by Paul Singh
The temporal lobe, located beneath the lateral fissure on both cerebral hemispheres, provides advanced memory retention and management, so that one has a sense of oneself, one’s experiences, and one’s storehouse of knowledge across time. The medial temporal lobe consists of structures that are vital for declarative or long-term memory. Declarative (denotative) or explicit memory is conscious memory divided into semantic memory (facts) and episodic memory (events). Medial temporal lobe structures that are critical for long-term memory include the amygdala, brainstem, and hippocampus along with the surrounding hippocampal region consisting of the perirhinal, parahippocampal and entorhinal neocortical regions.
Neuroscientists Barrs, Franklin, and Ramsoy describe the complex interactions in the cortical lobes as follows:
Most regions of the cortical lobes are thoroughly connected with each other and the thalamus region in dense webs of neural pathways (the ‘C-T’ system). . . These long pathways are targeted in very precise and regular topographies. Local cortical links are also very numerous. Tractographic studies indicate that the connectivity of the C-T system follows small-world network properties. . . . The C-T core constitutes by far the biggest parallel-interactive structure in the mammalian brain, showing massive wave-like activities during active states. . . . Most sensory pathways flow into the C-T system, while motor pathways flow outward for subcortical,craniospinal, and autonomic control.14
Conscious activity crucially depends on those intense intercommunications at the interface between the cortex and the deep brain. None of the cortical lobes can sustain consciousness if the brain stem and limbic system aren’t functioning well. Significant damage to these lower core regions always reduces conscious awareness or eliminates it, resulting in vegetative states or comas.15 Minimal conscious awareness is powered by the core brain areas, which in turn activate the complex kinds of conscious sentience and thinking produced by the cortex.
From an evolutionary perspective, the core brain regions would have to be crucial because they evolved first. The simplest ways of sensing, feeling, and emoting came along with complex brains when vertebrates evolved around 500 million years ago. It is possible that the faintest of sensations and feelings were present in even simpler nervous systems going back to arthropods and mollusks before vertebrates, and insects, and octopuses were able to develop states of consciousness.
Detecting consciousness in simpler animals will remain challenging. Seeking the kinds of brain activity that we associate with our rich conscious lives in the lives of simpler animals is unfair and unwarranted. And there is no scientific reason to think that we are alone in being conscious, or that the conscious awareness in other animals has to be just like ours. Biology seems to seek diversity, and create different organic solutions to different survival problems. The kinds of awareness invented by evolution may be as varied as the body shapes of animals.
As for human brains, we depend on properly functioning cortexes to realize how we are aware and sentient and to think about what being conscious is like. Animals with small cortexes aren’t doing all that, much less talking about it. We shouldn’t expect proof of consciousness where none is possible. Prominent neuroscientist Christof Koch relates the following story:
After lecturing about consciousness in animals, I was approached by a lady who emphatically exclaimed, “You will never be able to convince me that a monkey is conscious!” “And you can never convince me that you are conscious,” I retorted. She was taken aback by my response, but then the light of understanding dawned on her face: The inability to feel what a monkey, a dog, or a bird feels applies to people as well, though to a lesser degree. Consider a spy working undercover, a cheating lover, or a professional actor. They fake feelings of trust, patriotism, love, or friendship. You can never be absolutely confident about the feelings of anybody! You can watch their eyes, parse what they say, but in the end you cannot truly know their mind by observing them.16
When the Brain produces Consciousness
However difficult it may be to verify another person’s consciousness directly, it isn’t impossible to figure out when conscious awareness must be absent. Forms of deep but dim awareness can survive the failure of higher levels of cortical activity, but the brain stem’s death is the permanent end of all feeling. When the brain stem stops functioning, the entire brain is now dead, and the person has ceased to exist. Science fiction novels that depict people in “comas” for years are still fictional. What popular culture depicts as coma is a vegetative state. A person is in a vegetative state when the brain stem is quite functional, a sleep-wake cycle and reflexes are observed, and the eyes are opened. Feeble bodily responses to strong stimuli are possible, but no useful motions can be accomplished, like turning one’s head or opening the mouth. People can live in this condition for many years, thanks to the insertion of a feeding tube. If the brain functioning can’t improve further, they are said to be in a “persistent vegetative state.”
Unlike people in comas, people in vegetative states have some feeling and awareness. But they can’t display any purposive actions and so they lack sentience, and they probably have few thoughts about themselves or their condition. The parts of their cortex responsible for thinking about anything are not getting used. The clinical boundary distinguishing a vegetative state from a minimally conscious state isn’t firm, and some cases are difficult to categorize. The primary indications for the minimally conscious state are the signs of sentience: focused attention directed to people around them, gesturing or speaking in response to talking to them, and a few effective actions such as grasping nearby objects. People in minimally conscious states can often improve with treatment and therapy, so that an impaired but fully conscious condition is achieved.17
New technologies have made the boundary between vegetative states and minimally conscious states much more difficult to distinguish. As portions of the cortex start to get used when a person gradually improves from a vegetative state, there may be an intermediary state. For example, although a person cannot move the tongue or mouth to speak, the part of the cortex responsible for thinking about what to say can be working. A handful of notable cases have been investigated in recent years.
