The Disordered Mind: What Unusual Brains Tell Us About Ourselves

The fourth principle, which derives from the first three, is that information flows in one direction only—from the dendrites to the cell body to the axon, then along the axon to the synapse. We now call this flow of information in the brain the principle of dynamic polarization.

immediately began to hear clicking noises, a fast rapping similar to Morse code. The clicking noise was an electrical signal, an action potential, the fundamental unit of neural communication. Adrian was listening in on the language of neurons. What produced the action

Descartes’s mind-body dualism has proved hard to shake because it reflects the way we experience ourselves.

Each gene encodes—that is, issues the instructions for making—a particular protein. Proteins determine the structure, function, and other biological characteristics of every cell in our body.

For example, Alzheimer’s disease, which primarily affects memory; Parkinson’s disease, which primarily affects movement; and Huntington’s disease, which affects movement, mood, and cognition, are all thought to involve faulty protein folding, as we shall see in later chapters. The three disorders produce strikingly different symptoms because the abnormal folding affects different proteins and different regions of the brain. We will undoubtedly discover common mechanisms in other diseases as well.

Because of neurology’s traditional emphasis on anatomy, we know a great deal more about the neural circuitry of neurological disorders than of psychiatric disorders. In addition, the underlying neural circuitry of psychiatric disorders is more complex than that of neurological disorders. Scientists have only recently begun to explore the brain regions involved in thought, planning, and motivation, the

other people have a mind of their own, that they have their own beliefs, aspirations, desires, and intentions. This innate understanding is different from a shared emotion. A very young child will smile when you smile or frown when you frown. But realizing that the person you’re looking at may be thinking about something different from what you’re thinking about is a profound skill that arises only later in normal development, around the age of three or four.

Thus, one of the reasons people with autism have difficulty with social interactions is that they have limited capacity to read socially meaningful biological actions such as reaching to shake hands.

while a mutation in a single gene is responsible for some disorders, such as Huntington’s disease, single mutations do not cause most other brain disorders, including autism, depression, bipolar disorder, and schizophrenia.

Rather than relying on higher, cognitive regions such as the medial region of the temporal lobe, implicit memory depends more on regions of the brain that respond to stimuli, for example the amygdala, the cerebellum, and the basal ganglia, or, in the simplest instances, the reflex pathways themselves.

Short-term memory results from strengthening existing synaptic connections, making them function better, whereas long-term memory results from the growth of new synapses. Put another way, long-term memory leads to anatomical changes in the brain, whereas short-term memory does not. When synaptic connections weaken or disappear over time, memory fades or is lost.

benign senescent forgetfulness,

found that age-related memory loss involves the dentate gyrus, a structure within the hippocampus.

that bone is an endocrine organ and that it releases a hormone called osteocalcin. Karsenty found that osteocalcin acts on many organs of the body and also gets into the brain, where it promotes spatial memory and learning by influencing the production of serotonin, dopamine, GABA, and other neurotransmitters. 8

ability to recognize faces resides in the right fusiform gyrus of the inferior medial temporal lobe of the brain. People with damage to the front of that region are face-blind,

similar in nature, although more modest in scope, to the creative process of the artist. This creative process is known as the beholder’s share.

experience moments in their work in which they undergo, in a controlled manner, a relatively free communication between the unconscious and conscious parts of their mind. He calls this controlled access to our unconscious “regression in the service of the ego.”

Max Ernst, a leader first of Dada and later of Surrealist art, bought a copy of Prinzhorn’s book and took it to Paris, where it became the “Picture Bible” of the Surrealists.

organizational logic of the brain as a whole. In the broadest sense, the task of every circuit in the nervous system is to add up the total excitatory and inhibitory information it receives and determine

whether to pass that information along. Sherrington called this principle “the integrative action of the nervous system.”

the disease worsens, other areas of the brain besides the substantia nigra become involved.

Initially, L-dopa was viewed as a cure, but after a honeymoon of several years, it fell out of favor because it was only effective as long as there were dopamine-producing cells in the substantia nigra. It turned out that as more dopamine-producing cells died, the drug’s beneficial effects wore off abruptly, leaving patients with involuntary movements, called dyskinesias. Clearly, an alternative treatment was needed.

found that a particular area of the basal ganglia, the subthalamic nucleus, is also rich in dopamine-producing nerve cells and plays an essential role in the control of movement.

