Agitation in closed head injury: haloperidol effects on rehabilitation outcome.

The role of agitation as a prognostic indicator of outcome in 26 patients with severe traumatic closed head injury was studied to explore haloperidol effects on the outcome of rehabilitation treatment. The incidence and degree of agitation and post-traumatic amnesia (PTA) in brain-injured patients undergoing comprehensive inpatient rehabilitation were also studied. Variables measured included length of coma, PTA, rehabilitation admission and discharge functional status, and CT scan results. Of the 26 patients, 25 were agitated after emerging from coma and 11 required intervention with haloperidol. Treated and nontreated patients were compared statistically. No differences were found between groups as to demographics, length of coma, and most importantly, in success of rehabilitation outcome. The duration of PTA was significantly longer in the treated group.

Corticofugal influences in the rat on responses of neurons in the trigeminal nucleus interpolaris to mechanical stimulation.

We recorded effects of electrical stimulation of sensorimotor cortex on the responses of 45 neurons in the interpolar trigeminal nucleus to mechanical stimulation of vibrissae. Responses elicited by peripheral mechanical stimulation were enhanced when a neuron's receptive field (RF) included the RF of the cortical stimulating locus, and suppressed when the RFs of the cortical site and the interpolar neuron did not overlap. Several interpolaris neurons influenced by cortical stimulation were shown to project to the cerebellum.

Congruence of spatial organization of tactile projections to granule cell and Purkinje cell layers of cerebellar hemispheres of the albino rat: vertical organization of cerebellar cortex.

1. We compared the spatial pattern of shortest latency somatosensory (tactile) projections to the Purkinje cell (PC) layer and to the underlying granule cell (GC) layer in tactile areas of rat cerebellar cortex. Micro-mapping methods were used to sample single units in the PC layer and multiple units in the GC layer of both anesthetized and unanesthetized rats. Mechanical and electrical stimulation of the body surface were employed. Responsiveness of PCs to cutaneous stimulation was assessed by constructing histograms of simple spike activity and statistically comparing poststimulus activity to nonstimulated base-line PC activity. 2. We found that PCs respond to tactile stimulation with increases (7-10 ms) followed by decreases (8-15 ms) in simple spike activity. Increases in simple spike activity followed activation of the underlying GC layer by 1-4 ms, while decreases in simple spike activity were found 2-5 ms after GC layer activation. 3. PCs were found to have both excitatory and inhibitory receptive fields (RFs). Excitatory RFs were restricted to small areas of a single body part and for each PC were very similar or identical to the RFs of neurons in the immediately subjacent GC layer. Inhibitory PC RFs were larger, often containing more than one body part and for each PC, were only partially similar to the RFs of subjacent GCs. PC inhibitory RFs also often included body surfaces projecting to the nearby but not to the underlying GC layer. 4. Stimulation of a single peripheral locus resulted in small, distinct regions of PC layer excitation and inhibition. Areas of PC excitation overlie activated regions of the GC layer, while inhibited PCs overlie both activated and nonactivated GC regions. 5. We found PCs to be organized in groups or patches with respect to the specific body region that was capable of activating them (upper lip, lower lip, etc.). Adjacent patches of PCs often represented widely separated body parts. This pattern of PC layer activating RF projections was congruent with the pattern of excitatory RF projections to the underlying GC layer. 6. These results indicate that there is a vertical organization in GC-PC excitatory relations, while GC-induced PC inhibition is slightly more widely distributed. 7. Our finding that the patchlike activation of PCs is congruent with that of the underlying GC layer contrasts with the classical concept that PCs are activated by parallel fibers in a "beamlike" fashion from a patch of GCs. Thus, a reevaluation of the role of parallel fibers seems to us to be in order. 8. In conclusion, our results support the view that short-latency afferent tactile projections to both the GC and PC layers of cerebellar cortex are highly organized spatially. This specificity of body surface projections must be incorporated into modern views of the functional organization of cerebellar cortex.

Trigeminocerebellar mossy fiber branching to granule cell layer patches in the rat cerebellum.

Recent micromapping studies of tactile areas in rat cerebellum have revealed a spatially precise mosaic of granule cell layer areas termed 'patches', with multiple patches on several folia resulting in multiple representations of the same body part. The research reported in the present paper tested the hypothesis that trigeminocerebellar mossy fiber branching is patch-related, so that collaterals terminate only within the boundaries of one or more of the tiny (often less than 1 sq. mm) patches having similar receptive fields. This hypothesis was supported by 3 separate series of electrophysiological experiments: (1) electrical stimulation in a patch resulted in short latency, low threshold responses confined within the boundaries of a second patch having a similar receptive field; (2) antidromic collison tests demonstrated that collaterals of axons originating in nucleus interpolaris reach pairs of patches with similar receptive fields; and (3) micromapping of the area from which a particular interpolaris neuron could be antidromically activated revealed that local terminal branching of a given mossy fiber axon appeared to be confined within the boundaries of a single patch. Together these results indicate that trigeminocerebellar mossy fiber branching is related to the fractured somatotopical organization of the granule cell layer. Possible functional implications of such mossy fiber branching are discussed.

Concept of neuron types in gustation in the rat.

1. In taste neurophysiology, from Pfaffmann's (49, 50) pioneering work until the present, the possibility of types of neurons corresponding in some sense with the "primary" taste qualities of Henning (33) has been entertained: recently types of gustatory neurons in peripheral nerves have been established according to which of the four classical stimuli is the "best stimulus." However, considerable variation occurs in the response profiles within neurons classified as belonging to the same type. The purpose of this research is to determine, using mathematical techniques where appropriate, if the within-type variation is spurious or, instead, indicates the absence of a typology of taste neurons. The data used were counts of the spike discharges of 50 individual taste neurons in the nucleus of the solitary tract of the rat, evoked by 32 diverse chemical stimuli. 2. Using as input the matrix of Pearson r correlation coefficients calculated for the responses of all pairings of neurons to all stimuli, multidimensional scaling analysis revealed a two-dimensional space in which no clear groupings of neurons occurred. 3. In a hierarchical cluster analysis of the neuron response profile similarities, no evidence of grouping was found, suggesting a more-or-less continuous variation among neurons. 4. When the organization of the 32 stimuli utilized was studied by the same techniques, no clear evidence for stimulus types was found, although the possibility of two stimulus types--"sweet" and "nonsweet"--was raised. 5. Construction of a joint neuron-stimulus space supported a spatial model of taste neuron-stimulus interaction, while analysis of the number and pattern of high correlations among neurons--even after allowance for attenuation due to measurement error--failed to support the notion of types of taste neurons with identical response profiles. 6. Aspects of the logical role of types of neurons in gustatory coding were discussed, and the results and methods of the present investigation were related to classification schemes for neurons in general. Suggestions for a formal taxonomy of neurons were given. 7. It should be emphasized that the present study and conclusions are of second-order, CNS neurons, whereas the studies advocating the presence of neurons types were of peripheral neurons. Taken together, the implication to be drawn from these studies is that if neural types do exist in peripheral taste nerves, the typology is lost at the first synapse and is thus unavailable to the CNS for coding purposes, at least in the rat.