Temporal lobe medial

Neurons are arranged in distributed networks to govern human behavior (Mesulam, 1998). Here we focus on four major anatomical systems the cortex, the thalamus, the basal ganglia, and the medial temporal lobe (Fig. 2.1). 

The thalamus is the gateway to cortical processing of all incoming sensory information, represented in Figure 2.1 by the three major systems somatosensory (S), auditory (A), and visual (V). Primary sensory cortices (SI, Al, VI) receive information from the appropriate input modules (sensory organ -I- thalamus). The association cortex integrates information from primary cortices, from subcortical structures, and from brain areas affiliated with memory to create an internal representation of the sensory information. The medial temporal lobe (i.e., hippocampus, amygdala) serves two major... 

Patients with COS have morphometric abnormalities similar to those seen in adult patients with the disorder (Kumra et al., 2000 Sowell et ah, 2000). Initial scans of 46 COS patients and 82 matched healthy control subjects showed, as expected, reduced total cerebral volume (secondary to gray matter loss) and midsagittal thalamic area, and increased lateral ventricular volume (Kumra et al., 2000 see Table 15.1). While volumetric reductions in medial temporal lobe structures are found consistently in studies of adults with schizophrenia (Wright et al., 2000), differences between patients with COS and controls in these structures were not significant at the time of the initial scan (Jacobsen et al., 1996a Kumra et al., 2000). 

Brain morphometric studies of cocaine abusers have revealed evidence for enlargement of caudate and puta-men during initial abstinence, but no evidence for changes in total brain volume or volume of medial temporal lobe structures (Jacobsen et ah, 2001 a,b). Enlargement of basal ganglia structures likely reflects dopamine depletion that appears to develop following cessation of chronic cocaine use. 

Jacobsen, L.K., Giedd, J.N., Kreek, M.J., Gottschalk, C., and Kosten, T.R (2001 b) Quantitative medial temporal lobe brain morphology and hypothalamic-pituitary-adrenal axis function in cocaine dependence a preliminary report. Drug Alcohol Depend 62 49-56. 

Squire LR, Zola-Morgan S (1991) The medial temporal lobe memory system. Science 253 1380-1386... 

Object recognition is an attractive task for testing compounds for their potential against cognitive deficits in schizophrenia. It is a relatively simple task, with the additional benefit that it can be performed across species. Although the literature for the neural substrates involved in this task remains controversial, there does seem to be some overlap in the neural circuits that mediate object recognition in rats, primates, and humans and that contain medial temporal lobe structures (106-113). 

Squire LR, Stark CE, Clark RE. The medial temporal lobe. Annu Rev Neurosci 2004 27 279-306. 

Marsh L, Suddath RL, Higgins N, Weinberger DR. 1994. Medial temporal lobe structures in schizophrenia Relationship of size to duration of illness. Schizophr Res 11 ... 

Hippocampus Hippocampus dentate gyrus Thalamus Cerebellum Cingulate gyrus Temporal cortex Parietal cortex Hippocampus Frontal cortex Medial temporal lobe... 

Eastwood SL, Harrison PJ. 1995a. Decreased synaptophysin in the medial temporal lobe in schizophrenia demonstrated using immunoautoradiography. Neuroscience 69 ... 

Two different patterns of abnormal hippocampal activity at rest have been described in schizophrenia lower regional cerebral glucose metabolic rates (rCMRglc) in the hippocampus (Buchsbaum et al., 1992 Tamminga et al., 1992 Nordahl et al., 1996) and increased medial temporal lobe regional cerebral blood... 

Eastwod SL, McDonald B, Burnet PWJ, Beckwith TP, Kerwin RW, et al. 1995. Decreased expression of mRNAs encoding non-NMDA glutamate receptors GluRl and GluR2 in medial temporal lobe neurons in schizophrenia. Mol Brain Res 29 211-223. 

Harrison PJ, Eastwood SL. 1998. Preferential involvement of excitatory neurons in medial temporal lobe in schizophrenia. Lancet 352 1669-1673. 

Holt D J, Kunkel L, Weiss AP, Goff DC, Wright Cl, et al. 2006. Increased medial temporal lobe activation during the passive viewing of emotional and neutral facial expressions in schizophrenia. Schizophr Res 82 153-162. 

Beneyto M, Kristiansen LV, Oni-Orisan A, McCullumsmith RE, Meador-Woodruff JH. 2007. Abnormal glutamate receptor expression in the medial temporal lobe in schizophrenia and mood disorders. Neuropsychopharmacology 32 1888-1902. 

Eastwood SL, Kerwin RW, Harrison PJ. 1997b. Immunoautor-adiographic evidence for a loss of alpha-amino-3-hydroxy-5-methyi-4-isoxazole propionate-preferring non-N-methyl-D-aspartate glutamate receptors within the medial temporal lobe in schizophrenia. Biol Psychiatry 41 636-643. 

Meador-Woodruff JH, Davis KL, Haroutunian V. 2001. Abnormal kainate receptor expression in prefrontal cortex in schizophrenia. Neuropsychopharmacology 24 545-552. Meador-Woodruff JH, Grandy DK, Van Tol HH, Damask SP, Little KY, et al. 1994. Dopamine receptor gene expression in the human medial temporal lobe. Neuropsychopharmacology 10 239-248. 

Seidman LJ, Pantelis C, Keshavan MS, Faraone SV, Goldstein JM, et al. 2003. A review and new report of medial temporal lobe dysfunction as a vulnerability indicator for schizophrenia A magnetic resonance imaging morphometric family study of the parahippocampal gyrus. Schizophr Bull 29(4) 803-830. 

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