Chapter 2 Cognitive Psychology

Neuron Function

Transmit and receive info

How were neurons discovered?

• 19th century: brain tissue was stained, revealing a continuous nerve net (Camillo Golgi)

• Ramon y Cajal later discovered the neuron doctrine: individual cells transmit signals in the nervous system, but not continuously

Neuron parts

• Cell body: metabolic center

• Dendrites: receive signals

• Axons: transmit signals

• Synapse: gap between neurons

Neural circuits

Interconnected neurons responsible for processing

Receptors

Specialized neurons for the envionment

Resting potential

The difference between the charges inside and outside the neuron when at rest (-70 mV)

Action potential

40 mV

• :Low-intensity: slow firing

• High-intensity: fast firing

Neurotransmitter

Chemical released by axons in response to action potentials

Principle of neural representation

Everything we experience is based on representations in the neural system

Feature detectors

Neurons that respond to visual features or more complex features that make up environmental stimuli

• Hubel and Weisel found that cats responded more to vertical lines than horizontal ones

Experience dependent plasticity

Neurons develop to respond most effectively to exposed stimulation

Hierarchical processing

Occurs from lower to higher areas of the brain

Sensory code

How firing neurons represent environmental characteristics

Specificity coding

Representation of a stimulus by the firing of specialized neurons for that specific stimulus

Population coding

Representation of a stimulus by the pattern firing several neurons

Sparse coding

Representation of a stimulus by a pattern of firing only a small group of neurons, with most being silent

Cortical equipotentiality

Brain operates as a whole, not in specialized areas

Broca’s area and aphasia

• Area: place in frontal lobe where judgement if formed

• Aphasia: Damage to Broca’s area, difficulty forming words

• B for building words

Wernicke’s area and aphasia

• Area: in temporal lobe, helps understand language

• Aphasia: difficulty understanding speech

Prosopagnosia

Inability to recognize faces, caused by damage to the lower right side of the temporal lobe

• Area is called the fusiform face area

fMRI

• Measures change in blood flow in response to cognitive activity, shows localization

Structural MRI

Measures hydrogen to show brain structure

Neural networks

Interconnected brain areas

• Functional connectivity: extent of correlation in brain areas

Track-weighted imaging

Determining connectivity via diffusion in nerve fibers

Default mode network

Structures that respond without specific task involvement

Parahippocampal place area

Responds specifically to places (indoor/outdoor scenes)

Extrastriate body area

Responds to pictures of bodies and body parts

Distributed representation

Idea that specific cognitive functions active many brain areas

Central principle of cognition

Most of our experience is multidimensional, affected by several parts of the brain

Electroencephalogram

Measures gross electrical activity in the brain