Where Does Consciousness Begin?

Executive Summary

Modern consciousness science is pulled by two questions, and both end up in clinical work. Cody Cottier's (2026) Scientific American article, "Are the roots of consciousness hidden in the ancient deep brain?," raises the first: does conscious experience have to begin in the cerebral cortex, or could its roots run deeper? A separate body of neuroimaging raises the second, which is what consciousness actually looks like in a living brain, and which networks track awareness?

Consciousness covers several things at once: wakefulness, perception, emotion, pain, self-reflection, and the drive to act on a need.

The clearest neuroimaging findings center on the cortex. They point to top-down processing and a few networks, namely the attention networks, the default mode network, and the claustrum. Whether deeper structures add anything to basic feeling and arousal is still argued.

The clinical stakes are real. The default mode network that carries daydreaming and the sense of self is altered in anxiety, depression, schizophrenia, and Alzheimer's disease. Disorders of consciousness like the vegetative state and locked-in syndrome show how easily a preserved mind gets overlooked. Running through all of it is a single working rule: when someone cannot tell you what they feel, do not assume the feeling is gone.

A thought experiment about the deep brain

Consciousness is subjective experience. There is something it is like to see red, feel panic, taste coffee, or surface from anesthesia. Cottier opens with a thought experiment: if a living body had no machinery for experience, would using it be ethically harmless? The scenario is meant to unsettle, and it does, but its real job is to ask what kind of brain any inner life requires (Cottier, 2026).

You meet a softer version of this every week. A client denies distress while their body broadcasts it. Another reports almost nothing while clearly feeling a great deal. The mismatch between report and state is ordinary clinical ground, and the deep-brain debate is the same problem written large.

Training programs teach, rightly, that the outer brain layer drives language, planning, and voluntary reports. That does not settle where felt experience begins. Cottier's contribution is to pull apart two things that often get bundled together: sophisticated cognition, and plain sentience, the capacity for felt states such as comfort, distress, or pain (Cottier, 2026).

Keep that distinction handy. Before concluding that a client feels nothing, ask what you are measuring. Someone can fail to report an experience because it is not there, or because speech, movement, attention, arousal, or the testing conditions got in the way.

What we mean by consciousness

Consciousness resists definition. One dictionary of psychology went so far as to call it impossible to specify and to claim that nothing worth reading had been written about it (Sutherland, 1989). That is too gloomy, but it names a genuine difficulty, since you can never directly observe the inner state a client is describing.

The word carries at least three meanings.

The simplest is wakefulness, the physiological difference between being awake and being in sleep, anesthesia, or coma (Purves et al., 2013).

A second is subjective awareness of the world, which is not the same thing, because a person can be wide awake and still oblivious to most of what is around them or inside them.

A third meaning adds subjective experience and self-awareness, the sense of being a self set apart from other selves, together with qualia, the private textures of experience such as the specific redness of red or the throb of one toothache.

Philosophers split the easy problem of consciousness, which is explaining the functions that go along with awareness such as wakefulness, perception, and report, from the hard problem of consciousness, which is explaining why all that processing feels like anything at all. Pinker put the recursive part well: we do not only feel pain, we can also notice ourselves feeling it (Pinker, 1997).

William James gave us the most durable image, the stream of consciousness, the always-moving, never-repeating flow of mind that he set against the dead sample in a pail of water (James, 1890).

Most of what the brain does never reaches that stream. Awareness is the tip of the iceberg over a large unconscious base, or a lit stage where attention works a narrow spotlight (Baars & Edelman, 2012).

Mapping the regions involved

Begin with the anatomy. The cortex is the folded outer sheet of the mammalian brain, doing the heavy lifting for perception, language, memory, planning, and reflective thought. The subcortex is the older set of structures underneath, handling arousal, bodily regulation, emotion, motivation, and the routing of sensory signals.

Within that deep system, the brain stem, at the base, keeps wakefulness and vital functions going. The thalamus is a hub that relays and coordinates traffic between sensory systems and cortex. The amygdala weighs emotional significance, especially threat and salience.

