of Anesthetized and Unanesthetized Restrained Rats

Simon

Poindessous‐Jazat²,

Dutar³

et al. 2006

140

Cholinergic and GABAergic neurons in the medial septum-diagonal band of Broca (MS-DB) project to the hippocampus where they are involved in generating theta rhythmicity. So far, the functional properties of neurochemically identified MS-DB neurons are not fully characterized. In this study, MS-DB neurons recorded in urethane anesthetized rats and in unanesthetized restrained rats were labeled with neurobiotin and processed for immunohistochemistry against glutamic acid decarboxylase (GAD), parvalbumin (PV), and choline acetyltransferase (ChAT). The majority of the 90 labeled neurons (75.5%) were GADϩ. Among them, 34.0% were also PVϩ, but none were ChATϩ. Only 8.8% of the labeled neurons were found ChATϩ. Remaining neurons (15.5%) were not identified. In anesthetized rats, all of the PV/GADϩ and 65% of GADϩ neurons exhibited burst-firing activity at the theta frequency. PV/GADϩ neurons displayed higher discharge rate and longer burst duration compared with GADϩ neurons. At variance, all of the ChATϩ neurons were slow-firing. Cluster-firing and tonic-firing were observed in GADϩ and unidentified neurons. In unanesthetized rats, during wakefulness or rapid eye movement sleep with hippocampal theta, the bursting neurons were PV/GADϩ or GADϩ, whereas all of the ChATϩ neurons were slow-firing. Across the sleep-wake cycle, the GABAergic component of the septohippocampal pathway was always more active than the cholinergic one. The fact that cholinergic MS-DB neurons do not display theta-related bursting or tonic activity but have a very low firing rate questions how acetylcholine exerts its activating role in the septohippocampal system.