Discourse on information processes requires terms as a system, program, option, signal, and feedback. Human logical skill does not work in denial of the nervous system. The system can be discussed as an information processing and managing structure, beginning with the single cell and ending with the intricate coordination by the human brain. Congruence to become averred in the above terms, feedback incidence shall be appreciated for a natural principle of biological function.
1.1. Feedback phenomena at the cellular level of human neural structures
Positive and negative feedback processes have been evidenced in human nervous systems already at the level of single cells, during change of bioelectric potential. As within the ionic hypothesis by Alan Lloyd Hodgkin and Andrew Fielding Huxley, natural action potentials engage positive feedback for the depolarizing phase. The active transport that provides for intra-cellular balance works on negative feedback (Vander et al., 1985).
Language performance to require action potentials, and the potential to be a brief, all-or-none reversal in neuron polarity (ibidem), natural language can be stated to use processing of options. Importantly, neuron singular impulses are more than likely to fall within systemic allowance for error, and saltatory propagation depends on combined synaptic effects. The basic level of nervous system organization, individual cells deserve acknowledgment in higher neural variables only as part in network efficacy, neural networks to build on neuron particular sites.
1.2. Space and time in intercellular communication
A single neuron may link with thousands of synapses. Signals are initiated mostly by joined synaptic activity and launched in series. Integrant in neural diversity and specialization, spatial arrangement of synapses or cell receptors can be considered essential, neuron particular sites further to be capable of varied thresholds. Second messenger extrasynaptic interaction to take place in areas of high-density non-myelinated brain tissue, spatial adjacency can decide on neural conveyance. Flexibility as already in the single cell permits multiple responses, dependent on neural signal place, as well as type (Vander et al., 1985).
Neural communication time span yet cannot be disregarded, inhibitory and excitatory values to summate in real time. In neural transmission for language as well, feedback depends on the time extent for effect (ibidem), and outcomes of neural correlativity depend on biological functioning in place as well as time, to extents greater than assumed within theories of extrinsic timing (in Puppel, 1988).
The theories approve of the temporal aspect as extrinsic to the speech plan, the time span to be set on phonetic segments in the speech act implementation phase. A major argument to the contrary may come with the property by human nervous systems constantly to show part preparatory actuation, diagnostic techniques as PET-scan or MRI to focus on the degree of cellular engagement, rather than its presence alone: biological performance pertains with any living cell.
Neurons that are not part in a specific speech plan cannot be referenced as inactive, their resting state to be a dynamic balance between cell interior and exterior. Intrinsic in timing, human homeostatic activity may result in action potentials. Excitation as of an isolated cell to remain predictable only in terms of statistic approximation (Vander et al., 1985), the intrinsic time interval will be of quality in the combined actuation for speech and language.
M. Coles and P. Duncan-Jones (in Ciarkowska, 1993) stipulated for principles of biological function to correspond at lower and higher levels of systemic structuring. In keeping with the position, feedback reliance should hold true for the single neuron as well as language capable networks in the brain.
1.3. Human systemic dynamics
Neurons tend to connect into schemata and correlate into networks. Schemata alone may embody speech sound or letter shape representations; networks are indispensable in neural planning for spoken or written discourse (Puppel, 1992). Brain preparatory activity makes the relationship between neural activity and motor behavior difficult to detect and measure (Vander et al); speech and language yet observably employ feedback-mediated inner dynamics rather than strictly a hierarchy.
Brain neocortex is the tissue of the highest intricacy, yet the brainstem reticular structure is vital to mediate neural transmission for the systemic long distance. Reticular projections help guide multisynaptic pathways and communicate the autonomic, central, and peripheral extents of the nervous system. The brainstem has been indicated for neural information processing by ten cranial nerves, of the twelve. It helps coordinate eye movement, cardiovascular and respiratory performance, the neural patterns for sleep, as well as wakefulness and focused behavior (ibidem).
A subcortical body, the brainstem assists phonation and visual language processing, whereas cortical activity may influence breathing, the very reticular form to convey the cortical signal. Autonomic activity is vital in pupillary response and the muscle tone for speech, reading, or writing.
