Table 4.
Means (standard errors are omitted due to space limitations) of retrogradely labeled neurons plotted in various afferent structures following injections of tracer into the ventral tegmental area (VTA), rostromedial tegmental nucleus (RMTg) and lateral habenula (LHb). Structures providing afferents are listed in the left column and numbers of retrogradely labeled neurons projecting to the VTA, RMTg and LHb are also binned with the aid of color-coding in three columns of boxes on the right (see color legend on Figure). Statistically significant differences are indicated by values inserted between the columns of blocks as described in column headings above - VTA vs. RMTg, VTA vs. LHb and RMTg vs. LHb. The symbol <, oriented appropriately and accompanied by the relevant value for p, is utilized to indicate lesser and greater values of pairs of significantly different values. The symbol « indicates the same for pairs of which one of the values being 0 renders the pair not subject to statistical testing. INJ indicates structures were tracer injection sites, which precluded counting retrogradely labeled neurons. Results of statistical analyses are reported in Table 3. * - interstitial nucleus of the posterior limb of the anterior commissure; ** - lateral preoptic area-lateral hypothalamus transition; *** - juxta-paraventricular nucleus.
| Structures exhibiting retrograde labeling | Injection sites (VTA, RMTg and LHb), mean numbers of retrogradely labeled neurons/structure and statistical comparisons | |||||
|---|---|---|---|---|---|---|
|
| ||||||
| VTA | VTA vs RMTg | RMTg | VTA vs LHb | RMTg vs LHb | LHb | |
| A. Statistically more labeling after VTA as compared to both other structures | ||||||
| dorsal peduncular cortex | 372 | 0.05> | 202 | 0.01> | 71 | |
| endopiriform n/claustrum | 445 | 0.01> | 236 | 0.01> | 122 | |
| accumbens rostral pole | 97 | ≫ | 236 | ≫ | ≫ | 0 |
| accumbens core | 751 | 0.01> | 56 | ≫ | ≫ | 0 |
| accumbens shell | 2307 | 0.001> | 519 | 0.001> | 37 | |
| medial septum | 210 | 0.05> | 90 | 0.05> | 99 | |
| ventral pallidum | 1357 | 0.01> | 539 | 0.01> | 503 | |
| magnocellular preoptic area | 129 | 0.05> | 58 | 0.01> | 28 | |
| bed n stria terminalis | 533 | 0.01> | 175 | 0.01> | 235 | |
| IPAC* | 159 | 0.01> | 46 | ≫ | ≫ | 0 |
| sublenticular ext amygdala | 631 | 0.01> | 293 | 0.05> | 319 | |
| anterior amygdaloid area | 151 | 0.001> | 44 | 0.001> | 24 | |
| basomedial amygdaloid n | 132 | 0.001> | 17 | ≫ | ≫ | 0 |
| central amygdaloid n | 249 | 0.001> | 58 | ≫ | ≫ | 0 |
| dorsal raphe | 639 | 0.01> | 447 | 0.001> | 0.001> | 27 |
| B. Statistically more labeling after RMTg as compared to both other structures | ||||||
| lateral habenula | 537 | <0.001 | 1314 | INJ | ||
| superior colliculus, contralat | 247 | <0.001 | 1136 | 0.001> | 157 | |
| retrorubral field | 70 | <0.01 | 145 | 0.001> | 15 | |
| pontine reticular formation | 194 | <0.01 | 411 | 0.05> | 0.001> | 62 |
| dorsomedial tegmental area | 84 | <0.05 | 151 | ≫ | 0 | |
| raphe interpositus | 54 | <0.05 | 92 | ≫ | ≫ | 0 |
| deep cerebellar n | 11 | <0.001 | 780 | ≫ | 0 | |
| C. Statistically more labeling after LHb as compared to one or both other structures | ||||||
| retrosplenial cx | 0 | 0 | ≪ | ≪ | 209 | |
| lateral preotic area | 1374 | 955 | <0.05 | 1700 | ||
| LPO-LH** transition | 336 | 197 | <0.01 | <0.001 | 826 | |
| entopeduncular n | 0 | 0 | ≪ | ≪ | 258 | |
| lateral hypothalamus, juxta-PA*** | 372 | 303 | <0.05 | <0.05 | 580 | |
| anteroventral thalamic n | 0 | 0 | ≪ | ≪ | 29 | |
| paraventricular thalamic n | 0 | 0 | ≪ | ≪ | 39 | |
| laterodorsal thalamic n | 0 | 0 | ≪ | ≪ | 6 | |
| ventrolateral geniculate n | 0 | 0 | ≪ | ≪ | 62 | |
| Numbers of retrogradely labeled neurons: | 0 | 1-100 | 101-300 | 301-700 | 701-1500 | 1501-3100 |
| D. Statistically less labeling after LHb as compared to one or both other structures | ||||||
| insular cx | 359 | 328 | 0.05> | 0.05> | 87 | |
| lateral orbital cx | 100 | 169 | 0.01> | 27 | ||
| tenia tecta | 266 | 169 | 0.05> | 64 | ||
| navicular n | 181 | 75 | 0.05> | 17 | ||
| anterior cortical amygdala | 82 | 35 | ≫ | ≫ | 0 | |
| paraventricular n hypothalamus | 96 | 77 | 0.05> | 0.05> | 32 | |
| zona incerta | 301 | 472 | ≫ | ≫ | 0 | |
| parafascicular thalamic n | 110 | 152 | ≫ | ≫ | 0 | |
| deep mesencephalic n | 762 | 723 | 0.05> | 0.05> | 97 | |
| rostromedial tegmental n | 125 | INJ | ≫ | 0 | ||
| parabrachial n | 678 | 559 | ≫ | ≫ | 0 | |
| Barrington's n | 111 | 109 | ≫ | ≫ | 0 | |
| pedunculopontine tegmental n | 374 | 370 | 0.001> | 0.001> | 46 | |
| laterodorsal tegmental n | 323 | 439 | 0.01> | 0.001> | 70 | |
| pontine central gray | 225 | 323 | 0.01> | 0.001> | 22 | |
| E. No statistically different labeling | ||||||
| medial orbital cx | 150 | 156 | 151 | |||
| ventral orbital cx | 227 | 162 | 137 | |||
| cingulate cx | 194 | 542 | 503 | |||
| prelimbic cx | 332 | 672 | 679 | |||
| infralimbic cx | 172 | 217 | 183 | |||
| lateral septum | 829 | 678 | 720 | |||
| medial preoptic area | 700 | 415 | 356 | |||
| diagonal band, horizontal limb | 245 | 143 | 263 | |||
| medial amygdaloid n | 156 | 68 | 149 | |||
| anterior hypothalamic area | 70 | 49 | 261 | |||
| lateral hypothalamus | 1211 | 1254 | 1304 | |||
| ventromedial hypothalamus | 317 | 297 | 253 | |||
| dorsal hypothalmus | 225 | 173 | 207 | |||
| posterior hypothalamus | 567 | 560 | 368 | |||
| premammillary region | 210 | 283 | 38 | |||
| dorsal PAG**** | 711 | 773 | 578 | |||
| ventrolateral/lateral PAG | 579 | 454 | 339 | |||
| suprior colliculus, ipsilateral | 600 | 443 | 592 | |||
| ventral tegmental area | INJ | 324 | 332 | |||
| substantia nigra | 130 | 243 | 198 | |||
| median raphe | 189 | 246 | 113 | |||
| cunieform n | 136 | 122 | 141 | |||
| locus ceruleus | 6 | 10 | 20 | |||
| raphe magnus | 62 | 66 | 1 | |||