NBLAST

NBLAST is a method to quantify morphological similarity.

NBLAST

NBLAST (Costa et al., 2016) is a method to quantify morphological similarity. It works on “dotprops” which represent neurons as tangent vectors. For each tangent vector in the query neuron, NBLAST finds the closest tangent vector in the target neuron and calculates a score from the distance between and the dotproduct of the two vectors. The final NBLAST score is the sum over all query-target vector pairs. Typically, this score is normalized to a self-self comparison (i.e. a perfect match would be 1).

nblast

VFB computes NBLAST scores for all neurons in its database. So if all you want is a list of similar neurons, it’s fastest (and easiest) to get those directly from VFB.

# Import libs and initialise API objects
from vfb_connect.cross_server_tools import VfbConnect
import navis.interfaces.neuprint as neu

import pandas as pd
import navis

navis.set_pbars(jupyter=False)

vc = VfbConnect()
client = neu.Client('https://neuprint.janelia.org', dataset='hemibrain:v1.1')

First let’s write a little function to grab VFB neurons and turn them into navis neurons. This is modified from vc.neo_query_wrapper.get_images.

import requests
from tqdm import tqdm

def get_vfb_neurons(vfb_ids, template='JRC2018Unisex'):
    """Load neurons from VFB as navis.TreeNeurons."""
    vfb_ids = list(navis.utils.make_iterable(vfb_ids))
    inds = vc.neo_query_wrapper.get_anatomical_individual_TermInfo(short_forms=vfb_ids)
    nl = []
    # Note: queries should be parallelized in the future 
    # -> for pymaid I use request-futures which works really well
    for i in tqdm(inds, desc='Loading VFB neurons', leave=False):        
        if not ('has_image' in i['term']['core']['types']):
            continue
        label = i['term']['core']['label']
        image_matches = [x['image'] for x in i['channel_image']]
        if not image_matches:
            continue
        for imv in image_matches:
            if imv['template_anatomy']['label'] == template:
                r = requests.get(imv['image_folder'] + '/volume.swc')
                ### Slightly dodgy warning - could mask network errors
                if not r.ok:
                    warnings.warn("No '%s' file found for '%s'." % (image_type, label))
                    continue

                # `id` should ideally be unique but that's not enforced
                n = navis.TreeNeuron(r.text, name=label, id=i['term']['core']['short_form'])   

                # This registers attributes that you want to show in the summary
                # alternatively we could have a generic attribute like so:
                # n.template = template
                n._register_attr("template", template, temporary=False)

                # I assume all available templates are in microns?
                # @Robbie -do we have this metadata on templates?  If not, we should add ASAP.
                n.units = '1 micron'

                nl.append(n)
    return navis.NeuronList(nl)
# Search for similar neurons using the VFB ID of an ellipsoid body neuron in FAFB
# We got that ID from a search on the VFB website
similar_to_EPG6L1 = vc.get_similar_neurons('VFB_001012ay')
similar_to_EPG6L1 

id NBLAST_score label types source_id accession_in_source
0 VFB_jrchjtk6 0.525 EPG(PB08)_L6 - 541870397 [EB-PB 1 glomerulus-D/Vgall neuron] neuprint_JRC_Hemibrain_1point1 541870397
1 VFB_jrchjtk8 0.524 EPG(PB08)_L6 - 912601268 [EB-PB 1 glomerulus-D/Vgall neuron] neuprint_JRC_Hemibrain_1point1 912601268
2 VFB_jrchjtkb 0.504 EPG(PB08)_L6 - 788794171 [EB-PB 1 glomerulus-D/Vgall neuron] neuprint_JRC_Hemibrain_1point1 788794171
3 VFB_jrchjtji 0.481 EL(EQ5)_L - 1036753721 [EBw.AMP.s-Dga-s.b neuron] neuprint_JRC_Hemibrain_1point1 1036753721
# Read those neurons from VFB 
query = get_vfb_neurons('VFB_001012ay')
matches = get_vfb_neurons(similar_to_EPG6L1.id.values)
matches

type name id n_nodes n_connectors n_branches n_leafs cable_length soma units template
0 navis.TreeNeuron EPG(PB08)_L6 - 912601268 VFB_jrchjtk8 9819 None 1000 1015 2211.292188 None 1 micron JRC2018Unisex
1 navis.TreeNeuron EL(EQ5)_L - 1036753721 VFB_jrchjtji 13864 None 1942 1974 3403.311508 [1] 1 micron JRC2018Unisex
2 navis.TreeNeuron EPG(PB08)_L6 - 788794171 VFB_jrchjtkb 9651 None 962 987 2125.364857 None 1 micron JRC2018Unisex
3 navis.TreeNeuron EPG(PB08)_L6 - 541870397 VFB_jrchjtk6 11042 None 1099 1127 2432.101351 [1] 1 micron JRC2018Unisex
# Define colors such that query is black 
import seaborn as sns 
colors = ['k'] + sns.color_palette('muted', len(matches))

navis.plot3d([query, matches], color=colors)

So that looks decent!

