Discourse on information processes requires terms as a system, program, option, signal, and feedback. Human logical skill does not act 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 in terms to become attained, feedback incidence shall be appreciated for a natural principle.
1.1. Feedback in the single neuron
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 to provide for intra-cellular balance works on negative feedback (Vander et al., 1985).
Action potentials to be brief, all-or-none reversals 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, saltatory propagation to depend on combined synaptic effects. The basic level of nervous system organization, individual cells deserve acknowledgment with regard to higher neural variables, yet only as part in network efficacy, neural networks to build on neuron particular sites.
1.2. Space and time in intercellular communication
Individual neurons may communicate 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 is 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 may 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. Feedback depends on the time extent for effect, in neural transmission for language as well; 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.
Nonparticipant of a specific process, neurons are not in standard terms inactive, cell resting state to be interior dynamic balance with exterior. Intrinsic in timing, neuron homeostatic activity may result in action potentials. Excitation as in an isolated cell to remain predictable only in terms of statistic approximation (Vander et al., 1985), intrinsic time intervals must be of quality in combined neural actuation for speech and language.
Coles and Duncan-Jones (in Ciarkowska, 1993) premised for principles of biological function to correspond at lower and higher levels of systemic structuring, living formation controlled and controlling sets to show interdependence. 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
Neural linkage joins mostly into schemata or networks. Human schemata alone may embody speech sound or letter shape representations; networks are indispensable in neural planning for spoken or written discourse (Puppel, 1992). The relationship between neural activity and motor behavior is difficult to detect and measure, owing to cell preparatory actuation (Vander et al). Observably however, speech and language employ feedback-mediated inner dynamics rather than strictly a hierarchy.
Brain neocortex is the tissue of the highest intricacy; brainstem reticular structure is yet 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 those for wakefulness and focused behavior, inclusive of language and learning (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 coordination is direct, in the pupillary or smooth muscle rapport for speech, reading, or writing.
John Lacey’s experiments on environment stereotyped intake or rejection (in Ciarkowska, 1993), were to explore on human systemic contiguity. He detected a cortico-cardiac outputs that held for people who evaluated the concurrent experimental context, as well as the 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. Their parameters corresponded with psychological tasks, thus to report on a learned factor in autonomic processing. Autonomic activity is supposed naturally reflex. Neural path individuate negotiation would likely involve systemic 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. Research in human neurophysiology would yet have declared 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 consist of a stimulus to nerve A, looped via the brain with nerve B. The nerve 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 often difficult to name arc components. Beside human reflex notable structural diversity, neurochemicals of immediate effectiveness have a potential for multiple accomplishment (ibidem).
Messengers can act as neurotransmitters at neuron terminals, as hormones or neurohormones when acting via the bloodstream, and as paracrines or autocrines. Vasopressin is a multifunctional messenger. A vasoconstrictor in homeostatic controls, it may be released upon change in peripheral blood vessel resistance. Connoted with response to stress, it has been found of significance to learning and memory in contexts not to demand exertion (ibidem).
1.5. Human reflex and voluntary behavior
Voluntariness has been disputed, with regard to living structure neurophysiological function, inclusive of man. Esteeming skill and knowledge, majority of human neural 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 interneuron networks to engage neural information pools by spinal local levels. Interneurons may work as “signal changers” between afferent and efferent terminals (ibidem). The same cells may take inner descending command and participate in local patterns. Upon local feedback, motor pattern change is in a good degree reflex.
Corticospinal and brainstem paths remain mostly outside interoception. The former are prominent in supplying the hands; the latter are essential in positioning and movement of the head (ibidem). Not only writing, the fine motor behavior of the speech act as well, would exercise a substantial amount of established patterns of no aware percept for 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 would occur (Puppel, 1988).
Relevant motor linkage can work only with relevant neural paths, and a term as relevant neuro-motor patterns has become of use (Vander et al., 1985). Favorable reference may advocate a phrase as neuro-motor-articulatory mastery (Puppel, 1992). An outline on relevant pattern build may broaden the view to human intended and reflex behavior.
1.6. Relevant neuro-motor patterns
Volitional practice is not opposed to, or independent of reflex activity, already in pattern formative stages. Specifics are unlikely to become universal, for the multineuronal loops that mediate motor behavior, or the neural network hidden layers to be part in pattern shaping. Some hypotheses on the biomechanics for neuro-motor pattern founding yet have been developed (Vander et al., 1985).
