Chapter 2 Brain Function and Structure PDF

Overview of brain function and structure: The brain’s primary function is to produce movement, and collectively these movements are termed behaviour. To produce effective behaviour, we take in sensory information (such as vision, audition, olfactory, gustation, and somatosensation) as we search, exp...

Overview of brain function and structure: The brain’s primary function is to produce movement, and collectively these movements are termed behaviour. To produce effective behaviour, we take in sensory information (such as vision, audition, olfactory, gustation, and somatosensation) as we search, explore, and manipulate our environment. Plastic Patterns of Neural Organization The brain is plastic: neural tissue has the capacity to change in response to the world by altering how it is organized. For us to learn and remember anything new, neural circuits must change to represent and store this knowledge. As we learn to play a musical instrument or speak a new language, the particular cortical regions taking part can actually increase in size as they accommodate the new skill. An important aspect of human learning and brain plasticity is related to the development of language and to the expansion of the brain regions associated with language. Humans have learned to read, to calculate, to compose and play music, and develop the sciences. While the human nervous system evolved long before we mastered these achievements, it is still able to learn and remember these new abilities because of brain plasticity. In turn, culture plays a dominant role in shaping our behaviour. Because we drive cars and communicate electronically, we-and our nervous systems- are modified in some new ways compared to those of our ancestors who did not engage in these activities. The basis for change in the nervous system is neuroplasticity. Neuroplasticity- the nervous system’s fundamental potential to physically or chemically modify itself in response to a changing environment and to compensate for age related changes and injury Although it is tempting to see neuroplasticity as a trait unique to animals' nervous systems, it is really part of a larger biologic capacity called phenotypic plasticity. Phenotypic Plasticity: the individual’s capacity to develop a range of phenotypes- the characteristics we can see or measure. An individual’s genotype (genetic makeup) interacts with the environment to elicit a specific phenotype. This phenotype emerges from a larger genetic repertoire of possibilities, a phenomenon that in turn results from epigenetic influences. Functional organization of the nervous system: The brain and spinal cord tiger make up the central nervous system. The nerve fibres radiating out beyond the brain and spinal cord as well as all the neurons outside the brain and spinal cord, form the peripheral nervous system. Nerves in the peripheral nervous system (PNS) transmit sensory information to the central nervous system (CNS) and they carry motor instructions from the CS to the body’s muscle and tissues, including those that perform such functions as blood circulation and digestion Anatomical organization: Neurons in the somatic division of the PNS connect through the cranial and spinal nerves to receptors on the body’s surface and on its muscles. Somatic neurons gather sensory information for the CNS and convey information from the CNS to move muscles of the head, neck, face, trunk and limbs. Similarly, the autonomic division of the PNS enables the CNS to govern the workings of your body’s internal organs- your heartbeat, urination, pupillary response, and the diaphragm movements that inflate and deflate your lungs. The enteric nervous system, which is often considered part of the autonomic nervous system , controls digestion and stomach contractions. From a functional standpoint, the major PNS divisions, along with the CNS, form an interacting 4 part system: ​ The CNS includes the brain and the spinal cord: the nervous system core, which mediates behaviour ​ The Somatic nervous system (SNS): includes all the spinal and cranial nerves carrying sensory information to the CNS from the muscles, joints, and skin. It also transmits outgoing motor instructions that produce movement. ​ The Autonomic nervous system (ANS): produces the rest and digest response through the parasympathetic (calming) nerves and its opposite, the fight or flight response, and vigorous activity through the sympathetic (arousing) nerves. ​ The Enteric nervous system (ENS): formed by a mesh of neurons embedded in the lining of the gut, controls the gut. The ENS can communicate with the CNS via the ANS but mostly operates autonomously. Afferent information (incoming): is sensory, coming into the CNS or one of its parts. Efferent information (outgoing): leaves the CNS or one of its parts.