connection to CSTC model of psychedelics' proposition, interesting....

States 1, 4, and 6 are the ones that show the biggest discrepancy between non-intoxicated and intoxicated states

explains why I get so instrospective and aware of my thoughts

true that it definitely increases ecological validity (how well it can be applied to the real world) but also allows for a lot of confounding variables...

important

• surround suppresion: what happening around the central stimulus is suppressing the response of neurons

• overlay suppression: suppression that happens within the classical receptive field

• local competition

b option actually facilitates the response, rather than inhibits

adding in a bunch of extra stuff in the extra-classical receptive field (area surrounding the region of space to which the neuron is tuned) will make the response go down - neurons must be cross communicating (so it becomes non-linear)

• Classical receptive field: an area of space to which something is responding to
• presenting the same stimulus outside the receptive field will yield no activity from the neurons of the receptive field

• open circles represnet luminance
• why does the color system respond more to lower spatial frequencies but drop off faster?
• color system has generally larger receptive fields, so not as able to get at fine details
• Bandpass: selective and passing a particular range of frequencies (luminance)
• has a clear peak

• Lowpass: processing everything below a particular frequency (color)

• **Slide not included, showing same face at diff. spatial frequencies

• there are certain spatial frequencies that code more for identity (automated process)

• stronger sensitivity to the cardinal orientations (vertical/horizontal) relative to oblique orientations
• called the oblique effect

- measuring the relative sensitivity at all spatial frequencies

• only the neurons on the far left, towards the bottom are gonna be active in response to the stimulus
• comes down to the tuning function of the neuron

convert the first image to a filter - everything outside the light is set to zero - last image is exactly what that circled neuron responds to - enables us to present stimuli behaviorally

• we dont quite understand how all these spatial frequencies get combined to create the image
• not a linear process
• as that final image is being passed through the retina, the visual cortex is basically conducting fourier analysis
• representation is being brought to us by each individual channel

• work as filters

And I think these radical new perspectives could be exactly what psychedelic research could bring to the table

Revolutionary! This is medicine!

• purpose of amplitude spectrum is to give you an idea of what neurons are gonna be active
• useful because given what we know about stiate neurons, we can take an image

• trying to get a measure of contrast
• amplitude spectrum is plotting polar coordinates where each point represents a specific spatial frequency and phase orientation
• at the center is mere luminance (how on average bright is the image, we ignore it)
• pick a trajectory, and the farther away you get from the center the spatial frequencies get higher and higher
• speckling varies (the brighter the spot the higher the contrast)
• each trace (line from the center to the end) represents a specific orientation
• discret measure (not continuous)
• radius tells us spatial frequency, theta tells us orientation
• amplitude spectrum is rotated 90 degress
• space is mirror symmetric, what's on the top half is the exact same as what's on the bottom (anywhere on the circle)
• large receptive field neurons are gonna be the most active looking at the amplitude spectrum, because why?
• little line in the middle is saying that the image is lighter on top than on the bottom

• amplitude relation to contrast (goes down as contrast goes down)
• phase is the relative positioning of where the light and dark parts of the stimuli start
• where in the waveform does it start (top left vs. bottom left, one starts at top and one starts at bottom)
• any combination of spatial frequency, playing around with phase and amplittude, can create any stimulus/image
• visual system is doing the opposite, taking the image and breaking it down

• simple cells like all of these things, are selective for them

• EXTREMELY IMPORTANT
• way of taking any kind of signal and breaking it down into its component spatial frequencies
• take complex representations and tell us how much contrast/amplitutde is at every possible spatial frequencies in the image

• any possible retinal image is made up by the sum of many possible sine-frequencies
• the level of contrast tells us how active the neural populations are gonna be
• gives us infor about population response

• all the neurons tuned for vertical orientations will be activated in square-wave grating
• referred to as being "broad band"
• sine-wave grating gives you a more precise measure, and a pure frequency (pure luminance oscillation_
• only gonna get one population of neurons responding, narrow-band not broad-band
• tend to be go-to stimulus due to its ability to isolate small-population response

