DrmDoc

I agree, we should focus on what we know and that should probably begin with a primary imperative of brain functions, which is homeostasis. Although we currently understand the thalamus by little more than its circuitry and mapping, it's clearly the structural core of the brain and, thereby, the core of brain function. Whatever affects the thalamus should also affects brain function and its functional imperative. We know there's more than sufficient evidence suggesting that what happens in the cortex is secondary to thalamus function and its that secondary activity that produces our behavioral output. We know that our sensory experiences impact thalamic function and that impact transmutes as neural impulses that initiate a cascade of recipricol cortical neural responses sufficient to address that sensory impact. On a neural basis alone, this is the equivalent of the brain producing sufficient neural feedback to suppress some homeostatic destabilizing neural effect. It's that neural feedback that carries our behavioral responses to sensory stimulus. I agree; I think of filtering as what one might do with an air or water purifier, I don't think that's what the thalamus does. I don't think the evidence suggests that any processing occurs in the thalamus other than to transfer sensory stimulus to destined cortical structures in continuous unfiltered waves of neural impulses until suppressed by recipricating waves from the cortex albeit via defined neural circuitry from well-studied structures. No regrets: the thalamus has been my obsession for quite some time and it's maddening...but it has led me to avenues of understanding I've never previously considered.

An interesting question, but what I perceive may not be as abstract. If we think of the thalamus as an organ that transmutes sensory afferences into neural impulses equivalent to varying tonal waves and frequencies, then surround brain tissue would be those structures with an affinity for the distinct tonal characteristics or measure of each neural wave and frequency. The job of those surrounding structures would be to generate neural feedback sufficient to initially match then mute or suppress the effects of those distinct neural tones at their source. In the brain, that neural feedback from surrounding structures transmutes through the thalamus as behavioral output addressing the source of a stimulus. This, as I envision, is what produces the behaviors toddlers exhibit when, for example, learning language—all they appear to understand initially is that mimicking what they’re continuously asked to say is frequently sufficient to suppress the asking. Addressing your analogy, the rock would be the sensory stimulus, the pond would be the thalamus, and the shore would be the surrounding brain structures. The difference would be an endless ripple onto shore by that single rock until met by counter wave energy from the shore.

Just to clarify this bit, I don’t perceive thalamic function as letting in everything as if an open door. I perceive that function as more akin to a tuning fork or bell that, instead of sound, continuously emits neural impulses into surrounding brain structures upon impact of sensory stimulus. From my perspective, stimulus data arrives in unfiltered waves of neural impulses from the thalamus to our cortex and it is our cortical responses or lack of response to that data that defines our perceptions or behavioral output as filtered or unfiltered. Rather than a result of some sophisticated neural process, from my perspective, our cortical responses are little more than a type of neural noise suppression or reduction process comprising equivalent neural frequencies manifesting our behavioral responses--as similarly suggested by a toddler's response when asked to repeat a phrase, which the child may do to accomplish little more than to end the asking.

With one sentence, you've masterfully conveyed thoughts I've struggled to express over several previous posts. It was apparent to me that the Nova participant's brain was parallel processing more than visual cues from the objects she correctly selected. This appears to suggest that her brain was receiving more stimulus from those objects than what might affect that portion of her visual cortex if not damaged. Therefore, she was clearly conscious of something because, as I believe, even our unconscious reactions require a coordinated and focus response from brain function to execute those reactions. I'm suggesting that it's the function of our brain's core (thalamus) that makes these reactions possible. As I said previously, I don't believe the thalamus is a kind of neural relay station and I don't believe it has the capacity to filter the afferent flow of sensory it receives. In fact, I believe it lets everything about our experiences into every area of the brain and the stimulus that's most impactful on those areas is what receives a focus response--conscious or otherwise.

