There is no doubt that Paul Broca’s contributions have been critical in terms of understanding a number of cognitive brain functions. He was the first person to discover that lacerations (in the caudal section of the lower anterior gyrus) were connected with complications in language comprehension. It is worthy to note that most of Paul Broca’s contributions are still relevant to date.
This is exemplified by the escalating number of researches that show the involvement of both the ventral premotor cortex and lower anterior gyrus in language comprehension. As a matter of fact, music, language and action have a familiar syntactic-like structure.
The unearthing of a mirror neuron system in monkeys motivated researchers to attempt to create a connection between motor and perceptual mechanisms for language.
Some researchers believe that the activation of the human left frontal motor-Broca’s area- while listening to speech is caused by phonological and/or articulatory coding during phonetic perception (Imada et al 957).This paper will therefore dwell upon the role of Broca’s area in language comprehension as well as other critical human capabilities
Broca’s Area and Language Ability
Paul Broca (a French neurologist) was the first person to establish that the posterior section of the left inferior frontal gyrus (IFG) played a major role with respect to language acquisition. Leborgne was one of Broca’s notable patients who experienced difficulties in language comprehension.
Leborgne language deficits were caused by the damage on his left frontal gyrus that extended from the lower section of the third anterior circumvolution to the striatum as well as the insula.
Broca’s aphasia was consequently portrayed as a condition characterized by anomalous grammatical form, phonemic and semantic paraphasias, articulation and melodic line impairment and production of telegraphic phrases (Fadiga, Craighero and D’Ausilio 448).
A number of scientific studies have been carried out to determine the role of Broca’s region in language acquisition as well as comprehension. Most of these researches have concluded that Broca’s area plays an important role in not only language production but also language comprehension in human beings (Fadiga, Craighero and D’Ausilio 449).
Broca’s Area and Cognitive Capability
There is a growing body of literature (particularly neuro-imaging proof) which demonstrates that Broca’s area (apart from its role in language acquisition) seems to be involved in a number of cognitive abilities. These abilities include calculation, music and working memory. Another critical contribution of Broca’s area (as demonstrated by studies involving monkeys) relates to the motor domain.
In one study, researchers discovered that the Broca’s area (of monkeys) was fully functional when sorting out man-made artifacts from natural objects. A similar phenomenon was observed when subjects were asked to signify probable actions based on manipulable objects. As a result, the researchers concluded that artifact manipulability as well as object observation facilitates a more affluent motor-based demonstration.
Other studies also revealed a noteworthy activation of Broca’s area when distal actions (e.g. grasping) were executed by the subjects. The activation of Broca’s area is not only limited to motor execution but also entails motor imagery (Fadiga, Craighero and D’Ausilio 451).
Passive examination of graspable artifacts (with respect to monkey’s canonical neuron system) was discovered to elicit inferior, premotor and motor frontal activities in human beings. The brains of the subjects were scanned simultaneously as they looked at 3D artifacts (actual objects appended on a panel), observed bi-dimensional colored images as well as during soundless identification of the objects presented.
The researchers discovered the activation of premotor cortex when the participants looked at the objects displayed before them. The premotor cortex was further activated when participants described the objects before them (Fadiga, Craighero and D’Ausilio 452).
A PET study revealed that the perception of non-objects weighed against perception of objects (regardless of the type of task the subject was asked to perform) was linked to the left hemisphere activations of Broca’s area, the inferior parietal lobule, the ventral and dorsal pre-central gyrus as well as the occipito-temporal junction.
Some researchers also carried out several experiments to assess brain activity when the subjects looked at various gestures made by human hands. They discovered activations in the inferior as well as premotor frontal cortex with similar functional characteristics seen in monkey’s mirror neurons.
Consequently, scientists were able to prove that the Broca’s area remained inactive when subjects looked at worthless motions/objects. This was contracted with goal-oriented actions (e.g. purposeful gesture made by human hands) that triggered activations in Broca’s area (Fadiga, Craighero and D’Ausilio 452).
A laceration to Broca’s region normally generates a significant language deficit. For example, neuropsychological studies on people with frontal aphasia have revealed deficits in a number of elements of the motor domain. These phenomena serve as evidence of the integral role played by Broca’s area in language abilities.
In addition, some studies have demonstrated that patients with damaged left frontal brain (the Broca’s area) experience hardships in term as of identifying pantomimes, signs and other gestures. For instance, a study carried out by Tranel and others showed that patients with injuries to left frontal brain experienced problems grasping details of an activity when they were given cards representing various actions.
Researchers have proved that people with aphasia show a relationship between reading comprehension deficits and action comprehension (Fadiga, Craighero and D’Ausilio 452).
