Luokat: Kaikki - schizophrenia - neurons

jonka Joerg Bauer 15 vuotta sitten

539

Schizophrenia

The relationship between schizophrenia and the synchronization of electrical synapses in the brain is examined, particularly through the role of NMDA receptors. These receptors, located throughout the brain, are integral to the synchronization of neuronal oscillations.

Schizophrenia

Q2 Schizophrenia

Symptoms of sciciphrenia

Negative Symtoms
Social Withdrawal
Cognitive Impairments

undordered thinking

Inabiltiy to focus attention

Inabilty of filtering out unimportant stuff

Positive Symptoms
Hallucinations

Auditory

Visual

hyothesis

Schizo vs. Epilepsy
However the missing sync is only oneof the problems in schizo - also problems in attention
Epilepsy caused by the synchronous firing of many neurons ending inSeizure

Perhaps missing sync in schizo causes 2 "I" s one of which is less dominant and only heard

Schizophrenia could be seen as a mild for of Epiliepsy

Drug work by decreasing efficacy of overactive sodium channel

Perhaps those very fast electrical synapses syncronize other connected neurons with the help of those NDMA coincidence detectors.
Perhaps solution to major problem of communication: in brain if 2 neurons oscillate at the same speed the information belongs together
Book 1 Page 142 Binding Problem:there is no sinlge point where information flows togher: Where is shape colour category and sound of a car connected into one unified perception or awarness of a car

How much are NMDA receptors and Oscillations linked?Evidence in Book? / Plausibility from knowledge of Book?

Article
Ocillations

Where

not stated

What?

Disrupted patterns of oscllations seen in Schizophrenia

NMDA

What ...

Disrupted Oscillations

Lacking or malfunctioningNMDA receptors as causal

Where ...

Generally in the brain

Role in Interneurons

Books
Where does one find NMDA receptors?

Book: Amygdala

Cole in fear conditioning

Book: Hippocampus

Role in Learning / LTP (Book 5 Chapter 1)

What is a NMDA Receptor?

Hebbian Learning

Hebbian Synapse

A synapse that can be modiefied / made more efficient

In hebbian one neuron mightnot cause the other one to firebut be merely active at the same time

Modification of the synapse: Learing is increasing the efficiency of firing

By firing the post synaptic neuron is modified to work more efficient next time(more likely to fire)

Book 4 page 24Glutamate acts on many different types of receptor. One type, called the N-methyl-D-aspartate receptor (or NMDA receptor) is a neurotransmitter-gated ion channel that,unlike most other glutamate receptor-channels, is permeable to calcium ions. Inappropriate activation of this receptor induces toxic levels of intracellular calcium which canultimately lead to cell death (this toxic mechanism, termed excitotoxicity, is largely responsible for the brain damage induced by ischaemia and stroke)

role memory andLearning

Book 39 role in the initiation of memory consolidation

STM-->LTM

LTM

Strong Activation of NDMA-->LTM

STM

Activation of NDMA-->STM

Book 4 Initiation of Protein synthesis needed to maintain LTP

role several types learning

Book Classical Conditioning

Book 38: especially spatial learning

Book 4 NMDA is a receptor in Hipporcampal Glutamatergic neurons=a Glutamate gated Ion channel

Book 4 Page24-NMDA receptor is malregulated it can be toxic

Book: The dual role of the NMDA receptor as an activity coincidencedetector and gateway for calcium entry during the induction of LTP

Book5: It is the influx of calcium ions into the postsynaptic cell, via the NMDA channel, that triggers the biochemical cascade that leads to the increase in synaptic efficiency

Book 5 page 35: NDMA receptor acts as a conincidence detector– it opens only when there is a conjunction of neurotransmitter in the synaptic cleft and a critical level of depolarization in the postsynaptic neuron, a temporal pairing of presynaptic and postsynaptic activation: a Hebbian synapse.

Book 4 Glutamate: The most widespread excitatory neurotransmitter in the brain but active i.e. in the hippocampus

Book 4 page 23:and aspartate excite virtually all neurons in the brain and spinal cord. Upon release from aglutamatergic terminal, glutamateis inactivated by reuptake intothe presynaptic and postsynaptic neurons

What are oscillations?

Role in the singalling of elctrical synapsesbook 4 page 14

What do they do?

Book: Current Fuction is only Speculative: Current data suggest that the role of gap junctions is to facilitate instantaneous electrical rhythmicity in populations of neurons, if not whole brain structures. It has even been speculated that ultra-high frequency oscillations represent the ‘mind’ itselfBook: Whilst the function of these gap junction oscillations remains amystery, it has been proposed that in the cortex and hippocampus they may be implicated in cognitive processing, sensory perception and certain forms of distributed memory formation."

Book: What and where Elctrical Synapses produces Oscillations:"In the retina of the eye, for example, they are involved in the local integration of electrical activity between ensembles of retinal cells. Elsewhere in the brain they are involved in the generation of high-frequency electrical oscillations, similar to those seen during an epileptic seizure.

Cognitive processing

Distributed Memoryformation

If whole modules are distributed I.e. an emotional memory and the emotion itself the firing of thosestructures may need to besynchronized.

If memory is ditributed, what belongs together has to be signalled somehow

Were do electircal synapses exist

Role in In hippocampus and Cortex

Role in the retina

(b) potential changes in brain oscillations and neurotransmitter function in schizophrenia correspond with the information presented in the course materials?(Hint: oscillations are mentioned in the course in the context of communications between neurons.)

Oscillations: Signal Theory

To what extent does the information presented in the article on (a) the general role of NMDA receptors and ...

Role of NDMA receptors
What does the book say?