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A typical neuron makes about ten thousand connections to neighboring neurons.
Given the billions of neurons, this means there are as many connections in a single cubic centimeter of brain tissue as there are stars in the Milky Way galaxy.
Thoughts seem to be a kind of tremendous magic.
alterations to the brain change the kinds of thoughts we can think.
The state of the physical material determines the state of the thoughts.
most of what we do and think and feel is not under our conscious control.
Brains are in the business of gathering information and steering behavior appropriately. It doesn’t matter whether consciousness is involved in the decision making. And most of the time, it’s not.
Our brains run mostly on autopilot, and the conscious mind has little access to the giant and mysterious factory that runs below it.
Consciousness developed because it was advantageous, but advantageous only in limited amounts.
Your conscious mind is that newspaper.
When an idea is served up from behind the scenes, your neural circuitry has been working on it for hours or days or years, consolidating information and trying out new combinations.
The brain runs its show incognito.
As Carl Jung put it, “In each of us there is another whom we do not know.” As Pink Floyd put it, “There’s someone in my head, but it’s not me.”
Herbart coined the term “apperceptive mass” to indicate that an idea becomes conscious not in isolation, but only in assimilation with a complex of other ideas already in consciousness.
This suggested to him that we are not directly aware of the outside world, but instead only of the signals in the nervous system.
consciousness is a way of projecting all the activity in your nervous system into a simpler form.
It may come as a surprise that about one-third of the human brain is devoted to vision.
the brain doesn’t actually use a 3-D model—instead, it builds up something like a 2½-D sketch at best.
The brain generally does not need to know most things; it merely knows how to go out and retrieve the data. It computes on a need-to-know basis.
As your eyes interrogate the world, they are like agents on a mission, optimizing their strategy for the data. Even though they are “your” eyes, you have little idea what duty they’re on. Like a black ops mission, the eyes operate below the radar, too fast for your clunky consciousness to keep up with.
Perceptual switching happens if we present one image to your left eye (say, a cow) and a different image to your right eye (say, an airplane).
You’re not perceiving what’s out there. You’re perceiving whatever your brain tells you.
He concluded that the brain must make assumptions about the incoming data, and that these assumptions are based on our previous experience.
In other words, given a little information, your brain uses its best guesses to turn it into something larger.
Just as with the waterfall effect, her condition of motion blindness tells us that position and motion are separable in the brain.
Motion is “painted on” our views of the world, just as it is erroneously painted on the images above.
the conscious experience of vision occurs only when there is accurate prediction of sensory consequences,
So although vision seems like a rendition of something that’s objectively out there, it doesn’t come for free. It has to be learned.
that we see not with our eyes but rather with our brains.
At least 15 percent of human females possess a genetic mutation that gives them an extra (fourth) type of color photoreceptor—and this allows them to discriminate between colors that look identical to the majority of us with a mere three types of color photoreceptors.
During dream sleep the brain is isolated from its normal input, so internal activation is the only source of cortical stimulation. In the awake state,
internal activity is the basis for imagination and hallucinations.
The more surprising aspect of this framework is that the internal data is not generated by external sensory d...
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The deep secret of the brain is that not only the spinal cord but the entire central nervous system works this way: internally generated activity is modulated by sensory input.
In this view, the difference between being awake and being asleep is merely that the data coming in from the eyes anchors the perception.
Asleep vision (dreaming) is perception that is not tied down to anything in the real world; waking perception is something like dreaming with a little ...
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Throughout the brain there is as much feedback as feedforward—a feature of brain wiring that is technically called recurrence and colloquially called loopiness.
Vision usually dominates over hearing,
The brain internally simulates what will happen if you were to perform some action under specific conditions.
perception works not by building up bits of captured data, but instead by matching expectations to incoming sensory data.
the visual cortex is fundamentally a machine whose job is to generate a model of the world.
the primary visual cortex constructs an internal model that allows it to anticipate the data streaming up from the retina (see the appendix for an anatomical guide). The cortex sends its predictions to the thalamus, which reports on the difference between what comes in through the eyes and what was already anticipated. The thalamus sends back to the cortex only that difference information—that is, the bit that wasn’t predicted away. This unpredicted information adjusts the internal model so there will be less of a mismatch in the future.
perception reflects the active comparison of sensory inputs with internal predictions.
awareness of your surroundings occurs only when sensory inputs violate expectations.
This predictability that you develop between your own actions and the resulting sensations is the reason you cannot tickle yourself.
It is not only vision and hearing that are constructions of the brain. The perception of time is also a construction.
Just because you believe something to be true, just because you know it’s true, that doesn’t mean it is true.
There is a looming chasm between what your brain knows and what your mind is capable of accessing.
You are not consciously aware of the vast majority of your brain’s ongoing activities, and nor would you want to be—it would interfere with the brain’s well-oiled processes.
The ability to remember motor acts like changing lanes is called procedural memory, and it is a type of implicit memory—meaning that your brain holds knowledge of something that your mind cannot explicitly access.
