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TASK 8 (Article: A historical perspective on cognitive neuroscience…
TASK 8
Article: A historical perspective on cognitive neuroscience
• The Greeks first determined that the brain was the psychical sea of the mind
middle ages, the ventricles filled with cerebrospinal fluid were the focus of theories relating the mind and the brain
• During the Renaissance the ventricular doctrine began to lose influence and writings of René Descartes mark a transitional phase
• Franz Joseph Gall is together with Johann Spurzheim most famous for the general theory of cerebral localization (Phrenology)
• Jean-Baptiste Bouillaud (1825) presented a large series of clinical cases of loss of speech following frontal lesions
mid 1860s the issue of hemispheric asymmetry entered the debate on localization. In the debate Paul Broca who did not initially take a position, reported of one of his patients who suffered from epilepsy and loss of speech
o After the post-mortem analysis of Tan’s brain, localism seemed evident
• Edward Hitzig and Gustav Fritsch established that the motor functions are localized in the anterior cortex and demonstrated experimentally the somatotopic organization of the motor cortex
Connectionism
= models mental or behavioral phenomena as the emergent processes of interconnected networks of simple units
• John Hughlings Jackson however was one of the sceptics that viewed the nervous system not as a series of centers connected by pathways bus as a hierarchically organized and highly interactive whole
• In the 1960s/1970s a different approach than case studies was developed to study brain behavior relations = Expriments
• Patient based cognitive neuroscience was born when the theories and methods of cognitive psychology and neuropsychology were finally combined
•
Feature integration theory
= a theory of attention developed in 1980 that states that when perceiving a stimulus, features are registered early, automatically and in parallel while objects are identified separately
Ideas in Ancient Egypt and Ancient Greece
Edwin Smith Papyrus
= A series of 48 cases were described dealing with the consequences of head and neck injuries. One case includes the first known description of the brain’s interior
The roles of the heart and the brain in ancient Greece
Hippocrates and Plato placed the soul in the brain. According to Plato the soul was divided into three parts
1) Highest part = responsible for reasoning, situated in the brain. It came directly from the soul of the universe, was immortal and separated from the body
2) Second part = dealt with sensation, was mortal and situated in the heat. To avoid it polluting the divine soul, a neck was in between to separate them
3) Lower Part = dealt with appetite and was placed in the liver, far away from the other two
Aristotle
= he thought that the heart was the seat of the soul. The function of the brain, was to counterbalance the heat of the heart
Galen
= he started to experiment on animals. animal spirits in the ventricles communicated with the rest of the body. The spirits travelled between the soul and the organs via the nerves
Andreas Versalius 16th century
• Front ventricle – Common sense = receive information from the senses, includes also fantasy and imagination
• Second ventricle = middle of the head included thought and judgement
• Third ventricle = back of the head contained memory
development in 17th and 18th century
changing focus from ventricles to brian
Thomas Willis, published a book Cerebri Anatome in 1664. Many scholars started to doubt the existence of spirits in the nerves, hypothesizing that fluids flowed in them
Increased interest in reflexes (18th)
= some behaviors were elicited automatically as Galen had already mentioned as “sympathy”.
Descartes was interested in reflexive movements as well because they fitted within his mechanistic view of the body.
Jiri Prochaska
, Czech in late 18th century argued that reflexes were not controlled by the brain but by the spinal cord
The 5 breakthroughs of the 19th century
The discovery of the cerebrospinal axis
• There were many body functions that did not require the cerebral hemispheres. new view was established that the spinal cord together with the subcortical regions controlled the physical body functions
Growing focus on reflexes/ The reflex arc = Marshall Hall introduced the notion of the reflex arc to refer to the mechanisms involved in the involuntary movements elicited by sensory stimuli - Russia ->All higher functions of the brain were of a reflex nature. This influenced Pavlov who was a student of his
Localization of brain functions.
