Neuroanatomy of the Brain
The brain described in terms of its general structure and key anatomical areas. It may also be described in terms of the cellular or subcellular structure of the different types of cells that constitute the brain. Finally it is considered in terms of its functional importance in memory, consciousness and control of bodily functions. However the brain is described, each level of organization is essentially linked to another level of organization. Conventionally, neuroscientists have concentrated on the structural aspects of the brain and its cellular components while psychologists and psychiatrists have concentrated on the more functional aspects such as consciousness, thought processing and emotion. With the advent of sophisticated imaging methods and the introduction of novel drugs that combine therapeutic efficacy with subcellular specificity of action, it is now possible to show how all the levels of brain structure and function are interlinked.The principal regions of the human brain which are important in psychiatry and neurology .
Structural and functional subdivision of the brain
In brief, the brain may be divided into the brainstem (consisting of the medulla, pons and midbrain) that is linked to the diencephalon which is composed of the thalamus and the hypothalamus. The two cerebral hemispheres are linked by the corpus callosum, (a large tract of nerve fibres that enables the two)
Amygdala – An anatomically coherent subsystem within the basal forebrain. Verbal and non-verbal expressions of fear and anger are interpreted by the amygdala.
Cerebellum – One of the seven parts of the brain that is responsible for muscle co-ordination and modulation of the force and range of movement. It is involved in the learning of motor skills.
Cortex – The most highly developed area in humans and divided into four main regions, namely frontal, parietal, temporal and occipital. The cortex mediates and integrates higher motor, sensory and association functions.
Dorsal raphe´ – Main serotonin (5-HT)-containing neurons that project through the brain.Other raphe´ neurons project down the spinal cord where they act as a gating mechanism for pain perception from the periphery. Main activity is in the regulation of mood, anxiety, sexual behaviour, sleep.
Hippocampus – Region primarily concerned with learning and short-term memory.
Hypothalamus – Part of the diencephalon comprising several nuclei where hormones such as oxytocin and antidiuretic hormone are synthesized and pass to the pituitary gland. Involved in the regulation of the peripheral autonomic system and pituitary hormones such as prolactin, growth hormone and adrenocorticotrophic hormone.
Locus coeruleus – Collection of cell bodies containing about 50% of the noradrenergic neurons. Main activity is in the regulation of mood, anxiety and attention. Noradrenergic tracts innervate most regions of the brain.
Thalamus – This acts as a relay station for pain, temperature and other bodily sensations.halves of the brain to communicate. The brain is permeated by four ventricles, the two largest of which occur beneath the cerebral cortex.
The basal ganglia consists of the corpus striatum (consisting of the caudate nucleus, globus pallidus and putamen) and the substantia nigra. This region is concerned primarily with the control of movement and is malfunctional in Parkinson’s disease and Huntington’s disease. It is apparent that the brain is really an assembly of organs all of which are structurally and functionally interconnected. Undoubtedly one of the most important areas for the psychopharmacologist is the so-called limbic system which is concerned with emotion. This region consists of the hippocampus (concerned with memoryprocessing), the thalamus and hypothalamus (concerned with the control of the endocrine system, temperature regulation, feeding, etc.), the amygdale and septum (the emotional centres of the subcortex), the fornix and the cingulate gyrus of the cortex. The cerebral cortex is conventionally subdivided into four main regions that may be delineated by the sulci, or large clefts, termed the frontal, temporal, parietal and occipital lobes. These names are derived from the bones of the skull which overlay them. Each lobe may be further subdivided according to its cellular structure and composition. Thus Brodmann has divided the cortex into approximately 50 discrete areas according to the specific cellular structure and function. For example, electrical stimulation of the strip of cerebral cortex in front of the central sulcus is responsible for motor commands to the muscles. This is termed the primary motor cortex and can be further subdivided according to which muscles are controlled in different parts of the body. Similar maps exist in other parts of the brain; for example, the areas concerned with sensory input such as the primary somatosensory cortex . Such brain maps of the body are important because information from various organs converge on the brain in a highly organized fashion and can therefore be reflected at all levels of information processing. Suchintegration also allows the brain to obtain a true representation of the external environment as projected by the sensory organs. The functional importance of specific cortical and subcortical regions of the brain may also be elucidated by studying the consequences of specific neurological lesions. For example, it has been shown by imaging methods that blood flow to the hippocampus of patients with Alzheimer’s disease is dramatically reduced, the reduction paralleling the degree of short-term memory impairment. In addition, blood flow to the parietotemporal association cortex is also greatly reduced. Such changes in he functional activity of these brain areas may account for the memory and cognitive deficits that are symptomatic of the disease, the main function of the parietotemporal association cortex being the integration of sensory and cognitive processes in the brain.