The cerebellum, at the back, handles movement, timing, prediction, and learning, and it mostly stays out of the consciousness debate. The live question is causal. Does the subcortex only keep the cortex awake, or can it carry some rudimentary experience by itself?

Almost everyone agrees that ordinary human consciousness runs on loops between cortex and subcortex. Arousal with no content is not a conscious life, and content with no arousal never reaches the person. The narrower and harder question is whether any basic feeling survives when the cortex is gone, damaged, or bypassed.

Why visual studies favored the cortex

Vision has dominated the field because it is easy to control in an experiment. Flash a stimulus, mask it, ask whether the person saw it, and compare the brain on the trials they did and did not consciously perceive. The neural correlates of consciousness (NCC) are the activations and deactivations that track a specific conscious experience, such as seeing a face as opposed to merely registering light.

The trail usually leads to cortex. Visual signals reach primary visual cortex and move through higher cortical networks, and conscious report tends to show up once recurrent activity, the feedback among areas, is strong enough to sustain awareness (Seth & Bayne, 2022; Weiskrantz et al., 1974). Stimulation points the same way. Current delivered to the posterior cortex, called the posterior hot zone, can produce sensations and feelings, while stimulating much of the prefrontal cortex produces little that the person experiences directly (Koch, 2018).

The standard complication is blindsight, in which some people with visual cortex damage say they see nothing yet point to a stimulus, or guess its features, well above chance. Behavior is being driven by information that never becomes conscious. So orienting, flinching, or reaching toward something does not, on its own, prove there is an experience behind it.

The same caution belongs in the consulting room. A client's behavior is evidence about their mind, not a readout of it. When language is missing, with infants, with some neurological patients, with clients who cannot communicate, the question becomes how much weight the remaining evidence can bear.

The case for feeling and the deep brain

Mark Solms and other subcortical theorists think the field went wrong by starting with vision instead of feeling. Solms puts affect at the base, the felt states with positive or negative tone such as fear, hunger, relief, or distress. An animal needs feelings to rank competing needs on the spot, not to write about them later (Parvizi & Damasio, 2001; Solms, 2019).

There is a familiar logic here. Behavior is organized around regulation, since the body has to keep temperature, energy, safety, and contact within bounds. On this account a feeling is the organism's quick summary of how things are going and what to do next.

Some of the hardest evidence to set aside comes from hydranencephaly, a rare developmental condition in which much of the cerebral cortex is absent or replaced by cerebrospinal fluid. Merker reported that certain children with hydranencephaly nonetheless showed emotional responsiveness, social engagement, orienting, and play-like behavior, despite lacking the tissue usually assumed necessary for consciousness (Aleman & Merker, 2014; Merker, 2007).

This does not show that those children have the same experience as typical children. It does make a flat cortex-or-nothing position hard to hold. When caregivers report comfort, distress, anticipation, and social response over and over, those observations deserve weight rather than reflexive dismissal. Stimulation studies add to the pressure, since current delivered to deep targets can change or interrupt consciousness, usually by acting on networks rather than one site (Koubeissi et al., 2014).

Animals and the ethics of uncertainty

The stakes rise once we look past humans. Birds have no mammalian cortex, but they do have a pallium, a forebrain structure that supports complex cognition along lines partly analogous to cortical processing.

Fish, reptiles, cephalopods, and insects are harder to read, since their brains are built differently.

The New York Declaration on Animal Consciousness reports strong support for conscious experience in mammals and birds and a realistic possibility of it across vertebrates and many invertebrates, and argues that this uncertainty should inform welfare decisions rather than excuse ignoring possible suffering (Andrews et al., 2024; Birch et al., 2020; Cottier, 2026).

One behavioral marker of self-awareness is the mirror test of consciousness, recognizing one's own reflection. Great apes, elephants, pigs, dolphins, and a few birds such as magpies show signs of passing it, some species pass only after training on prerequisite skills, and dogs reliably fail (Breedlove & Watson, 2023; Chang et al., 2017).

