**7. The ontogeny of language: The piggyback ride of working memory**

At birth young infants exhibit a universal capacity to detect differences between phonetic contrasts used in world's language [23]. The mother (or father) has to entrain the attentional mechanisms of the child through *Social Gaze* with subsequent motherese (or fatherse or parentese), a form of language that involves lot of changes in pitch, is melodious and repetitive. *Social Gaze or Eye Contact* with the mother forms the essence or pre-requisite of genesis of language, wherein the *vowels* (and that too the *extremes of vowels, i.e., 'a' and 'o' 'u'*) precede *consonants* for the mere fact that lips movements is maximal for vowels and due to the simplified mechanism(s) that underlie the *neurolinguistics* of vowel. The language development or transition of the human mind onto the axes of language has been hypothesised to take place along two neural phases, namely *Phase I* and *Phase II.*

### **7.1 Phase I (neurodynamical phase)**

*The neurodynamical phase* also known as the *general open-system* is uncommitted and open to change and plasticity and is the phase where priming of the human mind takes place. The universal capacity of the human mind is dramatically altered by the language experience starting as early as 6 months for *vowels (a, e, i, o, u)* and by 10 months for *consonants*. The *extremes of vowels, namely 'a', 'o' and 'u'* involve maximal movements of the lips that the child gets enamoured through the mental landscape so formed by the stochastic trajectory initiated in the *Phase-Space of Human Mind* by the system of *Mirror Neurones.*

#### **7.2 Phase II (linguistic phase)**

It represents the language specific phase wherein the human mind becomes committed to the specific language that is being acquired and usually starts from end of the first year of life. Neural oscillations across the coordinates of time (brainwaves),

*Language as the Working Model of Human Mind DOI: http://dx.doi.org/10.5772/intechopen.98536*

within individual neurones or through interactions among neurones, *are rhythmic or repetitive patterns of neural activity of the central nervous system* and *such patterned neural dynamics signify and describes the respective neurophysiological functional characteristics*. The techniques of *Biological Signal Processing (BSP)* have been employed to classify and categorise EEG signals through linear domain of power spectral density (PSD), linear discriminant analysis (LDA) and varied non – linear domains of neural networks.

The concept of human mind in acquisition of language or general learning mechanism(s) contribute to such an evolved mechanism of spoken and written language that imprisons the mechanistic of mirror neurone system (MNS) and *synaptic neuroplasticity*. *MNS* plays a pivotal role and is considered to be an interface between the qualia of sensorium and motor system of the intricately woven *Human Mind*, wherein activation of *Mirror Neurone System* initiates the process of image formation in the virtual phase-space trajectory of human mind so evolved by the baseline reverberating chaotic neural dynamics, a phenomenon learnt and hard-wired through the neurophysiological process of memory.

**The neural signature of** *Working Memory (WM), the primacy of emergent Human Mind* [24]*,* for *Encoding, Registration and Retrieval of Memory* [25, 26] inputs has been postulated to be served by *three EEG Wave-Forms Complex of Theta* [27, 28]*, Alpha and Gamma frequency bands* [10] with a bootstrapping blueprint wherein the *gamma waveforms or bursts hitchhike or piggy back rides the theta wave responsible for feature detection* **along with** *alpha-theta wave-form that coincidentally allocates attentional resources onto the evolved dedicated neuronal circuitry that are stimulus-specific* [29, 30]. These frequency oscillations have been observed to **modulate neuronal excitability** by controlling neuronal firing, and could be responsible for **holding of stimulus-specific information in space and time along the coordinates of working memory neuronal pool** [31]. Such a neural synchronisation proposal may provide a solution to underlying mechanism(s) of synthesis and amalgamation of features of an object through coordinated firing patterns that in essence underlie the *feature detector mechanism(s) of neuronal process* [32].