It can, but I don't believe that is true regarding the Nova experiment. There’s a distinct difference between blind spots caused by damage to the eye only and those caused by damage to the optical cortex of the brain. It’s a distinction between the photo stimulus impeded by damaged or obscured photoreceptors and unimpeded stimulus that actually traverse our optic nerves through the thalamus into brain structures. That Nova experiment targeted a blind spot caused by brain rather than eye damage with test objects placed in a fixed field of blindness unobservable by the other unaffected eye. I believe that experiment proved that our visual experiences impact us in more ways and on more levels than those that are visual. That impact clearly doesn’t radiate from the visual cortex, it radiates from the core of brain structure, which is the thalamus.

Greetings, Adding a bit more clarity to my last comment, visual experiences are likely processed in the brain in ways that are more than just visual. For example, if you know the instrument, we don't have to see a drum to identify it by it's percussive sound, feel or tactile outline with our eyes closed. What this suggest about the Nova experiment I described earlier in this discussion thread is that the visual information the participant in that experiment experienced likely resonated with the non-visual processing areas of her brain in a way that allowed her to correctly select which objects were place in the blind spot of her vision field--those correctly selected objects likely resonated with her in a way that was non-visual.

Possibly apt, but decidedly amusing. However, I think the explanation for how a person may be able to perceive objects within a visual blind spot caused by brain damage is that the visual information for those objects are resonants of the thalamus that do not abate because they do not receive the visually interpretive/abating neural feedback from the damaged brain areas associated with such neural responses. It’s analogous to sonar where a stimulated thalamus emits an information laden, neural ping into surrounding brain structures that don’t return an visually identifying, reciprocal hit because the structures associated with discerning that information has been damaged...but that doesn't suggest that surrounding, undamage structures are unaffected by that neural pinging nor does it suggest they are unresponsive. I think the person in this Nova episode was able to correctly select the objects placed in her blind spot from among objects that were not because the objects she identified had the same or similiar resonant affect on her thalamus--they were correctly selected by how they made her feel rather than how they visually appeared.

Greetings, I discovered this interesting rebroadcast while scrolling through several PBS Nova science episodes. Midway through, this specific episode profiled an experiment involving a subject who suffered a blind spot in her vision field due to a stroke that damaged a portion of her brain’s vision processing center. Despite that, an experiment during this Nova episode showed that this person was somehow able to perceive objects placed in her blind spot though seemingly not consciously aware of those objects. For Nova commentators, this compelling paradox posed the larger question of whether there’s a need for consciousness when we may be quite able to perceive our environment without it. The answer, according to those commentators, may involve the importance of conscious awareness to infant learning--but that answer, in my view, completely ignored the question of why the subject in experiment was able to perceive objects without being consciously awareness of those objects. Towards the end of this 30-minute Nova episode, its commentators focused on a blanket explanation that offered a perspective of how our brain stitches together our reality from very little information. However, I generally find that the perspectives of brain function that these commentators and most neuroscientists agree with are flawed. For example, most neuroscientists believe that the thalamus generally functions as neural relay station that filters what sensory information ultimately reaches the cortex where sophisticated neural processing occurs. Until recently, I believed similarly but they and I were wrong. Although I have a keen interest in neuroscience, I am not a neuroscientist. However, what the overall evidence in science suggests to me now is that the thalamus functions more like a tuning fork during infancy that becomes more like a central alarm as we mature. This distinction is important because it explains what may be happening in a brain that produces aberrant output and behaviors such as schizophrenia, autism, dementia, and perception in the absence of conscious awareness. As I perceive the evidence, our brain function comprises two structural components: the thalamus and everything in the cranial cavity other than the thalamus. There may be maladies and physical defects affecting these components that can and do contribute to the aberrance our brain function may produce but understanding the precise functional role of these components--minus potential maladies and defects--is crucial to understanding and ameliorating the potential aberrance each component could produce. I welcome your thoughts.