In 2013 researchers in England announced new results from working with a patient in a vegetative state. Applying electroencephalography (EEG) to measure the strength and location of this patient’s brain activity, researchers looked for internal responses to verbal instructions. Although the parts of the cortex responsible for speaking in reply couldn’t do anything, other parts of the cortex did show increased activity in order to follow instructions, such as listening for a particular word and ignoring other words. People in an ordinary conscious condition can imitate this activity by closing their eyes and imagining that they are speaking a single word like “Yes” without moving their mouth at all. These researchers made headlines first in 2006 when they applied fMRI scanning to a vegetative state patient. They showed how portions of the cortex would jump into activity in response to certain instructions, indicating that this patient could pay attention to spoken language and make a purposeful response in the imagination. Although it is difficult to determine how much thinking is really going on in these cases, it is becoming clear that there are many kinds of minimally conscious states, depending on which parts of the cortex can function.18
These exciting new discoveries by the brain sciences are again confirming how tests that depend on only one or another part of the brain won’t be able to expose where the ‘consciousness’ is. Conscious awareness, and especially meaningful conscious thoughts, arise from several brain regions signaling back and forth in synch, and not from a single part of the brain. As Koch states, “Consciousness does not arise from regions but from highly networked neurons within and across regions.”19
The distributive and communicative nature to conscious awareness and sentience offers an explanation for the relationship between the innumerable subconscious processes occurring in each part of
the brain. We must first be reminded how much work done by the brain is supposed to be beneath conscious awareness.
Even when the organism is in a fully conscious and alert state, it is not capable of being conscious of the brain processes themselves. Many brain processes are devoted to the regulation of homeostasis, and at least in humans, hormone secretion, digestion, breathing, immune defense, and the like are in principle unconscious. We can learn about them, but have no direct access to them, and only feel the consequences of their functions and dysfunctions. What the organism can be conscious of depends on its sensory, cognitive, and behavioral faculties.20
Second, because any subconscious brain process influences many other subconscious processes, we mustn’t suppose that their simplicity means that they have straightforward results. Innumerable simple processes are all occurring simultaneously in the brain. They only have simple functions, but together they are influencing the organism’s behaviors in many ways. There is never a guarantee that subconscious processes are driving an organism to the same behaviors. Some may be activating muscles for going on the attack, while others may be activating the muscles needed for fleeing instead.
Animals with small brains, such as fish, display a limited range of possible behaviors, and they are often confused and ineffective in unfamiliar surroundings. The moderate-sized brains of amphibians and birds permit more complex and intelligent behaviors. The large-brained animals, such as beavers and bears, have far more options, and they can cleverly consider options before taking action. Behavioral flexibility comes with larger brains. However, the increased brain size in large animals is mostly due to a larger and complex cortex.
What is Consciousness For?
The larger cortex of land animals is responsible for complex behaviors, behaviors made possible because there is greater coordination and flexible management of subconscious processing. We mustn’t suppose that subconscious processing by itself doesn’t have much coordination; after all, small-brained animals have survived very well, far longer in evolutionary time than we large-brained primates. There is surely a great deal of coordination among the workings of a fish’s brain. However, the number of different behaviors that a typical fish can perform is not large, and most fish are very poor learners for dealing with anything but simple stimuli. Larger brained animals are good observers and learners, and they can flexibly change their behaviors depending on very slight changes in their environments or situations. There are even more subconscious processes to handle all that extra information from the environment and to drive reactions in response.
If the brain consisted of nothing but discrete regions and each only doing a limited amount of subconscious processing, no consciousness would arise because none would need to arise. However, an organism like that wouldn’t be able to perform any complex behaviors. Tough situations must cause the subconscious processes—all those “zombie” systems as Francis Crick and Christof Koch have called them in their joint writings21— to impede and confuse each other. Sentience is the organization of mere feeling, as high-level structures of the C-T system, that connect smaller brain regions, place demands on their coordination even as they “mindlessly” compete for control over behavior. That effort at coordination by the conscious C-T system, despite disorganization and distraction, is precisely what we experience as our inner life of conscious attention.22
The amount of conscious control exerted over all of those unconscious processes is not great; managing their insistent impulses is partial at best. Nevertheless, the conscious sentience possessed by complex animals capable of learning behaviors and discrimination must be possible because of overriding attention to some subconscious information rather than other subconscious information, and the ability to shift that attention as needed. The tensions and struggles for control are what get felt as consciousness. Consciousness doesn’t add feelings or thoughts about competing subsystems; those sensitivities to the uneven and shifting tensions are conscious sentience itself. There is a reason why being conscious is a scene of unending shiftiness and refocusing, and why getting into a thoughtfully placid and tensionless state is so difficult. The most arresting and interesting conscious states of mind we have are due to the kinds of tension-filled disruptions and searches for the re-equilibrium our nervous system must undergo.