It has been envisioned that,


Pfurtscheller and Klimesch [38]*,* Pfurtscheller and Aranibar [39] and Pfurtscheller and Lopes da Silva [40] had reported that during visual stimulation **alpha wave-form desynchronises** giving rise to *ERD* **over occipital recording sites** whereas **over motor cortex synchrony in form of** *ERS* could be observed. Sauseng et al. [41], [42] put forward the observation of **change in** *PSD of alpha wave-form* **that is observed at the occipital and pre-frontal areas during** *top-down processing in a working memory task*, wherein a *decrease in alpha PSD power at occipital site* with a **consequential** *increased alpha PSD power is observed at prefrontal EEG electrode site*. **The** *ERD quantum* **of alpha frequency wave-form during encoding** in a visual working memory task has been correlated with the memory load [29, 30, 33–36].

**However**, [43] reported that the processing of working memory of **encoding and retention involves the oscillatory activities along multiple frequency bands of**

**EEG wave forms inclusive of** *alpha frequency as well* through local and long-range neural networks proposing the existence of **multiple parallel functional mechanisms of alpha oscillations** [44]. In this context of equivocal representation of alpha oscillations, it would be interesting to examine changes in alpha oscillations pattern that could be sensitive and characteristic to working memory task.

The observation documented from our laboratory of *theta wave form band synchrony***, known as** *Event-Related Synchrony (ERS)* **mirroring increased** *PSD,* across distributed range of task relevant areas of brain namely,


The assessment of power-spectral density of EEG signals from our laboratory paved the way for appreciation of closely intertwined intricate dance of *ERS/ERD along the coordinates of space and time that probably seems to be the flip-flop switch for the flow of corporeal and legible information* (**Figure 3**) [49]. The ERS of theta wave-form with significantly appreciable change in Power Spectral Density (PSD) at EEG electrode pair of T4 (**Figure 1**) along with concomitant ERD of alpha wave form skewing

#### **Figure 2.**

*Power spectral densities (PSDs) of theta frequency wave form in three memory conditions of retention, semantic manipulation and backward manipulation with raw EEG data being processed through BESS software where epochs (epoch length = 1000 ms) were separated for each trial [54 trials being part of delayed-match-to-sample (DMTS) task] and data was averaged separately respectively for each electrode for each condition (FP1, FP2, F7, F3, AFz, Fz, F4, F8,T3, C3, Cz, C4,T4, P7, P3, Pz, P4, P8, O1, O2 electrodes were selected). ERS as evinced through enhanced PSD (increase in mean amplitude power in sq. microvolts), was observed in theta wave-form in all three conditions/manoeuvres of retention (FZ, F3, F4, F7,T3,T4) semantic forward information processing (FP1, FP2, AFZ, FZ, F3, F4, F7, F8, C3, P7,T3,T4) and backward information processing (FP1, FP2, AFZ, FZ, F3, F4, F7, F8, C3,T3,T4) of EEG electrode pairs and on comparative evaluation with basal EEG time-series run along said EEG electrode pairs, significant difference in PSD could be appreciated only along T4 EEG electrode pair in conditions of retention (p = 0.05), semantic manipulation (p = 0.05) and backward manipulation (p = 0.01) by using one way ANOVA at 5% level of significance.*

*Language as the Working Model of Human Mind DOI: http://dx.doi.org/10.5772/intechopen.98536*

#### **Figure 3.**

*Portrays Lateral Asymmetry Index (LAI) ratio of different conditions of Alpha Frequency Band at P3-P4 EEG electrode site. Significant difference could be appreciated at parietal region of P3-P4 EEG electrode pair along alpha frequency band using T-test with p = 0.004, p=0.002 (p < 0.05) at 5% level of significance with left hemisphere lateralisation (skewed neurophysiological processes) during retention condition and semantic manipulation condition, respectively. In backward manipulation condition, significant difference could be appreciated at additional parietal EEG lead pairs of P7-P8 besides P3-P4 with p = 0.02 in both electrode pairs (p < 0.05) at 5% level of significance with left hemisphere lateralisation. 1 = Control Condition, 2 = RetentionCondition, 3 = Semantic Condition, 4 = Backward Condition. LAI = [P (left) - P (right)]/[P (left) + p (right)].*