• turning off 99% of your neural population when you look at it

• the smaller the receptive field, the more likely they're going to respond to small details, the higher spatial frequency it's going to be selective for

visual angle is a function of distance - depending on where we're sitting in the class, we're getting info from different populations of neurons

benchmark - 1/3 of a mm is 1degree of visual angle (important) -

First one: low spatial frequency - increases with each image - last one has the most luminance oscillations, most spatial frequency - big receptive field neurons are extracting information about coarse luminance

Spatial frequency: the way to measure response characterisitivs of these neurons - idea is to express the stimulus in terms of some level of detail (e.g. the smaller the pixels in an image the more detialed it is) - idea of grain as level of detail, we want ot be able to quantify it, which is where spatial frequency comes in. - ultimately the amount of change in luminance over some pre-defined area of space, how much it is changing from one point to the next point

• wanna know how much of the back of the eye my stimulus is taking up
• what is the probabiltiy of a stimulus of this particular size activating the receptive fields of
• looking at the angle of the object
• two factors that need to be taken into account: size and distance
• as distance increases, the size on the back of the eye is decreasing
• visual angle gives us an idea of which receptive fields are going to be responding

• a lot of variance in what each neuron is responding to
• system has evolved to code each source of information

When a simply cell fires, it gives you information about the relative orientation of the stimulus - 1st image: light in both the excitatory and inhibitory, so it's not gonna fire - size slectivity also has a tuning curve

neurons selective for all visual orientations also tile in the cortex - both ocular dominance columns from both eyes combined creates a hyper column - visual field is essentially tiled with hyper-columns - it's a population response: there's the possibility that all of them could respond, it just depends on what orientation input is being taken in'

if input from one eye is dyed, it will staain bands of striate cortex, white patches are the other eye that wasn't stimulated

Leads to concept of tuning curve - has peak preference - have a cell that has a preferred stimulus orientation - if we start to tilt the line, response goes down - as it's rotating, the light bar starts to encroach on the inhibitory cells

Simple cells have preferred orientations

3 major pathways 1. selective largely for luninance only 2. red-green channel 3. blue-yellow - All ultimately integrating in the same way

Color works the same way

• piece of tissue in retina has corresponding ganglion cells, each one of those ganglion cells projects to the LGN (with the same layout), and those project to cells in the striate cortex to activate the simple cell system (no longer preserving the layout)

(Look on next slide) - the thing at the bottom represents the striate cortex - taking projections from a whole slew of ganglion cells - collection of neurons all synapse down onto that single neuron, meaning it's integrating down the inputs from all 12 receptive fields - light is smeared out over space such that it's falling on each of the center of the fields - organization at the top of receptive fields is the same way they're organized in the LGN - excitatory zone is smeared out over space

internalized disorders' relation to attentional biases is interesting. How does this inform therapy and treatment? - related to idea of psychedelics "clearing the slate" of your mind and its thought patters/biases.

• cone systems for color
• red and green always goes together, blue and yellow
• circle represents center of the fovea
• why is the red-green concentrated in the center-most location, and blue on the periphery
• blue wavelengths cannot get to the center of the fovea because they would refract
• color system is quite coarse, not great for detail

• some collection of photoreceptors filtering down to a single ganglion cells
• uniform tile of receptive surface (don't overlap much)
• larger receptive fields overlay smaller ones (represented by the circles)
• convergence is increasing
• at any given location

• lateral inhibition
• lateral connections (taking inputs from the periphery of the receptive field) are sending inhibitory signals

Two major classes of ganglion cells - defined by how they respond to onset of light - majority of receptive fields are circular - picture is cross section of the receptive field, all the bubbles are photoreceptors - On-center/off-surround, - any spot of light presented in the center of the region will produce excitatory response - how to maximally activate the ganglion cell? - something bright in the center with dark background

Important distinction - Visual field: area of space out in front of you that you're trying to perceive and process - Receptive field: surface area of the retina that when activated, creates a corresponding activation on the final receptor cell (ganglion cell)

In first image, when two spots are activating only one photoreceptor, only one ganglion cell, person would only be able to perceive one dot

The more pooling that is done, the lower the resolution

• Visual acuity:
• ability to differentiate between small little specs of detail

IMPORTANT TRADEOFF

rod system exhibits much more converision than the cone system, increases as you move

Huge concentration of cones in the fovea - No rods in the fovea - **Not an even distribution a

