Higher Order Brain functions:Brain correlates, Language, Speech Comprehension

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Neurological Basis of Behavior (PSY - 610)

Lesson42

Higher Order Brain functions

Objectives:

The students would be familiarized with the role of higher order brain functioning. This is the role of the

highly evolved areas of the brain, the cerebral cortex.

Brain correlates

· a) Language Speech Production Comprehensions, Aphasias

· b) Visuospatial, The man who mistook his wife for a hat?

· c) Apraxias.( Neuropsychological tools)

· d) Brain correlates of Learning and Memory, Amnesia, Verbal, Non verbal memory,

· e) (Neuropsychological tools)

When we refer to the higher order functioning we are focusing on the cortical control of major

functions. As we stated in our earlier chapters, the higher the animal on the evolutionary scale the more

the cerebral cortical control over these functions and development of newer functional connections.

Behavioral neurosciences is attempting to

Understand functions such as language, emotions, learning, memory and psychopathology,

Develop models to explain the function of cortical areas as they relate to behavior

We would discuss language which humans have evolved as specialized communication. This is not just

communication but language is intertwined with development of healthy and pathological behaviors

Language

This is among the most important higher order function, and is uniquely human but not so, because if

we look around us we can see examples of communication in other animals as well. For example, Bird

songs dog's growling are complex communication system, with the variation - which can communicate

the state of one dog to another even across species communication can take place through these

signals.

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Neurological Basis of Behavior (PSY - 610)

In the squirrel monkeys language comes under limbic control, in humans vocalization is both limbic

(non verbal: cries, groan, gasps,) and cortical (: verbal, and symbolic). The development of language

is based on capabilities already present in the nervous system.

Therefore the evolution of language involves

Appropriate development and evolution of cognitive and communication abilities and

apparatus. The abilities of primates are limited with categorization of calls i.e. the alarm calls

are different from the mating calls. These do not have the sophisticated mechanism for

variation as humans have.

A structure of language in a formal system of signs and symbols

Development of the language in children who have the capability of doing so

Speech is difficult (fairly impossible) for a non human primate and young humans as the

appropriate mechanisms have not developed physically. It is only about 50,000 years ago the tracts

and physical apparatus for language evolved (this is controversial and the brain and language

capabilities must have evolved together).

Language in Non Human Primates.

Communication Non human primates: primitive, gestures, postures, (more non verbal) calls of

different types: alarm, distress, territoriality threat but not complex communication such as, how

are you today? This is not possible for animals even the higher order primates (except for humans).

In innovative experiment carried out by Gardiner and Gardiner where they trained a chimpanzee

Washoe to communicate with humans using the American Sign Language. The chimpanzee learnt

over a hundred signs and exhibited capability of communication equivalent to two years (human)

with "slot grammar" such as a human child would use: long darkness for tunnel. However this

chimpanzee was not able to verbalize.

In primate's one call, one sound is communicating one message, whereas human language uses a

combination of a few sounds to lead to thousands of words (with intonations entirely different

interpretation, grammatical limitations and boundaries. The same sound uttered in different ways in

different situation leads to a different interpretation

However, many experimenters such as Premack and Premack have led us to rethink. First and

foremost man and chimpanzee share 96% genes it is possible that chimpanzee can develop language

as humans did.

Lana, a chimpanzee at the Yerkes Primate Institute, developed grammatical relationships on her

own such as saying "Lana wants banana" and connected novel strings of symbols using computer

and other symbols, innovation in picking up and expanding on the learnt words demonstrated that

there were capabilities in the primates closest to humans. There was not much learning by

interaction and socialization

We must understand that language development requires learning by interaction and socialization.

How does a child learn a language? Through imitation and reinforcement of the words expressed till

they become meaningful and can get the desired objects such as candy or food. Even human

children if brought up without such stimulation do not develop language even though they have the

capability of doing so. For example children reared by wolves don't have the human language; they

can only communicate like the wolves by snarling, growling or barking.

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Neurological Basis of Behavior (PSY - 610)

Speech Production and Comprehension (Carlson and Pinel)

In order to understand speech we move through the absence of speech. Stroke, accident or any other

traumas which lead to loss of speech.

One of the disorders of speech is Aphasia which is disorder of comprehension or production of

speech

Speech production: is based on several abilities: sensation and perception of the surrounding,

memories and imagination; connection between past and present, vocal capabilities, articulation

musculature.

