Answer:
Ethical    
Explanation:
Ethics defines the correct rules of behavior or conduct necessary during research. The researcher has a moral responsibility to safeguard research participants from any sort of harm.
Four ethical principles to be followed while conducting psychological research: 
1. To obtain informed consent.
2. Providing the right to withdraw anytime during the research.
3. Protecting confidentiality and anonymity.
4. To avoid deceptive practices.
 
        
             
        
        
        
Answer: see explanation below
Explanation: the synapse is the junction between the terminal of a neuron and either another neuron or a muscle or gland cell, over which nerve impulses pass. Typically when the same experiences trigger nerve responses over synapses, they are remembered (strengthened) leading to even faster responses very much like the muscle memory. The NMDA receptors (NMDARs) are glutamate-gated cation channels with high calcium permeability, very critical for the development of the central nervous system and various processes vital to learning, memory, and the formation of neural networks during development in the central nervous system (CNS). Since memories are assumed to be represented by vastly interconnected neural circuits in the brain, synaptic plasticity is key to learning and memory. In this, the NMDA receptor is very crucial for controlling synaptic plasticity (the ability of synapses to strengthen or weaken, in response to increases or decreases in their activity over time) and memory function. 
 
        
             
        
        
        
I'm not fully understanding your question could you please reword and retype it.
        
             
        
        
        
Answer: replacing held with clutched