Rods vs. Cones - outer segments (top) are where the photons are absorbed, the energy of light is coming in, energy ultimately creates an ion chain propogating down - Cones - Rods: nighttime vision (very sensitive), bad at detajks, don't see detail

• we have more rods than cones

• Arranged into two processing streams: vertical and horizontal
• vertical:
• starts with photoreceptors (rods n cones)
• Ganglion cells: final output layer, the ones that are transmitting signlas to the brain
• horizontal:
• making connections amongst multiple vertical pathways
• Interplexiform Cells
• laminates up between photoreceptors and bipolar cells, as well as down between bipolar and amicrine cells
• sparsely distributed, not much is known
• integrating and connecting info between vertical pathways (useful with receptive field dynamics)
• Amicrine cells connect different vertical cells

• 5 major neurons in the retina
• dangly bits are photoreceptors (where transduction begins)
• picture is the majority of the retina excluding the fovea
• photons entering the eye get bounced around and scattered before hitting photoreceptors

• why don't we notice how 95% of the retina is periphery vision, the blurring
• attention: process that brings information into the system, and in normative situations the attention is coupled with the fovea
• attention allows info to be encoded, be consiously processed, so we're ignoring everything in the periphery

• optic disc reflects most of the light
• Fovea: responsible for all of detail vision (corresponds to line of sight)
• vast majority of consciousness and attention is tied to the fovea
• only about 5% of the area of the eye
• medical term: macula (whole darkened area)
• Everything else is peripheral vision

• Eye refracts light at 4 diff locations
• 1. air to cornea
• 1. cornea to aqueous humor
• 1. aqueous humor to lens
• 1. lens to retina

• That's what creates the proximal stimulus

• light coming in directly in the center of our visual system is refracted very little

• pinhole optics (poking a tiny hole in an index card and looking thru it allows you to see with perfect clarity)

Measure of the amount the photoreceptors in the eye will refract or bend the light - how much light is deviated (bent) from its orignial sources - function of how the energy interacts with the medium (shorter wavelengths are deviated more)

• when quanta are absorbed by the photoreceptors it leads to the opening and closing of ion channels
• shorter wavelengths generally carry more energy
• e.g. if you look at the sun long enough you create a blind spot (large amount of energy from the shorter wavelengths lead to the rapid oxidation)

• our brain turns the different wavelenths into the different colors we see (so colors are just perception)

• electromagnetic radiation
• tiny band on the spectrum is what we use for vision
• why only this band? they are the only wavelengths that bounce off surfaces, the rest all pass through solid structures

• open angle
• angle needs to be open so the fluid can come out
• some form of blockage so the fluid isn't leaving as well

• direct access to the exit point

• closed angle

• also a blockage
• Iris attaches itself to the lens itself

• so as the fluid comes in, it builds up and bulges against the wall

• whole eye swells

• Big genetic link
• leading cause of nerve blindness
• directly related to the increase in pressure
• all of the axons leaving through the optic nerve create a little bundle by the optic disk, the increase in pressure squeezes down on those bundles, cutting off blood supply

• Fluid is being pumped in, but there needs to be some back pressure (so that it doesn't just flow out)
• then enters the canal of schlemm
• anything that blocks this process will lead to an increase in ocular pressure

Limbus: region between the cornea and the sclera (transition zone) - houses canal of schlemm - contains stem cells for regenerating surface of the cornea - Posterior Chamber - Anterior Chamber - both are filled with aqueous humor (produced by the ciliary body) - flows underneath posterior chamber, eventually into the anterior - eventually drains out through the canal

• Glaucoma is the leading cause of nerve damage
• related to this pressure-regulating system within the eye
• very important to maintain

Iris is a set of muscles - two main muscles controlling this - majority of adjustments are made by sphincter muscles - fine-tune adjustments are done by the dilator muscle

• leads to a partially focused image
• most common type: symmetrical (certain things are crisp, some are blurred)
• primarily corneal
• one of the axes (vertical or horizontal) is squished together/compressed, the other remains okay
• leads to a horizontal or vertical compression of the cornea
• the thicker the lens, the stronger the focal power

• Ability to resolve things nearby gets worse and worse (gets farther and farther away)
• muscles weaken, lens loses ability to shrink back to where it should be
• lens thickens over time as well

