Test: The Bases of Human Behaviour- 1 - Grade 11 MCQ

The neuron is the basic unit of the whole nervous system. Dendrites are a component of the neuron and glial cells provide support to neurons. The brain and spinal cord comprise the central nervous system.

The brain appears to solve complex problems to negotiate our environments by processing incoming information simultaneously (parallel) by different modules (modular) in the brain. Visual processing refers to a particular type of incoming information. Independent refers to the modular component of this information processing. Neuronal processing is not a term used to refer to differentiation of processing within the brain.

The nervous system has both central and peripheral components. The central part includes the brain and the spinal cord; the peripheral part includes the nerves through which the central nervous system interacts with the rest of the body. ‘Nerve’ is a familiar word and is used in various ways in ordinary conversation. But in psychology, we use it specifically to mean a cord of neuronal axons bundled together passing through the human body.
We have probably all had the experience of hitting our ‘funny bone’ – the discomfort is due to the compression of the ulnar nerve. Nerves are typically sensory (afferent) – carrying information to the central nervous system from sensory neurones whose cell bodies are located in the periphery of the body – or motor (efferent) – extending out from the central nervous system to the organs and regulating muscular movement or glandular secretion.

How do we solve complex problems of visual geometry so rapidly? The key lies in the brain’s parallel processing capacity. In principle, different aspects of a visual stimulus are analysed by different modules in the brain. One module may deal with form, another with motion, and another with colour. By splitting up the task in this way, it is possible to solve complicated problems rapidly. There might also be an evolutionary explanation for modularity in the brain.
To add a new perceptual analysis feature to our existing perceptual analysis systems, the simplest route would be to leave the existing analysis systems unchanged and simply ‘bolt on’ a new feature. The alternative would be to rewire and reconfigure all the existing systems to add the mechanisms for the new analysis. It is harder to imagine how this might happen without the risk of radically disrupting the pre-existing systems.
A computational stratagem like this poses new problems, however. There needs to be some way of ensuring that the different aspects of a stimulus, although processed separately, are none the less related to each other. A cricket ball heading towards you is red, shiny, round and moving. You need to know that these separate attributes all refer to the same object. How does our brain solve this problem? It is possible that the different brain regions analysing different aspects of the same stimulus show synchronized oscillations, which act to link these structures together.

Neurons come in many shapes – or morphologies – which give them their different functions, but all neurons share some basic similarities. The heart of the neuron is the cell body – the neuronal cell’s nucleus – and this is where the cell’s metabolic activities take place. Input from other neurons typically comes via the dendrites. These can be a relatively simple tuft of fine, fibre-like extensions from the cell body, or massive branches like the twigs and leaves of a tree.
The output of the neuron is transmitted via its axon to the dendrites of other neurons, or other targets such as muscles. Axons can be very long, reaching right down the spinal cord, or so short that it is difficult to tell them apart from the dendrites.
Some neurons have just a single axon, although it may still make contact with a number of different target cells by branching out towards its end. Other cells have axons that are split into quite separate axon collaterals, each of which may go to an entirely different target structure.

This research has shown that transplanted dopamine cell bodies create new synaptic connections where they can release dopamine in appropriate amounts, thereby suggesting that we can repair some types of damaged brains. This research cannot speak to prevention of brain damage, at least not at this time.

The three main components of the neuron include the cell body, dendrites and axon. Nerves comprise the peripheral nervous system. White matter refers to the part of the brain consisting mainly of axons rather than cell bodies. The terms in answer D do not refer to components of the neuron.

The question of whether it might be possible to induce the central nervous system to regenerate has taken a new turn since the early 1970s. At this time, it became clear that adult neurons can sometimes form new connections. If one input to a target area is lost, the remaining inputs sometimes send out new branches from their axons to colonize the vacant space.
If the transplanted neurons are themselves taken from a brain at the right stage of development, they will grow in an adult host brain and form new connections, leading at least to a partial restoration of normal function.
This has been most convincingly demonstrated in the dopamine system running from the substantia nigra to the caudate-putamen at the base of the forebrain. Destruction of this dopaminergic pathway leads to movement disorders in rats, and to Parkinson’s disease in humans (Hornykiewicz, 1973; Ungerstedt, 1971). Transplants of dopamine cell bodies lead to a clear restoration of some motor functions in the rat (Dunnett et al., 1981), and alleviate some of the symptoms of Parkinson’s disease in human patients (Hagell et al., 1999).

The autonomic system controls the internal environment. The sympathetic system prepares the body for action whereas the parasympathetic system returns the body to regular functioning. The somatic system is part of the peripheral system which enables us to interact with external environment.

One key element in LTP is a particular subtype of glutamate receptor, the NMDA receptor. Calcium entry into the cell is one of the triggers for the development of LTP. The NMDA receptor controls a calcium ion channel that is both transmitter dependent and voltage dependent. This means that even when the NMDA receptor is activated by glutamate, no calcium will pass into a cell through the NMDA-controlled channel unless the target cell has also recently been depolarized. So NMDA-dependent LTP can only develop in a cell that has been depolarized and then receives a further input – exactly the conditions that apply during a burst of high-frequency stimulation.
The LTP system, particularly in the hippocampus, has been a focus of intense research activity. Rat experiments have shown the blockade of the NMDA receptor by the drug AP5 prevents the development of LTP, and at the same time appears to prevent the normal operation of hippocampus-dependent spatial memory. More recently still, psychological studies of ‘knockout’ mice, genetically engineered so they can no longer show LTP in the hippocampus, have also shown striking failures of hippocampus-dependent spatial memory tasks that neatly parallel the effects on LTP.