1990 he published the amazing result: damaging the subthalamic nucleus in one side of the brain of a monkey with Parkinson’s disease caused the tremor and muscular rigidity on the other side of the body to vanish. 9

As we have seen, the death of dopamine-producing neurons, caused by misfolded proteins, leads to Parkinson’s disease.

restrict the word “emotion” to the observable, unconscious behavioral component and use “feeling” to refer to the subjective experience of emotion.

Many structures in the brain are involved in emotion, but four of them are particularly important: the hypothalamus, which is the executor of emotion; the amygdala, which orchestrates emotion; the striatum, which comes into play when

we form habits, including addictions; and the prefrontal cortex, which evaluates whether a particular emotional response is appropriate to the situation at hand (fig. 8.4). The prefrontal cortex interacts with, and in part controls, the amygdala and striatum.

“Anyone can become angry—that is easy,” he wrote in The Nicomachean Ethics. “But to be angry with the right person and to the right degree and at the right time and for the right purpose, and in the right way—that is not within everybody’s power and is not easy.”

“Anyone can become angry—that is easy,” he wrote in The Nicomachean Ethics. “But to be angry with the right person and to the right degree and at the right time and for

ventromedial prefrontal cortex. This structure is also important for what we would call moral emotions—indignation, compassion, embarrassment, and shame.

dorsal prefrontal cortex, is actually the point at which our conscious mind—our volition, or will—can impose itself on the way emotion is being carried out.

epigenetic changes, that is, molecular changes in reaction to the environment that do not alter the DNA of a gene but do affect the expression of that gene.

People in the treatment group were given propranolol, a drug that blocks the action of

noradrenaline, a neurotransmitter released in response to stress that triggers our fight, flight, or freeze response.

Swedish pharmacologist Arvid Carlsson, dopamine is released primarily by neurons in two regions of the brain: the ventral tegmental area and the substantia nigra (fig.

communications network, known as the mesolimbic pathway, is the major network in the brain’s reward system. It puts dopamine-producing neurons in a position to broadcast information widely, including to regions throughout the cerebral cortex.

Activation of dopamine signaling, along with activation of several other important reward signals that vary from drug to drug, is responsible for the initial high that people experience on drugs.

Adaptive habits are promoted by the release of dopamine into the prefrontal cortex and the striatum, the areas of the

brain involved with control and with reward and motivation.

brain imaging reveals that cocaine, a highly addictive drug, interferes with the removal of dopamine from the synapse. As a result, dopamine lingers there and continues to produce pleasurable feelings that persist beyond those produced by ordinary physiological stimuli. In this way cocaine hijacks the brain’s reward system.

series of imaging

involves Vietnam veterans who had become hooked on very high quality heroin while overseas. Amazingly, most of them were able to conquer their addiction when they returned to the United States because none of the cues that had encouraged them to use heroin in Vietnam were present at home. 4

to nicotine modifies their dopamine-receiving neurons in such a way that they respond more powerfully to cocaine. In contrast, giving the animals cocaine first has no effect on their subsequent response to nicotine. 13 Thus, nicotine primes the brain for cocaine addiction.

obesity seemed to spread through a social network like a virus. In fact, if one person became obese, the likelihood that a friend would follow suit increased by 171 percent.

As we have seen, drug addiction is a form of long-term memory. The brain becomes conditioned to associate certain environmental cues with pleasure, and encountering those cues can trigger an urge to use the drug.

Unfortunately, pharmaceutical companies have devoted very little effort to developing drugs to treat addiction. One reason is their perception that they cannot recover their research costs from addicted people.

Gender identity is not the same thing as sexual orientation, a person’s romantic attraction to the opposite sex, the same sex, or both sexes. At present, we know too little about the biology of sexual orientation to discuss it here.

Does our brain contain neural circuits for both male and female behavior, like the mouse brain, or does it have separate neural circuits for men and for women?

About 20 percent of the neurons located on the border between the two populations can be active during either mating or aggression.

brain contains a system—which they

called the reticular activating system—that extends from the brain stem and midbrain to the thalamus, and from the thalamus to the cortex.

In theory, we should be able to determine whether neural correlates cause consciousness by the usual methods: see if consciousness can be turned on by turning on the neural correlates of consciousness, and see if consciousness can be turned off by turning off the neural correlates of consciousness. We’re not quite able to do that yet.

they discovered the anterior insular cortex, or insula, a little island in the cortex located between the parietal and temporal lobes. The insula is where our feelings are represented—