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d873156
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games. A summary: Exposing children to a violent TV or film clip increases their odds of aggression soon after.41 Interestingly, the effect is stronger in girls (amid their having lower overall levels of aggression). Effects are stronger when kids are younger or when the violence is more realistic and/or is presented as heroic. Such exposure can make kids more accepting of aggression--in one study, watching violent music videos increased ad..
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Robert M. Sapolsky |
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41782eb
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Oxytocin and vasopressin facilitate mother-infant bond formation and monogamous pair-bonding, decrease anxiety and stress, enhance trust and social affiliation, and make people more cooperative and generous. But this comes with a huge caveat--these hormones increase prosociality only toward an Us. When dealing with Thems, they make us more ethnocentric and xenophobic. Oxytocin is not a universal luv hormone. It's a parochial one.
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Robert M. Sapolsky |
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b844a5b
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Two Last Thoughts If you had to boil this book down to a single phrase, it would be "It's complicated." Nothing seems to cause anything; instead everything just modulates something else. Scientists keep saying, "We used to think X, but now we realize that ..." Fixing one thing often messes up ten more, as the law of unintended consequences reigns. On any big, important issue it seems like 51 percent of the scientific studies conclude one th..
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Robert M. Sapolsky |
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aa9ab84
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Remarkably, studies have examined brains of transgender individuals, concentrating on brain regions that, on the average, differ in size between men and women. And consistently, regardless of the desired direction of the sex change and, in fact, regardless of whether the person had undergone a sex change yet, the dimorphic brain regions in transgender individuals resembled the sex of the person they had always felt themselves to be, not the..
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Robert M. Sapolsky |
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c36fa3e
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Here's an imaginary twin pair that would be God's gift to behavior geneticists--identical twin boys separated at birth. One, Shmuel, is raised as an Orthodox Jew in the Amazon; the other, Wolfie, is raised as a Nazi in the Sahara. Reunite them as adults and see if they do similar quirky things like, say, flushing the toilet before using it. Flabbergastingly, one twin pair came close to that. They were born in 1933 in Trinidad to a German Ca..
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Robert M. Sapolsky |
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ecd1c30
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Perhaps fifty years since we learned that reading problems of a type that we now call dyslexia aren't due to laziness but instead involve microscopic cortical malformations.
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Robert M. Sapolsky |
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a1e42f4
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Most child behavioral development research is implicitly stage oriented, concerning: (a) the sequence with which stages emerge; (b) how experience influences the speed and surety with which that sequential tape of maturation unreels; and (c) how this helps create the adult a child ultimately becomes.
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Robert M. Sapolsky |
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14e73f8
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No brain region is an island, and the formation of circuits connecting far-flung brain regions is crucial--how else can the frontal cortex use its few myelinated neurons to talk to neurons in the brain's subbasement to make you toilet trained?2 As we saw, mammalian fetuses overproduce neurons and synapses; ineffective or unessential synapses and neurons are pruned, producing leaner, meaner, more efficient circuitry. To reiterate a theme fro..
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Robert M. Sapolsky |
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f3a4de8
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Damasio has produced an influential theory about emotion-laden decision making, rooted in the philosophies of Hume and William James; this will soon be discussed.61 Briefly, the frontal cortex runs "as if" experiments of gut feelings--"How would I feel if this outcome occurred?"--and makes choices with the answer in mind. Damaging the vmPFC, thus removing limbic input to the PFC, eliminates gut feelings, making decisions harder." --
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Robert M. Sapolsky |
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46b96f2
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Glutamate signaling works in a fancier way that is essential to learning.2 To simplify considerably, while dendritic spines typically contain only one type of receptor, those responsive to glutamate contain two. The first (the "non-NMDA") works in a conventional way--for every little smidgen of glutamate binding to these receptors, a smidgen of sodium flows in, causing a smidgen of excitation. The second (the "NMDA") works in a nonlinear, t..
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Robert M. Sapolsky |
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c7466f9
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A behavior has occurred that is good, bad, or ambiguous. How have cultural factors stretching back to the origins of humans contributed to that behavior? And rustling cattle on a moonless night; or setting aside tending your cassava garden to raid your Amazonian neighbours; or building fortifications; or butchering every man, woman, and child in a village is irrelevant to that question. That's because all these study subjects are pastoralis..
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Robert M. Sapolsky |
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e5e9d36
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stress weakens frontal connections with the hippocampus--essential for incorporating the new information that should prompt shifting to a new strategy--while strengthening frontal connections with more habitual brain circuits.