Behavior autonomous repetition can alter the number or effectiveness of synapses between relevant neurons (ibidem). Early stages of pattern forming would depend on intrinsic feedback heavily. Repetitiveness to have encouraged new synaptic accord, the initially extensive reliance on feedback would gradually diminish, to advance behavior economy and ease. 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 cluster or syllable processing may compare with reflex behavior, the inner monitoring for spoken or written ability never does cease completely.
Neocortical feedback can initiate, terminate, as well as in real time instruct established neuro-motor sequences also for language new, generative activity. The sustained monitoring helps error-detection and supports cortical command in feedforward, the anticipatory neuro-motor planning to allow that language spoken or written shapes become purposed for smooth articulation or inscribing (ibidem). The volitional, central ability integrates all sensory modalities.
1.7. Human pooling of sensory information
Language acquisition and learning may favor conscious and selective focus to auditory, tactile, and visual sense data, for relevant pattern forming. Cortical monitoring for established linguistic routines would yet use pools of sensory information, which enables feedback on paralleled inputs whenever difficulty or disadvantage cannot be moderated within the central scope to augment sensory processing, known as intra-modal adjustability (Vander et al., 1985).
Proprioception and kinesthesia make part the information for central monitoring structures in speaking or writing; distortions promote reliance on visual inputs (Puppel, 1992). Limitation on visual acuity would impel increased attention to touch, hearing, kinesthesia, and proprioception. Auricular obstruction would direct focus to 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. Though own speech patterns belong with validated neural linkage, elevated auditory feedback would be to help verify the spoken performance. The sensory pool might accord extended reliance on tongue tactile variables as well; evolved for higher systemic variables (Vander et al., 1985), the pool would work with neocortex ideational linkage for language contexts.
1.8. The pool model for human homeostasis
Homeostasis requires that biochemical and thermal gain as well as loss in exchange with environment does balance for intra-systemic inputs. In humans, the homeostatic “operating point” is in reality a spectrum of variables to contribute to a standard threshold. Another name 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 actuation to counter change. Body temperature is anticipated in homeostatic feedforward, where internal thermo-sensitive sites continually support a discrepancy against receptors in the skin. The feedforward is in part a learned, feedback capacity. Homeostatic operative values never do balance error signals entirely, the difference to help sustain receptor activity (ibidem).
Biochemical equilibrium is of relevance to 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 array narrowing to become misinterpreted for response, or to induce a compensatory yield from central structures. Systemic feedback must be important, in threshold maintained reference and regeneration of balance. Human brainwork and signal specificity come to the foreground, in regard of systemic feedback in human inner function.
1.9. Signal specificity and the human brain
Human brains are capable of neural network labile function. Failure by a constituent of a labile formation may bring a spectrum for a response. The gray matter also 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, basal ganglia, cerebellum, and the spinal cord, while transverse paths intercommunicate the hemispheres, the corpus callosum making the most acknowledged connective (Akmajian et al., 1984).
Brain frontal associative areas have parietal, temporal, and limbic connectivity, which enhances and refines neural processing for sense data, language, memory, and focus. Frontal feedback can change the limbic emotional component; limbic inputs have been given much credit for personal realization on the self and the environment (Vander et al., 1985). The cerebellum feeds back with the cerebral cortex and brainstem nuclei, integrating vestibular information from the ears, eyes, muscles, and skin. Cerebellar memory is part the feedforward in movement planning; timing signals for the cortex and spinal generators, cerebellar inputs are highly specific (ibidem).
Brainstem reticulate structure extends cranial convergence for descending, local, and ascending pathways; the links share in neural network learning generally. Another eminent center to coordinate 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).
Of areas widely connoted with speech and language, motor sequencing is assisted by frontal lobe Broca, adjacent to the motor strip; it feeds back with temporal lobe Wernicke for underlying structure build. Brain occipital regions to furnish visual sense data for language written forms, and temporal tissues to deliver for speech acoustic shapes, parietal structures harmonize sensory and cognitive variables, lexical items potentially to engage trace visual representations, and written text to have the power to invoke trace auditory features.
Brain primary receptive areas neighbor on gnostic or secondary structures. 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). Neocortical 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, interoceptive feedback loops to work with tactile, proprioceptive, and kinesthetic information of also cognitive mapping value; exteroceptive loops would use mostly auditory and visual inputs. Interoceptive or exteroceptive abilities are yet only 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.
Figure 1. A 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 those of permanent circuitry, or mere reiteration of instructions. For speech, a self-oriented loop may become of function for the articulators, the speech sound medium, the ears, the primary auditory cortex, and brain secondary areas. In conversations, the environmental loop may stand for linguistic engagement, without which cotemporaneous verbal behavior would be that of monologuing individuals