FUTURE DIRECTIONS
The field of molecular genetics and new techniques which allow for organisms to be developed with their genetic karyotype manipulated are huge developments for psychological research. For example, one experiment (Tecott, Sun, Akana, Stack, Lowenstein, Dallman & Julius, 1995) which bred mice without 5HT2C receptors has highlighted this monoaminergic neurotransmitter's possible role in seizure disorders. These mice exhibit an inability to control eating behaviour and become obese. Moreover, the mice die early in development because they are particularly prone to seizures. These findings demonstrate that serotonin (5HT) is likely to be involved in the regulation of appetite. The abnormal presentation of seizures also indicates that the 5HT2C receptor may be involved in controlling the "tonic inhibition of neuronal network excitability" (Tecott, Sun, Akana, Stack, Lowenstein, Dallman & Julius, 1995, 542). This evidence concurs with previous pharmacological studies which
show that 5HT systems are involved in the regulation of threshold levels for seizure activity (Tecott, Sun, Akana, Stack, Lowenstein, Dallman & Julius, 1995). Moreover, due to the high concentration of 5HT2C receptors in the hippocampus it is possible that some abnormality in this region or in serotonergic regulation is responsible for epileptic conditions which involve stereotypic or repetitive movements (Tecott, Sun Akana, Stack, Lowenstein, Dallman & Julius, 1995). These types of technical advancements and the experiments which can be undertaken using these methods may provide important data for the development of new anticonvulsant agents which can correct the abnormal neurotransmitter activities in epileptic conditions.
In conclusion, kindling experiments have provided evidence about the normal and abnormal functioning of brain structures, particularly those of the limbic system. In this way, it is possible to compare the kindling-elicited behaviours with those exhibited in human cases of epilepsy and extrapolate the findings to hypothesize about the involvement of particular brain regions. As a result of this knowledge, kindling experiments have provided useful models to study the neurochemical and electrographic activities involved in epilepsy and to develop possible treatments by testing different pharmacological agents. Newer techniques, such as the development of genetically mutated models, may replace kindling as the primary form of experimentation in the study of human epilepsy. Regardless, the kindling model of epilepsy has provided the necessary knowledge of the limbic system and other brain regions to make informed decisions about the direction of future research in the area of epileptogenic phenomena.
References
Adamec, R. and Stark-Adamec, C. (1986). Limbic hyperfunction, limbic epilepsy and interictal behavior: Models and methods of detection. In Doane, B. & Livingstone K. (eds.), The Limbic System: Functional Organization and Clinical Disorders. (pp.129-145). NY: Raven.
Bear, D. (1986). Hemispheric assymetries in emotional function: A reflection of lateral specialization in cortical-limbic connections. In Doane, B. & Livingstone, K. (eds.), The Limbic System: Functional Organization and Clinical Disorders. (pp.29-42). NY: Raven.
Goddard, G. (1967). Development of epileptic seizures through brain stimulation at low intensity. Nature, 214, 1020-1021.
Goddard, G., Dragunow, M., Maru, E. & MacLoed, E. (1986). In Doane, B. & Livingstone, K. (eds.), The Limbic System: Functional Organization and Clinical Disorders. (pp.95-108). NY: Raven.
Kline, A., Revilla, V. and Hernandez, T. (1997). Antecedent tone presentation differentially alters the rate of amygdala kindling: Continued exposure is not required for this region-specific effect. Experimental Neurology, 143, 124-131.
Leung, L., Brzozowski, D. & Shen, B. (1996). Partial hippocampal kindling affects retention but not acquisition and place but not cue tasks on the radial arm maze. Behavioral Neuroscience, 110(5):1017-1024.
MacLean P. (1986). Culminating developments in the evolution of the limbic system: The thalamocingulate division. In Doane, B. & Livingstone, K. (eds.), The Limbic System: Functional Organization and Clinical Disorders. (pp.1-28). NY: Raven.
Nauta, W. (1986). Circuitous connections linking the cerebral cortex, limbic system and corpus striatum. In Doane, B. & Livingstone, K. (eds.), The Limbic System: Functional Organization and Clinical Disorders. (pp.43-54). NY: Raven.
Nieminen S., Sirvio, J., Teittinen, K., Pitkanen, A., Airaksinen, M. & Riekkinen, P. (1992). Amygdala kindling increased fear-response, but it did not impair spatial memory in rats. Physiology and Behavior, 51, 845-849.
Pinel, J. & Rovner, B. (1978). Experimental epileptogenesis: Kindling-induced epilepsy in rats. Experimental Neurology, 58, 190-202.
Racine, R., Livingston, K. & Joaquin, A. (1975). Effects of procaine hydrochloride in cortical and subcortical structures in rats. Electroencephalography and Clinical Neurophysiology, 38, 355-365.
Racine, R. & McIntyre, D. (1986). Mechanisms of kindling: A current view. In Doane, B. & Livingston, K. (eds.), The Limbic System: Functional Organization and Clinical Disorders. (pp.109-122). NY: Raven.
Rosen, J., Hamerman, E., Sitcoske, M., Glowa, J. & Schulkin, J. (1996). Behavioral Neuroscience, 110(1):43-50.
Tecott, L., Sun, L., Akana, S., Stack, A., Lowenstein, D., Dallman, M. & Julius, D. (1995). Eating disorder and epilepsy in mice lacking 5-HT2C serotonin receptors. Nature, 374, 542-546.
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