Joseph E. Ledoux Quotes

Once a genetic component has been established, the search for the genes involved can begin. This is a time-consuming and complex process that has recently been greatly facilitated by the information obtained by the Human Genome Project.51

Anxiety, in short, is a conscious feeling. It can arise in a bottom-up way, driven by activity in defensive circuits or from higher processes that conceptualize worry, either about an uncertain future or about existence itself.

What distinguishes the various kinds of fears is the combination and amount of the raw materials involved. What ties together all instances of fear is the awareness that a threat to well-being is present or is soon very likely to occur. In short, in order to be felt as fear, components of a nonconscious defensive motivational state have to invade and become a presence98 in conscious awareness. This can only happen in organisms that have the capacity to both be aware of brain representations of internal and external events and to know in a personal, autobiographical sense that the event is happening to them - someone has to be home in the brain in order to feel fear when the defensive state knocks on the door.99

Hebb's notion, as you'll recall, is that "when an axon of cell A is near enough to excite cell B or repeatedly and consistently takes part in firing it, some growth process or metabolic changes take place in one or both cells such that A's efficiency, as one of the cells firing B, is increased." Let's expand this idea a little so we can see how it might apply to memory, and especially to a memory of the fact that two stimuli once occurred together.

In order for two stimuli to be bound together in the mind, to become associated, the neural representations of the two events have to meet up in the brain. This means that there has to be some neuron (or a set of neurons) that receives information about both stimuli. Then, and only then, can the stimuli be linked together and an association be formed between them.

Learning is indeed a lifelong process. And as Alison Gopnik and colleagues argued in another recent book, every time the infant learns something, his or her brain is changed in a way that helps it learn something else. In a review of this book, a prominent developmental expert, Mark Johnson, noted that the early years are crucial not because the window of opportunity closes but because what is learned at this time becomes the foundation for subsequent learning. Indeed, much of the self is learned by making new memories out of old ones. Just as learning is the process of creating memories, the memories created are dependent on things we've learned before.

Because emotion systems coordinate learning, the broader the range of emotions that a child experiences the broader will be the emotional range of the self that develops. This is why childhood abuse is so devastating. If a significant proportion of the early emotional experiences one has are due to activation of the fear system rather than positive systems, then the characteristic personality that begins to build up from the parallel learning processes coordinated by the emotional state is one characterized by negativity and hopelessness rather than affection and optimism.

Heritability in psychiatric disorders typically involves complex inheritance patterns controlled by multiple genes that interact with environmental factors to produce their results.

The problem is that there may not be any way to really prove animal consciousness with data. Clever experiments can show that animals perform behaviorally in ways that people behave when they are in a particular state of phenomenal consciousness. But we can create robots that behave the way humans behave when we are having a phenomenal experience. Consciousness is, and probably always will be, an inner experience that is unobservable to anyone other than the experiencing organism. And in the absence of verbal report, there is little to measure.

The full sequence of communication between neurons is thus usually electrical-chemical-electrical: electrical signals coming down axons get converted into chemical messages that help trigger electrical signals in the next cell. There are also synapses through which communication between presynaptic and postsynaptic sites is purely electrical, but chemical transmission is the more prevalent form. Thus, much of what the brain does involves electrical-to-chemical-to-electrical coding of experience. As hard as it may be to imagine, electrochemical conversations between neurons make possible all of the wondrous (and sometimes dreadful) accomplishments of human minds. Your very understanding that the brain works this way is itself an electrochemical event.

Acceptance and commitment therapy, a variant on cognitive therapy, attempts to teach people to accept rather than change their emotions and make decisions within the context of what they value, as opposed to letting negative feelings control their behavior.

twin studies of anxiety have revealed that genetic factors account for roughly 30 percent to 50 percent of an individual's tendency to be generally anxious or to have a specific anxiety disorder.50

Researchers like Jonathan Winson, Gyorgy Buzsaki, Bruce McNaughton, and Matt Wilson believe memory consolidation occurs during sleep, and specifically that it is during sleep that the slow interleaving of information into cortical networks takes place. Recent studies support this notion. For example, Wilson and McNaughton recorded the activity of neurons in the rat hippocampus. Using technically sophisticated procedures, they were able to identify precise patterns of cell activity in the hippocampus as rats explored a novel environment. Subsequently, when the rats went to sleep, the neural patterns seemed to be repeated in the hippocampus, as if the rats were dreaming about the places they had explored. This is an impressive finding. Although it has not yet been demonstrated that the hippocampal playback during sleep is actually read and used by the cortex, the existing data are consistent with the possiblity.

Plasticity in all the brain's systems is an innately determined characteristic. This may sound like a nature-nurture contradiction, but it is not. An innate capacity for synapses to record and store information is what allows systems to encode experiences. If the synapses of a particular brain system cannot change, this system will not have the ability to be modified by experience and to maintain the modified state. As a result, the organism will not be able to learn and remember through the functioning of that system. All learning, in other words, depends ont he operation of genetically programmed capacities to learn. Learning involves the nurturing of nature.

Through the topic of motivation, we begin to see the mental trilogy in action. A mind is not, as cognitive science has traditionally suggested, just a thinking device. It's an integrated system that includes, in the broadest possible terms, synaptic networks devoted to cognitive, emotional, and motivational functions. More important, it involves interactions between networks involved in different aspects of mental life.

In Hull's view, all learning involves the reduction of basic drives (like hunger, thirst, sex, or pain), and current behavior is therefore a product of drive reduction in the past. That is, what we do today in a certain situation is a function of what we did in the past that was successful in reducing drives in similar situations. This is essentially a psychological version of the philosophical position known as hedonism, the idea that we live our lives in such a way as to seek pleasure and avoid pain.

Unfortunately, one of the most signifi cant things ever said about emotion may be that everyone knows what it is until they are asked to define it.

The fear structure is viewed as a program (in the sense of a computer program) for escaping or avoiding danger and includes several kinds of stored propositions: It includes propositions about threats - when the threat signal (CS) occurs, a bad thing (US) follows; propositions about physiological changes - when the CS occurs, I sweat and my heart beats faster; propositions

For example, one promising target is the peptide oxytocin, which has been reported to reduce anxiety, promote affiliation, attachment, and affection,33 and facilitate extinction of threat conditioning.

No doubt one of the reasons human cognition is so powerful is because we have language in our brains, which exponentially increases the ability to categorize information, to chunk. A whole culture, for instance, can be implied by a name.

Collectively this work suggests that the prefrontal cortex and the amygdala are reciprocally related. That is, in order for the amygdala to respond to fear reactions, the prefrontal region has to be shut down. By the same logic, when the prefrontal region is active, the amygdala would be inhibited, making it harder to express fear. Pathological fear, then, may occur when the amygdala is unchecked by the prefrontal cortex, and treatment of pathological fear may require that the patient learn to increase activity in the prefrontal region so that the amygdala is less free to express fear. Clearly, decision-making ability in emotional situations is impaired in humans with damage to the medial and ventral prefrontal cortex, and abnormalities there also may predispose people to develop fear and anxiety disorders. These abnormalities could be due to genetic or epigenetic organization of prefrontal synapses or to experiences that subtly alter prefrontal synaptic connections. Indeed, the behavior of animals with abmormalities of the medial prefrontal cortex is reminiscent of humans with anxiety disorders: they develop fear reactions that are difficult to regulate. Although objective information about the world may indicate that a situation is not dangerous, because they cannot properly regulate fear circuits, they experience fear and anxiety in these safe situations.

Emotional responses are not always external mirrors of internal feelings. but are rather controlled by more fundamental processes.