John Lacey’s experiments on stereotyped behavior in environment intake or rejection (in Ciarkowska, 1993), were to explore on human systemic rapport. He detected and measured a cortical effect over cardiac outputs that held for people to assess the experiment concurrent context, as well as expected developments. The researcher reported a pattern wider than direct response and pointed to afferent feedback, for the impression by intellective faculties over autonomic lifework.
Engel, Malmo, and Shagass (ibidem) proceeded further with the notion of psychosomatic variance, and postulated person-specific patterns for neurophysiological function. They reported parameters that corresponded with psychological tasks, thus to evidence a learned factor in autonomic processing.
Autonomic activity is supposed naturally reflex. Person-specific patterns might emerge in neural path individuate negotiation, potentially to involve feedback.
1.4. A human reflex arc
In definition, reflexes are automatic and indeliberate. Reflex arc typical constituents are the receptor, afferent pathway, integrating center, efferent pathway and the effector. Human neurophysiological research yet would declare that “most reflexes, no matter how basic they may appear to be, are subject to alteration by learning; that is, there is often no clear distinction between a basic reflex and one with a learned component” (Vander et al., 1985).
An arc may involve a stimulus to nerve A, looped via the brain with nerve B. Nerve B may synapse on endocrine gland B1, hormonally to communicate with gland C, which may in turn actuate a muscle with another messenger, as neurochemical C1. However, it is not unseldom that standard names fail truly to define arc components. Beside human reflex notable structural diversity, neurochemicals of immediate effectiveness have a potential for multiple accomplishment (ibidem).
Messengers can act as neurotransmitters when released from neuron terminals, as hormones or neurohormones when acting via the bloodstream, and as paracrines or autocrines. Vasopressin may serve an example of a multifunctional messenger. A vasoconstrictor in homeostatic controls, vasopressin may be released upon change in peripheral blood vessel resistance. Connoted with response to stress, it has been found of influence to learning and memory in contexts not accompanied by exertion (ibidem).
Individuate merger of autonomic and learned performance cannot be a genetic program. The question to arise is whether voluntary movement naturally would incorporate reflex commitment, and if feedback would be part the scope.
1.5. Human reflex and voluntary behavior
Exactness has been disputed, for the term “voluntary” in regard of living structures, inclusive of man. Esteeming skill and knowledge, majority of human behavior would belong somewhere in a continuum between the voluntary and the involuntary, rather than within clearly defined boundaries of consciously actualized intention (Vander et al., 1985).
Walking, though conscious and volitional by standard, employs co-exercise of muscle structures that rely on networks of interneurons. The networks engage neural information pools by spinal local levels. Interneurons may work as “signal changers” between afferent and efferent terminals (ibidem). The same interneurons may take inner descending command, as well as participate in local patterns. Upon local feedback, motor pattern change is in a good degree reflex. Locomotion contributes to cognitive mapping and may encourage language.
Corticospinal and brainstem paths remain mostly outside interoception. The former connectivity type is prominent in supplying the hands; the latter is essential in positioning and movement of the head, especially in response to individually relevant percepts (ibidem). Not only writing, the fine motor behavior of the speech act as well, would exercise a substantial amount of established patterns, without awareness of the neural particular. Locally, these are neural elementary formations to manage antagonistic muscle routine inhibition. At language segmental level, production and perception do not need much focus to the fine motor detail, unless a disturbance should occur (Puppel, 1988).
Muscle relevant patterns require relevant neural patterns, and a term as relevant neuro-motor patterns has become of use (Vander et al., 1985). Favorable reference might advocate a phrase as neuro-motor-articulatory mastery, as well (Puppel, 1992). An outline on relevant pattern build may broaden the view to human intended and reflex behavior.
1.6. Relevant neuro-motor patterns
Already in pattern formative stages, volitional practice is not opposed to, or independent of reflex activity. Neurophysiology and human functioning cannot delineate between patterns consciously learned and those acquired. Specifics are unlikely to become universal, for the multineuronal loops that mediate motor behavior, or the neural network hidden layers that are part in pattern shaping. Some hypotheses on the biomechanics for neuro-motor pattern founding yet have been developed (Vander et al., 1985).
