Understanding the Brain

Cognitive neuroscience

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Cognitive neuroscience is an academic field concerned with the scientific study of biological substrates underlying cognition,[1] with a specific focus on the neural substrates of mental processes. It addresses the questions of how psychological/cognitive functions are produced by the brain. Cognitive neuroscience is a branch of both psychology and neuroscience, overlapping with disciplines such as physiological psychology, cognitive psychology and neuropsychology.[2] Cognitive neuroscience relies upon theories in cognitive science coupled with evidence from neuropsychology, and computational modelling.[2]

Due to its multidisciplinary nature, cognitive neuroscientists may have various backgrounds. Other than the associated disciplines just mentioned, cognitive neuroscientists may have backgrounds in these disciplines: neurobiology, bioengineering, psychiatry, neurology, physics, computer science, linguistics, philosophy and mathematics.

Methods employed in cognitive neuroscience include experimental paradigms from psychophysics and cognitive psychology, functional neuroimaging, electrophysiology, cognitive genomics and behavioral genetics. Studies of patients with cognitive deficits due to brain lesions constitute an important aspect of cognitive neuroscience (see neuropsychology). Theoretical approaches include computational neuroscience and cognitive psychology.

Historical origins

Although the task of cognitive neuroscience is to describe how the brain creates the mind, historically it has progressed by investigating how a certain area of the brain supports a given mental faculty. In other words, for most of its history, the biggest question of cognitive neuroscience was "Where?" We could begin with Aristotle, who argued that sensory information went from the senses to the heart, which he thought was the seat of reason. Later observers correctly identified the brain as the biological substrate for thinking. However, early efforts to subdivide the brain proved problematic. The phrenologist movement failed to supply a scientific basis for their theories and has since been rejected. However, the phrenological assumption that specific areas of the brain conduct specific functions still applies. The modern evidence for this specificity (sometimes called modularity) includes direct recording from single neurons, case studies of patients with brain damage or disease, recording of electrical or magnetic activity in the brain through advanced scanning techniques, and even direct manipulation of brain activity.

File:Phrenology-journal.jpg
A page from the American Phrenological Journal

Phrenology

The first roots of cognitive neuroscience lie in phrenology, which was a pseudoscientific approach that claimed that behavior could be determined by the shape of the scalp. In the early 19th century, Franz Joseph Gall and J. G. Spurzheim believed that the human brain was localized into approximately 35 different sections. In his book, The Anatomy and Physiology of the Nervous System in General, and of the Brain in Particular, Gall claimed that a larger bump in one of these areas meant that that area of the brain was used more frequently by that person. This theory gained significant public attention, leading to the publication of phrenology journals and the creation of phrenometers, which measured the bumps on a human subject's head. While phrenology remained a fixture at fairs and carnivals, it did not enjoy wide acceptance within the scientific community.

Aggregate field view

Pierre Flourens, a French experimental psychologist, was one of many scientists that challenged the views of the phrenologists. Through his study of living rabbits and pigeons, he discovered that lesions to particular areas of the brain produced no discernible change in behavior. He proposed the theory that the brain is an aggregate field, meaning that different areas of the brain participated in behavior.

Localizationist view

Studies performed in Europe by scientists such as John Hughlings Jackson caused the localizationist view to re-emerge as the primary view of behavior. Jackson studied patients with brain damage, particularly those with epilepsy. He discovered that the epileptic patients often made the same clonic and tonic movements of muscle during their seizures, leading Jackson to believe that they must be occurring in the same place every time. Jackson proposed that specific functions were localized to specific areas of the brain,[3] which was critical to future understanding of the brain lobes.

The emergence of neuropsychology

Broca's area and Wernicke's area.

In 1861, French neurologist Paul Broca came across a man who was able to understand language but unable to speak. The man could only produce the sound "tan". It was later discovered that the man had damage to an area of his left frontal lobe now known as Broca's area. Carl Wernicke, a German neurologist, found a similar patient, except that this patient could speak fluently but non-sensibly. The patient had been the victim of a stroke, and could not understand spoken or written language. This patient had a lesion in the area where the left parietal and temporal lobes meet, now known as Wernicke's area. These cases strongly supported the localizationists' views, because a lesion caused a specific behavioral change in both of these patients. The studies of Broca and Wernicke spawned a new research field, which studies the relationship between psychological phenomena and lesions (or otherwise induced deficits) of the brain: neuropsychology.

Mapping the brain

In 1870, German physicians Eduard Hitzig and Gustav Fritsch published their findings about the behavior of animals. Hitzig and Fritsch ran an electrical current through the cerebral cortex of a dog, causing the dog to produce characteristic movements based on where the current was applied. Since different areas produced different movements, the physicians concluded that behavior was rooted at the cellular level. German neuroanatomist Korbinian Brodmann used tissue staining techniques developed by Franz Nissl to see the different types of cells in the brain. Through this study, Brodmann concluded in 1909 that the human brain consisted of fifty-two distinct areas, now named Brodmann areas. Many of Brodmann's distinctions were very accurate, such as differentiating Brodmann area 17 from Brodmann area 18.