The mirror test is leaky. An animal may not read a mirror as a reflection at all, or may avoid the eye contact the task demands, so a failure says little about whether a mind is there.

The better picture drops the single ladder with humans at the top. Birch, Schnell, and Clayton describe several dimensions instead, including perceptual richness, evaluative richness, integration over time, and self-related processing. A bee, an octopus, a dog, and a person can differ across these dimensions without one of them holding a magic ingredient the others lack (Birch et al., 2020). The same graded view fits clients, who vary in awareness, emotional depth, and self-reflection rather than sorting neatly into conscious or not.

Networks of attention

The brain cannot take in everything at once, so it selects. Attention is that selection, boosting some stimuli and filtering the rest, and it runs on a finite budget, which is why nobody registers the whole scene at any instant. Two large cortical systems divide the labor.

The first is the dorsal attention network (DAN), behind voluntary attention, the deliberate kind you use to concentrate on purpose. This is top-down processing, set in motion by cortical goals rather than by the stimulus, and it runs along dorsal regions, those toward the top of the brain. Two of its hubs are the intraparietal sulcus (IPS), which holds a priority map for where attention should land, and the frontal eye field (FEF), which points the gaze toward whatever the current goal demands.

The second is the ventral attention network (VAN), behind reflexive attention, the kind a bang or a flash of movement seizes whether you want it to or not. This is bottom-up processing, driven by salient input rather than intention, and it sits in more ventral regions, toward the bottom. Its hubs include the temporoparietal junction (TPJ), which swings attention toward the unexpected and leans on the right hemisphere, and the ventral frontal cortex (VFC), which talks with the amygdala and flags important stimuli even when they were not being watched.

Neither system is purely cortical.

Functional connectivity analysis, which tracks how activity in anatomically separate regions rises and falls together over time, ties both networks to subcortical structures: brainstem nuclei, the superior colliculus, a midbrain region that drives attentional eye movements, the pulvinar, a thalamic nucleus that filters and redirects attention, and the head of the caudate nucleus (Alves et al., 2022).

Voluntary and reflexive attention only feel like one continuous stream because these cortical and subcortical parts work together.

Rest, the default mode network, and the claustrum

Attention is only half the story. Functional brain networks are groups of regions whose activity rises and falls together during a function, and one of them comes online exactly when outward tasks stop. This is the default mode network (DMN), which spans midline regions including the medial prefrontal cortex and the posterior cingulate cortex.

The DMN runs highest when a person is awake but not chasing any goal, during daydreaming, going back over the day, or letting the mind drift toward the self. It is task-negative, dropping out during demanding outward tasks, while the attention networks are task-positive and ramp up for them. The two are anticorrelated, so when one rises the other tends to fall (Fox et al., 2005).

A thin, sheet-like structure called the claustrum may help manage these switches. It connects in both directions with much of the cortex and is, by volume, among the most heavily connected structures in the brain. In one reported case, stimulation near it stopped a person's awareness while the current was on and returned it when the current stopped (Nikolenko et al., 2021). It may also help raise attention as tasks get harder and move the brain between its task-positive and task-negative states.

Two larger findings connect these parts. Using fMRI from 400 regions in people who were conscious, anesthetized, comatose, or diagnosed with conditions such as schizophrenia, Huang and colleagues (2023) found three cortical gradients that track dimensions of consciousness: arousability, awareness, and sensory organization.

A separate study combining behavioral, imaging, electrophysiological, and gene-expression data concluded that the overall state of consciousness reflects top-down hierarchical processing, with histamine-releasing neurons in the brainstem's ascending arousal system pushing cortical activity from below (Li et al., 2023).

One caution about this cortical emphasis: no single region is a task area, since functions like attention and language spread across coordinated regions rather than living in one place (Petersen & Fiez, 1993).

The default mode network in clinical disorders

The default mode network turns up across the conditions you treat. In anxiety, parts of it can be overactive, which lines up with the self-focused rumination that keeps a worried mind looping. In depression, comparable overactivity tracks with brooding, self-referential thought that pushes out engagement with the world.

