Course 1 Flashcards
What is neuropsychology?
- Neuropsychology is the study of relationships between brain function and behaviour, and of the effects of brain damage upon psychological processes
- An independent scientific discipline that evolved out of its parent disciplines neurology and psychology
What is clinical neuropsychology?
- Clinical neuropsychology : the clinical application of knowledge about the effect of brain dysfunction on a person’s behaviour
- evaluation and measurement of cognitive and behavioural function through review of medical, educational and occupational history, interview, observation and psychological testing to form an opinion about the presence and nature of brain dysfunction.
What are 5 related disciplines to neuropsychology?
- Cognitive neuropsychology : the study of abnormal cognition in order to understand normal cognition
- it is a subdiscipline of cognitive psychology
- the focus is on understanding the workings of the mind, not the brain
- abnormal cognition is manifest in acquired brain injury or developmental disorder
- now more of a two-way street
- Cognitive neuropsychiatry : the application of models from cognitive psychology in order to understand cognitive underpinnings of psychopathology
- Neuropsychiatry, Behavioural Neurology, Cognitive Neurology
- medical disciplines (first-cousin relationship with clinical neuropsychology)
- Occupational Therapy
- functional impact of neuropsychological conditions
- Speech Pathology
- characterisation and diagnosis of language disorders
What can happen neuropsychologically in brain injury cases?
• There can be near-complete recovery
• It may not be possible to return to some pre-injury activities
• Not unusual that the pattern of injury on brain scan does not
predict abilities and impairments well
What is the brain theory? (12)
- Source of behaviour
- Consists of two almost symmetrical hemispheres
- Surrounded by cerebrospinal fluid (CSF) to cushion the brain and carry away waste
- Outer layer is the neocortex
- Bumps are gyri (singular: gyrus)
- Grooves are sulci (singular: sulcus)
- Large grooves are called fissures
- Longitudinal fissure separates the two hemispheres
- Lateral fissure separates the temporal and frontal lobes
- Commissures are connections between parts of the brain
- Corpus callosum is the largest, connecting the two hemispheres
- There are two of each lobe, one in the left hemisphere and one in the right hemisphere
What are the 3 Perspectives on Brain and Behaviour throughout history?
Mentalism
Dualism
Materialism
What is mentalism?
MENTALISM (Aristotle ~350 B.C.E)
• Aristotle among the first philosophers to develop theory of behaviour
• A nonmaterial ‘psyche’ responsible thought, perception, emotion, memory, and reasoning
• Psyche independent of the body and works via the heart
• ‘Psyche’ translates to ‘mind’
• Mentalism is the notion that the mind is responsible for behaviour
• Until the 2nd Century C.E the soul was thought to be housed in several body parts, with intellect located in the head
• Galen (130-200 CE) performed experiments using animals
• evidence that the brain was the centre of the nervous system and responsible for sensation, motion and thinking
What is dualism?
DUALISM (Descartes ~1600 CE)
• Wrote what is considered the first neuropsychology text Trait de L’Homme’
• Accepted the concept of the mind but argued the brain also had an important role in behaviour – mind/body interaction
• Body: is material like a machine and responds mechanically to events that affect it i.e., reflexes
• Mind: nonmaterial and could independently decide on a course of action
• Mind located in the pineal gland and modulated release of CSF via nerves to muscles to make them move – hydraulics!
• The cortex viewed as a protective cover for the pineal gland
• The mind-body problem: A person is only capable of having consciousness and rationality because of the mind, but how can a nonmaterial mind produce movements in a material body?
• Descartes also proposed animals do not have minds, that the mind develops with language (not until aged 7!), and that mental disorder impairs the mind, hence the term
“lost their mind”
• He urged scientists to study animals to find indicators of language and reasoning because this would support the presence of the mind
What is materialism?
Materialism (Darwin ~1800s)
• From the 19th Century to the present
• No need for a ‘mind’. Behaviour can be fully explained by workings of the nervous system
• Debate focused on how mental activities (cognitive processes) are organised in the brain
• An early idea (the localisationist view) proposed that specific mental functions were carried out by specific parts of the brain
• An alternative idea (the equipotential view) developed which argued that all parts of the brain were equally involved in all mental activity
What is the localisationist perspective?
- The first general theory to present the idea that different parts of the brain have different functions was developed by German anatomist Franz Josef Gall (1758-1828) and his colleague Johann Casper Spurzheim (1776-1832)
- Proposed that the cortex and its gyri were more than simply a protective covering for the pineal body!
- Showed that dissection of the corticospinal tract (motor pathway) resulted in contralateral movement difficulties in the body
- Also recognised that two hemispheres of the brain are connected by corpus callosum and can interact
- By the age of nine, Gall had formulated a hypothesis that good verbal memory was associated with bulging eyes
- Gall later explained this relationship: verbal memory was located in the front part of the brain, and when verbal memory was especially developed, the orbits were pushed forward
- Further developed this idea and termed it ‘localisation of function’
- A specific brain area controls each type of behaviour
- Gall’s descriptive neuroanatomy, based on his radically new and informative dissection techniques, was superior to that of his predecessors and contemporaries
- Gall and Spurzheim proposed the cortex and its gyri were functioning parts of the brain
- The cortex sends instructions to the spinal cord to command movement of muscles
- Distnguished between grey and white matter
- Recognised two interconnected hemispheres
- But he also attempted to develop a functional anatomy that served the purpose of his doctrine of localisation
What were Gall’s Organology and Spurzheim’s Phrenology?
