O'Driscoll, Tara; (2023) Investigating the emergence of neural circuits for navigation in developing rats using wireless technology. Doctoral thesis (Ph.D), UCL (University College London).

Preview

Text O’Driscoll_10179394_PhD.pdf Download (17MB) | Preview

Abstract

The neural representation of space is encoded by spatially-modulated neurons including head direction cells (HD cells), place cells, and grid cells. Previous work has shown that these cell types emerge sequentially in rat postnatal development. Typically, spatial cognition experiments using in vivo electrophysiology are made as a single animal forages in an openfield environment while tethered to an acquisition system. In developmental studies, this requires the removal of the rat pup from its homecage, mother and littermates. Wireless technology is emerging as a promising alternative: neural data loggers permit the recording of single-unit neuronal activity in an animal’s homecage, thereby tracking spatial cell development while minimising disruption of early sensory experiences. Wireless recordings of spatial cells have not previously been conducted in the developing rat. The first experiment presented in this thesis was therefore a feasibility study demonstrating that wireless recordings of spatial cells in rat pups are comparable to standard techniques, focusing on HD cells in the anterodorsal thalamic nucleus (ADN), and place cells in the CA1 region of the hippocampus. The second experiment of this thesis employed wireless homecage recordings to investigate whether the activity patterns of HD cells during development differed from those observed in traditional open-field recordings. To address the research question, HD cell ensembles in the ADN were wirelessly recorded in the homecage from postnatal day (P)12 to P16. The directional modulation of HD cells was analysed by calculating both the mean resultant vector length (RV length) and directional information. Whilst RV length reflects the unidirectional tuning preference of individual HD cells, directional information quantifies any directional modulation of a cell, whether unidirectional or multidirectional. The results revealed that HD cells in the homecage exhibited lower RV lengths compared to those in the open field, indicating poorer unidirectional tuning. However, this difference was not reflected in the directional information of recorded cells, which remained consistent between environments until P16. This suggests that while heading direction in the open field is primarily encoded in a unidirectional manner, in the homecage it may be encoded through multiple preferred firing directions within a trial, indicating frequent resetting of HD cells. This phenomenon had the effect of equalising the directional information of cells between the two environments. The temporal and spatial coupling of recorded cells was also investigated on short-timescales. Strikingly, in contrast to previous reports (Bassett et al., 2018), the temporal and spatial synchronisation of HD cell ensemble firing did not precede the establishment of stable unidirectional tuning in the homecage. The internal spatial organisation of the network did also not appear to be maintained between recording environments, which may be as a result of differing movement statistics between environments. This finding suggests that the attractor network properties of HD cells in developing rats may be contingent on the context in which they are studied.

Download activity - last month

Export as JSONXMLCSV

Download activity - last 12 months

Export as JSONCSVXML

Downloads by country - last 12 months

Export as XMLCSVJSON

Archive Staff Only

View Item