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Robert M. Sapolsky |
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e8d0e7d
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in general, major stressors make people of both genders more risk taking. But moderate stressors bias men toward, and women away from, risk taking. In the absence of stress, men tend toward more risk taking than women; thus,
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Robert M. Sapolsky |
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2719988
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Most broadly, the PFC chooses between conflicting options--Coke or Pepsi; blurting out what you really think or restraining yourself; pulling the trigger or not. And often the conflict being resolved is between a decision heavily driven by cognition and one driven by emotions. Once it has decided, the PFC sends orders via projections to the rest of the frontal cortex, sitting just behind it. Those neurons then talk to the "premotor cortex,"..
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Robert M. Sapolsky |
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450dbd4
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aggression, violence, compassion, empathy, sympathy, competition, cooperation, altruism, envy, schadenfreude, spite, forgiveness, reconciliation, revenge, reciprocity, and (why not?) love.
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Robert M. Sapolsky |
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682d616
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In our world riddled with male violence, the problem isn't that testosterone can increase levels of aggression. The problem is the frequency with which we reward aggression.
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Robert M. Sapolsky |
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997d740
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it's human behavior, human social behavior, and in many cases abnormal human social behavior. And it is indeed a mess, a subject involving brain chemistry, hormones, sensory cues, prenatal environment, early experience, genes, both biological and cultural evolution, and ecological pressures, among other things.
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Robert M. Sapolsky |
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fc9eabe
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It's not until the non-NMDA has been stimulated over and over by a long train of glutamate release, allowing enough sodium to flow in, that this activates the NMDA receptor. It suddenly responds to all that glutamate, opening its channels, allowing an explosion of excitation. This is the essence of learning.
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Robert M. Sapolsky |
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40f7b8e
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This is a central point of this book--we don't hate violence. We hate and fear the wrong kind of violence, violence in the wrong context. Because violence in the right context is different. We pay good money to watch it in a stadium, we teach our kids to fight back, we feel proud when, in creaky middle age, we manage a dirty hip-check in a weekend basketball game. Our conversations are filled with military metaphors--we rally the troops aft..
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Robert M. Sapolsky |
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c14d05d
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Greene calls "the Tragedy of Commonsense Morality" is shown by the fact that most intergroup conflicts on our planet ultimately are cultural disagreements about whose "right" is righter."
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Robert M. Sapolsky |
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40dbccb
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the fetal brain generates far more neurons than are found in the adult.
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Robert M. Sapolsky |
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1e8b6ad
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Moving beyond mere correlation, if you lesion the amygdala in an animal, rates of aggression decline. The same occurs transiently when you temporarily silence the amygdala by injecting Novocain into it. Conversely, implanting electrodes that stimulate neurons there, or spritzing in excitatory neurotransmitters (stay tuned), triggers aggression.4
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Robert M. Sapolsky |
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af634bd
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Stick recording electrodes into numerous species' amygdalaefn9 and see when neurons there have action potentials; this turns out to be when the animal is being aggressive.fn10 In a related approach, determine which brain regions consume extra oxygen or glucose, or synthesize certain activity-related proteins, during aggression--the amygdala tops the list.
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Robert M. Sapolsky |
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97789c1
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Joseph LeDoux at New York University has shown how the BLA learns fear.fn14,20 Expose a rat to an innate trigger of fear--a shock. When this "unconditioned stimulus" occurs, the central amygdala activates, stress hormones are secreted, the sympathetic nervous system mobilizes, and, as a clear end point, the rat freezes in place--"What was that? What do I do?" Now do some conditioning. Before each shock, expose the rat to a stimulus that nor..
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Robert M. Sapolsky |
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72553f8
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LeDoux and others have shown how auditory information about the tone stimulates BLA neurons. At first, activation of those neurons is irrelevant to the central amygdala (whose neurons are destined to activate following the shock). But with repeated coupling of tone with shock, there is remapping and those BLA neurons acquire the means to activate the central amygdala.fn16
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Robert M. Sapolsky |
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25649c3
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Willpower is more than just a metaphor; self-control is a finite resource. Frontal neurons are expensive cells, and expensive cells are vulnerable cells. Consistent
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Robert M. Sapolsky |
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8a9b664
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Success in everything from athletics to chess to the stock market boosts testosterone levels.
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Robert M. Sapolsky |
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36a7ad1
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Logically, when the amygdala wants to mobilize a behavior--say, fleeing--it talks to the frontal cortex, seeking its executive approval. But if sufficiently aroused, the amygdala talks directly to subcortical, reflexive motor pathways. Again, there's a trade-off--increased speed by by-passing the cortex, but decreased accuracy. Thus the input shortcut may prompt you to see the cell phone as a gun. And the output shortcut may prompt you to p..
