Brain Sensory systems

The function of a sensory system is to select suitable modalities from the multitude presented by the environment, and translate them into corresponding modalities of sensory information that are then projected and processed into the various parts and finally submitted to the central processing-unit, the brain. A working hypothesis of the mechanism by which the taste system senses chemical compounds is that macromolecules that are... 

Nervous system disorders are diagnosed by examining the patient s mental status, cranial nerve function, motor system reflexes, and sensory systems. An electroencephalogram (EEG) tests higher brain and nervous system functions. 

In brain slices, even though no anesthesia is present, there is a reduction in both noradrenergic and other inputs to these cells (e.g., from sensory systems) thus most of these neurons become silent. Consistent with this interpretation is the fact that all presumed serotonergic neurons we have tested in the brain slice are uniformly activated by norepinephrine or the < ragonist phenylephrine, applied either iontophoretically or in the perfusion medium (51). Similarly, in... 

So it would appear that the brain alertness systems can either be cranked up to a hyperattentive level such that one hears voices and ascribes malevolent intentions to them, or cranked down to so low a level that intrinsic pseudo-sensory signals cause us to see and feel things that we cannot integrate cognitively because our short-term memory capacity is simultaneously disenabled. 

Sensory neurons transduce physical stimuli, such as smell, light, or sound, into action potentials, which are then transmitted to the spinal cord or brain. Sensory neurons, which bring information into the central nervous system, are also referred to as afferent neurons. Motor neurons transmit nerve impulses away from the brain and spinal cord to muscles or glands and are also called efferent neurons. Intemeurons transmit nerve impulses between sensory neurons and the motor neurons. Interneurons are responsible for receiving, relaying, integrating, and sending nerve impulses. Intemeurons are found exclusively in the central nervous system and account for almost 99% of all the nerve cells in the body. 

Human perception is the active reception and coordination of information received through our sensory systems in order to make sense of the environment and to behave effectively within it. In contrast with the direct and immediate sensations actually received and transmitted, perception is the transformation of that information into nerve cell activity that is transferred to the brain where further processing occurs. Our perceptual systems do not passively receive stimuli from the world, instead they actively select, organize, interpret, and sometimes distort sensory information. The real world then may not be the same as the one we perceive. Broadly, perception can be said to be the study of the human organism s relation to the physical world. 

There are more things in the world than there are possible behaviours. Thus, in order to fulfil the needs of life, the things in the outside world need to be funnelled into far fewer behavioural matters of concern. Integrating the sensory system with the biological needs to come up with appropriate behaviour is what brains have evolved for. It is this triad of things, needs and actions that neurobiology needs to understand. 

Action potentials can be recorded from the primary auditory neurons that transmit information about sound and from the pulse vestibular neurons that transmit information about head position to the brain. Fractal behavior is ubiquitous in these and other such sensory systems [42]. Without including the references given by Teich et al. [42], we quote their review of the evidence for this observation ... 

Nature uses chemical signalling in sensory systems snch as taste and smell. The most important means for information processing in nature is based on information exchange between DNA and RNA our brain use signals relying on the behaviour of ions, etc. This... 

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