ENG2003

1. ENG2003 Neurolinguistics and Biolinguistics

2. Language and the Brain: Fields of Research Neurolinguistics – The study of how language is realized in the brain • clinical research: aphasias • behavioural and neuroimaging techniques, cortical stimulation Psycholinguistics – The study of how the mind processes language • behavioural and (recently) neuroimaging techniques Biolinguistics – The study of biological aspects of language • includes genetics, language universals, correlates of language across species

3. Language and the Brain: Background 1st studies that correlated specific areas of the brain with language were in the late 19th century. Broca (1824-1880), and then Wernicke (1848-1905), noticed that individuals with language impairment had lesions in a specific part of the left hemisphere of the brain. Paul Broca’s patient “Tan”. Post-mortem autopsy, 1861.

4. Language and the Brain: Background 1st studies that correlated specific areas of the brain with language were in the late 19th century. Broca (1824-1880), and then Wernicke (1848-1905), noticed that individuals with language impairment had lesions in a specific part of the left hemisphere of the brain. Context: Debates went back and forth at the time as to whether the brain had discrete components for completing different tasks (functional specialization) or worked as a whole. Broca’s and Wernicke’s studies were among the first studies that offered physical evidence for functional specialization.

5. Language and the Brain: Background Aphasia – A condition resulting from brain injury which impairs language use. Broca’s aphasia (aka non-fluent aphasia) – immense difficulty in speaking; drastic loss of both lexical items (cat, dog, apple) and functional items (the, is, does, etc.); loss of many grammatical abilities Wernicke’s aphasia (aka fluent aphasia) – full sentences are produced with much the same grammatical principles as normal individuals, but are typically meaningless:

6. Language and the Brain: Background Aphasia – A condition resulting from brain injury which impairs language use. Broca’s aphasia (aka non-fluent aphasia) : “Yes... ah... Monday... er... Dad and Peter H... (his own name), and Dad.... er... hospital... and ah... Wednesday... Wednesday, nine o'clock... and oh... Thursday... ten o'clock, ah doctors... two... an' doctors... and er... teeth... Yah.” (Goodglass & Geschwind, 1976) Wernicke’s aphasia (aka fluent aphasia) : “You know that smoodle pinkered and that I want to get him round and take care of him like you want before.” (http://www.nidcd.nih.gov/health/voice/aphasia.html)

7. Language and the Brain: Structure The Nervous System Two main divisions: Central Nervous System (CNS): The brain and the spinal cord. Peripheral Nervous System (PNS): Interfaces with the CNS and the rest of the body: Somatic Nervous System (SNS): responsible for volitional control of muscles, also consists of sensory neurons. Autonomic Nervous System (ANS): responsible for involuntary reactions, breathing, heart rate, etc. Neuron – The basic, cellular unit of the nervous system

8. Language and the Brain: Structure The two hemispheres are connected by the Corpus Callosum

9. Language and the Brain: Structure Each hemisphere contains four lobes. Broca’s area (red oval) – in the frontal lobe Wernicke’s area (yellow oval) – in the temporal lobe

10. Language and the Brain: Structure Frontal Lobe • responsible for planning, prediction, speech, discrete body movement • separated by the central sulcus and the lateral fissure central sulcus lateral fissure

11. Language and the Brain: Structure • Temporal Lobe • responsible for audition, memory processing and sensory integration • separated by the lateral sulcus • contains the superior temporal gyrus – auditory cortex superior temporal gyrus lateral fissure

12. Language and the Brain: Structure • Parietal Lobe • responsible for reading, tactile sensations, pain • separated by the central sulcus and the lateral fissure • contains the angular gyrus – plays a role in reading central sulcus angular gyrus lateral fissure

13. Language and the Brain: Structure • Occipital Lobe • responsible for visual processing • located behind the angular gyrus angular gyrus

14. Language and the Brain: Lateralization Many physiological functions are lateralized to one side of the brain or the other. Language is left-lateralized in about 90% of the population. Evidence: Broca and Wernicke: discovered lesions in specific areas of the left side of the brain in aphasic individuals. The planum temporale is larger in the left hemisphere than its corresponding area in the right hemisphere. This difference is more pronounced in fetal brains (31 weeks), suggesting a preparation for language acquisition. Planum temporale: the heart of Wernicke’s area

15. Language and the Brain: Lateralization: Evidence Cortical and Subcortical Aspects of Speech and Language Experiments on specific sites in the brain of conscious patients show that many parts of the brain are functionally specified, with language activities consistently showing up on the left side. The thalamus and basal ganglia have also been implicated in language processing, but exact details are far from clear.

16. Language and the Brain: Lateralization: Evidence Contralateralization Each half of the brain receives input from and sends signals to the opposite side of the body (contralateralization).

17. Language and the Brain: Lateralization: Evidence Contralateralization Patients with damage on one side of the brain may suffer seizures on the opposite side of the body. In severe cases of epilepsy, the corpus callosum (the bundle of fibres linking the two halves of the brain) is severed (split-brain individual). In split-brain individuals, information received on one side of the brain cannot be relayed to the other side of the brain. If an image or word is shown to the left field of vision of a split-brain individual, this information is received only by the right side of the brain (due to contralateralization). This information is not sent to the left side of the brain (where language is processed – lateralization). Thus, split-brain individuals cannot name objects or read words presented to the left field of vision, although they still recognize objects and know what they are used for. http://www.youtube.com/watch?v=lfGwsAdS9Dc

18. Language and the Brain: Lateralization: Evidence Dichotic Listening Research Test subjects are given different stimuli to each ear via headphones. For example, the left ear hears ‘base’ and the right ear hears ‘ball’ It is found that speech stimuli given to the right ear (which sends information to the left side of the brain) has an advantage  Right Ear Advantage It has been found that most language related stimuli (including such things as Morse code) are susceptible to the Right Ear Advantage, but non-linguistic vocalizations are not (such as laughing and coughing).

