“What a person is, and what he or she thinks, feels, and does, is by no stretch of the imagination influenced only by consciousness. Many of our thoughts, feelings, and actions take place automatically, with consciousness only coming to know them as they happen, if at all. Figuring out the mechanism of consciousness would surely be a major scientific coup, but it wouldn’t explain how the brain works, or how our brains make us the individuals we are.”
“In a fusion of faith and psychological theory, Descartes equated the soul with consciousness, and said only humans have conscious control of their behavior. Therefore, only human souls can gain or lose access to heaven by their actions. The behaviors of other animals were, in Descartes’s scheme, reflexive or automatic, and carried out without thoughts. So, for Descartes, if it wasn’t conscious, it wasn’t mental. Descartes didn’t exactly deny the existence of unconscious processes, but simply relegated them to the physical world, proposing that they function in humans the way they do in mindless (soulless) animals.
But if the ‘the physical’ and ‘the mental’ are completely different entities, how can the conscious soul (the mental) be responsible for the physical body? Descartes’s solution was that the conscious soul substance can interact with the material body by means of a small region of the brain called the pineal gland. While most parts of the brain exist in duplicate, the pineal gland is singular and centrally located, which suggested to Descartes that it must be the seat of mind-body interaction - a place where commands from the soul can influence the body, and where information from the body (either about the outside world or the body itself) can enter the soul as perceptions, emotions, and knowledge.
In Descartes’s scheme, the nonphysical soul substance actually served the dual function of communicating with the physical body as well as with God.”
“Descartes’s framing of the philosophical question (How does the mind interact with the body?), and his particular answer to it (a mind-body interaction in the brain), set up the conundrum known as as the mind-body problem, which philosophers have struggled with ever since. “
“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.”
“The exact role of neural activity, though, is heatedly debated, with the main issue of contention being whether activity, especially activity initiated by environmental stimulation, helps create the mature connections or just selects from the initial set of intrinsically established connections those that will be retained. This instruction vs. selection debate cuts deep into the heart of human nature: Is the self sculpted from a preexisting set of synaptic choices, or does experience instruct and add to the synaptic basis of the self as we go through early life? As we will see, since environmentally triggered neural activity is involved in both instructing and selecting connectivity, this is not so much a debate about genes vs. environmental experience as one about the precise contribution of experience.”
“Only those cells that compete successfully for neurotrophins (those that are active) survive. In the presence of neurotrophins, the surviving terminals (those that were active) also begin to sprout new connections. Selection can be a step along the path toward activity-instructed growth – in other words, selection and instruction are partners in synaptic development.”
“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.”
“Stimulus recognition requires only that an immediately present stimulus match some representation of a similar stimulus in memory. There is no need to have conscious awareness to have recognition.”
“Pleasure, to the extent it is experienced, would not come during the anticipatory state but instead during consummation. Since dopamine is involved only in the anticipatory phase, and not in the consummatory phase, its effects (at least in the case of primary need states) cannot be explained in terms of pleasure.”
“… animals become active or invigorated when dopamine is injected into the accumbens. This occurs because dopamine facilitates synaptic transmission in the pathway from the accumbens to the pallidum, which in turn connects with movement-control regions in the cortex with movement-control regions in the cortex and brain stem. With the pallidal output amplified, the motor regions are strongly activated, and movement is initiated. Behavior can potentially be invigorated by anything that activates tegmental cells and causes them to release dopamine in the accumbens. Novel stimuli, and conditioned and unconditioned incentives, are prime examples of invigorating stimuli.”
“But invigoration alone is not sufficient: behavior also needs to be guided or directed. Guidance of behavior is the job of conditioned incentives processed by the amygdala. The basal nucleus of the amygdala, as we’ve seen, receives information about a conditioned incentive from the lateral nucleus. It then transfers this conditioned incentive to the accumbens. When dopamine is elevated in the accumbens (as a result of the central nucleus’s activation of dopamine neurons in the tegmentum that release dopamine in the accumbens), the arrival of an incentive stimulus in the accumbens from the basal nucleus will have a bigger effect on the activity of accumbens cells, and presumably on neurons in the ventral pallidum that are downstream from the accumbens. The incentive thus leads to the release of dopamine, and dopamine facilitates the ability of the incentive to both invigorate and direct behavior.”