Two main types as well - Refractive - optical power is weaker, ends up resolving the image somewhere behind the retina - cannot converge the image fast enough to - Axial - results in partially resolved image

• Person can resolve things
• First kind, most common: refractive
• optical power is too strong, which ultimately causes the image to be refracted somehwere before the retina (floating in space, where the rays cross)
• Less common: Axial myopia

• Lens allows you to visualize things at different distances (accomodation process)
• when you're trying to see something far away, the ciliary bodies relax to pull on and enlarge the eye

• leading cause worldwide of blindness
• can form anywhere, buildup of proteins
• lens has a nucleus
• typical form of cataracts is nuclear (happens in the nucleus of the lens)
• Acts to scatter the light (not necessarily block it), diverts the passage of photons

• Collagen fibers of cornea are packed so densely that when a photon hits it, it transfers it (ricochets)
• scelra reflects all the light, which is why it's white (?)
• cilliary processes are what is hanging off of the lens

Everything before the line: Anterior segment - Cornea: clear part - main optical element of the eye - focuses the image on the eye - Iris - band of muscles - automated function, controls the diameter of the pupil - ultimately controls the amount of light that goes into the eye - works together with the pupil - trying to keep the amount of light entering the eye consistent - when you're aroused, your pupils dilate, and faces that have larger pupils are rated as more attractive (so you make yourself more attractive to those) - Lens - made up of structures that can stretch and bend - it by itself does nothing, it's being acted upon by the muscles around it - helps to percieve different distances - Zonule - aka suspensatory ligaments - attach the lens to the Cilliary process - what hold the - Ciliary Body - ciliar muscles (three bands) ultimately responsible for controlling the lens (pulling on it, constricting) - Ciliary process - Canal of Schlemm - series of ducts that wrap around the circumference of the cornea - diverting aqueous - Retina - primary nerve fiber layer - transduction begins here - Fovea - what you're focusing on gets projected directly onto it - give you central vision - optic nerve - Choroid - vasular layer, getting blood supply to and from our retina, giving the neurons oxygen - job is to the feed the neurons in our retina - Sclera - white part - extremely dense - material that makes up the scera and cornea is exactly the same: collagen fibers

• we get the performance back from the system, which is then used to create a confusion matrix
• columns represent what was actually presented, rows are what the model identified
• comes down to a signal-to-nose ratio
• most telling part are the off-diagonals (where the machine is getting confused, where should people be struggling in this task of differentiation)
• if main diagonal is good, means there's reasonable reliability is the system (it's a good model)
• but with the grey boxes, we want to see if humans also have trouble differentiating those emotions, so that is tested and then we see

Take another part of the data that the classifier has never seen before, feed it into the classifier, and ask it to identify which emotion (category) it is - then calculate percentage correct of the machine - making sure the pattern is reliable (if it is, you would be able to put in the rest of the emotion 1 data, and it would identify it as emotion 1)

• Take some small fraction of your trials, feed them into a classifier (most common one is support vector machine, job is to draw line between clusters of data, the lines would represent patterns)
• the more reliable the data is, the more the data is gonna cluster, the better the classifier will be able to draw lines
• classifier job: to learn patterns in the data, categorize (by drawing lines)

• Idea of machine learning: using a multivariate statistical test to classify patterns of data
• if we collected enough data, reliability can be checked within the

Graph is a subset of voxels - looking at the activity of each one of the voxels - can see a pattern of activity distributed across the voxels, then we ask if there is something about the pattern of responses that is representative of the particular emotion - if we switch to a new emotion, it is crucial to be able to see a different pattern

• need to demonstrate that every time the person looks are the certain emotion, there is a different pattern
• need to establish that the pattern is not just noise
• need the pattern to be reliable
• and the patterns are the neural representation

**VERY IMPORTANT - Activation-based approach: looking for general increases in activity - boxcar designs are still used today, but not as often (not as detailed as modern methods) - big limitation: can be misleading in terms of what networks are activated - E.g. looking at whether a certain brain region is responsible for recognizing different human emotions, record activity for each expression (set of faces), average the voxel patterns, subtract the control - question: can this brain region tell the difference (looking for general differences in activity) - in this example, answer would be no since the results are all so similar