Next: Let’s say you have a set of neurons and you want to group them into morphologically similar “types”. To demonstrate this, we will take ellipsoid body (protocerebral bridge) neurons from VFB and cluster them using NBLAST.

# Find instances of EB-PB neurons
eb_pb_ids = pd.DataFrame.from_records(vc.get_instances("eb-pb-vbo neuron"))
eb_pb_ids.head()

label symbol id tags parents_label parents_id data_source accession templates dataset license
0 EPGt(PB09)_L9 - 1168664447 VFB_jrchjtlc Entity|has_image|Adult|Anatomy|has_neuron_conn... EB slice 8-GA-PB slice 9 neuron FBbt_00111423 neuprint_JRC_Hemibrain_1point1 1168664447 JRC_FlyEM_Hemibrain|JRC2018Unisex Xu2020NeuronsV1point1 https://creativecommons.org/licenses/by/4.0/le...
1 EPGt(PB09)_R9 - 1219069439 VFB_jrchjtl9 Entity|has_image|Adult|Anatomy|has_neuron_conn... EB slice 8-GA-PB slice 9 neuron FBbt_00111423 neuprint_JRC_Hemibrain_1point1 1219069439 JRC2018Unisex|JRC_FlyEM_Hemibrain Xu2020NeuronsV1point1 https://creativecommons.org/licenses/by/4.0/le...
2 EPG(PB08)_L2 - 697001770 VFB_jrchjtkw Entity|has_image|Adult|Anatomy|has_neuron_conn... EB-PB 1 glomerulus-D/Vgall neuron FBbt_00047030 neuprint_JRC_Hemibrain_1point1 697001770 JRC2018Unisex|JRC_FlyEM_Hemibrain Xu2020NeuronsV1point1 https://creativecommons.org/licenses/by/4.0/le...
3 EPG(PB08)_R8 - 1125964814 VFB_jrchjtl5 Entity|has_image|Adult|Anatomy|has_neuron_conn... EB-PB 1 glomerulus-D/Vgall neuron FBbt_00047030 neuprint_JRC_Hemibrain_1point1 1125964814 JRC2018Unisex|JRC_FlyEM_Hemibrain Xu2020NeuronsV1point1 https://creativecommons.org/licenses/by/4.0/le...
4 EPG(PB08)_L6 - 912601268 VFB_jrchjtk8 Entity|has_image|Adult|Anatomy|has_neuron_conn... EB-PB 1 glomerulus-D/Vgall neuron FBbt_00047030 neuprint_JRC_Hemibrain_1point1 912601268 JRC2018Unisex|JRC_FlyEM_Hemibrain Xu2020NeuronsV1point1 https://creativecommons.org/licenses/by/4.0/le...
# Get the neurons from VFB
eb_pb = get_vfb_neurons(eb_pb_ids.id.values)
eb_pb
Loading VFB neurons: 100%|██████████| 62/62 [01:04<00:00,  1.04s/it]

type name id n_nodes n_connectors n_branches n_leafs cable_length soma units
0 navis.TreeNeuron EPG(PB08)_R5 - 725951521 VFB_jrchjtk5 11097 None 1223 1251 2221.279929 [1] 1 dimensionless
1 navis.TreeNeuron EPG(PB08)_R2 - 632544268 VFB_jrchjtkt 12861 None 1475 1507 2664.323311 [1] 1 dimensionless
... ... ... ... ... ... ... ... ... ... ...
60 navis.TreeNeuron EPG(PB08)_R5 - 694920753 VFB_jrchjtk7 11358 None 1348 1376 2335.616245 [1] 1 dimensionless
61 navis.TreeNeuron EPG(PB08)_R6 - 910438331 VFB_jrchjtkc 10983 None 1086 1107 2340.485198 [1] 1 dimensionless

Now that we have the skeletons, we need to turn them into dotprops. Couple things to keep in mind:

  1. NBLAST is optimized for data in microns. Since our neurons are in the JRC2018Unisex template, they already are.
  2. Neurons should have the same sampling rate (i.e. nodes per micron). To ensure this we will resample the neurons to 1 point per micron.
  3. We won’t be doing this this time around but we typically simplify the neurons slightly by e.g. pruning small twigs (navis.prune_twigs()) to reduce noise.
eb_dps = navis.make_dotprops(eb_pb, resample=1, k=5)