The brain described in terms of its general structure and key anatomical areas. It may also be described in terms of the cellular or subcellular structure of the different types of cells that constitute the brain. Finally it is considered in terms of its functional importance in memory, consciousness and control of bodily functions. However the brain is described, each level of organization is essentially linked to another level of organization. Conventionally, neuroscientists have concentrated on the structural aspects of the brain and its cellular components while psychologists and psychiatrists have concentrated on the more functional aspects such as consciousness, thought processing and emotion. With the advent of sophisticated imaging methods and the introduction of novel drugs that combine therapeutic efficacy with subcellular specificity of action, it is now possible to show how all the levels of brain structure and function are interlinked.The principal regions of the human brain which are important in psychiatry and neurology .
Structural and functional subdivision of the brain
In brief, the brain may be divided into the brainstem (consisting of the medulla, pons and midbrain) that is linked to the diencephalon which is composed of the thalamus and the hypothalamus. The two cerebral hemispheres are linked by the corpus callosum, (a large tract of nerve fibres that enables the two)
Amygdala – An anatomically coherent subsystem within the basal forebrain. Verbal and non-verbal expressions of fear and anger are interpreted by the amygdala.
Cerebellum – One of the seven parts of the brain that is responsible for muscle co-ordination and modulation of the force and range of movement. It is involved in the learning of motor skills.
Cortex – The most highly developed area in humans and divided into four main regions, namely frontal, parietal, temporal and occipital. The cortex mediates and integrates higher motor, sensory and association functions.
Dorsal raphe´ – Main serotonin (5-HT)-containing neurons that project through the brain.Other raphe´ neurons project down the spinal cord where they act as a gating mechanism for pain perception from the periphery. Main activity is in the regulation of mood, anxiety, sexual behaviour, sleep.
Hippocampus – Region primarily concerned with learning and short-term memory.
Hypothalamus – Part of the diencephalon comprising several nuclei where hormones such as oxytocin and antidiuretic hormone are synthesized and pass to the pituitary gland. Involved in the regulation of the peripheral autonomic system and pituitary hormones such as prolactin, growth hormone and adrenocorticotrophic hormone.
Locus coeruleus – Collection of cell bodies containing about 50% of the noradrenergic neurons. Main activity is in the regulation of mood, anxiety and attention. Noradrenergic tracts innervate most regions of the brain.
Thalamus – This acts as a relay station for pain, temperature and other bodily sensations.halves of the brain to communicate. The brain is permeated by four ventricles, the two largest of which occur beneath the cerebral cortex.
The basal ganglia consists of the corpus striatum (consisting of the caudate nucleus, globus pallidus and putamen) and the substantia nigra. This region is concerned primarily with the control of movement and is malfunctional in Parkinson’s disease and Huntington’s disease. It is apparent that the brain is really an assembly of organs all of which are structurally and functionally interconnected. Undoubtedly one of the most important areas for the psychopharmacologist is the so-called limbic system which is concerned with emotion. This region consists of the hippocampus (concerned with memoryprocessing), the thalamus and hypothalamus (concerned with the control of the endocrine system, temperature regulation, feeding, etc.), the amygdale and septum (the emotional centres of the subcortex), the fornix and the cingulate gyrus of the cortex. The cerebral cortex is conventionally subdivided into four main regions that may be delineated by the sulci, or large clefts, termed the frontal, temporal, parietal and occipital lobes. These names are derived from the bones of the skull which overlay them. Each lobe may be further subdivided according to its cellular structure and composition. Thus Brodmann has divided the cortex into approximately 50 discrete areas according to the specific cellular structure and function. For example, electrical stimulation of the strip of cerebral cortex in front of the central sulcus is responsible for motor commands to the muscles. This is termed the primary motor cortex and can be further subdivided according to which muscles are controlled in different parts of the body. Similar maps exist in other parts of the brain; for example, the areas concerned with sensory input such as the primary somatosensory cortex . Such brain maps of the body are important because information from various organs converge on the brain in a highly organized fashion and can therefore be reflected at all levels of information processing. Suchintegration also allows the brain to obtain a true representation of the external environment as projected by the sensory organs. The functional importance of specific cortical and subcortical regions of the brain may also be elucidated by studying the consequences of specific neurological lesions. For example, it has been shown by imaging methods that blood flow to the hippocampus of patients with Alzheimer’s disease is dramatically reduced, the reduction paralleling the degree of short-term memory impairment. In addition, blood flow to the parietotemporal association cortex is also greatly reduced. Such changes in he functional activity of these brain areas may account for the memory and cognitive deficits that are symptomatic of the disease, the main function of the parietotemporal association cortex being the integration of sensory and cognitive processes in the brain.
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