First and foremost, behavior autonomous repetition is capable of altering the number or effectiveness of synapses between relevant neurons (ibidem). Early stages of pattern formation would depend on intrinsic feedback heavily. Repetitiveness having encouraged new synaptic accord, the extensive reliance on feedback would gradually diminish, to advance behavior ease and economy. For speech and language, skill observably affords less focus to articulation, or the graphemic minutiae.
To cluster or syllable extents, established patterns for speech and language do compare with programs, in their work as open-loop consecutions, evidenced for natural language segmental levels (Puppel, 1992). However the speech sound or syllable, segmental processing may compare with reflex behavior, the inner monitoring for spoken or written ability never does cease completely.
Feedback with the neocortex can initiate, end, and also in real time instruct established neuro-motor sequences for language new, generative activity. Sustained feedback helps error-detection as well as feedforward, the anticipatory neuro-motor planning to allow that speech and language segments become purposed for smooth articulation or writing (ibidem).
Speech and language patterns require goal-oriented behavior for forming, intrinsic feedback other roles to be pattern verification and potentially change. The volitional, central abilities do naturally integrate all sensory modalities into a feedback pool for real-time compensation.
1.7. Sensory compensation
Language acquisition and learning may favor conscious and selective focus to auditory, tactile, and visual sense data. Cortical monitoring for established linguistic routines yet operates on pools of sensory information, which enables feedback on paralleled inputs whenever intra-modal adjustability cannot moderate difficulty or disadvantage (Vander et al., 1985).
Distortions to proprioception or kinesthesia promote reliance on visual inputs; the modalities make part the information for central monitoring structures during speaking or writing (Puppel, 1992). Limitation on visual acuity impels increased attention to touch, hearing, kinesthesia, and proprioception. Auricular obstruction directs focus onto tactile and visual variables (Vander et al., 1985).
Intra-modal adjustability may show in a person’s raising his or her voice to speak, also if wearing headphones on purpose. Elevated auditory feedback would be to help verify the spoken performance, though own speech patterns belong with validated neural linkage. The adjustability might accord a cerebral resolve as augmented reliance on tongue tactile variables.
The reconcilement works with neocortex ideational structures for language; sensory information pooling has evolved for higher variables generally (Vander et al., 1985). A feedback model for human internal equilibrium can be discussed.
1.8. The pool model for internal balance
Homeostasis requires that the biochemical gain and loss between the organism and the environment balances with intra-systemic inputs. In humans, the homeostatic operating point is a spectrum of variables. Another term for the spectrum is that of the homeostatic pool (Vander et al., 1985).
Human neurophysiological equilibrium works essentially on negative feedback. In thermoregulation, both increase and decrease would induce activity that counters change, body temperature to be anticipated in homeostatic feedforward, internal thermo-sensitive sites continually to support a discrepancy with receptors in the skin. The feedforward is a part learned feedback capacity, homeostatic operative values never to balance error signals entirely. The difference helps sustain receptor activity (ibidem).
Biochemical equilibrium may influence human cognitive faculties directly, as in distortions compelled by illness or extrinsic factor presence. Experiments with sensory privation (Lindsay and Norman, 1991) had healthy and otherwise unimpeded volunteers exhibit perceptual defects upon limitation in sensory processing. Low-level unvaried stimuli proved even more “hallucinogenic” than privation alone. Tolerance to feedback impoverishment was evidenced lower than for fasting, and financial offers did not motivate further endurance (ibidem).
In a system to operate on a spectrum for a threshold, a constraint on inner processing may result in homeostatic spectra narrowing to become misinterpreted for response, or to induce a compensatory yield from central structures. Intrinsic feedback must have been important, in threshold maintained reference and regeneration of balance. Human brainwork and signal specificity come to the foreground, as regards the role of feedback in human inner function.