# Note this neuronlist contains dotprops now
eb_dps

type name id k units n_points
0 navis.Dotprops EPG(PB08)_R5 - 725951521 VFB_jrchjtk5 5 1 dimensionless 2683
1 navis.Dotprops EPG(PB08)_R2 - 632544268 VFB_jrchjtkt 5 1 dimensionless 3152
... ... ... ... ... ... ...
60 navis.Dotprops EPG(PB08)_R5 - 694920753 VFB_jrchjtk7 5 1 dimensionless 2924
61 navis.Dotprops EPG(PB08)_R6 - 910438331 VFB_jrchjtkc 5 1 dimensionless 2486

To illustrate what dotprops are, lets visualize one side-by-side with its skeleton.

sk = eb_pb[0].copy()
dp = eb_dps[0].copy()

# Slightly offset the dotprops by a micron 
dp.points[:, 0] += 1

navis.plot3d([sk, dp], color=['k', 'r'])

Now we can run the NBLAST. Note that in this case, we run an all-by-all NBLAST which means that we don’t really have to worry about the directionality - i.e. whether we NBLAST A->B or B->A.

scores = navis.nblast_allbyall(eb_dps)
scores.head()

VFB_jrchjtk5 VFB_jrchjtkt VFB_001012ba VFB_jrchjtkj VFB_jrchjtkp VFB_jrchjtke VFB_jrchjtkr VFB_jrchjtkb VFB_00004319 VFB_00009714 ... VFB_jrchjtk8 VFB_001012bp VFB_jrchjtk9 VFB_jrchjtki VFB_jrchjtl3 VFB_jrchjtkv VFB_001012b9 VFB_001012bb VFB_jrchjtk7 VFB_jrchjtkc
VFB_jrchjtk5 1.000000 -0.083960 0.427659 0.058210 0.021904 0.484210 0.168235 0.178954 0.065457 0.355732 ... 0.130788 0.528314 0.569923 -0.029195 -0.130578 -0.072185 0.381668 0.139970 0.816455 0.504740
VFB_jrchjtkt -0.062465 1.000000 -0.030980 -0.124326 0.507521 -0.122518 -0.143298 0.091243 -0.124431 -0.142560 ... 0.172337 -0.059201 0.078412 -0.116040 0.129102 -0.034670 -0.053382 0.103465 -0.063922 -0.073508
VFB_001012ba 0.129771 -0.115879 1.000000 0.374231 -0.091531 0.549519 0.450368 -0.130200 0.161574 0.112378 ... -0.127990 0.786001 0.013910 0.330330 -0.000875 0.212914 0.817302 -0.110084 0.200497 0.569953
VFB_jrchjtkj -0.027448 -0.219602 0.483341 1.000000 -0.031111 0.443643 0.461981 -0.025682 0.061803 0.434210 ... -0.034895 0.389407 -0.091165 0.819716 0.217721 0.552982 0.447278 -0.053055 0.045722 0.485596
VFB_jrchjtkp -0.158602 0.493915 -0.161524 -0.103061 1.000000 -0.212700 -0.221368 0.405601 -0.163415 -0.130491 ... 0.515069 -0.170831 0.024440 -0.095100 -0.032720 -0.082523 -0.182386 0.412998 -0.158171 -0.197676

5 rows × 62 columns

Next, we need to take those forward scores (A->B) and symmetrize by calculating mean scores (A<->B).

# Symmetrize scores
scores_mean = (scores + scores.T) / 2

scores_mean.head()

VFB_jrchjtk5 VFB_jrchjtkt VFB_001012ba VFB_jrchjtkj VFB_jrchjtkp VFB_jrchjtke VFB_jrchjtkr VFB_jrchjtkb VFB_00004319 VFB_00009714 ... VFB_jrchjtk8 VFB_001012bp VFB_jrchjtk9 VFB_jrchjtki VFB_jrchjtl3 VFB_jrchjtkv VFB_001012b9 VFB_001012bb VFB_jrchjtk7 VFB_jrchjtkc
VFB_jrchjtk5 1.000000 -0.073212 0.278715 0.015381 -0.068349 0.411257 0.098761 0.142277 0.032064 0.187264 ... 0.070828 0.437337 0.572156 -0.043306 -0.140155 -0.092071 0.271765 0.131925 0.820455 0.398975
VFB_jrchjtkt -0.073212 1.000000 -0.073429 -0.171964 0.500718 -0.142672 -0.164992 0.062182 -0.115399 -0.162311 ... 0.176281 -0.099006 0.074666 -0.162002 0.097262 -0.082222 -0.089534 0.120931 -0.075555 -0.114645
VFB_001012ba 0.278715 -0.073429 1.000000 0.428786 -0.126527 0.667980 0.527915 -0.128599 0.220682 0.068423 ... -0.143015 0.792216 0.070675 0.389590 0.018090 0.176492 0.826461 -0.102122 0.332148 0.684591
VFB_jrchjtkj 0.015381 -0.171964 0.428786 1.000000 -0.067086 0.436914 0.494708 -0.031511 -0.030539 0.489038 ... -0.045253 0.396773 -0.069074 0.824681 0.168068 0.508538 0.395092 -0.062799 0.100087 0.509110
VFB_jrchjtkp -0.068349 0.500718 -0.126527 -0.067086 1.000000 -0.164867 -0.203583 0.413305 -0.171488 -0.124160 ... 0.537125 -0.109346 0.020020 -0.074199 -0.011358 -0.093459 -0.133473 0.435029 -0.062292 -0.161714

