Cognitive Neuroscience: A Very Short Introduction

A Recent Field

• Visualization Techniques:
  • PET (Positron Emission Tomography) - 1980s
  • fMRI (Functional Magnetic Brain Imaging) - 1990s - the ratio of oxygenated to de-oxygenated blood.
• Help us learn about:
  • Human capacities
  • Human limitations
  • Disorders of the nervous system

Perceiving

• Lateral Occipital (LO) complex - an area that is activated when people recognize objects. Critical for the ability to use the ahape and orientation of an object to guide the way in which the hand approaches it.
• Information from vision, hearing, touch, and smell is relayed to from the sense organs to separate regions of the brain, which are referred to collectively as the primary sensory areas:
  • V1 - the primary visual area, with secondary areas V2, V3, V4, etc. The primary visual cortex relays information via these and other areas to the temporal lobe and the parietal lobe. These relays are termed the ventral and dorsal visual pathways.
• The brain has a parallel architecture with some choke points
• Localization of function - the brain is a patchwork of discrete areas. Each area consists of a host of neurons arranged in six layers, each layer being many neurons thick. The areas differ in the thickness of the layers, the density of the packing, and the frequency of the different types of neuron.
• The incoming connections determine the information that the area can process, the outgoing connections determine the influence that it can exert on other areas.
• The outside world is mapped onto the brain in a point-to-point fashion. The primary somatosensory area (S1) is a map of the body with different parts responding when the hands, body, or legs are touched. In the primary visual cortex (V1) there is a retinotopic map - the retina is mapped onto the cortex such that the location of the activity in the cortex depends on which part of the retina is stimulated by light.
• Because we use our hands for manipulating objects, much more tissue is devoted to the hand than to the foot. In the V1, more tissue is devoted to central than peripheral vision. In the centre of the eye there is a pit or fovea and it is here that there is the greatest density of light receptors. When we inspect an object is is with the fovea that we focus our gaze.
• Integration between sensory modalities is achieved by connections to common reas, and these are referred to as "multimodal" areas, including the parietal cortex and the prefrontal cortex. These areas are multimodal because they can be activated irrespective of whether the stimuli are visual, auditory, or tactile.
• Processing occurs via successive stages in the visual relay. The earlier stages process the elements and the later stages integrate them via a hierarchical arrangement in which each higher-order neuron in area B receives an input from many lower order neurons in area A, and so on up through the stages.
• Lower-order neurons respond maximally when we see an object from a particular view whereas higher-order neurons integtrate the information from lower order neurons and are thus able to learn to respond irrespective of the view to let us form a view-independent representation of the object.
• As a child we are taught