1.9. Signal specificity and the human brain
Phylogenetically evolved into distinctive regions and ontogenetically integral, human brains are capable of inner network labile function. Failure by a constituent of a labile formation may bring a spectrum for a response. On the other hand, cerebral tissue has a cumulative complementary potential; the brain can replace or even void an intellectually defective variable (Styczek, 1983).
Intracerebral coherence becomes possible with neural radiations and tracts. Principally three fiber types have been named in brain integrated performance. Associative connectivities communicate areas within the same hemisphere; projection processes link the cortex with the brainstem, the basal ganglia, the cerebellum, and the spinal cord, while transverse paths intercommunicate the hemispheres, the corpus callosum making the most acknowledged connective (Akmajian et al., 1984).
The aforesaid brainstem reticulate structure extends convergence for descending, local, and ascending pathways. Brainstem links share in brain network learning generally. Another eminent center for coordinating cortical and subcortical inputs is the thalamus to produce the wavelike, rhythmical oscillations as perceived in brain EEG patterns. Thalamic function is important in variable isolation and analysis (Vander et al., 1985).
The cerebellum feeds back with brainstem nuclei as well as the cerebral cortex, integrating vestibular information from the ears, eyes, muscles, and skin. Cerebellar memory provides feedforward in movement planning, and assists comparison between intended and actualized motor sequences. Timing signals for the cortex and spinal generators, cerebellar inputs are highly specific (ibidem).
The frontal lobes are vital in goal or idea formation and recognition. Frontal associative areas have parietal, temporal, and limbic connectivity, which helps discernment in sense data and refines perception for language, memory, and focus. Frontal feedback is able to change the limbic emotional component; limbic inputs to frontal areas have been given much credit for personal realization on the self and the environment (Vander et al., 1985).
Of areas broadly associated with speech and language, Broca is located in the frontal lobe, adjacent to the motor strip. It assists motor program choice in language production, feeding back for structure underlying formation with temporal lobe Wernicke. Brain occipital regions to furnish visual sense data for written forms of language, and temporal tissues to deliver for speech acoustic shapes, parietal structures harmonize the variables, lexical items potentially to engage trace visual representations, and written text to have the power to invoke trace auditory features. The parietal capacity works in feedback with established neural schemata for language.
Brain primary receptive areas neighbor on gnostic or secondary structures that enhance signal interpretation. This is most probably the dominant gnostic or secondary auditory area to have the neural array capable of forms that Wernicke can reconstrue (Styczek, 1983). The capacity for signal reprocessing would be the “phonetic buffer” as in Puppel (1998), or the “echo box” as in Lindsay and Norman (1991). Ability to pool and manage auditory information is vital in comprehending spoken discourse.
Systemic specificity for speech is emboldened by cranial nerves. The trigeminal, facial, glossopharyngeal, vagus, abducens, and trochlear nerves consist of both motor and sensory fibers, thus qualifying for feedback connectivities thoroughly (Vander et al., 1985).
A closed-loop capability is part any spoken or written act, the competence to embrace interoceptive and exteroceptive types of feedback. Interoceptive loops can work for tactile, as well as proprioceptive and kinesthetic information, of also cognitive mapping value. Exteroceptive loops would work mainly on auditory and visual inputs.
Interoceptive or exteroceptive abilities are yet classes in which to note rather than delimit on the senses, tongue tactile variables to be interoceptive, and palpation exteroceptive. A dual model as well may help picture feedback for interlocutory contexts, the egocentric loop to represent human self-monitoring powers, and the environmental one to symbolize verbal exchange, within natural settings as inclusive of other humans.
Figure 1. The dual-loop feedback model for conversational exchange.
Individually as well as inter-personally, the notion of a feedback loop should not be understood for parallel with that of a closed circuit or mere reiteration of instructions. For speech, the self-oriented loop might consist of the articulators, the speech sound medium, the ears, the primary auditory cortex, and brain secondary areas to elaborate on signal for intellection. In conversational contexts, the environmental loop may stand for linguistic engagement, without which contemporaneous verbal behavior would be that of monologuing individuals.