- Gall wanted to show that the brain was the undisputed organ of the mind and to identify the fundamental faculties and organs of the brain
- He relied mainly on comparative anatomy to develop his doctrine of organology, collecting hundreds of skulls and plaster casts of the heads of living and deceased humans and animals
- Gall attempted to correlate physical aspects of the skulls and plaster casts of heads with prominent characteristics of human and animal behaviour or human personality
- Gall proposed the brain was composed of multiple interconnected organs, each responsible for a separate behavioural characteristic, based on two assumptions:
- If a faculty, power, or trait was prominent or well developed in an individual, the area of the brain responsible for that trait also must be “well developed” or “prominent”
- If an area of the brain responsible for such a trait was prominent, the portion of the skull that covered this region likewise would reflect this difference by being more prominent (bulging)
- Gall and Spurzheim later had a falling out, due to differing views about scientific investigation:
- Gall had tried to determine the existence of faculties through observation and experimentation, retrospectively
- Spurzheim leaned toward a prospective approach, viewing phrenology as a way of predicting behaviour
- He became more concerned with the popularisation of phrenology than with further scientific investigation and evaluation of the doctrine
- The hallmark contribution of phrenology though, was the idea of localised functions.
- After the rift, Spurzheim published his version of localisation and successfully created the phrenological movement
- He modified Gall’s original organology in terms of both the number, character, and location of the faculties
- Spurzheim’s term phrenology became popularly accepted to represent both Gall’s and his own versions of the doctrine of localisation, and it also became a generic term applied to other versions of localisation
What is equipotentiality?
• French physiologist Pierre Flourens (1794-1867) insisted that the brain was a homogeneous substance similar to, for instance, the liver in its physiological functioning
• Flourens viewed the brain as having some degree of localised function, but also argued that the cerebral cortex could not be divided into functional units (all parts of the cortex were responsible for intelligence, the will and perception)
• After removing the cerebral hemispheres of pigeons, he noted they remained in a state of perpetual sleep
• They would open their eyes if disturbed, but quickly return to their quiescent state
• Flourens concluded that when deprived of the entire cerebral cortex, these animals lost all higher cognitive abilities, including sensation, judgment, memory and volition, while retaining basic motor skills
• Flourens surgically removed parts of the brains of animals:
• If small lesions were made (regardless of localisation on the cortex) no behavioural effects were noted
• As larger amounts of cortical tissue were removed, behavioural deficits became apparent, and with sufficient loss of brain mass might be lost completely
• Yet all of the various functions seemed to decline (or be lost) at the same rate, at the same time, again regardless of the particular site of the lesion
• He also noted that when a function was lost as a result of a circumscribed cortical lesion, it frequently would be restored over time
• Regions were equipotential in nature
He concluded that “The cerebral lobes are the exclusive site of sensations, perceptions and volitions, but these functions concurrently occupy the same areas. Therefore the ability to feel, to perceive and to desire constitute only one essentially single faculty”
• Flourens was influential and had a significant negative impact on the credibility of Gall’s organology
• BUT this critique would hold back the ultimately accepted concept of discrete localisation of brain function for more than 40 years
What is the Localisation and Lateralisation of Language?
• Gall’s ideas survived and experienced a renaissance in the 1860s, mainly as a result of the efforts of a French neurologist, Jean-Baptiste Bouillaud (1796-1881)
• Gall had localised the memory of words and the sense of language in the orbital portion of the inferior surface of the frontal lobe
• Bouillaud was an enthusiastic supporter of Gall’s scientific work, and accumulated many clinical cases in which he established what he believed to be a link between frontal lobe damage and loss of speech
• Ernest Auburtin (1825-1893) was also a firm believer in Bouillaud’s hypothesis and argued strongly for the localisation of speech to the frontal lobes
• he issued a challenge, offering to renounce his views if autopsy showed the frontal lobes were intact in a patient he had recently followed
• Five days after hearing Aubertin’s conviction, Paul Broca (1824-1880) examined M. Leborgne, who was able to say only the word “tan” (and a few obscenities)
• he had paralysis on the right side of his body but in other respects seemed intelligent and normal
• the muscles needed for speech appeared to be preserved and no disturbances in comprehension of spoken language were observed
• Examination of Tan’s brain revealed many infarcts, including a large area of damage in the left frontal lobe
• But the damage observed in Tan’s brain did not correspond to Gall’s prominences labelled 14 (memory of words) and 15 (sense of language and speech) on the
orbital surface of the frontal lobes
• the most prominent lesion was in the inferior convolution (gyrus) of the frontal lobe
• By 1863 Broca had seen many cases who had lost speech and were paralysed on the right side
• lesions were restricted to the posterior part of the inferior convolution (gyrus) of the left frontal lobe
• localisation of language and lateralisation of function
• the anterior speech region of the brain is now known as Broca’s area; the syndrome resulting from its damage is
Broca’s aphasia
• Although never formally acknowledged by Broca, Gall’s
legacy underpinned the foundations of modern localisation
and lateralisation of function
• Carl Wernicke (1848-1904) saw cases different from those
reported by Broca:
• aphasia was associated with left hemisphere damage in
the superior temporal gyrus
• there was no opposite side paralysis
• patients spoke fluently but did not make sense
• patients could hear but could not understand or repeat
• This syndrome is called Wernicke’s aphasia and the
associated region of the temporal lobe (the posterior region of the superior temporal gyrus) is called Wernicke’s area
What goes Beyond Localisation and Lateralisation of Cognition?
- Norman Geschwind (1926-1984) developed the model further, recognising that cognitive deficits could arise due to disconnection between functioning local areas
- disconnection syndrome : “wiring fault”
- e.g., pure alexia (“pure word blindness”)
- visual processing areas are disconnected from Wernicke’s (word meaning) area
- the Wernicke-Geschwind model
- Connectomics: cognition is the emergent property of network traffic
- Neuroplasticity: reminiscent of equipotentiality