Paul Broca a French neurologist described a patient who had great difficulty in producing speech.

Broca described the cases of 14 patients at a conference and his paper went unnoticed. These were

stroke patients who had middle cerebral arterial supply of blood to the Sylvain fissure affected

leading to similar difficulties. He then identified this area as inferior prefrontal cortex

Broca's aphasia( Aphasia: Greek word, A: without, phasia: speaking out): Broca's area in the

frontal lobe controls the musculature and other mechanisms (air vibrating in the vocal cords) and

damage to inferior left frontal lobe, The Broca's area contains motor memories of tongue, lips, jaw,

coordinated and sequenced movements. It lies adjacent to the controls of face and lip, though the

posterior parts of Cerebral Cortex want to say it but the frontal damaged area makes it difficult

Brocas aphasia: is mainly a disorder of expressive speech. This results in slow laborious and non

fluent speech. Broca's aphasics make an effort to locate words to express what they want to say,

they mispronounce words but usually come out with meaningful sentences. These aphasics have

difficulty in small grammatical mistakes such as the use of a, the, some, in, about (linking words)

They can articulate little words with grammatical meanings: Function words are difficult, but

content words come easily, as they can convey what the patient is trying to say, "Ah Monday, Ah

DAD, Paul and Dad, hospital... Wed.... 9p.m. (Goodglass 1976, p 278 cf Carlson 1994 and

Bridgeman 1988)

Their speech is telegraphic, and there is no impairment of speech comprehension

A series of Neuropsychological tests which can assess Broca's aphasia are for example:

A picture is shown to the patient where a horse and a cow are standing in the same posture. In one

picture the cow is kicking the hind leg of the horse with its hind legs, and the second picture the

kicking is reversed. There are questions of what is happening who is kicking who and where? The

correct grammatical order is required (Shwartz, Saffron and Marin 1980)

Task sequencing commands are also given, word order is disrupted because they difficulty in

carrying out a sequenced response. If this area is stimulated it leads to a coordinated movement,

lesioning blocks the coordinated sequence. Questions can be "Pick up a red ball and touch green

circle," difficulty in saying it is difficulty of muscles of speech production.

Speech Comprehension

In Speech Comprehension the areas in the auditory lobe are involved. Wernicke's area is located in

the Middle and Posterior region of Superior Temporal Gyrus.

The speech comprehension area collects information, matches, recognizes, and analyzes it and sends

it to the articulation areas (through the arcuate fasciculus). Recognition of a word involves

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Neurological Basis of Behavior (PSY - 610)

a) Sensation,

b) Perception

c) Memories of the sequencing of sound articulation.

Damage to this region leads to receptive speech disorder

Primary characteristic of Wernicke's aphasia is that the speech appears better than Broca's fluency

rhythm as the articulation intact but what they say does not make sense. However, they cannot recognize

the deficit. Poor speech comprehension and production of string of meaningless words characterizes

Wernicke's aphasia. Wernicke's patients are not aware of their problems with speech. Wernicke's

patients not aware of their problems are speech. They are not aware that people don't understand them,

or they are having any difficulty. What they say or hear is incomprehensible to them and others

Speech appears correct to a foreigner but to those who know the language it is nonsensical. As an

example,

When asked what do you do?

The patient replies, "Mista oxycge,wann tell happened when happened, herent, kell, cam ho, renrapiers"

and the patient is satisfied that he was answering the question

The neuropsychological tests for speech comprehension e.g. the Patient tested through questions of

receptive speech: point to pen, your nose,

The deficit is at the semantic level (meaning of the words) their deficit is in understanding speech and

its meaning

References:

1. Carlson N.R. (2005) Foundations of Physiological Psychology Allyn and Bacon, Boston

2. Pinel, John P.J. (2003) Biopsychology (5th edition) Allyn and Bacon Singapore

3. Bloom F, Nelson and Lazerson (2001), Behavioral Neuroscience: Brain, Mind and Behaviors (3rd

edition) Worth Publishers New York

4. Bridgeman, B (1988) The Biology of Behaviour and Mind. John Wiley and Sons New York

5. Brown,T.S. and Wallace.(1980) P.M Physiological Psychology

Academic Press New York

6. Bradshaw J.L. and Mattingley, J.B. (1995) Clinical Neuropsychology: Behavioral and Brain

Sciences. ACADEMIC PRESS

Note: References 2, 5, 6 more closely followed in addition to the references cited in text.

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