Brain equipotentiality theory
= view that the brain functions as a whole with all parts having an equal significance
Localization theory
= mental functions are localized in specific parts of the brain
Language production is controlled by the left frontal lobe
= in the 19th century/1861 Paul Broca presented evidence that speech problems showed widespread damage to the left frontal lobe only
Language understanding and the posterior part of the brain
= Karl Wernicke presented evidence in 1874that language problems could also result after damage to the rear part of the left hemisphere
Phyognomy = belief that personality can be deduced from the appearance in particular of the head and the face
The discovery of the nerve cell
The availability of better microscopes (19th)
New techniques to stain the brain tissue
= the Italian physician Camillo Golgi in 1873 used silver to color the brain tissue. • Santiago Ramon y Cajal made the staining method better
Disentangling communication in the CNS. Individual neurons instead of a continuous network
= the big question was whether the network was a continuous structure or whether in consisted of individual cells
The first to find empirical evidence for the involvement of electricity in the nervous system was Luigi Galvani in 1786. • Von Helmholtz measured in 1852 speed of signal transmission in the nerve to come to the conclusion that chemicals (neurotransmitter) are eliciting the electricity
The emergence of neuropsychology in the 20th century
Localization studies in the world wars
vision problems after shot wounds at the back of the head)
Gordon Holmes (1876-1965)
WWII Prosopagnosia
= a German physician described soldiers who lost their ability to recognize faces as a consequence of brain injury at the rear brain -> Joachim Bodamer (1947)
Neuropsychology = In the second half of the 20th century psychologists became involved in studying the behavioral consequences of brain injury. They started to call themselves neuropsychologists
A change of focus: Cognitive Neuropsychology
The localization issue turned out to address on the basis of human brain injuries
1) All that could be done was establishing correlations
2) The damage is usually widespread and not limited to a specific brain structure
The results of the examinations rarely went beyond a list of symptoms displayed by various patients
1) There was little theory, little effort to link the various findings and draw implications for normal functioning
2) Instead of looking for anatomical localizations neuropsychologists should investigate the functional implications of injuries
Deep dyslexia = landmark publication that referred to reading problems either caused by developmental factors or by brain damage
• Morton and Patterson (1980) postulated a distinction between a logogen system (lexicon) and a cognitive system (meaning of the word). They argued that there were three different logogen systems for visual, auditory and spoken words
• In patients with dyslexia only the third route is said to function
1) Grapheme conversion route = converts letters into sounds
2) Second route is said to have a direct connection between the visual and the output logogen system
3) The third route was important to name written words via the visual through the cognitive system and then to the logogen output
Brain Imaging and the turn to neuroscience
EEG recording
= in 1928
Hans Berger
published an article that would dramatically change brain research. He reasoned that if brain activity was electrical activity, he might be able to pick up some signals if he put electrodes on the human scalp
ERP and EEG = 2 applications became available
1) Measurement of changes in the electrical signal as a function of specific stimuli
2) One could try to localize the source of the electrical signal
Measuring blood flow in the Brain
PETm MRI, fMRI, TMS
In defense of cognitive neuroscience
= despite the doubts about whether brain imaging studies are able to provide anything more than the localization o brain activity, critics cannot deny that cognitive neuroscience deeply influenced psychological thinking and is likely to do so
Delusions
= strong erroneous beliefs that are not supported by empirical evidence
Joseph Capgras (1873-1959) Mm M. was a patient of Capgras suffering from delusions. Capgras published several papers on that case and started to interpret the delusions in terms of Freudian thinking
• Ellis & Young (1990) put forward the hypothesis that what might be happening in the Capgras delusion is that the unconscious, emotion-based face processing route has been injured -> such a disconnection would result in the patients still recognize the person at a conscious level but fail to experience the according emotional response
Article: The Galileo of neurology
Arthur Ladbroke Wigan (died 1847)
= was a british doctor who formulated the idea that the left and right cerebral hemispheres are not two parts of one organ but separated brains without own feelings and thoughts
• He claimed that delusions were orderly dialogues between the two brains
• Phantoms were produced by the sick brain in which the powers of observation must have been disturbed so it began to process non-existent stimuli
• Double consciousness was the phenomenon that patients seemed to have “two memories” that they could asses either while sleep walking or being conscious