The basal forebrain cholinergic system in the raccoon.

The distribution of neurons displaying choline acetyltransferase (ChAT) immunoreactivity was examined in the raccoon basal forebrain using a rabbit antiserum and a monoclonal antibody. Alternating sections were used for Nissl staining. ChAT-positive neurons were arranged in a continuous mass extending from the medial septum to the caudal pole of the pallidum.

High-affinity uptake of GABA and glutamate decarboxylase activity in rat primary somatosensory cortex after sciatic nerve injury.

We have studied the changes in the GABAergic system in the rat somatosensory cortex 1-14 d after sensory deprivation of the hind-limb representation area. Glutamate decarboxylase (GAD) activity was measured in the individual cortical layers using serial sections cut on a freezing microtome parallel to the cortical surface. Gamma-aminobutyric acid (GABA) high-affinity uptake was studied in cortical homogenates of the hind-limb representation area.

Functional regions within the map of a single digit in raccoon primary somatosensory cortex.

Electrophysiological recordings were made at a large number of sites in the primary somatosensory cortex of six anesthetized raccoons. A high density of penetrations (110-229 per animal), within or near the representation of the fourth digit, allowed identification of three cortical regions with different physiological properties: a glabrous zone, containing a highly detailed, somatotopically ordered representation of the glabrous surface of the digit; rostral to this a claw-dominant zone, in which the neurons at most penetrations respond to stimulation of the claw of the fourth digit, but may also receive input from the hairy skin or surrounding glabrous skin; and a more rostral multidigit zone, in which the neurons respond to stimulation of two to five digits, with the dominant digit usually being the one represented caudally (i.e.

Long-term enhancement of evoked potentials in raccoon somatosensory cortex following co-activation of the nucleus basalis of Meynert complex and cutaneous receptors.

Long-term enhancement of the evoked potential was induced in the primary somatosensory cortex of anaesthetized raccoons after mechanical stimulation of the skin was paired with electrical stimulation of the nucleus basalis of Meynert (NBM). Sets of 4 pulses, 0.5 ms duration at 300 Hz were delivered at 2-s intervals to the basal forebrain 80 ms before the glabrous skin on the 4th digit of the contralateral forepaw was stimulated mechanically.

Basal forebrain lesions with or without reserpine injection inhibit cortical reorganization in rat hindpaw primary somatosensory cortex following sciatic nerve section.

To test the hypothesis that cortical reorganization depends on acetylcholine and one or more of the monoamines, the hindpaw cortex was mapped in eight different groups of mature rats: (1) untreated; (2) after sciatic nerve transection; (3) after intraperitoneal injections of reserpine, to reduce the level of cortical monoamines; (4) after ibotenic acid lesion of the nucleus basalis of Meynert (NBM), to destroy cholinergic cells projecting to the cortex; (5) after reserpine treatment and transection; (6) after ibotenic acid lesion and transection; (7) after reserpine treatment and ibotenic acid lesion; and (8) after reserpine treatment, ibotenic acid lesion, and transection. Four days after transection, the cortex had reorganized in the transected group. However, this process of reorganization was prevented in transected animals with NBM lesions.