Stronger the magnet, higher the resolution - keep in mind recording is 3-dimensional - so pixels are 3-D (referred to as voxels) - voxel: smallest unit of resolution for this technique - 3-T can get you approximately down to 1mm cubes, which can hold a lot of neurons, so we're always making inference about the activity of a population

• don't reach the peak of the neural signal until the stimulus is basically gone
• LFP: local field potentials

• What can/cannot say about the activation?
• Still can't really say if it's excitatory or inhibitory... why? if an inhibitory neuron becomes active, it also needs oxygen just like an excitatory

Standard "block designs" (aka box car design) - Method of subtraction: Take the difference between brain activity of experimental condition and control, creating a difference image - Issue with calculating a mean difference image: assumes everybody's brain is the same, which is not the case - Solution: putting everybody's activity brain into a standardized brain space (MNI) (involves warping) - Coordinates of where the activity was taking place is called Talairach coordinates - Big issue with this approach too: blurs the data

• Anatomical: MRI (often called T-1 weighted anatomical)
• Functional: fMRI (gives us info about the functioning of the brain) (can often be called T-2* weighted functional)

• often lower resolution, because it's measuring vascularization, the changes in oxygenation in the blood

• Have to take both

The hemoglobin has a particular magnetic field when it's oxygenated, which changes when it become de-oxygenated

How blood is moving thru the arteries in the brain - Arterial: Fully oxygenated blood going to a particular region - Venous system: returning some oxygenated blood - looking at the relative changes in the oxygenated blood (because that's indicative of how active certain parts of the brain are) - brain picks up on signals, sends more oxygenated blood there as a result - when a part of the brain becomes active, we see a little little dip in oxygenation (as the neurons use the oxygen in the blood) and then we see a huge increase in oxygenated blood as the brain compensates (usually overkill) - not necssarily a represation of how active the brain region was - measuring a correlate of neural activity and oxygenation

• signal extracted from MRI scanner
• giant magnet
• Head coil: largely to help with the resolution of the anatomical scale (MRI image)
• Surface coil: purpose is to boost the resolution of the functional scale (put behind a certain part of the head as almost a magnifying glass)

• still an estimate, not a direct cortical recording
• inverse problem, using the dipoles to make estimation about where the activity is
• struggles with localizing deep subcortical structures

Much much better than EEG at localizing the source - magnetic field does NOT interact with the skull, it diffuses across the skull - purpose is to get both spatial and temporal precision - largely dominated by signal within sulci (sulcal walls) *no assumptions are made regarding excitatory or inhibitory signals

Data looks virtually identical to EEG - look at deflections relative to baseline - very sensitive, high resolution temporal data

• measuring the perpendicular magnetic field (mentioned earlier)
• sensors used: SQUIDs (super something something)
• sensors have to be supercooled in order to operate
• not surprising to find something active with MEG that you couldn't see with EEG (cuz it's complimentary signal)

• looking at the transition area to estimate where the signal is coming from (between the part of brain giving off negative charge and the one giving off positive, where they meet)
• the source is always gonna be in between dipoles
• fine for large parts of cortex

There are varied numbers of ways to estimate where the source is coming from - best way to do is use the participants anatomy of the brain - ideally using MRI

Great for timing of neural responses, the temporal dynamics - source localization issue: hard to figure out where the signal is coming from - Why is it hard? - if there are two gyral crowns pointed in the same direction, they're gonna sum together - electric potentials interact signficantly with the skull, it can even bounce

Need thousands of neurons to measure with EEG Membrane potentials are actually whats being recorded, not action potentials - when there's a bunch

• majority of the signals come from the gyral crown/surface

• largely a cortical measure, harder to measure subcortical signals

Basal dendrites will depolarize Apical dendrites will hyperpolarize - creates an electrical field as a current begins to flow - simultaneously, there is a horizontal magnetic field (measured by MEGs)

Pyramidal neuron being shown, most common in the brain - dendrites that come straight off then basal - dendrites extending way out are apical dendrites

Traditional way is to look at one electrode - how is the voltage changing overtime from one electrode - deviation from baseline is indicative of some sort of potential occuring - P1: "component", significant deviation from baseline