In schizophrenia the DMN is overactive at some moments and underactive at others, a pattern tied to hallucinations and delusions and set within a broader model where imbalance among the default mode, salience, and attention networks produces a range of symptoms (Menon, 2011). Reading those symptoms as faulty switching between inward and outward modes is closer to the data than blaming one broken region.

At the other end, the DMN is underactive in disorders of consciousness, in Alzheimer's disease and other dementias, and during epileptic seizures, and patients with consciousness disorders usually show little resting DMN activity even when they respond to tasks (Guldenmund et al., 2012).

Alzheimer's disease brings the familiar memory loss, but it can also wear away consciousness and the sense of self, which is part of why families say a relative no longer seems like the same person. For a counselor sitting with that family, naming the loss of self as a real change in the brain can give a hard-to-explain grief something to hold onto.

Reading silence with care

One good way to learn what a region does is to study people in whom it has failed, which is why disorders of attention and consciousness have been so informative. Hemispatial neglect, usually from right parietal damage, leaves a person no longer attending to one side of space, sometimes one side of their own body, and shows that injury can split attention from awareness. Disorders of consciousness do the same thing on a larger scale, with much higher stakes.

These states map better onto two dimensions, arousal and awareness, than onto a single on-off switch (Laureys, 2005). In the unresponsive wakefulness syndrome/vegetative state (UWS/VS), a person opens their eyes and produces reflex behavior with no clear sign of awareness. In the minimally conscious state, the signs are inconsistent but real, such as localizing pain or moving with apparent purpose. Both are easy to misread as empty when they are not.

Neuroimaging has upended that assumption. In one widely cited study, a woman who had been unresponsive for months after a car crash was asked inside a scanner to imagine playing tennis or walking through her home, and her motor and spatial regions activated much as healthy volunteers' did, evidence of awareness her body could not show (Owen et al., 2006).

Hospitals now run task-based scans like this to catch diagnoses behavior would miss, and some patients with poor bedside prognoses later recover communication and independence. Locked-in syndrome (LIS) is the clearest case.

Damage to the pons in the brainstem, often from a stroke, can leave a person fully conscious but almost completely paralyzed, sometimes able only to blink. Jean-Dominique Bauby dictated a whole memoir by blinking, and surveys find many people with locked-in syndrome rating their quality of life and mental health close to that of healthy controls (Lulé et al., 2009).

Here the practical steps are clear.

Separate arousal from awareness first. Then check whether medication, sleep, pain, seizures, infection, sensory loss, aphasia, paralysis, depression, or fatigue is masking responses, and repeat the assessment over time, since consciousness fluctuates (Giacino et al., 2018).

Psychologists and counselors rarely run the scans, but they help teams convey uncertainty to families, swap stigmatizing language for accurate language, push for pain assessment, and hold steady through ambiguous decisions.

How to weigh the evidence

Start by naming the target. Wakefulness, reportable perception, pain, emotion, self-awareness, moral status, these are different questions.

A study of visual report will not settle one about fear, and a study of arousal will not settle one about reflective selfhood, so match the evidence to the question you actually have.

Next, keep correlation apart from necessity.

Imaging can show that a region is active during an experience without showing that the region produces it. Lesions, stimulation, and reversible interventions carry more weight, because they test whether changing a region changes what the person reports.

Then compare the explanations on the table. A child with hydranencephaly who settles at a parent's voice might be showing reflexive regulation, basic affective consciousness, or some of each. The discipline is to favor the reading that fits all the evidence with the fewest added assumptions, and to let whatever uncertainty remains push toward caution in care.

Finally, respect what the evidence cannot do. Consciousness disorders vary a lot from person to person, many imaging studies rest on small samples or single cases, and functional networks differ enough across people that one person's map may not match the group average (Laumann et al., 2015).

Some methods even hide their target, since the subtraction approach common in fMRI can make a structure like the claustrum look quiet when it is actually active in both of the conditions being compared.

Better tools for the next experiments

Part of why the deep-brain question stays open is technical. Stimulating the deep brain precisely is hard without surgery, and older methods tend to either flood broad areas or reach mainly cortex.

