My research interests focus on the functional significance of the hippocampal formation, as studied by neurophysiological and neuropharmacological techniques using acute in vivo and in vitro preparations and chronic preparations. Much of the research involves the cellular basis and the behavioral correlates of hippocampal theta rhythms, the latter principally involving sensory-motor integration.
Theta is an extracellular sinusoidal EEG activity defined by 3-12Hz frequency and <2mV amplitude. Hippocampal theta activity is linked to sensory processing of information relevant for learning, memory, arousal, and voluntary movement. Theta generation in the hippocampus is dependent on the neural activity in the ascending pathways, originating in the rostral pontine oralis (RPO). The RPO sends axonal projections to the cells in the posterior hypothalamus (PH), before reaching the hippocampaus (HPC) via the medial septum (MS).
Current work in the lab has focused on the functional significance of the median raphe (MR) in modulating the ascending brainstem hippocampal synchronizing pathway. We have found convincing evidence that motor activity is inhibited with simultaneous PH and MR stimulations. Click here to see a video demonstration.
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Below you can find some interesting videos from some of our past research. In order to play these videos, you will require a Quicktime plug-in. You can download this plug-in from the following website:
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Intracellular recording of an anatomically identified CA1 pyramidal phasic theta-ON cell, cycling between spontaneous asynchronous activity (LIA) and theta.
Intracellular recording of an anatomically identified CA1 layer basket cell phasic theta-OFF cell, cycling between spontaneous asynchronous activity (LIA) and theta.
Relationships between a phasic theta--ON cell recorded from the dentate layer of a Dutch Belted rabbit during immobility and spontaneously occurring movements.Note the cell increased its discharge rate just prior to and during the occurrence of movement.
Bland BH, Konopacki J, Dyck R (2005) Heterogeneity among hippocampal pyramidal neurons revealed by their relation to theta-band oscillation and synchrony. Experimental Neurology195(2):458-74.
Bland BH (2004) The power of theta: providing insights into the role of the hippocampal formation in sensorimotor integration. Hippocampus 14: 537-538.
Konopacki J, Bland BH, Dyck R (2003) Intracellular recording and labeling of neurons in midline structures of the rat brain in vivo using sharp electrodes. Journal of Neuroscience Methods 127(1): 85-93.
Dypvik AT, Bland BH (2004) Functional connectivity between the red nucleus and the hippocampus supports the role of the hippocampal formation in sensorimotor integration. Journal of Neurophysiology.
Bland BH, Oddie SD (2001) Theta band oscillation and synchrony in the hippocampal formation and associated structures: the case for its role in sensorimotor integration. Behavioral Brain Research 127: 119-136.
Bland BH, Oddie SD (1998) Anatomical, electrophysiological, and pharmacological studies of the ascending brainstem hippocampal synchronizing pathways. Neuroscience & Biobehavioral Reviews 22: 259-273.
Oddie SD, Stefanek W, Kirk IJ, Bland BH (1996) Intraseptal procaine abolishes hypothalamic stimulation induced wheel running and hippocampal theta field activity in rats. Journal of Neuroscience 16: 1948-1956.
Bland BH, Colom LV (1993) Extrinsic and intrinsic properties underlying oscillation and synchrony in limbic cortex. Progress in Neurobiology 41: 157-208.
Bland BH (1986) The physiology and pharmacology of hippocampal formation theta rhythms. Progress in Neurobiology 26: 1-54.