Topographic plot - can look at the entire surface, changes in positive/negative potential - key element: when is a process active (how those processes are changing overtime)

neurons become active, they generate electromagnetic fields, strong enough to leak across the scalp, so macro-electrodes on the surface of the skull can be used to measure the brain energy - easily affected by motor potentials, contaminates the trial - very temporaly sensitive, can get a lot of data all at once

each row is.a different recording from the same neuron

Correlation between stimulation and activity - build a spike train - spreadsheet, put a 0 when there's no activity, 1 when there is

How do you find where the electrode is going - end of the day, you don't really know - can reverse the flow of the current, deliver an electric shock to the animal's brain, kill them, take out the brain and find out if it was in the correct place - have to adjust the sensitivity theshold of the electrode, basically how far out the field of recording can be (with single-unit, has to be dialed up) - even when single-unit recording, chances are you're usually picking up a couple neurons - setting a high enough threshold on the recording amplifier enables one to record from a single or very small number of neurons

• also invasive
• piece of the skull is removed, microdrive system is mounted on top with an electrode(s) being inserted down into the brain
• Limitation: can't really map out specific receptive field processes because of the awake/alert state, but other aspects can better be studied

Measuring neurons within their natural environment (within the orgnaism) - electrical stimulation

Taking the tissue out of the organism, keeping it alive and studying them that way

In a single-interval paradigm, you have a very small response base - Hit: accurate - Correct rejection: accurate - False alarm: inaccurate - Miss: inaccurate

• no recognition, just discrimination
• Stimulus presentation method: Method of constant stimuli
• not able to generate all possible levels of stimulus in between, only fixed stimuli in order to used staircase or method of adjustment, stimulus usally needs to be continuous)
• Response design method: 2AFC is best
• could also be 2IFC, but that makes it more complicated because it requires the participant to remember the faces, while 2AFC allows for scrutinization
• trying to measure at what point they start to reliably discriminate between them

• leaving it up to the participant to give a response
• requires interpreting qualitative responses
• Caveat: unconstrained response base, no chance level (can't tell the level of accuracy, or if they're guessing), hard to get statistical

more than 2

• must pick one or the other
• ALTERNATIVE: 2 things being presented to the participant simultaneously, best for discrimination
• INTERVAL: present things one at a time, ask to choose one of them, memory is involved

How the response is being recorded

One thing is presented very quickly, yes or no

• usually involved in making some sort of perceptual matching (appearance more often than performace), best for that
• stimuli that are completely variable
• participant has total control, adjusting the stimulus themselves
• Caveats: adaptation (underlying sensory mechanisms could adjust to a visual stimulus such as contrast, don't want them staring at it too long)

• aka "adaptive measures"
• none of the manipulation is predetermined, all on the fly as the participant is doing the experiment
• can generate any possible stimulus level
• participant's "control" is that how they respond on a given trial determines the next trial (as they're getting things right and wrong, you're adjusting the next stimulus)
• Best for measuring threshold (can be used to reconstruct the psychometric function, but coarse estimate)
• you present the stimulus, then present it again to check for reliability, then change, then repeat
• quicker than method of constant stimuli

• e.g. measuring the psychometric function, X number of contrasts are presented
• best for measuring psychometric functions (threshold and slope)
• no matter how the participant responds to one trial, the next is still coming (doesn't affect the procedure)
• many repetitions, to achieve the most precision
• predetermined, fixed stimulus (not determined on the fly)

Separation: distance between two states of the system Normalized by the variance (response distributions)

Basically a t-test: difference in the means divided by pooled variance When you have these values, you can estimate the bias

D-prime caps out at 4 If it's at 1, it's at threshold A negative d-prime means the participant is operating below chance, and therefore not doing the task correctly (probably didn't understand the task)

Criterion: the participant's own decision-making, can get in the way and contaminate the percent correct, bias of the participant, odd measure of the underlying response mechanism Blue: Correct reject Green: Miss Pink: Hit Orange: False alarm

Estimating sensitivity can allow for minimizing the effect of the criterion

Higher action potential - how far away does this response distribution need to be from the noise signal before we can pick up on it

The base noise in the system (lights you see when you close your eyes)

relates to reading in chinese philosophy, achieved through attaining wu-wei

This is referring to the view of New York city from New Jersey, which is the epitome of an urban environment.