Transcranial focused ultrasound (tFUS), a noninvasive method that uses focused sound waves to modulate brain activity, including deep structures, with fairly fine spatial precision, may start to change that (Freeman et al., 2026).

Freeman, Odegaard, Yoo, and Michel (2026) argue that tFUS could help pin down which circuits are necessary for conscious perception. It will not solve the hard problem of why physical processing feels like anything. What it offers is testable: whether modulating a thalamic, cortical, or other deep target changes what a person reports seeing, feeling, or sensing.

That work could sharpen the cortex-subcortex debate, and eventually feed into clinical assessment. If altering deep structures changes pain, emotion, or perception in specific ways, the subcortical theories gain ground; if deep stimulation moves arousal or attention but not experience, the cortical theories do. Anil Seth, as Cottier presents him, holds the middle: strong evidence ties the cortex to consciousness, the deep brain is not yet mapped during experience, and no theory has won the field (Cottier, 2026; Seth & Bayne, 2022).

Integrative Summary

The picture that holds up is layered and networked rather than a single seat in a single spot.

The cortex, working through the attention networks, the default mode network, and the claustrum, and driven from below by brainstem arousal, supplies the detail of human experience, the inner self-model, and the switching between outer and inner worlds. Whether deeper structures can carry a more basic feeling on their own is the question Cottier (2026) poses.

For clinical work, the layered view earns its keep. It helps explain why a depressed client cannot simply decide to stop ruminating, why someone with Alzheimer's can lose a stable sense of self along with memories, and why a silent patient may still be present behind unmoving eyes.

Two things have to be held together. The cortex is essential to the full consciousness your most articulate clients draw on, and it is still a mistake to read a person who cannot speak or move as empty. Holding both at once is simply where the evidence leaves us for now.

Five Takeaways

1. Consciousness is not one thing but several, including wakefulness, awareness of the world, and self-aware subjective experience, so clarify which you mean before drawing conclusions about a client.

   
   

2. The best-mapped neural correlates of consciousness are cortical networks, namely the attention networks, the default mode network, and the claustrum, coordinated by top-down processing and brainstem arousal, while the contribution of deeper structures to basic feeling stays open.

   
   

3. The default mode network shows up across common presentations, running overactive in anxiety and depression, dysregulated in schizophrenia, and underactive in disorders of consciousness and Alzheimer's disease.

   
   

4. Behavior and report can mislead, since neuroimaging has found covert awareness in vegetative-state patients, and people with locked-in syndrome keep intact minds behind motionless bodies.

   
   

5. Work carefully when a person cannot report, separating arousal from awareness, ruling out confounders, reassessing over time, and giving possible experience the benefit of the doubt.

Glossary

affect: a basic feeling state with positive or negative tone, such as fear, distress, relief, or comfort, that helps guide behavior.

amygdala: a subcortical structure involved in evaluating emotional significance, especially threat, salience, and emotional learning.

attention: the selection of some stimuli for enhanced processing while other stimuli are filtered out.

blindsight: a condition in which a person with visual cortex damage can respond to visual stimuli without reporting conscious visual experience.

bottom-up: stimulus-driven processing triggered by salient input rather than by intention.

brain stem: the lower part of the brain that supports vital functions and the arousal systems needed for wakefulness.

cerebellum: a posterior brain structure important for coordination, timing, learning, and prediction, but usually not treated as central to the consciousness debate.

claustrum: a thin, sheet-like, highly connected subcortical structure that may coordinate transitions between attention and default mode states and support conscious experience.

consciousness: subjective experience, meaning that there is something it is like for an organism to feel, perceive, or be aware.

cortex: the outer sheet of the mammalian brain involved in perception, planning, language, memory, and flexible cognition.

default mode network (DMN): a task-negative network spanning medial prefrontal and posterior cingulate cortex that is active during inward, self-referential thought and deactivates during external tasks.

dorsal: toward the top of the brain.

dorsal attention network (DAN): a circuit including the intraparietal sulcus and frontal eye field that mediates voluntary, goal-driven attention.