5 rows × 62 columns

From here on out, we use cookie cutter scipy to produce a hierarchical clustering. First we need to take those similarity scores to distances because that’s what scipy operates on:

dist_mean = (scores_mean - 1) * -1
dist_mean.head()

VFB_jrchjtk5 VFB_jrchjtkt VFB_001012ba VFB_jrchjtkj VFB_jrchjtkp VFB_jrchjtke VFB_jrchjtkr VFB_jrchjtkb VFB_00004319 VFB_00009714 ... VFB_jrchjtk8 VFB_001012bp VFB_jrchjtk9 VFB_jrchjtki VFB_jrchjtl3 VFB_jrchjtkv VFB_001012b9 VFB_001012bb VFB_jrchjtk7 VFB_jrchjtkc
VFB_jrchjtk5 -0.000000 1.073212 0.721285 0.984619 1.068349 0.588743 0.901239 0.857723 0.967936 0.812736 ... 0.929172 0.562663 0.427844 1.043306 1.140155 1.092071 0.728235 0.868075 0.179545 0.601025
VFB_jrchjtkt 1.073212 -0.000000 1.073429 1.171964 0.499282 1.142672 1.164992 0.937818 1.115399 1.162311 ... 0.823719 1.099006 0.925334 1.162002 0.902738 1.082222 1.089534 0.879069 1.075555 1.114645
VFB_001012ba 0.721285 1.073429 -0.000000 0.571214 1.126527 0.332020 0.472085 1.128599 0.779318 0.931577 ... 1.143015 0.207784 0.929325 0.610410 0.981910 0.823508 0.173539 1.102122 0.667852 0.315409
VFB_jrchjtkj 0.984619 1.171964 0.571214 -0.000000 1.067086 0.563086 0.505292 1.031511 1.030539 0.510962 ... 1.045253 0.603227 1.069074 0.175319 0.831932 0.491462 0.604908 1.062799 0.899913 0.490890
VFB_jrchjtkp 1.068349 0.499282 1.126527 1.067086 -0.000000 1.164867 1.203583 0.586695 1.171488 1.124160 ... 0.462875 1.109346 0.979980 1.074199 1.011358 1.093459 1.133473 0.564971 1.062292 1.161714

5 rows × 62 columns

from scipy.spatial.distance import squareform
from scipy.cluster.hierarchy import linkage, dendrogram, fcluster

# This turns the square distance matrix into 1-d vector form
dist_sq = squareform(dist_mean)

# This does the actual hierarchical clustering
Z = linkage(dist_sq, method='ward', optimal_ordering=True)
# Plot a quick dendrogram
import matplotlib.pyplot as plt 
import seaborn as sns 

# Generate the canvas
fig, ax = plt.subplots(figsize=(12, 5))

# Make some more meaningful labels 
vfb2name = dict(zip(eb_pb.id, eb_pb.name))
labels = dist_mean.index.map(lambda x: vfb2name[x].split(' - ')[0])

# Plot the dendrogram
dn = dendrogram(Z, ax=ax, labels=labels, color_threshold=.65, above_threshold_color='lightgrey')

# Make xticks biggger
ax.set_xticklabels(ax.get_xticklabels(), size=11)

# Clean axes
sns.despine(bottom=True)

png

# Make cluster matching the color threshold in the dendrogram
clusters = fcluster(Z, t=.65, criterion='distance')
clusters
array([16, 14,  4,  5, 11,  4,  3, 12,  2, 19, 13,  4,  8,  3, 19,  2,  5,
       13,  3, 11, 17, 14, 16,  6, 12, 15, 18, 11, 12, 15, 15, 18,  5, 10,
        9,  2, 19,  8,  1,  9, 19,  3,  1, 10,  2,  9,  7, 18,  9,  2, 17,
       13, 12,  4, 17,  5,  7,  6,  4, 12, 16,  4], dtype=int32)
# We have to downsample the neurons for visualization 
# because DeepNote enforces a limit on the size of plots
eb_pb_ds = eb_pb.downsample(10)
# Make a color per cluster 
palette = sns.color_palette('tab20', max(clusters))
cmap = dict(zip(range(1, max(clusters) + 1), palette))

colors = [cmap[i] for i in clusters]

navis.plot3d(eb_pb_ds, color=colors)

Last modified January 27, 2022: reverting to list (dd75b36)