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Robert M. Sapolsky |
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85edfac
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Infuse oxytocin into the brain of a virgin rat, and she'll act maternally--retrieving, grooming, and licking pups. Block the actions of oxytocin in a rodent mother,*23 and she'll stop maternal behaviors, including nursing. Oxytocin
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Robert M. Sapolsky |
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c7eae87
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Thus there's dopaminergic activation during schadenfreude--gloating over an envied person's fall from grace.
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Robert M. Sapolsky |
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a816601
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genes and fetal environment are relevant. But most important, recall the logic of collapsing different types of trauma into a single category. What counts is the sheer number of times a child is bludgeoned by life and the number of protective factors.
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Robert M. Sapolsky |
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d1528fc
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There's support for the idea--three of my favorites are that (a) forcing depressed people to smile makes them feel better; (b) instructing people to take on a more "dominant" posture makes them feel more so (lowers stress hormone levels); and (c) muscle relaxants decrease anxiety ("Things are still awful, but if my muscles are so relaxed that I'm dribbling out of this chair, things must be improving"). Nonetheless,"
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Robert M. Sapolsky |
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c853c48
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The most convincing data concern rare humans with damage restricted to the amygdala, either due to a type of encephalitis or a congenital disorder called Urbach-Wiethe disease, or where the amygdala was surgically destroyed to control severe, drug-resistant seizures originating there.5 Such individuals are impaired in detecting angry facial expressions (while being fine at recognizing other emotional states--stay tuned).
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Robert M. Sapolsky |
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0b76f25
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in adults the anterior cingulate cortex activates when they see someone hurt. Ditto for the amygdala and insula, especially in instances of intentional harm--there is anger and disgust. PFC regions including the (emotional) vmPFC are on board. Observing physical pain (e.g., a finger being poked with a needle) produces a concrete, vicarious pattern: there is activation of the periaqueductal gray (PAG), a region central to your own pain perce..
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Robert M. Sapolsky |
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a45e870
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women with variants of genes that produce higher levels of oxytocin or oxytocin receptors average higher levels of touching their infants and more synchronized gazing with them.
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Robert M. Sapolsky |
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9ba6a77
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So oxytocin is central to female mammals nursing, wanting to nurse their child, and remembering which one is their child.
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Robert M. Sapolsky |
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0c8c53e
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in adults the anterior cingulate cortex activates when they see someone hurt. Ditto for the amygdala and insula, especially in instances of intentional harm--there is anger and disgust. PFC regions including the (emotional) vmPFC are on board. Observing physical pain (e.g., a finger being poked with a needle) produces a concrete, vicarious pattern: there is activation of the periaqueductal gray (PAG), a region central to your own pain perce..
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Robert M. Sapolsky |
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1be7806
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Gerontologists studying the aging process find increasing evidence that most of us will age with a fair degree of success. There's far less institutionalization and disability than one might have guessed. While the size of social networks shrink with age, the quality of the relationships improves. There are types of cognitive skills that improve in old age (these are related to social intelligence and to making good strategic use of facts, ..
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Robert M. Sapolsky |
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fac72e4
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And their brains? Decreased total brain size, gray matter, white matter, frontal cortical metabolism, connectivity between regions, sizes of individual brain regions. Except for the amygdala. Which is enlarged. That pretty much says it all.
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Robert M. Sapolsky |
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05d8825
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Meanwhile, the parasympathetic nervous system (PNS) arises from different midbrain/brain-stem nuclei that project down the spine to the body. In contrast to the SNS and the four Fs, the PNS is about calm, vegetative states. The SNS speeds up the heart; the PNS slows it down. The PNS promotes digestion; the SNS inhibits it (which makes sense--if you're running for your life, avoiding being someone's lunch, don't waste energy digesting breakf..
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Robert M. Sapolsky |
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7be6d40
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When a rat wins a fight, the number of testosterone receptors increases in the ventral tegmentum and accumbens, increasing sensitivity to the hormone's feel-good effects.10
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Robert M. Sapolsky |
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b833ba7
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contemporary studies show that the worst stress-related health typically occurs in middle management, with its killer combo of high work demands but little autonomy--responsibility without control.
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Robert M. Sapolsky |
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980da85
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So testosterone does subtle things to behavior. Nonetheless, this doesn't tell us much because everything can be interpreted every which way. Testosterone increases anxiety--you feel threatened and become more reactively aggressive. Testosterone decreases anxiety--you feel cocky and overconfident, become more preemptively aggressive. Testosterone increases risk taking--"Hey, let's gamble and invade." Testosterone increases risk taking--"Hey..
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Robert M. Sapolsky |
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1243bd2
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This context dependency means that rather than causing X, testosterone amplifies the power of something else to cause X.
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Robert M. Sapolsky |