easy problem of consciousness: explaining the functions and behaviors that accompany awareness, such as wakefulness, perception, and report.

frontal eye field (FEF): a frontal structure that directs gaze according to cognitive goals rather than stimulus features.

functional brain networks: brain regions that exhibit correlated activity when performing a function such as attention.

functional connectivity analysis: assessing the statistical dependencies between physiological signals from anatomically distinct regions over time.

hard problem of consciousness: explaining why physical brain processing is accompanied by subjective experience, or qualia, at all.

hemispatial neglect: a syndrome, usually from right parietal damage, in which a person fails to attend to one side of space or of their own body.

hydranencephaly: a rare developmental condition in which much of the cerebral cortex is absent or replaced by cerebrospinal fluid.

intraparietal sulcus (IPS): a parietal structure that encodes a salience or priority map to guide voluntary attention.

locked-in syndrome (LIS): a condition, usually from damage to the pons, in which a person is fully conscious yet almost completely paralyzed.

minimally conscious state: a disorder of consciousness in which a person shows inconsistent but reproducible signs of awareness, such as pain localization or purposeful movement.

mirror test of consciousness: a test of self-recognition in which an animal is assessed for recognizing its own reflection.

neural correlates of consciousness (NCC): the brain activations and deactivations that reliably accompany a specific conscious experience or state.

pallium: a forebrain structure in birds and other vertebrates that supports complex processing, partly analogous to functions of the mammalian cortex.

posterior hot zone: a proposed posterior cortical network—mainly parietal, occipital, and posterior temporal regions—thought to be especially important for the specific contents of conscious experience, such as visual percepts, bodily sensations, imagery, and dream content.

pulvinar: a posterior thalamic nucleus that helps process visual information, filter stimuli, and redirect attention.

qualia: the private, subjective textures of experience that cannot be fully conveyed to others, such as the particular redness of red.

reflexive attention: bottom-up attention captured automatically by salient stimuli and guided by the ventral attention network.

stream of consciousness: a metaphor, introduced by William James, for the continuously flowing and ever-changing contents of mind.

subcortex: deep, evolutionarily older brain structures beneath the cortex that support arousal, emotion, motivation, bodily regulation, and sensory routing.

superior colliculus: a midbrain structure that directs attentional eye movements.

task-negative: deactivating during a demanding external attentional task.

task-positive: activating during a demanding external attentional task.

temporoparietal junction (TPJ): a region, right-hemisphere weighted, that reorients attention to unexpected stimuli.

thalamus: a subcortical hub that relays and coordinates sensory, motor, and cortical signals.

top-down: goal-driven processing initiated by higher cortical areas rather than by the stimulus.

transcranial focused ultrasound (tFUS): a noninvasive brain stimulation method that uses focused sound waves to modulate targeted neural tissue, including deep brain structures.

unresponsive wakefulness syndrome/vegetative state (UWS/VS): a disorder of consciousness in which a person opens their eyes and shows reflex behavior but no clear signs of awareness.

ventral: toward the bottom of the brain.

ventral attention network (VAN): a circuit including the temporoparietal junction and ventral frontal cortex that mediates reflexive attention.

ventral frontal cortex (VFC): a region that communicates with the amygdala and detects salient, behaviorally relevant stimuli, especially when unattended.

voluntary attention: top-down, goal-driven attention guided by the dorsal attention network.

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About the Author

Fred Shaffer earned his PhD in Psychology from Oklahoma State University. He earned BCIA certifications in Biofeedback and HRV Biofeedback. Fred is an Allen Fellow and Professor of Psychology at Truman State University, where he has taught for 50 years. He is a Biological Psychologist who consults and lectures in heart rate variability biofeedback, Physiological Psychology, and Psychopharmacology. Fred helped to edit Evidence-Based Practice in Biofeedback and Neurofeedback (3rd and 4th eds.) and helps to maintain BCIA's certification programs. He is a recipient of AAPB's Distinguished Scientist Award and BFE's Lifetime Impact Award.

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