Hyperpolarization-activated currents (Ih) in hippocampal CA1 pyramidal neurons were studied using cell-attached and whole-cell patch-clamp techniques. Ih currents were found to increase significantly from the soma to distal dendrites, with a sixfold increase in density. Activation curves showed that a significant fraction of Ih channels are active near rest, with a more pronounced hyperpolarization in distal dendrites. Ih currents are voltage- and temperature-dependent, with activation and deactivation time constants decreasing with hyperpolarization and depolarization, respectively. Ih currents exhibit a mixed Na⁺-K⁺ conductance and are sensitive to external CsCl. Dual whole-cell recordings revealed regional differences in input resistance (Rin) and membrane polarization rates (τmem) across the somatodendritic axis. The primary site of excitatory synaptic input into hippocampal pyramidal neurons is the dendritic arbor, which comprises over 95% of the cell's membrane surface area. Dendritic integration and synaptic plasticity are crucial for information processing. Ih channels, which are voltage-gated, play a significant role in dendritic function. While the relative densities and biophysical characteristics of Na⁺, K⁺, and Ca²⁺ channels in CA1 pyramidal neurons have been studied, little is known about Ih channels in CA1 dendrites. Ih currents modulate various membrane parameters and phenomena, including rectification, oscillatory activity, and action potential firing rates. The presence of Ih in CA1 pyramidal neurons could significantly impact dendritic integration of subthreshold synaptic activity and action potential propagation. Using cell-attached and outside-out patch-clamp techniques, the biophysical properties and subcellular distribution of Ih were investigated. The impact of Ih on subthreshold voltage signals and action potentials was determined using simultaneous whole-cell voltage recordings from both the soma and dendrites. The study found that Ih currents increase with distance from the soma, with a sevenfold increase across the somatodendritic axis. The activation voltage range of Ih channels in distal dendrites is shifted hyperpolarized compared to proximal regions, which reduces the impact of elevated channel density on resting membrane properties. The activation and deactivation kinetics of Ih are temperature-dependent, with a Q10 of approximately 4.5 for activation and 4.7 for deactivation. The presence of Na⁺ in the external solution shifts the activation curve depolarized, indicating that Ih channels are influenced by ionic composition. The ionic selectivity of Ih currents was determined using reversal potentials, showing a mixed Na⁺/K⁺ permeability ratio. The presence of external Na⁺ slows channel deactivation, and the effect of Cs⁺ on Ih currents was studied, showing significant blockade at higher concentrations. The impact of Ih on membrane properties, such as input resistance and membrane time constant, was examined, with Ih blockade increasing input resistance and reducingHyperpolarization-activated currents (Ih) in hippocampal CA1 pyramidal neurons were studied using cell-attached and whole-cell patch-clamp techniques. Ih currents were found to increase significantly from the soma to distal dendrites, with a sixfold increase in density. Activation curves showed that a significant fraction of Ih channels are active near rest, with a more pronounced hyperpolarization in distal dendrites. Ih currents are voltage- and temperature-dependent, with activation and deactivation time constants decreasing with hyperpolarization and depolarization, respectively. Ih currents exhibit a mixed Na⁺-K⁺ conductance and are sensitive to external CsCl. Dual whole-cell recordings revealed regional differences in input resistance (Rin) and membrane polarization rates (τmem) across the somatodendritic axis. The primary site of excitatory synaptic input into hippocampal pyramidal neurons is the dendritic arbor, which comprises over 95% of the cell's membrane surface area. Dendritic integration and synaptic plasticity are crucial for information processing. Ih channels, which are voltage-gated, play a significant role in dendritic function. While the relative densities and biophysical characteristics of Na⁺, K⁺, and Ca²⁺ channels in CA1 pyramidal neurons have been studied, little is known about Ih channels in CA1 dendrites. Ih currents modulate various membrane parameters and phenomena, including rectification, oscillatory activity, and action potential firing rates. The presence of Ih in CA1 pyramidal neurons could significantly impact dendritic integration of subthreshold synaptic activity and action potential propagation. Using cell-attached and outside-out patch-clamp techniques, the biophysical properties and subcellular distribution of Ih were investigated. The impact of Ih on subthreshold voltage signals and action potentials was determined using simultaneous whole-cell voltage recordings from both the soma and dendrites. The study found that Ih currents increase with distance from the soma, with a sevenfold increase across the somatodendritic axis. The activation voltage range of Ih channels in distal dendrites is shifted hyperpolarized compared to proximal regions, which reduces the impact of elevated channel density on resting membrane properties. The activation and deactivation kinetics of Ih are temperature-dependent, with a Q10 of approximately 4.5 for activation and 4.7 for deactivation. The presence of Na⁺ in the external solution shifts the activation curve depolarized, indicating that Ih channels are influenced by ionic composition. The ionic selectivity of Ih currents was determined using reversal potentials, showing a mixed Na⁺/K⁺ permeability ratio. The presence of external Na⁺ slows channel deactivation, and the effect of Cs⁺ on Ih currents was studied, showing significant blockade at higher concentrations. The impact of Ih on membrane properties, such as input resistance and membrane time constant, was examined, with Ih blockade increasing input resistance and reducing