Biology subjects

McNaughton, B. L.

Publications and source records attributed to McNaughton, B. L..

4 recordsLinked to original sources

bioRxiv2018

Impaired Spatial Reorientation in the 3xTg-AD Mouse Model of Alzheimer’s Disease

In early Alzheimers disease (AD) spatial navigation is impaired; however, the precise cause of this impairment is unclear. Recent evidence suggests that getting lost in new surroundings is one of the first impairments to emerge in AD. It is possible that getting lost in new surroundings represents a failure to use distal cues to get oriented in space. Therefore, we set out to look for impaired use of distal cues for spatial orientation in a mouse model of amyloidosis (3xTg-AD). To do this, we trained mice to shuttle to the end of a track and back to an enclosed start box to receive a water reward. Then, mice were trained to stop in an unmarked reward zone to receive a brain stimulation reward. The time required to remain in the zone for a reward was increased across training, and the track was positioned in a random start location for each trial. We found that 6-month female, but not male, 3xTg-AD mice were impaired. Male and female mice had only intracellular pathology and male mice had less pathology, particularly in the dorsal hippocampus. Thus, AD may cause spatial disorientation as a result of impaired use of landmarks.

neuroscience↗

bioRxiv2017

Encoding of Tactile Context in the Mouse Visual Cortex

Multisensory integration is key for perception and animal survival yet how information from separate senses is integrated has been debated for decades. In the cortex, information from each sense is first processed in primary sensory areas and then combined in association areas. An alternative hypothesis to this hierarchical model is that primary sensory cortices partake in multisensory encoding. We probed tactile and visual responses in primary somatosensory and visual cortices in awake behaving animals using two-photon calcium imaging from layer 2/3 excitatory neurons. In support of an hierarchical model we found segregation of visual and tactile responses. Tactile stimuli evoked responses in S1 neurons. In striking contrast, V1 neurons failed to respond to tactile stimuli. This was true for passive whisker stimulation and for stimulation during active whisking. Furthermore, responses of V1 neurons to congruent visuo-tactile cues during active exploration, a condition where vision precedes touch, were completely abolished in darkness. The rostro-lateral area of the visual cortex responded to both visual and tactile aspects of the stimuli and may form a substrate for encoding multisensory signals during active exploration. Our results indicate that primary sensory areas mainly encode their primary sense and that the impact of other modalities may be restricted to modulatory effects.

neuroscience↗

bioRxiv2017

A high-performance, inexpensive setup for simultaneous multi-site recording of electrophysiological signals and wide-field optical imaging of the mouse cortex

Simultaneous recording of optical and electrophysiological signals from multiple cortical areas may provide crucial information to expand our understanding of cortical function. However, the insertion of multiple electrodes into the brain may compromise optical imaging by both restricting the field of view, and interfering with the approaches used to stabilize the specimen. Existing methods that combine electrophysiological recording and optical imaging in vivo implement either multiple surface electrodes or a single electrode for deeper recordings. To address such limitation, we built a microelectrode array (hyperdrive) compatible with wide-field imaging that allows insertion of up to 12 probes into a large brain area (8 mm diameter). The developed hyperdrive is comprised of a circle of individual microdrives where probes are positioned at an angle leaving a large brain area unobstructed for wide-field imaging. Multiple tetrodes and voltage-sensitive dye imaging (VSDI) were used for simultaneous registration of spontaneous and evoked cortical activity. The electrophysiological signals were used to extract local field potential (LFP) traces, multiunit and single-unit spiking activity. To demonstrate our approach, we compared LFP and VSD signals over multiple regions of the cortex and analyzed the relationship between single-unit and global cortical population activities. The study of the interactions between cortical activity at local and global scales, such as the one presented in this work, can help to expand our knowledge of brain function.

neuroscience↗

bioRxiv2017

Laminar organization of encoding and memory reactivation in the parietal cortex

Egocentric neural coding has been observed in parietal cortex (PC), but its topographical and laminar organization is not well characterized. We used multi-site recording to look for evidence of local clustering and laminar consistency of linear and angular velocity encoding in multi-neuronal spiking activity (MUA) and in the high-frequency (300-900 Hz) component of the local field potential (HF-LFP), believed to reflect local spiking activity. Rats were trained to run many trials on a large circular platform, either to LED-cued goal locations or as a spatial sequence from memory. Tuning to specific self-motion states was observed consistently, and exhibited distinct cortical depth-invariant coding properties. These patterns of collective local and laminar activation during behavior were reactivated in compressed form during post-experience sleep, and temporally coupled to hippocampal sharp wave ripples. Thus, PC neuron motion encoding is consistent across cortical laminae, and this consistency is maintained during memory reactivation.\n\nHighlights O_LIParietal cortex MUA encodes specific movements coherently across laminae.\nC_LIO_LIThis organizational scheme is maintained during subsequent memory reactivation\nC_LIO_LIMUA and HF-LFP showed similar self-motion tuning and memory reactivation dynamics\nC_LIO_LIThis establishes the utility of MUA and HF-LFP for human memory reactivation studies\nC_LI

neuroscience↗