The quote from Carl Sagan, a famous American astronomer, planetary scientist, cosmologist, and astrophysicist, is the perfect closing stanza for this poem. Sagan emphasizes the fact that everything on earth, plants, animals, and humans are all products of the sun, which is simply one of billions of stars.

I found this short video of Carl Sagan that explains this concept further, which I found very enlightening. He explains how the origin of all life comes from the stars, so that not only our existence, but the process of our creation and development comes from solar energy as well. https://youtu.be/tLPkpBN6bEI

The "monkey rulers" seems to be a metaphor for the human race, us eventually being thrown "off into space" is a metaphor for our eventual extinction. The wording here also suggests our insignificance to the Earth, that we're just hanging on "her back" and can be easily expelled.

This section of the poem was confusing to me; I don't completely understand the symbolism of the deep well, the light without shadow, and the "circumference." I interpreted this as a reference to the inevitable extinction of humankind.

According to Peter Brannen's "Anthopocen is a Joke," is tens or hundred of millions of years, any trace of human life or the legacy we left behind will completely buried underneath layers and layers of rock, and will be extremely unlikely to ever be exposed again. Essentially, there will be no indication that we ever existed.

I think the poem is referencing this idea here, the phrase "[the length of death's shadow] is the same cast everywhere as deep; no one's is further from death than another's" alluding to the big-picture insignificance of the human race.

Source: https://www.theatlantic.com/science/archive/2019/08/arrogance-anthropocene/595795/

Is the "she" here referring to planet Earth? If so, is this metaphor alluding to the issues of climate change humans have imposed upon the planet; the dirt and sores and infection being representations of pollution, greenhouse gases, depletion of nonrenewable resource, deforestation, etc.?

The Verrazano is a suspension bridge in Staten-Island, New York, spanning 13,700 feet in length. I really like this part of the poem, as it points out that even though this bridge is very long and very strong, it is still fundamentally affected by the Earth itself. I find this to be a strong yet subtle message about the concept that no matter how big of an impact we think we are making on the planet, we can't even begin to fathom how little we actually are. The Earth doesn't bend to our will, we bend to its.

Here, geologic formations and structures are contrasted with built ones (e.g. mountains vs. skyscrapers) in the sense that geologic formations have existed for much longer and thus have exponentially greater bearing on the planet. What is on the outside of, say, a mountain, was once on the inside, either raised up from the earth by the collision of tectonic plates, or spewed out by volcanic eruptions and hardened into their structures.

This is another allusion to the built environment, in comparison to the natural environment. The "dirt-stiffened, unyielding, tarmac of marsh grass" seems to be referring to the man-made "natural" areas that are simply illusions of what used to be.

Commenting on the ignorance of humans, and the way we forget about out impact on the environment, including animals. We often see nature, but just as often forget that there used to be so much more of it, and how much destruction and harm we've caused to it over the time period of the Anthropocene.

I find the word choice here to be clever and significant; the word "corps" technically means a squadron of armed forces, or a specialized branch of the military. Here, the use of the word suggests that mankind's use of technology has become a sort of troop in itself, bulldozing the natural landscape to shape it to their own desires, locked in a figurative and literal battle against nature.

This is referring to urban landscapes, in contrast to rural. It is flat because that is the way humans have manually constructed it to be: our own built environment that is far from natural.

This seems to be a reference to how dependent humans have become on technology as tools for things as simple as telling the time; no one would think to use the age-old and natural tool of light and shadows anymore to gauge the hour of the day. The question is: is this a positive or a negative? Because of technology we live life with much more convenience than ever before, but in this process of development have we lost touch with nature, and the organic tools with which the Earth provides us?

Eclogue definition: A short pastoral poem on the subject of rural life and the society of shepherds, depicting rural life as a sort of freedom from the complications and corruption of urban civilization.

Source: https://www.britannica.com/art/eclogue

Gnomen definition: the piece on a sundial that projects a shadow indicating the time by its length and position

Source: https://www.merriam-webster.com/dictionary/gnomon

I think this is referring to our ecological footprint that we as humans leave on the Earth. The connotation of these few stanzas is very bleak and cold, suggesting the grim fate of the human race in the future.