The Association Cortex

The Neocortex

The Association Cortices (Brodmann’s Areas)

space ,time, motion, planning, decision making, emotional reactivity, memory,recall, etc.

HOW DO WE KNOW THIS?????

Association Cortices Across Species

Basic Properties of the Association Cortex

• At least 1 primary source of INPUT and OUTPUT from other cortical or sub-cortical brain areas

Thalamus: Gateway of Neural Information

• If you recall….– vision (hearing) made possible through the

travel of neuronal information from the retina (cochlea) to the occipital (temporal) cortex via lateral (medial) geniculate leaflet

• Pulvinar Nucleus: Parietal Assocation Cortex

• Lateral Posterior: Temporal Association Cortex

• Medial Dorsal: Frontal Association Cortex

Basic Properties of the Association Cortex

• Connections to and from the association cortex on vertical (columnar) and horizontal (lateral) axes

Spatial Representation of Vertical Inputs to Association Cortex

Basic Properties of Association Cortex

• Cells with similar functions aligned radially (for the most part)

• Any functionally similar cell groups that are aligned horizontally are done so through interneurons

Basic Properties of Association Cortex

• Contralateral information travels via the corpus callosum or anterior commissure

Disruption: Dyslexia

Damage to Association Cortices

• Frontal• Parietal• Temporal• Lesions and Ischemic Damage

to these cortices result in neglect or agnosias– Difference: Neglect= “Don’t See

It” vs. Agnosia= “See it, but Don’t Know It”

Frontal Damage

• Historical case study of Phineas Gage (1800s) and his new polarizing personality

Deficits of Attention, Decision Making, and Gratification

• Anterior cingulate cortex• Neuropathology of

ADD, for example

• Patients perform poorly

on Stroop Test

Deficits of Attention, Decision Making, and Gratification

• Orbitofrontal Cortex• Neuropathology of

OCD and antisocial

personality disorder,

for example

Deficits in Planning

• Dorsolateral Prefrontal

• Delayed Response

Task is a measure of planning deficiency

Delayed Response Task in Monkeys

Parietal Damage• Contralateral Neglect Syndrome (Visuospatial

Deficit of “Not Seeing”)

Primarily due to damage of right parietal association cortex

Temporal Damage• Agnosias (“Seeing, but Not Knowing”)• Great leisurely, science reading on these

syndromes by Oliver Sacks

-The Man Who Mistook His Wife for a Hat

- The Island of the Colorblind– Prosopagnosia– Appreceptive – Akinestopsia– Achromatopisa (*hereditary)

Prosopagnosia• The inability to differentiate and remember faces

due to damage of the inferior temporal lobe

Appreceptive Agnosia• An inability to differentiate and remember

objects due to damage of the posterior right

hemisphere

Akinestopsia• An inability to differentiate motion due to

damage of the medial temporal cortex (“A Life

In Still Frames”)

Achromatopsia• An inability to differentiate between colors

(“A Life in Black and White”) due to a hereditary

deficit resulting in improper brain development

Deep Brain Stimulation• A brain pacemaker• Novel treatment strategy

for Parkinson’s and

associative disorders like

OCD, ADD, and depression