Broca’s Area and Musical Abilities
The unearthing of tri-modal-auditory, visual and motor- mirror neurons in the ventral premotor cortex in the monkey has stimulated researchers to study the human mirror neural system (particularly the characteristics of the system). Some researchers believe that this system plays an important role in mapping the auditory depictions of actions into the motor plan essential for generating those actions.
As a matter of fact, some musicians crave to know how specific training can be used to enhance somato-sensory depiction of digits employed in practicing a musical instrument. It is worthy to note that the human motor system experiences vital plastic alterations subject to the type of musical instrument used during practice session (Pascula- Leone 306).
One of the salient features between music and language is the homogenous intricacy of language and musical syntaxes. As a matter of fact, numerous comparisons can be made between language and musical domains. For example, Maess and others carried out a study to establish the location of musical syntax. They discovered that it was located in the bilateral inferior frontal gyrus.
Researchers have (in a number of instances) compared the rules as well as the predictability of harmonics governing music composition with language syntax (Musso et al 778). For instance, Maess and others produced a type of musical syntactic infringement when they inserted unexpected harmonics in a musical composition.
Maess and colleagues used MEG (magnet-encephalography) to assess the neuronal complement of hearing harmonic absurdity and discovered an ERAN (early right anterior negativity) which is normally activated when an infringement is made on the music syntax (Pascula-Leone 1039).
A similar research demonstrated that the human brain system processes musical information in a similar manner found in the language processing system. It is worthy to mention that this study revealed that Wernickie’s area; Broca’s region; Heschl’s gyrus; the superior temporal sulcus; superior insular cortex; and anterior insular cortex were active when the participants were asked to listen to unexpected musical chords.
This phenomenon is a clear demonstration of the apparent role played by the inferior frontal cortex in terms of the syntactic relations between language and music abilities. In conclusion, several studies have reported the surfacing of an early right anterior negativity when participants were asked to listen to structurally unbalanced musical chords.
It is important to note the early right anterior negativity bears similar features with other deviance-related negativity for example the ELAN which shows the syntax structure process in language (Fadiga, Craighero and D’Ausilio 454).
Broca’s Area and Supra-modal Representation
As discussed above, numerous studies have demonstrated the important role of Broca’s region in cognitive domains such as language comprehension, musical abilities and actions. Nonetheless, the role of Broca’s area has been broadened to cover the receptive functions with respect to incorporated brain network models. There is no doubt that the functional relation between receptive and productive mechanisms is a time-honored issue.
However, there is a renewed interest on this issue as a result of neuro-physiological researches carried out on monkeys. These researches (which describe the neuronal processes for harmonizing observed and executed actions) spurred a number of neuro-psychological as well as neuro-imaging studies that aimed to establish a similar pattern in human beings.
Researchers eventually discovered that Broca’s area was the hub of a brain network used to encode action goals (executed or observed). In addition, action depiction in Broca’s region was also shown to be set off by its acoustical complement (as evidenced in cases involving humans and monkey).
Finally, researchers established that Broca’s region played a significant role in the encoding of musical syntax just like it does the language syntax (Koelsch 536) Furthermore, researchers have shown that lacerations on the Broca’s area (especially on the left interior frontal gyrus) results to an impairment in signal comprehension.
These findings are in concurrence with those of Tranel and others and clearly demonstrate that damages on left frontal cortex compromise the abilities of patients to grasp the details of action when given cards that depict different actions.
It is against this background that some researchers have suggested that Broca’s area could be a hub of brain network that encodes hierarchical structures irrespective of the manner in which they are used-language, music or action (Langheim 905).
This proposition is also in concurrences with the latest researches which reported that patients with lacerations on Broca’s area experience difficulties in understating the syntactic/hierarchical structure (except the temporal one that entails chronological tasks).
The common attributes of language comprehension, action and musical syntax (seen in human beings) may therefore involve the use of syntactical/hierarchical structures and these findings sustain the concept of supramodal function for Broca’s area (Fadiga, Craighero and D’Ausilio 455).
Works Cited
Fadiga et al. Broca’s Area in Language, Action and Music. Journal of Academic Science, 1169(2009): 448-458.
Imada et al. Infant speech perception activates Broca’s area: a developmental magnetoencephalography study. Neuro Report, 17(2006): 957-962.
Koelsch et al. Brain indices of music processing: nonmusicians are musical. J. Cogn. Neurosci, 12 (2000): 520–541.
Langheim et al. Cortical systems associated with covert music rehearsal. Neuro Image 16(2002): 901–908.
Musso et al. Broca’s Area and the Language Instinct. Nature Neuroscience, 6(2003): 774-781
Pascula-Leone et al. Modulation of Muscle Responses Evoked by Transcranial Magnetic Stimulation during the Acquisition of New Fine Motor Skills. Neurophysiol, 74(1995): 1037-1045.