For example, take the sensation of pain. The unpleasantness of pain is due to its associations with the dramatic tensions of muscular withdrawal and immediate quest for its stoppage, and not anything intrinsic to the quality of the sensation in itself. A pain sensation could have been anything attention-grabbing; it didn’t have to feel the precise way it does—because evolutionarily speaking, that couldn’t matter. All that matters is that your nervous system abruptly goes in an emergency mode, along with that surge of adrenaline to speed the heart and other autonomic reactions designed for driving you away from whatever could be responsible for the pain. A pain sensation is unpleasant because of all those other bodily tensions seizing and driving you, and not because of the sensation itself. In fact, with great effort and mindful control over one’s self, a tight focus on just that painful sensation, to the exclusion of attention to anything else of bodily urgency, one can take away its painfulness. All that is left is a curious, unique, indescribable sort of sensation, like an intense orange color or the sound of a buzzing insect.
Therefore, the petulant demand for a scientific explanation of why a certain sensation is the sensation of pain and not something else can be easily answered. There couldn’t be any special explanation why “painfulness” feels exactly that way, because it never had to—any sufficiently attention-getting sensation would have served equally well, and the brain’s subsystem handling that sensory arousal just happened to get manifested in that way. The intrinsic sensation of “pain” could have felt differently if those subsystems had evolved a little differently. There is no biological reason why “painfulness” is actually the same sort of sensation across the different phyla of the animal kingdom, even if pain is probably quite similar across mammals.
There is no innate significance to many of the feelings that possess us. The feeling of love, if all the automatic bodily responses and nervous tensions were set aside, would be less interesting than the taste of cotton. Biology doesn’t care what any feeling intrinsically must be. So long as the organism responds in an appropriate manner to a sensation or a feeling, it serves its function. The feeling or sensation or emotion, in itself, is as arbitrary as selecting a square shape or an octagonal shape for a stop sign. Those conscious phenomena are manifestations of the nervous and musculature impulses and tensions, but they only mean anything if those impulses and tensions lead to specific behaviors.
It is impossible to feel angry, to offer another example, if your heart rate and breathing are slow and regular, your muscles are in a relaxed and comfortable position, and you exhibit no twitchy or repetitive behaviors. You can imagine being very angry, but that doesn’t make you actually angry. If you actually were to become angry, your own body would betray you, because your sensed bodily responses are your anger. The emotion of anger is quickly suffused with additional feelings as you consider what the anger is really about and what should be done. All the same, it isn’t the case that the emotion arises first, and then causes all of the associated bodily tensions and reactions, and is next followed by cool reasoning.23 Although the specific feelings attached to emotions have no straightforward evolutionary purpose, the reasons why we have emotional responses, as well as why we can thoughtfully control our emotions, must involve our biological evolution.
Evolution and Consciousness
It is necessary to keep in mind how evolution doesn’t acknowledge any higher or lower levels, not in biological reality. Each species has evolved and survived to this day with its own unique way of enjoying and engaging the world.
Our peculiar modes of complex consciousness, such as intelligence, sentience, and self-consciousness, evolved under the special pressures from the
difficult terrains of East Africa over the past two million years, and especially from the complications of social life that hominids descended from Homo erectus have experienced during the past 500,000 years.24 Other animals use similarly long-evolved and specialized nervous systems, but just because they didn’t need reflective self-awareness doesn’t mean they must lack all awareness. To arbitrarily suppose otherwise, out of some parochial preference for one’s own species, makes human consciousness more of a mystery, not less.
Yes, birds are instinctive and thoughtless—just like a newborn baby, but there is no doubt that birds are conscious if babies are conscious. Birds and babies can be conscious of exactly what their evolution permits them to be conscious of. It’s not even out of the question that bees might have some dim level of awareness. It couldn’t be much, to be sure, for bees. Bees only respond to very limited ranges of stimuli, and notice very little in their surroundings. Reptiles, birds, and mammals are very different. But that only means, biologically, that a bee’s simple nervous system is able to sample very little of its environment and take even less interest in what is going on around it. It must have a very different kind of awareness from ours—quite limited in scope and possessing far less intensity. Imagine peering down a narrow tube to see just a circle of meadow in front of you glowing under the dim light of the moon. There would be a few faint sensations besides vision; some high-frequency sounds, and sensitivity to specific odors. So different from our own human consciousness, and so impoverished! Just as evolution did not produce the same sort of nervous system in every animal, it wouldn’t have produced the same sort of awareness and sentience in every animal.
