Lecture 5 - binding and schizophrenia

Question 1

How do we know V5 is involved in motion?

Answer 1

Patient MP had bilateral lesions of V5 and this caused akinetopsia.

Question 2

Temporal binding

Answer 2

the solution to the binding problem. A unified percept is created as distributed neural responses are tied together by the coordinated timing of their firing patterns. This synchrony is associated with repeated, oscillatory activity. Cells firing in synchrony form cell assemblies that collectively represent a given object at a moment in time. This shared timing tags specific cells as sharing the same “message” and links the features of an object together.

Question 3

Glutamate and GABA in schizophrenia

Answer 3

GABA is a neurotransmitter that suppresses activity in neurons (inhibitory). There is decreased activity of this neurotransmitter associated with schizophrenia. Whereas glutamate is used to transfer messages rapidly and schizophrenia results in decreased activity at the NMDA subtype of glutamate receptors. There are links between inhibitory and excitatory neurons. However, There is altered excitation-inhibition connectivity between neurons in schizophrenia. Inhibitory neurons modulate excitation via NMDA (glutamate) receptors. When a message is sent from the excitatory neuron to the inhibitory neuron, it feeds back that message to the neuron through GABA to suppress its activity. However, ​​decreased NMDA receptor signalling disrupts excitation monitoring and feed-back inhibition. This results in too little or too high excitation. This means either the breaks are taken off the neurons or the cell is going to fire in bursts, which has important implication on brain oscillations (rhythms).