Now that I’m am a PI I can post pictures of the new office space.

But …fine grained connectivity seems to have little to do with cytoarchitecture (see Gou et al 2025).

The relationship between spont. and response activity in the PFC? Well, regular firing (“PFC signature”) neurons (cat. 1-3) do not really show sound responses. The emerging pattern is that all types of sound responses are displayed by neurons with a high spontaneous firing rate (cat. 4-6).

13/n

Again, ROIs were grouped, this time into response modules, outlining a new map of the PFC, again defying cytoarchitecture. The map appears to reflect the axonal input from the auditory cortex to the PFC.

12/n

Do PFC responses also map to connectivity? We mapped the responses to a 10 kHz pure tone, identifying a range of responses across the PFC space. Importantly, sensory responses are non-stationary events – precluding use of our 3 spontaneous activity metrics!

11/n

Gao et al. 2022 mapped the intra-PFC connectivity and outlined an intra-PFC hierarchy (again, defying cytoarchitecture). Using this data we identified that spontaneous activity correlated with intra-PFC hierarchy; e.g., high hierarchy ROIs are enriched in regular firing neurons.

10/n

ROIs were grouped into modules based on their enrichment of the 8 neuron types, identifying activity modules with differential enrichment profiles. This new, activity-driven PFC map does not align well with cytoarchitecture.

9/n

Alright, so far we grouped activity based on cytoarchitecture, potentially obscuring a "true" activity map. For a view of PFC activity not biased by cytoarchitecture we partitioned the PFC into ROIs, such that each ROI holds ~200 units (shown here on a 2D flatmap of the PFC).

8/n

Again, our dataset KI and the dataset IBL agree. Correlation between enrichment of neuron type 2 and hierarchy (b) and the correlation between the 8 neuron types and cortical hierarchy for our dataset KI and the IBL dataset (c).

7/n

The enrichment of certain activity-based neuron types correlated with anatomical hierarchy of cortical regions (Harris et al. 2019). Correlation between enrichment of neuron type 2 and hierarchy.

6/n

These findings were reproduced using parallel data from the IBL dataset. The enrichment of ww neuron type 1 in deep cortical (sub)regions:

5/n

Quantification of the enrichment (E-score) of ww neuron types (categories) across brain regions identified a regular-firing signature specifically for PFC subregions – the ORBl being an exception.

4/n

To capture the diversity of firing patterns, we identified 3 mathematically independent metrics (rate, burstiness, and memory) and used self-organizing maps to classify functional neuron types/categories . The activity landscape for >19,000 wide-waveform units (ww), outlining 8 neuron types:

3/n

Cytoarchitecture has been the dominant, ever-changing canvas to study brain regions. We here started with a clean slate and instead approached organization of brain regions by profiling spontaneous activity of single neurons. Do PFC neurons hold unique firing properties?

2/n

Excellent. Exactly what I needed to get started. Please add me to the list as well. I am not close to my rig but you get a picture of a goat for the next sacrifice to the ephys gods.