Greetings, Following up on my last comments, I said that nightmares and dreams in general are responses in sleep to the neural resonance our thalamus emits during sleep. What most of us don’t realize is that all dreams are essentially nightmares because they are all responses to the metabolic imbalance arising from the neural affects radiating from our brain’s core (thalamus) in sleep. Specifically, dream experiences are an effect of the lingering and continuous impact life experience has on our thalamic function; thereby, our psyche. It’s analogous to meteorites and craters—our experiences are meteorites and dreams are indicative of the mental, emotional, and social craters they cause. Much like those rocky projectiles from space, life experience can impact our psyche significantly and insignificantly. Relative to brain function, nightmares particularly suggest the larger, more significant impact of those experiences on thalamic function. Make no mistake, all dreams are meaningful in that they comprise the wave of neural responses our brain generates to suppress the linger impact that our actual life experience has had on the core of our brain function in sleep. Rather than describe or interpret our actual experience, dream content describes and interprets the impact of those experiences—they describe and interpret craters rather than meteorites. I welcome your thoughts.

Greetings, In my last post, I said that nightmares and dreams generally “reflect” something our brain believes it has experienced during sleep. I chose that wording specifically because it speaks to the basic nature of the processes in brain function producing those sleep experiences. Understanding the precise nature of the processes of brain function has been at times a nightmarish pursuit for me because it required me to accept some basic truths about those processes and, ultimately, about myself. I would not recommend pursuit of this topic for those who are not prepared to accept some basic and empirical truths about themselves. One basic truth of brain function is that its primary imperative is homeostasis, which is essentially our brain’s effort to maintain its metabolic stability. Understanding how homeostasis drives brain function will eventually require acceptance of how its functional instability drives our behavior and ultimately belies the concept of mental stability. Homeostasis in the brain is basically about maintaining a continuous and stable flow of the nutrients its cellular matrix requires. In my view, how our brain maintains that flow involves the neural equivalent of a convection process set in motion by the continuous sensory experiences affecting our brain’s core—the thalamus. Other than olfactory, the thalamus is where all neural pathways ultimately traverse in and out of the brain. From my perspective, our brain’s functional matrix basically comprises neural exchanges between just two primary constituents--the thalamus and everything other than the thalamus. The sensory stimulus our thalamus experiences via its incoming neural connections causes a continuous wave of neural resonance from the thalamus into surrounding brain structures and those brain structures respond with waves counter to that resonance. Those waves are what produces the behaviors we engage in response to conscious experience. Nightmares and dreams in general are responses in sleep to the neural resonance of the thalamus.

In the early days, we were oblivious to the effects of many harmful substances. Now, in present day, America has a president who wants to eliminate our protection from similarly harmful substances in the air we breathe and return us to our early days of oblivion...shameful!

Greetings, Relative to brain function, nightmares are like any other unremarkable dream experiences in that they are basically a byproduct of the glymphatic processes occurring in the brain during sleep. Those processes decrease the toxic brain chemistry that impede and suppresses our brain's wakeful activity such as the removal of beta-amyloids and tau, which are waste byproducts of our brain's metabolic activity. As that toxicity diminishes, our sleeping brain becomes increasingly sensitive to stimuli. But even as byproducts of basic brain processes during sleep, nightmares and regular dreams aren’t any less meaningful in that they reflect something our brain believes it has experienced during sleep. Rather than random neural firings as some scientists propose, dreams are meaningful, which is even more so suggested by nightmares and their alarming content: I awoke to the presence of relatives--my deceased mother and stepfather--in my bedroom. But what was most alarming to me was the presence lying next to me, in my bed, beneath my bedsheets. Pealing those sheets back slowly revealed a sleeping man underneath with an unnervingly large and elongated head. I shouted, “Who is this?!” and woke immediately. That nightmare occurred a few week back and was the result of revisiting nonsensical theories about the nature of mind and consciousness espoused by Edgar Cayce who, in his day, was popularly refered to as The Sleeping Prophet.

