feb 7 review

Feb 7 Review• Discussed how the concept of vector and vector space

applies to modeling the encoding of faces– Implications for facial concepts such as beauty and caricatures

• Discussed the goals of Hawkins book• Described the basic organizational features of the

cerebral cortex– The major regions of the cortex– The 6 layer structure of the cortex

• Discussed Hawkins insight regarding the shared architecture of all cortical areas– Described the basic features of architectural maps and their

arrangement into hierarchies

Feb 7 Review- con’t• Reviewed Churchland’s description of the architecture of

a facial recognition network– Principles of operation of a 3-layer network– Described how networks are trained via back-propagation– Differentiated between a training set and a testing set– Described how network can recognize degraded/occluded faces– Discussed the organization of the face space created and how

categories emerge (male/female)– Described the vector dimensions of the middle layer – holons– Described how basins of attraction induce categorization

Case Studies of Prosopagnosia

• A clinical case of prosopagnosia

• Oliver Sacks – The Man Who Mistook his wife for a hat

• Paintings of Chuck Close

• The Prosopagnosia of Close

LeDoux – Building the Brain

• Neural networks – the false dichotomy between nature and nurture

• The functions of proteins in developing architecture – guiding, scaffolding

• Steps in neural development

Origin of Nervous System

Differentiation of Major Regions

Cells arise from ventricle and then migrate

Similar to Figure 4.1 in LeDoux

The Role of Stem Cells

Differentiation and the development of processes

Cell death and synaptogenesis

Development of neuroconnectivity in infancy

Issue of Selection vs. Instruction• Historical Issues• The major tenets of selection

– Exuberance, use and subtraction• Hubel and Wiesel’s observations

– Visual cortical cells form columns that are sensitive to one eye

– In young animals cells respond to both eyes– If eye is suture, functional connections only develop to

good eye– Axons increase in complexity during development-

activity serves as instruction

Activity based Neuroconnectivity

• An alternative to back-propagation• Cells that fire together wire together –

Hebbian connectivity• Hebbian principle’s operation during

development- synchronized waves along retina

• Role of NMDA-glutamate receptors• Role of neurotrophins

Implications for Evolutionary Psychology

• A priori knowledge in classic nativism - innate ideas

• A priori knowledge innate predispositions– Plasticity present in all neural circuits within

systems• Fear [Garcia effect]• Language

• Neural network – nativism vs. constructionism - Elman / Quartz / Sejnowski

Ethology emphasize nativism

Predisposition to Learn- Constructivism

Garcia Effect- A classic study illustrating the interaction between nature and nurture

Nature and nurture in language

Williams Syndrome illustrates how plasticity is system specific

Although all motor maps are basically the same, Merzenich studied how they can be constructed by

experience

This principle has been applied to dyslexia by providing phonemic stimulation to dyslexic children