onto left hemisphere lateralisation of neurophysiological processes [as exemplified by Oblique Lateral Asymmetry Index (LAI)] during the select conditions of retention, semantic manipulation and backward manipulation (**Figure 2**) is yet another example of concomitant stimulatory and inhibitory dedicated neuronal pools that evolve during and are responsible for the stimulus-specific adequate response. More likely, the looped fractals of neuronal pools (modules) of on-centre ERS theta wave form, oncentre ERD alpha and offsurround ERS alpha or off-centre ERS alpha and onsurround ERD alpha have a tendency to self-iterate that tends to etch the stochastic trajectory along the Human Mind Phase-Space.

**The characteristic of temporal distribution of** *ERS/ERD PSD* **along the run of EEG time-series** was evaluated in our laboratory and during the **DMTS task**, **the temporal distribution across** *two frequency bands of theta and alpha* was accessed to assess neuronal oscillatory activities during **WM tasks** across select cortical regions [50–52] and to assess modular memory facets and processes that entrain dedicated self-iterating fractals of neuronal pools in human brain resulting in memory consolidation processes concluding into **language acquisition, manipulation and comprehension processes.**

**These chunks of information or memory codes** might generate a **particular patterned rhythm** which later during **retrieval** of information from dedicated neural networks might follow the phenomena of **pattern matching** during its response for same memory inputs.

**Figures 4** and **5** depicts *ERD/ERS percentage change {ERD% = (Actual Power-Reference Power)/Reference Power 100} of Power Spectral Densities of Alpha frequency wave form* when compared among male and females in *Retention Condition* where significant difference could be seen at CZ, P8, T4 electrode sites and **Figure 5** displays results of *ERD/ERS alpha activity i*n *Semantic Condition*, exhibiting significant differences along CZ, P4, T4 EEG electrode sites. The common denominator appreciates the

#### **Figure 4.**

*Depicts ERD/ERS percentage change [ERD% = (Actual Power-Reference Power)/Reference Power 100] of Power Spectral Densities of Alpha frequency wave form when compared among males and females in Retention Condition where significant difference could be observed at CZ, P8 and T4 EEG electrode sites.*

#### **Figure 5.**

*Illustrates ERD/ERS percentage change {ERD% = (Actual Power-Reference Power)/Reference Power 100} of Power Spectral Densities of Alpha frequency wave form when compared among male and females in Retention Condition where significant difference could be seen along CZ, P4,T4 EEG electrode sites.*

intricate interwoven *Off-Centre* **α** *ERS (Central)-On-Surround* **α** *ERD Neural Dynamics* as could be deduced and envisioned from observations of **Figures 4** and **5** that seem to be intertwined and interlocked through observations of findings of **Figures 2** and **3**, with the self-iterating trajectorial pathways of the looped alpha and theta wave forms through respective precepts of Event-Related Synchrony (ERS) and Event-Related Desynchrony (ERD).

In this context and with the characteristically patterned observations data from the present study [*Neuropsychological Trends* in print] the precepts of *Neural Dynamics of Working Memory Model* has been conceptualised as:


• **The** *Backward Processing in Memory warrants a similar Theta ERS-LAI Alpha ERD looping along temporal and parietal region (with additional inputs from parietal areas).*

The hypothesis posited is that the concept of *Neural Dynamics of Working Memory Model* reflects as under:


It seems that there are two aspects of processing of LTM in terms of mean PSD and LAI along theta and alpha frequency waveforms.

• *The Skewed Theta frequency waveform ERS along right temporal region* **during** *retention, semantic forward information processing and backward information processing conditions* along with
