Notable Preprints

During our research, we come across many interesting scientific articles. Here are our favories from BioRxiv.

Methods

Expressed genetically encoded voltage indicators pAce or AcemNeon2 in pyramidal cell somas in the hippocampus
Recorded voltage indicator fluorescence simultaneously with LFP during awake behavior in mice

pAce and LFP are highly correlated in the theta band, with pAce fluorescence preceeding LFP by ~20ms; this coherence increased during running.
pAce signals in hippocampal pyramidal cells display phase-amplitude coupling between theta and gamma oscillations, similarly to what’s seen in the LFP.
pAce fluorescence also responded to deep brain stimulation
System could be scaled up to simultaneously record from multiple site and/or multiple animals

Used Neuropixels probes to obtain simultaneous recordings in dorsal periaqueductal grey and its major inputs (superior colliculus and inferior colliculus in the midbrain, ventromedial hypothalamus and premammillary nucleus in the hypothalamus, and anterior cingulate cortex)
During escape behaviors (in response to threatening visual, auditory, or somatosensory stimuli), as well as a variety of other stimuli and behaviors related to the periaqueductal grey

Midbrain inputs showed the most influence over dorsal periaqueductal grey activity, followed by anterior cingulate cortex, and finally hypothalamic inputs
Determined that these relative strengths in functional connectivity cannot be explained by differences in presynaptic firing rates, or the physical location of the synapses
In vitro and modeling experiments showed that temporal summation has a larger influence on dorsal periaqueductal grey neurons than spatial summation. In conjunction with this, the three strongest inputs (from midbrain and anterior cingulate cortex) showed a higher concentration of short inter-spike intervals than those with less influence in the dorsal periaqueductal grey, the cell populations from midbrain were additionally shown to be more synchronous, which would additionally enhance temporal summation
Demonstrated that behavioral context caused a change in the short-term dynamics in anterior cingulate cortex firing, changing its functional connectivity with the dorsal periaqueductal grey

Using population vector correlation analysis and decoding, showed that place cell representations remain constant between conditions with the same lighting, but remap between light and dark conditions
Lesions of the lateral visual cortex (postrhinal cortex, lateromedial area, and laterointermediate area) prevented this mapping, suggesting that the visual information that influences place cell mapping flows through this area.
V1 and superior colliculus both project to lateral visual cortex, but only blocking the output of widefield cells in superior colliculus leads to a disruption of remapping, suggesting that the visual information used by place cells flows through this pathway rather than through V1.

Various combinations of fiber photometry recordings of calcium, dopamine, and acetylcholine signals in the dorsomedial striatum and its inputs
During visual stimulation

In dorsal medial striatum, visual stimuli evoke acetylcholine-dependent dopamine release
Cholinergic interneurons in the dorsal medial striatum are also activated during visual stimulation and may provide the source of acetylcholine
Using rabies-mediated retrograde labeling, determined that cholinergic interneurons receive innervation from the prefontal cortex (particularly from the anterior cingulate area).
Confirmed in vitro that activation of prefrontal cortex afferents both activated cholinergic interneurons and evoked dopamine release in the medial dorsal striatum; primary sensory cortical afferents did not.

Recordings of respiration along with simultaneous tetrode recordings of:
- projection neurons in the olfactory tubercle of the striatum and
- opto-tagged dopamine neurons in the ventral tegmental area
During learning in an olfactory go/no go task

Both cell types’ firing rates are phase-locked to the respiratory cycle
The preferred phase changes over the course of learning to the post-inspiratory phase
Cells that are locked to this phase participate in odor discrimination
Olfactory tubercule -> VTA communication is strongest during this phase (and is further strengthened by learning) as seen through a variety of analyses:
- Canonical correlation analysis over the two populations
- Functional connectivity analysis between interregional pairs of neurons
- Generalized linear mixed-effects model predicting communication strength from task performance