19. Language and the Brain: Lateralization: Right Side? What about the right side? There is evidence to suggest that the right hemisphere does play some role in language processing, but details are unclear due to: • methodologies, tasks, participants used in research • L2 and L3 effects • age and method of language acquisition • plasticity, damage, and recovery effects However, it is clear that damage to the left side of the brain in young children results in language-related functions being picked up by the right side of the brain. • This plasticity tends to disappear with age.

20. Aphasia Language functions in the left hemisphere of the brain are not uniformly distributed. Damage to any one specific area does not result in loss of all language function. Aphasia is any language impairment brought on by brain damage; however, there is a lack of uniform classification of types of aphasia. There are three widely accepted aphasia syndromes, however. Broca’s aphasia Wernicke’s aphasia conduction aphasia

21. Broca’s Aphasia Broca’s aphasia was originally assumed to be the result of a lesion in an area of the frontal lobe now known as Broca’s area. The cluster of symptoms associated with Broca’s aphasia typically results from more extensive damage, however. Broca’s area is close to the region of the brain that controls muscles involved in speech. symptoms: inability to speak clearly and fluently, speech is extremely laboured, function words are usually lacking as is inflectional morphology, once a string of words is finally uttered, it usually makes sense in the context of the conversation. It is believed that individuals who suffer from Broca’s aphasia can understand language input (speech uttered to them), there is some loss in comprehension. Broca’s patients are quite aware of their condition and the mistakes they make in speech and writing.

22. Wernicke’s Aphasia Wernicke’s aphasia results from a lesion in the temporal lobe – Wernicke’s area. Wernicke’s area is near the auditory cortex  Sufferers typically have severe loss of comprehension, although hearing itself is not affected. Symptoms vary, but usually include fluent speech with some minor problems related to word recall, and lack of clear meaning or any meaning at all in their utterances. Often sufferers will substitute phrases or words for individual lexical items that cannot be recalled. In severe cases, the patient will simply uses a nonce word. It is thought that Broca’s aphasia affects phonological systems, while Wernicke’s aphasia affects syntactic and semantic systems.

23. Conduction Aphasia results from lesions between the temporal lobe and the parietal lobe. It is thought that these are areas that are specifically responsible for associating meaning with form (sound). Patients exhibit fluent speech, but circumlocutions are frequent and there are aberrations in syntactic structure. Comprehension of oral and written material is only mildly affected. Conduction aphasia is thought to result from disruptions between the centres that control sound systems (phonology) and the centres that control structure and meaning (syntax and semantics, respectively)

24. Genes and Gene Function There is typically no one-to-one correspondence between genes and characteristics. Fallacious view: gene A characteristic A gene B characteristic B gene C characteristic C Realistic view: gene A characteristic A gene B characteristic B gene C characteristic C gene D characteristic D

25. Gene and Gene Function Genes encode proteins. FOXP2 – gene in humans foxp2 – gene in non-humans FoxP2 – gene product (protein) A gene is a section of a DNA molecule that contains a sequence of bases that functions as a unit. This sequence of bases encodes amino acids, which line up along an RNA molecule (1/2 a DNA molecule) and form a protein (a complex biomolecule comprised of a sequence of amino acids). Proteins have a multitude of functions in all living organisms such as tissue regeneration, respiration, digestion, transport of nutrients through the body, conversion of nutrients into products used by the organism. One recent approach to studying language is study the interaction between genes and language.

26. FOXP2 The first genetic link with language is FOXP2, a member of the FOX gene family. FOXP2 is a ‘regulatory gene’ – regulates the expression of other genes. FOXP2/foxp2 is highly conserved across many species (from yeast to humans). It is involved in brain and lung development and the development of the part of the brain used for bird songs. A family in Great Britain was found to suffer from a specific kind of language impairment that has the inheritance pattern as a single gene.  found to be a specific mutation on the FOXP2 gene. The description of the impairment has been controversial, but it either affects individuals fully or not at all. fMRI scans indicate various abnormalities in several parts of the brain implicated in speech and language processing, suggesting that FOXP2 is important in the development of these areas.

27. FOXP2 Linguistic studies (Myrna Gopnik) Specific grammatical errors: You got a tape recorders. I find a cops. I was make 140 box. He only got two arena. You make one points. Number agreement errors (also error in use of progressive) Neurophysiological studies (Faraneh Vargha-Khadem) General problems with facial muscle use. Problems afflict non-linguistic as well as linguistic phenomena (ex. Tongue movement) Problems in reproducing tapped rhythms

28. FOXP2 Exactly how FOXP2 affects language development is unknown. It may be directly related given its role in bird songs. It may related to motor control of vocal apparatus and not language per se. Recall that FOXP2 is a regulatory gene. One gene it regulates the expression of is CNTNAP2 – encodes for neurexin, which is expressed during the development of the human cortex. Specific mutations in CNTNAP2 are found to be correlated with a specific kind of heritable language impairment – the repetition of nonsense words. It is also been recently discovered that FOXP2 itself is regulated by other factors. Thus, the exact role of FOXP2 in language is far from clear.