Greetings! Imagine that…DrmDoc had a nightmare? Yes, indeed I did: I dreamed about leaving a classroom to visit a nearby store to satisfy an urge for something sweet. Arriving at the store, its layout was Cracker Barrel-est. There was clothing for sale up front, snack items behind a display case further in and, oddly, a deli/butcher counter. Looking around, I was a bit put off by several unruly children running around without parental supervision. As I turned to leave, some of them took notice of my displeasure and followed me out. I took that as an opportunity to impart some wisdom to one of my followers on the value of edification rather than disruption…but he had another interest. Approaching a street crossing, I felt the poke of what seemed like a gun barrel at my back and it was then that I realized my rowdy follower’s intent was to rob me. I wasn’t alarmed as I knew I could easily disarm him. If this dream doesn’t seem very nightmarish, that’s because it wasn’t a nightmare. It was an otherwise unremarkable dream experience I had subsequent to a recent nightmare I thought about sharing and discussing in this science forum. Interestingly—at the very least to me--this unremarkable dream explains both my motivation and hesitation for wanting to discuss nightmares here. My discussions regard the science of brain function and, unfortunately, psychology now holds very little interest to me without a clear and reliable basis in that function.

Although not today, I recently learned a very surprising bit of trivia...human are the only animals that have that protruding bit of bone and flesh we call a chin--and there's no agreement in science on why that is. Furtherstill, niether our primates cousins nor our hominds ancestors have or have had chins.

Please pardon this delayed response to your inquiry. Other than instinctive responses, which are primarily unconscious responses, some unconscious responses are a result of experience. From my perspective, our behavioral responses to stimuli issue from the thalamus in response the neural feedback (efference) the thalamus receives from surrounding cortical and subcortical structures in response to the stimuli (afference) the thalamus experiences. There are no cortical or subcortical efferent neural pathways that bypass the thalamus to our musculature; therefore, directives from our brain's neural hierarchy must pass through the thalamus to manifest as behavioral responses. In my opinion, conscious awareness generally occurs in the instance the thalamus receives neural feedback from the function of surrounding brain structures in response to the stimuli the thalamus receives from its sensory array. Learned responses isn't as much about focus as it is about continual stimulation of the afferent and efferent neural pathways associated with our behaviors. Learning is memory and memory, in my view, isn't the neural accumulation and storing of information, memory is the neural pathways that remain continuously stimulated by our experiences.

I believe you're asking about the nature of unconscious behaviors, which are the behaviors or reactions we appear to engage seemingly without conscious awareness. All behaviors we engage--including those defensive behaviors and reactions we engage without apparent conscious direction--are outputs of brain function. Our senses merely deliver information about ourselves and environment into brain function and it's that function that formulates and produces our responses. To some extent, all behaviors are learned, which for me infers that the neural pathways for our responses must be built and maintain by continual experience. Your continual experiences may have involved notable measures of threats where assessing and responding to potential physical harm have become second nature--it's akin to learning how to unconsciously maintain one's balance while riding a bike. For you, it's unconsciously maintaining your physical safety amid relaxed social settings.

Agreed and this isn't the forum for that discussion.

I agree and I now believe that perspective was @TheVat intent in adding that link to this discussion. The article does indeed explore a perspective on the incredible nauture of brain plasticity, but for me it further emphasizes my perspective on the subordinate nature of cortical structure relative to thalamic function..

The ideas expressed here were not clear from your previous comments regarding your link to Mr. Gazzaniga's article, but I would suspect moderators would not want us to digress in to speculations about other neural systems beyond the focus of this thread's discussion, which is the thalamus. There is, however, substantial research regarding the reticular activating system's contribution to conscious brain function by none regards that system the way they do thalamic function in the collection and relaying of the sensory information that our cognitive sense and expression of self--relative to our sensory environment--relies on. Forgive my misquote; however, in the opening paragraph to Mr. Gazzaniga's article he mentioned the case of a "white-collar worker" with a link to "without a brain". Mr. Gazzaniga goes on to discribe the worker as a "normal 44-year-old" with an "acceptable IQ" and a "gaping fluid-filled cavity where a brain would normally be." Selecting Mr. Gazzaniga's "without a brain" link led me to a Lancet article discussing the case of a man who suffered from postnatal hydrocephalus--and this was not the only reference to hydrocephalus cases in the focus of Mr. Gazzaniga's article. In fact, Mr. Gazzaniga also referenced the case of a 60 year-old male with a "head full of fluid and only a thin sheet of cortex" and the case of a 72 year-old living "largely without what we might recognize as 'a brain.'" The links to both these cases reference individuals with various types of hydrocephalus. I have to wonder if you read any of this article as Mr. Gazzaniga most certainly do reference cases arising from hydrocephalus. My apologies if my comments inferrred this as your first, but I share a similar sentiment when it comes to the depiction of hydrocephalus conditions as being "without a brain".

