operant-protocols-for-assessing-cost-benefit-analysis-during

Operant Protocols for Assessing the Cost-benefit Analysis During Reinforced Decision Making by Rodents

Reinforcement-guided decision making is the ability to choose between competing courses of action based on the relative value of the benefits and their ...

dual-extracellular-recordings-mouse-hippocampus-prefrontal

Dual Extracellular Recordings in the Mouse Hippocampus and Prefrontal Cortex

The technique of recording local field potentials (LFPs) is an electrophysiological method used to measure the electrical activity of localized neuronal ...

The University of Melbourne

The hippocampus and associated cholinergic inputs have important roles in spatial memory in rodents. Muscarinic acetylcholine receptors (mAChRs) are involved in the communication of cholinergic signals and regulate spatial memory. They have been found to impact the memory encoding process, but the effect on memory retrieval is controversial. Previous studies report that scopolamine (a non-selective antagonist of mAChR) induces cognitive deficits on animals, resulting in impaired memory encoding, but the effect on memory retrieval is less certain. We tested the effects of blocking mAChRs on hippocampal network activity and neural ensembles that had previously encoded spatial information. The activity of hundreds of neurons in mouse hippocampal CA1 was recorded using calcium imaging with a miniaturised fluorescent microscope and properties of place cells and neuronal ensemble behaviour in a linear track environment were observed. We found that the decoding accuracy and the stability of spatial representation revealed by hippocampal neural ensemble were significantly reduced after the administration of scopolamine. Several other parameters, including neural firing rate, total number of active neurons, place cell number and spatial information content were affected. Similar results were also observed in a simulated hippocampal network model. This study enhances the understanding of the function of mAChRs on spatial memory impairment.

Scopolamine Impairs Spatial Information Recorded With "Miniscope" Calcium Imaging in Hippocampal Place Cells.

Local field potentials (LFPs) recorded intracranially display a range of location-specific oscillatory spectra which have been related to cognitive processes. Although the mechanisms producing LFPs are not completely understood, it is likely that voltage-gated ion channels which produce action potentials and patterned discharges play a significant role. It is also known that antipsychotic drugs (APDs) affect LFP spectra and a direct inhibitory effect on voltage-gated potassium channels has been reported. Additionally, voltage-gated potassium channels have been implicated in the pathophysiology of schizophrenia, a disorder for which APDs are primary therapies. In this study we sought to: i) better characterise the effects of two APDs on LFPs spectra and connectivity measures and ii) examine the effects of potassium channel modulators on LFPs and potential overlap of effects with APDs. Intracranial electrodes were implanted in hippocampus (HIP) and pre-frontal cortex (PFC) of C57BL/6J mice; power spectra, coherence and phase-amplitude cross-frequency coupling were measured. Drugs tested were APDs haloperidol and clozapine as well as voltage-gated potassium channel modulators (KVMs) 4-aminopyridine (4-AP), tetraethylammonium, retigabine and E-4031. Both APDs and KVMs significantly reduced gamma power except 4-AP, which conversely increased gamma power. Clozapine and retigabine additionally reduced gamma coherence between HIP and PFC, while 4-AP demonstrated the opposite effect. Phase-amplitude coupling between theta and gamma oscillations in HIP was significantly reduced by the administration of haloperidol and retigabine. These results provide previously undescribed effects of APDs on LFP properties and demonstrate novel modulation of LFP characteristics by KVMs that intriguingly overlap with the APD effects.

Effects of antipsychotic drugs and potassium channel modulators on spectral properties of local field potentials in mouse hippocampus and pre-frontal cortex.

Two major theories have been proposed to explain hippocampal function: cognitive map and the relational theories. They differ in their views on whether hippocampal neurons can process non-spatial information independently. However, the explanatory power of these theories remains unresolved. Additionally, more complex aspects of hippocampal neural population responses to non-spatial stimuli have not been investigated. Here, we used miniaturized fluorescence microscopy to investigate mouse CA1 responses to spatial, visual, auditory modalities, and combinations. We found that while neuronal populations primarily processed spatial information, they also showed strong sensitivity to non-spatial modalities independent of spatial inputs, exhibiting distinct neuronal dynamics and coding patterns. These results provide strong support for the relational theories.

Dechuan Sun

Department of Medicine,
Neural Dynamics Laboratory,
Department of Electrical and Electronic Engineering,
Neural Dynamics Laboratory, Department of Medicine

The University of Melbourne

Operant Protocols for Assessing the Cost-benefit Analysis During Reinforced Decision Making by Rodents

Dual Extracellular Recordings in the Mouse Hippocampus and Prefrontal Cortex

Dechuan Sun

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Medicine,Neural Dynamics Laboratory,Department of Electrical and Electronic Engineering,Neural Dynamics Laboratory, Department of Medicine

The University of Melbourne

Operant Protocols for Assessing the Cost-benefit Analysis During Reinforced Decision Making by Rodents

Dual Extracellular Recordings in the Mouse Hippocampus and Prefrontal Cortex

Department of Medicine,
Neural Dynamics Laboratory,
Department of Electrical and Electronic Engineering,
Neural Dynamics Laboratory, Department of Medicine