Discourse on information processing requires terms as an option, a processing system, program, signal, and feedback. Human logical skill does not work in denial of the nervous system. The system is discussed as an information processing and managing structure, beginning with the single cell, and ending with the intricate connectedness of the human brain. Congruence averred in the above terms, 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 electric potential change. As within the ionic hypothesis by Alan Lloyd Hodgkin and Andrew Fielding Huxley, action potential generation employs positive feedback, in the depolarizing phase. The active transport system to provide for intracellular balance works on negative feedback (Vander et al., 1985).
An action 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; language performance to require action potentials, saltatory propagation depends on combined synaptic effects. The basic level of nervous system organization, individual cells deserve acknowledgment in neural higher variables only as part in network efficacy, neural networks to build on neuron particular sites.
1.2. Space and time in neural 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, the spatial arrangement of synapses or cell receptors can be stated essential, neuron particular sites further to be capable of varied thresholds. Second messenger extrasynaptic interaction also is known to take place in areas of high-density unmyelinated brain tissue, spatial adjacency thus to affect 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).
The temporal closure on neural communication yet cannot be disregarded, inhibitory and excitatory values to summate in real time. In neural transmission for language as well, cellular feedback depends on the closure for effect (ibidem). These are the grounds to posit for the outcome of neural correlativity to represent a biological function of space as well as time, to an extent greater than assumed within the theories of extrinsic timing (in Puppel, 1988).
The theories approve of the temporal aspect as extrinsic to the speech plan, the time closure to be set on phonetic segments in the speech act implementation phase. A major argument to the contrary may come with the property of the nervous system 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: continual 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, the 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), the intrinsic time interval will be of value 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 incidence 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 the neural planning for spoken or written discourse (Puppel, 1992). Speech and language employ feedback-mediated dynamics rather than strictly a hierarchy.
Brain neocortex is the tissue of the highest intricacy. However, it is the brainstem reticular structure to mediate long-distance neural transmission. 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 remains vital in pupillary response, and the tonus to allow muscle engagement for speech, reading or writing.
John Lacey’s experiments on environment intake or rejection in stereotyped behaviors (in Ciarkowska, 1993), were to explore on human systemic rapport. He detected and measured a cortical effect over cardiac outputs that held for individuals to assess concurrent experimental contexts, as well as for those to act on expected events. 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 response. They reported parameters that corresponded with psychological tasks, thus to evidence a learned factor in autonomic functioning. Autonomic activity is supposed naturally reflex. Person-specific patterns might emerge only via neural path individuate negotiation, possible in human learning.
1.4. A reflex arc
In definition, reflexes are automatic and indeliberate. Typical constituents of a reflex arc are the receptor, afferent pathway, integrating center, efferent pathway and the effector. 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).
A reflex arc may involve a stimulus to nerve A looped via the brain to nerve B. Nerve B may synapse on endocrine gland B1. The gland having secreted a hormone, gland C may become stimulated to communicate with a muscle by means of another messenger, neurochemical C1, for example. However, it is unseldom difficult to apply standard names to arc components. Beside arc notable structural diversity, neurochemicals of reflex productiveness 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 could not be a genetic program. The question to arise is whether voluntary movement naturally would incorporate reflex commitment, and that with an accompanying feedback scope.
1.5. Human reflex and voluntary behavior
Exactness of use has been disputed, for the term “voluntary” in regard of live 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 phenomena (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 routine inhibition of antagonistic muscles. 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 for speech might advocate a notion 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
At pattern formative stage as well, volitional practice cannot be labeled as opposed to, or independent of reflex activity. There is no clear borderline, on neurophysiological and functional grounds, between patterns that have been consciously learned and those to have been acquired. Specifics are unlikely to become universally described, 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, autonomous repetition of behavior can alter the number or effectiveness of synapses between relevant neurons (ibidem). Early stages of pattern forming would heavily depend on intrinsic feedback. Repetitiveness having encouraged new synaptic concord, dependence 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. The work has been evidenced for the segmental level of natural language, and does further compare with reflex behavior (Puppel, 1992). However, the inner monitoring for spoken or written ability never does cease completely.
The neocortex feeds back with the articulators or the grip in the hand, able not only to initiate or abandon, but also in real time to 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, for compensation.
1.7. Sensory compensation
Neuro-motor pattern formative stages may selectively refer for auditory, tactile, and visual sense data, as the modalities pertain with standard forms for language and speech. Cortical monitoring of established routines yet operates on pools for 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 to 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.
Feedback reconcilement would thus work with neocortex ideational structures; little is known about details and manner of the work, in comparison with speech motor aspects (Puppel, 1994). Sensory information pooling has evolved for balance in higher variables overall (Vander et al., 1985), rather than speech and language solely. The pool 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).
Neurophysiological homeostasis works essentially on negative feedback. In thermoregulation, increase as well as decrease from norm would induce activity that counters change, body temperature to be anticipated in homeostatic feedforward, where internal thermo-sensitive sites continually support a discrepancy with receptors in the skin. A feedback capacity, part the feedforward is learned, and humans are capable of a degree of climatic adaptation. Homeostatic operative values never balance error signals fully. The difference is to help receptor activity upkeep (ibidem).
Biochemical equilibrium may directly influence human perception and cognitive faculties, as in distortions compelled by illness or extrinsic factor presence. However, neocortex cognitive and ideational structures would keep inner processing balance as well. Experiments with sensory deprivation (Lindsay and Norman, 1991) had healthy and otherwise unimpeded volunteers exhibit perceptual defects, when limited on sensory modalities. Low-level unvaried stimulation proved even more “hallucinogenic” than deprivation alone. Tolerance to feedback impoverishment was evidenced lower than for fasting, and financial offers did not motivate further endurance. The participants resigned, and regained balance (ibidem).
Within the pool model, the homeostatic spectra were not wide enough for neural structures to work. Expected to remain idle, the persons experienced cognitive privation combine with receptor reactivity lowering. In a system to operate on a spectrum for a threshold, such constraint on inner processing may become interpreted for a response, or 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 management of information. True for the single neuron as well as language capable networks in the brain, feedback reliance can be advanced for a natural principle of function, where relevance would pertain with the self-preservation instinct.
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 in brain activity as perceived in EEG patterns (Vander et al., 1985). Thalamic function is important in variable isolation and analysis.
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, also for language. Frontal associative areas have parietal, temporal, and limbic connectivity. The function helps compare sense data and heightens discernment, for language, memory, and attention (Vander et al., 1985). Frontal feedback is able to change the limbic emotional component.
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 with temporal lobe Wernicke for underlying structure formation. Brain occipital regions to furnish visual sense data for written forms of language, and temporal tissues to deliver for acoustic shapes, parietal structures harmonize the variables, speech potentially to engage trace visual representations for lexical items, and written text to have the power of invoking trace auditory features. The parietal capacity works in feedback with established, memory 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 trace 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).
There is no manner or method strictly to divide between brain networks that converge for language production and those to connect in language perception or thought exercise (Vander et al., 1985). Standard language behavior requires medically unaltered consciousness and simultaneous use of inner linguistic and cognitive reference, intellection specifics to combine sensory data as relevant in real time. In the light, a human language faculty can be posited, selectively to imply the brain entire in human language command. The notion may become necessary with regard to the constraints a view to Wernicke or Broca areas exclusively would impose.
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. As trace data, human sensory competence would remain active also in exercise of abstract thought.
Interoceptive or exteroceptive feedback types 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 present feedback for interlocutory contexts, the loops to be visualized according to their egocentric or environmental orientation. The egocentric loop might represent human self-monitoring powers, 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.