Brain thalamus

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. 

Affinity constants for rat brain thalamus sites labelled by [ H]-(— )-nicotine... 

Dementia with Lewy bodies (DLB) is considered the second most common cause of dementia after AD. The disorder is characterized by progressive fluctuating cognitive impairment, visual hallucinations and motor features of Parkinsonism. Neocoitical cholinergic activity is more severely depleted in DLB than in AD, and DLB also affects the caudate nucleus, the thalamus and the brain stem. Tolerability of ChEI in DLB appears similar to AD, with some gastrointestinal effects and muscle cramps. 

Hi-receptors in the adrenal medulla stimulates the release of the two catecholamines noradrenaline and adrenaline as well as enkephalins. In the heart, histamine produces negative inotropic effects via Hr receptor stimulation, but these are normally masked by the positive effects of H2-receptor stimulation on heart rate and force of contraction. Histamine Hi-receptors are widely distributed in human brain and highest densities are found in neocortex, hippocampus, nucleus accumbens, thalamus and posterior hypothalamus where they predominantly excite neuronal activity. Histamine Hrreceptor stimulation can also activate peripheral sensory nerve endings leading to itching and a surrounding vasodilatation ( flare ) due to an axonal reflex and the consequent release of peptide neurotransmitters from collateral nerve endings. 

Brain structure below the thalamus and main portion of the ventral region of the diencephalon, controlling homeostatic and nonhomeostatic basic body and brain functions, including circadian and feeding rhythms, energy metabolism, thermogenesis, sympathoadrenal, and neuroendocrine outflow (secretion of hormones by the pituitary gland), behavioral state and memory functions. 

Highest concentrations of MOPs are found in the thalamus, caudate, neocortex in the brain, but the receptors are also present in gastrointestinal tract, immune cells, and other peripheral tissues. 

McCormick, DA, Pape, HC and Williamson, A (1991) Actions of norepinephrine in the cerebral cortex and thalamus implications for function of the central noradrenergic system. Prog. Brain Res. 88 293-305. 

Association of Pain, neuropathic pain is defined as pain initiated or caused by a primary lesion, dysfunction in the nervous system". Neuropathy can be divided broadly into peripheral and central neuropathic pain, depending on whether the primary lesion or dysfunction is situated in the peripheral or central nervous system. In the periphery, neuropathic pain can result from disease or inflammatory states that affect peripheral nerves (e.g. diabetes mellitus, herpes zoster, HIV) or alternatively due to neuroma formation (amputation, nerve transection), nerve compression (e.g. tumours, entrapment) or other injuries (e.g. nerve crush, trauma). Central pain syndromes, on the other hand, result from alterations in different regions of the brain or the spinal cord. Examples include tumour or trauma affecting particular CNS structures (e.g. brainstem and thalamus) or spinal cord injury. Both the symptoms and origins of neuropathic pain are extremely diverse. Due to this variability, neuropathic pain syndromes are often difficult to treat. Some of the clinical symptoms associated with this condition include spontaneous pain, tactile allodynia (touch-evoked pain), hyperalgesia (enhanced responses to a painful stimulus) and sensory deficits. 

The extrapyramidal motor system controls muscle movement through a system of pathways and nerve tracts that connect the cerebral cortex, basal ganglia, thalamus, cerebellum, reticular formation, and spinal neurons. Patients with PD lose dopamine neurons in the substantia nigra, which is located in the midbrain within the brain stem. The substantia... 

Anandamide is found in human brain 100 pmol/g in the hippocampus, 75 pmol/g in the thalamus, 60 pmol/g in the cerebellum, and 55 pmol/g in the striatum (Martin, 1999). The concentration of AEA increases postmortem, especially when the brain is kept at ambient temperature. Furthermore, AEA surges are observed when cerebellar granule cells are treated in hypoxic conditions (Hillard, 1997). Although such concentration increases may be artifacts of postmortem brain damage, they may also occur in living tissue under certain conditions, such as hypoxia. 

The brain is the integrative portion of the nervous system that serves to receive, process, and store sensory information and then plan and orchestrate the appropriate motor response. It is divided into several anatomically and functionally distinct regions (see Table 6.2). The forebrain consists of the cerebrum, basal ganglia, thalamus, and hypothalamus. The midbrain, along with the pons and the medulla of the hindbrain, composes the functional region referred to as the brainstem. The cerebellum is also considered a component of the hindbrain but is functionally distinct from the brainstem. 

Figure 6.2 Frontal section of the brain. The cerebrum is composed of two types of tissue internal white matter and external gray matter which forms the cerebral cortex. Embedded within the cerebral hemispheres are other masses of gray matter, basal ganglia, and thalamus. The ventricles are filled with cerebrospinal fluid (CSF).

As its name suggests, the hypothalamus lies beneath the thalamus and above the pituitary gland. Although it is quite small, accounting for only about 4 g of the total 1400 g of the adult human brain, it plays a vital role in maintenance of homeostasis in the body. It is composed of numerous cell groups and fiber pathways, each with a specific function. 

Stimulation of a nociceptor in the periphery of the body elicits action potentials in the first-order neuron, which transmits the signal to the second-order neuron in the dorsal horn of the spinal cord. From the spinal cord, the signal is transmitted to several regions of the brain. The most prominent ascending nociceptive pathway is the spinothalamic tract. Axons of the second-order sensory neurons project to the contralateral (opposite) side of the spinal cord and ascend in the white matter, terminating in the thalamus (see Figure 8.1). The thalamus contributes to the basic sensation or awareness of pain only it cannot determine the source of the painful stimulus. 

Figure 8.1 The pain pathway. The pain signal is transmitted to several regions of the brain, including the thalamus reticular formation hypothalamus limbic system and somatosensory cortex. Each region carries out a specific aspect of the response to pain.

Nerve signals from the thalamus and the reticular formation are transmitted to the limbic system as well as the hypothalamus. Together, these regions of the brain are responsible for behavioral and emotional responses to pain. The limbic system, in particular, may be involved with the mood-altering and attention-narrowing effect of pain. 

The cell bodies of third-order sensory neurons are located in the thalamus. These neurons transmit the pain signal to the somatosensory cortex. The function of this region of the brain is to localize and perceive the intensity of the painful stimulus. Further transmission of the signal to the association areas of the cerebral cortex is important for the perception and meaningfulness of the painful stimulus. 

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