The neuron doctrine

In the early 20th century, Santiago Ramón y Cajal and Camillo Golgi began working on the structure of the neuron. Golgi developed a silver staining method that could entirely stain several cells in a particular area, leading him to believe that neurons were directly connected with each other in one cytoplasm. Cajal challenged this view after staining areas of the brain that had less myelin and discovering that neurons were discrete cells. Cajal also discovered that cells transmit electrical signals down the neuron in one direction only. Both Golgi and Cajal were awarded a Nobel Prize in Physiology or Medicine in 1906 for this work on the neuron doctrine. The neuron doctrine has ever since provided a fundamental theory for understanding neurophysiology.

The birth of cognitive science

On September 11, 1956, a large-scale meeting of cognitivists took place at the Massachusetts Institute of Technology. George A. Miller presented his "The Magical Number Seven, Plus or Minus Two" paper while Noam Chomsky and Newell & Simon presented their findings on computer science. Ulric Neisser commented on many of the findings at this meeting in his 1967 book Cognitive Psychology. The term "psychology" had been waning in the 1950s and 1960s, causing the field to be referred to as "cognitive science". Behaviorists such as Miller began to focus on the representation of language rather than general behavior. David Marr's proposal of the hierarchical representation of memory caused many psychologists to embrace the idea that mental skills required significant processing in the brain, including algorithms.

Cognitive neuroscience

Before the 1980s, interaction between neuroscience and cognitive science was scarce.[4] The term 'cognitive neuroscience' was coined by George Miller and Michael Gazzaniga[4] "in the back seat of a New York City taxi"[5] toward the end of the 1970s. Cognitive neuroscience began to integrate the newly laid theoretical ground in cognitive science, that emerged between the 1950s and 1960s, with approaches in experimental psychology, neuropsychology and neuroscience. (Neuroscience was not established as a unified discipline until 1971[6]). In the very late 20th century new technologies evolved that are now the mainstay of the methodology of cognitive neuroscience, including TMS (1985) and fMRI (1991). Earlier methods used in cognitive neuroscience includes EEG (human EEG 1920) and MEG (1968). Occasionally cognitive neuroscientists utilize other brain imaging methods such as PET and SPECT. In some animals Single-unit recording can be used. Other methods include microneurography, facial EMG, and eye-tracking. Integrative neuroscience attempts to consolidate data in databases, and form unified descriptive models from various fields and scales: biology, psychology, anatomy, and clinical practice.

Cognitive neuroscience topics

Cognitive neuroscience methods

Experimental methods of specific psychology fields include:

Related WikiBooks

See also

Notes

  1. Gazzaniga, Ivry and Mangun 2002, cf. title
  2. 2.0 2.1 Gazzaniga 2002, p. xv
  3. Enersen, O. D. 2009
  4. 4.0 4.1 http://www.petemandik.com/philosophy/papers/brookmandik.pdf
  5. Gazzaniga et al. 2002, p.1
  6. Society for Neuroscience. Date of the first meeting of the Sociefy for Neuroscience

References

Further reading (Academic journals)

  • Acoustical Society of America
  • American Journal of Audiology
  • Attention, Perception, and Psychophysics
  • Auditory Research
  • Behavioural Neuroscience
  • Behavioural Brain Research
  • Brain
  • Brain Research
  • Cerebral Cortex
  • Clinical and Experimental Neuropsychology
  • Clinical Neuropharmacology
  • Clinical Neurophysiology
  • Clinical Neuropsychology
  • Clinical Neuroscience Research
  • Clinical Neuroscience
  • Cognition
  • Cognitive Brain Research
  • Cognitive Psychology
  • Cognitive Neuroscience
  • Consciousness and Cognition
  • Current Opinion in Neurobiology
  • Developmental Brain Research
  • Emotion
  • Electroencephalography and Clinical Neurophysiology
  • European Journal of Neuroscience
  • Experimental Neurology
  • Experimental Psychology
  • Glia
  • IEEE Transactions on Neural Networks
  • Hearing Research
  • Hippocampus
  • Human Brain Mapping
  • Human Neurobiology
  • Intelligence
  • Journal of Cognitive Neuroscience
  • Journal of Computational Neuroscience
  • Journal of Experimental Psychology: Human Perception and Performance
  • Journal of Experimental Psychology: Learning, Memory, & Cognition
  • Journal of Neurobiology
  • Journal of Neuroscience
  • Journal of Neuroscience Methods
  • Journal of Neurophysiology
  • Journal of Vision
  • Memory and Language
  • Nature
  • Nature Neuroscience
  • Neural Computation
  • Neural Networks
  • Neural Systems
  • Neurobiology of Aging
  • Neurochemical Research
  • Neurocomputing
  • NeuroImage
  • Neuron
  • Neuropsychologia
  • Neuropsychology
  • Neuropsychopharmacology
  • NeuroReport
  • Neuroscience
  • Neuroscience Letters
  • Neuroscience Research
  • Optical Society of America
  • Otology and Neurotology
  • Perception
  • PLoS One
  • PLoS Biology
  • Psychological Science
  • Progress in Brain Research
  • Progress in Neurobiology
  • Psychological Review
  • Quarterly Journal of Experimental Psychology
  • Science
  • Social neuroscience
  • Synapse
  • Trends in Neurosciences
  • Trends in Cognitive Sciences
  • Vision
  • Vision Research
  • Visual Cognition
  • Visual Neuroscience

External links