I believe your article references a condition known as hydrocephalus; wherein, cerebrospinal fluid fills the ventricles of the brain and compresses brain tissue into thin layers. It's disengenuous for the article's author to describe such individuals as having "no brain" because, in fact, these individuals do possess brain structures and tissue that can function as well as a normal brain when adapted sufficiently early in gestation or infancy. Therefore, cortical tissue is indeed required in these case and those of individuals with this condition who appear to lead normal, well adapted lives. For a clearer perspective of how behavior is affected by the absence or destruction of brain structure, you may want to look into decorticate and decerebrate brain studies involving both humans and animals.The effects of decortication and decerebration can be profound but survivable depending on whether there is brainstem damage and the stage of brain development when decortication/decerebration occurs. However, neither decortication, decerebration, nor hydrocephalus deminishes what this discussion thred topic suggests about what the thalamus does for brain function. From our sensory array, to our thalamus and cortex, there is indeed a holistic nature to what our central nervous system does to produce human conscousness but that doesn't render consciousness as a unique quality or exclusive to humans--which is what science rather than philosophy most clearly evinces, IMO.

Apologies, but I have very little interest in philosophy. However, if my philosophical baggage is weighted by methodologies that objectively and consistently provide and support evidence that either proves or disproves a hypothesis, then indeed I lean quite heavily on and will, unfortunately, continue to do so.

I agree; philosophy is philosophy and science is science.

https://www.msn.com/en-us/health/other/more-than-a-simple-relay-station-thalamus-may-guide-timing-of-brain-development-and-plasticity/ar-AA1KfkSf?ocid=msedgdhp&pc=HCTS&cvid=9c3891007f444aea94c6a49cfb2b23b0&ei=11 Yet more support for the central role of the thalamus in cognitive outcomes. From the article: "Our data indicate that the thalamus likely plays a more active role in determining when cortical regions are plastic, and therefore when they exhibit both adaptability and vulnerability to our environments." Interestingly, Sydnor and her colleagues observed that the maturation of structural connections between the human thalamus and cortex followed a sensorimotor-to-association sequence. This suggests that the development of cortical regions in children and adolescents is aligned with changes in the strength of connections with the thalamus. Thus, the thalamus might serve as a "timekeeper" of cortical maturation. "This is important given that the pace of cortical maturation is linked to cognitive and psychological outcomes," The article suggests that the thalamus is indeed "more than a simple relay station." Again, more evidence that cortical development, thereby, cortical function is secondary to thalamic connections and function.

I disagree; homeostasis explains everything about emergences of brain function--it's the engine propelling that function.

The idea that an organism must demonstrate "mental capabilities" or form some mental construct such as a "cognitive map" to be possessing of consciousness is a human standard. It's flawed because it infers no distinction between attributes of mind and consciousness--it's the idea that one attribute cannot exist without the other. Consciousness can certainly exist without the sophistication of a mind because consciousnes, at its most basic and primal level, is merely awareness. The sophistication of having a mind suggest a level of consciousness based wholely on a human standard, which is the only standard by which we can assess that quality in other organisms. In previous comments I said that "consciousness is relative" but, in my view, mind is not. Mind, from my perspective, is shown by non-instinctive behaviours--behaviours that suggest a thought process, which are behaviours we can readily determine based on our standards for that process.